Making the Turquoise Motor Controller
the Electric HubcapTM
Solid State PMSM/Brushless Motor Controller Making Manual
by Craig Carmichael
Inventor of the Electric HubcapTM
motor & system
Last Update: October 17th 2010
I've posted this manual chiefly for historical purposes.
This controller is a bipolar BLDC Motor controller using the MC33033
Motor Controller Chip,
with PWM Modulation (no CRM - current ramp modulation) and no improved
Some even older motor controller design ideas are present in the text.
Unipolar BLDC motor controller using MC33035 is to be posted when it's
2. Making The Wiring Box
3. The Motor Controller
b) The Layout
c) Mounting and Wiring the Power MOSFETs Assembly
d) The Circuit Board:
Control Electronics & MOSFET Gate Driver Schematics
e) Soldering the circuit board
4. Terminal Blocks for Heavy Wires
5. Mounting the Wiring Box Components
This manual discloses information about newly designed, innovative
equipment that may be hazardous to make and use, in ways known or
unforeseen. The author will accept no liability for anything whatsoever
that happens to anyone as a result of their making use of this
information. I am not omniscient. I have done my best to describe
potential problems as far as I can foresee them. I picked 36 volts for
the Electric Hubcap motor instead of 120 or more to curtail the
electrocutions. It is up to the user
of this information to take whatever precautions he feels are necessary
and to accept the consequences of his own actions.
While originally created for an
electric motor for a car, this is a rather generic solid state
motor controller design for three-phase permanent magnet
synchronous motors (PMSMÕs) or brushless motors
which are to be run from DC power supplies.
The motive components of these motors consist of a stator
with electromagnet coils and a rotor with permanent magnets,
usually supermagnets. Cycling the three sets of electromagnetic coils
north, south, and off at the correct points or rotor rotation
repeatedly and continuously pushes the rotor magnets in one direction,
clockwise or counterclockwise, and spins the motor. There are no
electrical connections to the rotor, and no commutator with brushes is
used. (hence the term "brushless motor".) Instead, the stator has
mounted at specific points
three solid state hall effect magnetic switches or a triple optical
commutator, to tell the motor controller where the rotor magnets
are in their rotation and hence which coils to activate at which
polarity at each instant to provide continuous turning thrust. These
are described here and in the Electric Hubcap Motor
The controller features variable power
(and hence variable speed) by pulse width modulation ("PWM") of
the coil currents, and forward/reverse control.
There are now two versions of the logic circuits, the one
originally which is mentioned mainly for historical reference, and a
second one based around the MC33033 brushless motor
controller chip from ON Semiconductor, which chip I hadnÕt known about.
(Now apparently that chip is to be phased out. The next version is to
incorporate the Allegro A3938 brushless motor controller
chip instead. A later version could be made with a microcontroller to
provide advanced features such as "recharge the batteries while driving
on gas", but I don't want to complicate things for "DIY" with the need
to program a chip.)
My first version incorporates a low motor speed
to limit drive current at stopped and low RPMs.
The MC33033 version incorporates a cycle by cycle
that shuts off the drive for the remainder of each PWM cycle when the
current through the mosfets hits a preset limit. This is better.
controller is mounted in the wiring box
inside the car near the motor. (Or of course anywhere one of these
motors is wanted - I've just made (2010/10/17) an "Electric Hubcap"
outboard motor, converted from a 7.5 HP gasoline outboard.) All wires
related to the electric drive system start or end inside the wiring
box: the batteries, the motor, and the operator controls (&
displays if any).
It could well be said that the nature of the task is
"making a wiring
box, which contains a number of components including a solid state
The box is made of aluminum, a convenient metal to work
with that also
conducts heat exceptionally well, making the entire box an extension of
the heat sink of the motor controller.
The wiring box has the following components:
1. Circuit breaker/switch.
Manually shuts off the entire system.
The motor controller can be
divided into two main sections:
2. "Solenoid" (12 volt coil Contactor
Relay). Switches the power on via
the carÕs ignition key.
3. Motor Controller.
4. Motor Spike Filter
5. Heavy Wire Terminal Blocks and
1. The control circuits,
mounted on a small printed circuit board.
2. The power drive circuits, a
hard-wired assembly of power mosfet
transistors on a heat sink, with their associated filter capacitors,
fuses, spike filters and
connection blocks for the motor wires.
The finished box is mounted inside
the car as closely as possible
to the motor it drives, both to reduce voltage drop and to minimize
transients. The power cable to the motor must be no more than about
three feet long. The leads on the motor (10" max?) and the output
leads on the controller (6" max?) are in addition to that, so it can be
a little over four feet total from the transistors to the coils.
Note: Sometimes a controller is
mounted in or on the motor itself,
but in the Electric Hubcap case such an arrangement seems
a. itÕs out in the weather,
If the vehicle is a pickup truck and a
rear wheel(s) is driven, the box
must be weatherproof or inside a weatherproof box or area. (I may mount
a controller under the hood of the outboard motor.)
b. itÕs added unsprung weight (perhaps
a minor point)
c. in this motor, thereÕs not enough
Making The Chassis/Wiring Box
current visualization (after considerable experience) of the
most practical layout is an aluminum box about 6" wide, 10" tall, and
4.5" deep, with the motor controller occupying one removable side. More
generally, the box has to have the height and depth of the motor
controller side piece, currently 4.25" x 10". The depth depends on the
circuit board size and on how closely the two rows of heat sink are
spaced. It could all be done in less space, but the power transistors
should be well spread out from each other for good cooling, to avoid
destructive thermal run-away. The width of the box is "whatever" as
long as there's room for the components and wiring. The test unit for
the shop is 7" wide, the one in the car is 6", and the one for the
outboard motor, if it is to fit under the hood of the outboard, must be
only about 2" or so - I'll be looking for a very small circuit breaker!
is intended that the box be mounted on a vertically oriented surface,
eg, the rear face screwed to a wall of the car. The box can be oriented
vertically (preferred), sideways with the heat sink fins up, or to any
diagonal position that fits well and lets rising air flow past the heat
sink fins -- or to any position if the cooling seems adequate.
In the prototypes the motor
controller was mounted in the
front cover of a shallower box. This was a poor arrangement. With the
heat sink fins attached, it was effectively quite deep anyway, the
power wires had to be longer to attach them to the open cover, and the
wires were being moved around as the cover was being closed, without
being able to ascertain they were in good positions (eg, not pushing on
circuit board components) once in place.
If, on the other hand, the motor controller had been
mounted in any
non-removable part of the box, the whole box would have to be
dismounted from the car to service it.
For that reason, the removable side idea was chosen. Even
off-the-shelf aluminum box is found, one side will have to be replaced
with a removable aluminum panel, about #12 gauge.
front and back of the box can
be flat aluminum covers that
screw on to the "frame" side pieces. The back should be about #12
gauge; the front cover can be thinner, #14 or #16 if desired.
Alternatively the back, top and bottom may be one piece (#12), bent
around, with 1/2" lips to hold the top and bottom edge of the front
On the left (or right) side panel (10" x 4.5") the motor
mounted. This whole side with the controller can be unscrewed and
removed from the rest of the box for replacement or servicing. The
aluminum "roof flashing" heat sink fins are on the outside of this
face. (Note that the screws for the back cover, and probably for the
top or bottom or both if used, must be screwed on from the inside to be
accessable once the box is mounted.)
The breaker/switch is located on the top or the other side
controller, as convenient, or an external battery post mounted switch
may be used.
The solenoid, terminal blocks and grounding post are
attached to the
back of the box.
The filter capacitors sit in the bottom of the box,
clamped in place.
Wire and cable entry holes are made where practical and convenient.
course, Turquoise Energy Ltd.
plans to offer ready-made wiring
boxes complete with controller and all parts as soon as itÕs possible
to do so. (That just isnÕt going to happen this month, April 2009!)
A convenient construction of the
box is with the following aluminum
sheet metal pieces:
1. a flat 6" x 10" back cover piece, #12 gauge.
2. a flat 6" x 10" front cover piece, #12 or #14 gauge.
There are a number of options for
the edges. If there is no access
to sheet metal bending equipment, the edge pieces are cut to just the
4.5" depth of the box, and six feet of ŌLÕ angle of about 1/2" x 1/2"
(or 3/4" x 3/4"), by about 1/8" thickness, are purchased to attach the
sides to the front and back covers. Another 12" - 16" or so of ŌLÕ can
be bought to connect the edges of the frame together at the corners.
Otherwise, the pieces are 6" (or 6.5") across and 1/2" (or
are bent along the edges forming a shallow bracket ( Ō[Õ ), leaving the
4.5" remaining width for the box depth. (Note: see drawings for the
I got excited when I found extruded aluminum brackets
made for windows, 2.5" wide with 3/4" lips. Surely four short lengths
of that would frame the controller box, with flat covers on both sides
and no aluminum bending required! Then I decided the motor controller
should go in the side, requiring a deeper box, and I couldnÕt find
similar but deeper 4.5-6" wide strips. (There are such shapes more or
less, but they are "structural", eg with aluminum 1/4" thick.)
4.5" or 5" ('depth', per above)
x 10" side piece of about #12
gauge to mount the motor controller on. This may be extended to 11" and
1/2" lips bent into the ends to meet (and maybe screw into) the other
The three remaining 'frame' edges
may be formed from one piece,
two or three, and may be a thinner gauge than the piece the motor
controller mounts on, eg #14, if desired:
a single 'depth' x 25" piece is
formed into a shallow bracket, '[', the folds being .75" each and the
main side area 4.5" across. The
edges are then cut at 45¼ angles to make 'V's at 7.5" and 17.5". The
piece is bent 90¼ at those locations to make three sides of a
rectangular frame. For the last .5" at each end the overhangs are cut
off and the ends are bent over 90¼ to form .5" lips onto the fourth
(b) Three separate pieces, 6", 6"
& 10". Again 1/2" can be added
as required for tabs to attach the frame pieces together.
The aluminum pieces for the box: Flat (a couple of pre-bent lips);
bent; fitted; motor controller side removed.
The size of the controller was at first 8" x 10". When I
the parts, it didn't seem to need that much room, and I cut it down to
6" x 10". It's looking like it could easily be smaller yet.
The motor controller (top side) in the chassis box
Box with controller side removed.
The next three diagrams show the pieces of sheet aluminum. (CAD?
What's that?) All the pieces should be about #12 gauge (~.080") except
the cover, which may be #12 or #14. If thinner pieces are used, the
screws that hold them together and hold the equipment in place may
strip and things will come loose. (I discovered this using a thinner
piece (#14 or #16) for the long side opposite the controller.) The
front cover may take bashing by luggage in the car, so it shouldn't be
too thin either.
The cover in the photos has seven holes, but four is
plenty as per the
diagrams. The side holes are really extras, and the middle hole on the
controller side puts the screw right against the circuit board and
should be omitted. Likewise, the center screw through the back cover
has the screwdriver rubbing up on the PCB and should be omitted.
Another good idea would be to make the side flaps of the
controller piece 1.5" deep like the bottom flap, with the screws at
1.25" also like the bottom. This would get the screwdriver a bit
farther from the circuit board. Note that there are no holes near the
bottom of the side flaps - it would just be too hard to get the screws
in and out.
I finally fabricated this motor controller enclosure
July 2009, after having done circuit boards in June.
Final dimensions of this enclosure are 10" x 6" x 4.5",
aluminum "roofing flashing" heat sink fins.
The 10" height allows speading the power components for
and for good heat dissipation.
The 4.5" depth is to the inside of the two covers, ie, the
heights. The motor controller won't fit if it's less. (A narrower PCB,
eg with surface mount components, would allow a slightly shallower box.)
The 6" width provided enough interior space. (Originally I
cut it 8"
wide, but it seemed to have waste space and I cut it down. Worse than
cutting the aluminum was having to re-do 2 of the 3 layout diagram
3. The Motor
a) Controller Versions: constant speed versus constant power
b) The Layout
There are two versions of the motor controller that differ
as to their mode of control, selected for best control for a given
In the first version, using the MC33033 chip, pulse width
modulation (PWM) is used to vary the effective voltage supplied to the
motor. The motor's no-load speed varies directly with the voltage. The
effect is as if the motor was being supplied from variable voltage
Hence, setting the control to a specific point causes a specific
no-load motor speed. This speed will drop
somewhat under load. If the load is too great, a separate fixed current
limiting system cuts each PWM cycle off early if maximum current is
reached, to prevent overloading the motor and to the controller.
Essentially, the motor speed under steady load can be set by the
position of the control and it will continue running at the set speed.
In the second version, using the A3932 or A3938 chip,
current limiting is the only control. Instead of fixed PWM, the current
limiting can be varied from 0 to the maximum allowed motor current. The
motor coils are powered, and the current starts to rise until the trip
current is reached. When that happens, the motor is shut off for a
short fixed off time, then another cycle commences. As the maximum
current selected rises, the cycles lengthen, with more and more ON time
versus the fixed OFF time. The effect is more like a car gas pedal: the
higher the current selected, the harder the motor drives, regardless of
its speed. With more current, it will continue speeding up until it
hits full speed, and with less, the thrust is reduced. It's ideal for a
car drive system, however it's difficult to set the motor to any
motor controller layout: Control circuit board, with
3-phase MOS gate driver and MOSFETs separate on heat sink. Note that
orientations of the circuit board and connector
pinouts in the text (eg "left" & "right") refer to the orientation
seen here. Use stranded wires to the circuit board, short and direct.
It seems bizarre to go straight from tiny component leeds to heavy
electrical wire - but it works. Use highly flexible heavy wires (also
short and direct) -- ones that
are too stiff are difficult to work with and could break pins off of
Earlier unit with fuses on every pair of mosfets - not needed
once units are working reliably.
Not shown, a 100 K - 270 K ohm resistor is now soldered between pins 9
and 13 on the MC33033 to pull the PWM input to ground, to prevent
unexpected motor starting if the controls aren't connected.
The general layout is
motor controller base is one side panel of the aluminum wiring box,
4.5" x 10". The power mosfets are screwed to two parallel bars of 1/4"
x 3/4" x 9" aluminum, one for the high side transistors and one for the
lows. Roofing tarpaper is used to electrically insulate the transistors
from the metal.
The bars mount by three or four screws each, through the
through two similar 1/4" x 1/2" x 9" bars on the outside. "Fans" of
thin aluminum "roof flashing" pieces are clamped under the outside bars
for heat dissipation from the mosfets to the air.
The edge of the logic circuit board having the mosfet
mounts on the screws holding three of the low side mosfets in place.
(The board could also screw onto a standoff or two near the other edge.)
"Roofing flashing" heat sink fins on the outside. On this first
prototype the clamping bars are 3/4" wide and there are three clamping
screws on each bar. This is now replaced with 1/2" wide bars. Note that
of some of these same screws are visible in a previous
image where holes are punched in the tarpaper between mosfets.
c) Mounting and Wiring the Power MOSFET assembly
For a circuit of a hundred and more amps, a printed
circuit board seemed
inappropriate. (A prototype board caught fire!) Direct wiring of the
power metallic oxide semiconductor
field effect transistors (MOSFETs) is employed. It is vital to
minimize wire lengths and to dampen transients to protect the
transistors. After trying or laying out in concept many arrangements, I
finally came up with the compact, short wires, two-row layout seen
Insulation (tarpaper) covers the two bars, which are
six holes for the MOSFET transistors.
TO-247 package MOSFETs (IRFP3206) are used to avoid the
extra bits and
finicky job of having to place insulators around the bolt holes as
would be the case with a TO-220 package.
The holes were marked on the tarpaper and then punched out
with a paper
punch. This is much easier and cleaner than using mica or specialty
cloths and silicone heat conducting grease. It appears to provide
acceptably good thermal contact. (Unfortunately the metal backs of the
transistors connect to the drain rather than the source, so both low
and high side drivers need to be isolated from the grounded heatsink.)
I insulated the area between the rows as well as an extra measure.
holes are drilled with a 3/32"
drill bit and tapped for #6-32
machine screws. That's the biggest size that will fit through the
mounting holes in the transistors. You need screws about 3/8" long for
1/4" thick aluminum bars.
The spacing between the two mounting hole rows is 2.25".
transistors in the rows are 1.5" apart. I offset the lower row 0.2" to
the right of the upper row so that the drain pins of the lower
transistors line up with the source pins of the upper ones. These are
soldered together with #10AWG bare solid wire. As the transistors are
doubled up, the two sets must be tied together and with the
cross-connection, the wire forms "N"s between the rows. They are
slightly 3-dimensional: the lower angle of the "N" is bent up to clear
the source pin it passes by so closely. Heavy #8 AWG wires are soldered
to the centers of the "N"s. These go to the filters and to the coils of
The spaced out layout provides room for filter capacitors
across the DC
lines, and spreads the transistors out across the heat sink for better
used six 100uF, 100V electrolytic
capacitors and six 0.1uF ceramic
capacitors in parallel, at each transistor pair. Electrolytic
capacitors are slow acting but can absorb large spikes, while ceramics
are fast acting on sudden or high-frequency spikes but of insufficient
capacity to smooth large potholes and rocks in the path. If the
capacitors start popping, replace them with higher rated ones. (I may
need to look for special "high current" capacitors.) Three 220uF, 63
volt capacitors popped on one prototype controller operating at about
frequency, hence I went to six of higher voltage rating, as well as a
lower PWM frequency for other reasons. Later the leads of the 100V
capacitors burned off, so
I'm about to try 200V ratings. Beyond that one might employ motor
"start" or "run" capacitors,
but those are physically very large.
Note: see next: no fuses on each transistor...
The drain pins of the high side are bent straight up and
two lugs for the automotive fuses (not as per photo, which shows an
older layout with single sloped fuses) and to the filter capacitors. A
"bus bar" (3/16" copper rod somewhat flattened with a hammer or a
rolling mill) is placed across the bodies of the transistors (as seen),
and the lugs for the other side of the fuses are soldered to it. The
lugs usually come with plastic over the solder/crimp end, and these
should be pulled off for this job.
The choice of four 30 amp AGO automotive fuses per phase
based on the
fact that they are common, cost under $1 each and are small, while any
amp fuses I could find are special order, very expensive, very large,
and sit in
fuse holders that are so large they might well necessitate a larger
wiring box. (Later I found more suitable fuses at a marine supply
store. The AGO are still much more common.)
It should be noted that although two IRFP3206 mosfets in
theoretically rated for 240 amps - and considerably more peak pulse
amps - and the four 30 amp fuses per phase should blow at 120 amps,
they aren't enough to protect the mosfets in all circumstances. [Note
June 2009: with the new MC33033 motor controller, the current is
limited to safe values by the controller, theoretically even if there's
a short circuit.]
Common Fuses for whole bus...
In view of protection by the motor controller chip, I've
decided in future controllers to simply have about 160 amps of fuses (4
- 40 amp fuses in parallel) on the main bus, and to simply solder the
mosfet +36V pins, bent upwards, to a common copper bus bar or wire run
across from left to right.
An alternate +36V bus bar design, 1/8" x 3/8" copper bar, from a
"foundry" metals dealer. Has holes drilled to solder in the fuse pin
sockets, which is a better arrangement.
The source pins of the low side transistors are done
similarly with a "bus bar", except on that side, I stripped the
insulation off the heavy
stranded black wire and continued it behind the front aluminum bar
under the transistor pins as the "bus bar", almost unseen in the foto.
The 'source' pins are bent down and soldered directly to the bare wire.
Try to connect everything to the thick base part of each
lead and cut off any useless extra length.
MOSFET Mounting and Wiring.
(PCB clamps onto three screws of the low-side mosfets, with its edge on
top of the mosfets.)
Markings on PCB solder pads:
"U" Mosfets -> H A L
"V" Mosfets -> H B L
"W" Mosfets -> H C L
(H = High gates, ABC = Phase Output for 'Sense', L = Low gates)
Other connection pads:
B+ (36 v to power PCB), Gnd (chassis), VS- (Mosfets current sense to
motor controller chip).
Not shown: the doubled-up fuse clips for dual 30 amps fuses.
d-NEW) The Control Circuits/PCB
In broad outline and working backwards, the motor
controller has spike
filter components to protect the output transistors, power MOSFET
output transistors rated to source or sink up to 240 amps to or from
each of the three motor coil wires, three "half-bridge" mosfet gate
driver chips (MGDs) that supply the floating voltages and high
transient currents required to drive the mosfets, and an MC33033
brushless motor controller chip that decides what coils are to go on
and off moment by moment, based on the operator controls and the
The control electronics and MGD circuit is mounted on a
circuit board (PCB). The basic "generic logic" controller is here
replaced with the new one with the MC33033 motor controller chip.
(Strangely enough, going to the custom chip saved only one chip, going
from 5 down to 4. However, they are smaller chips reducing the pin
count from 78 to 44, and there are also fewer passive components.)
Below is the schematic. The small
printed circuit board (PCB)
layout is [will be] on line at www.TurquoiseEnergy.com. Within broad
limits, the only changes required for various three-phase
PMSM/brushless motors of different RPM, voltage and current ratings are
a few component values and the number and ratings of the power mosfets
used to drive the motor coils.
The logic power is derived from the battery supply. Since
36 volts is
above the ratings of a common 7812 voltage regulator, a 12.6 volt zenor
diode feeds the base of a TO-220 case NPN transistor to derive 12 volts
for the logic. The resistor chosen will depend on the battery voltage
to supply adequate current to feed the base of the transistor while
keeping the zenor at 12.6 volts. The transistor should be chosen to
handle the intended battery voltage, ie 36 volts nominal for the
Electric Hubcap motor, so the transistor should be rated for at least
50 volts. I confess I haven't bothered to calculate the power of the
transistor. If it gets too warm, it may need some sort of heat sink.
It's also just possible the transistor should have a small capacitor
between the collector and base to eliminate any high frequency
oscillations, and again I haven't worried about it as I write this.
The motor overcurrent circuit senses by attaching the
ground supply through a sensing resistor. The overcurrent sensor is
tripped when the voltage across the resistor hits +0.10 volts above the
logic board's ground. For 150 amps this "resistor" is about a 6 inch
straight length of #12 wire. (Don't coil the wire - then it's an
inductor! That's bad.) You can look up the resistance per foot of
various copper wire guages on the web and calculate for your desired
maximum motor current.
Here's the pinout of the pads for the wires to the power
||Battery Plus Voltage (Powers Circuit Board)
||High Side MOSFET(s) Gates, phase A
||Output of phase A (floating voltage reference
for A high
||Low Side MOSFET(s) Gates, phase A
||High Side MOSFET(s) Gates, phase B
||Output of phase B (floating voltage reference
for B high gates)
||Low Side MOSFET(s) Gates, phase B
||High Side MOSFET(s) Gates, phase C
||Output of phase C (floating voltage reference
for C high gates)
||Low Side MOSFET(s) Gates, phase C
||"VS-" Common wire to MOSFETs low sides (Coils
||Secure ground for the circuit board - wire to
Here are the pinouts of the two header strip connectors, left to right.
(Check the orientation - I got a Pico header socket that has "1" marked
at the wrong end... But if I'd soldered the headers in the other way
around it would match.)
MOTOR LOGIC CONNECTOR (8 pin)
It is intended at the other end of the motor sensors cable to have a 5
pin "trailer lights" plug to the optics or hall effect sensors. A two
pin "trailer lights" plug will connect the temperature sensor.
1. Optics Ground
2. Optics LED
3. Opto A
4. Opto B
5. Opto C
6. Motor Temperature
OPERATOR CONTROLS CONNECTOR (10 pin - OLD VERSION)
2. Logic Supply (+12V)
(An Output for external use.)
3. Motor ON/*OFF
Motor is enabled by HI
- has pull-down res.
5. Gas Pedal Pot - wiper
3 leeds to potentiometer
6. Gas Pedal Pot - top end
(pot. bottom end goes to ground)
7. Opto A (Hall switch A)
8. Opto B (Hall switch B)
two are needed to sense motor direction
9. Motor Temperature
(10mV/degree K for LM335, AD590)
10. Battery Voltage Sense
Onboard resistor divider, B+ / 10 V
(11. Motor Current Sense)
(0 - 100 mV at 0 - max. current - for some
(for some future revision)
Note that one could stick a microcontroller between the
controls and these input lines, and "trick" this controller into doing
things like regenerative braking, beginning (eg) as soon as the foot is
near the top of or off the gas pedal, with heavier braking when the
brake light comes on. (Regenerative braking is the only reason for
the connection to Opto B - you only want the motor trying to run
vehicle motion, so you have to know which direction the vehicle is
going!) Of course, one could also replace the MC33033 with a
microcontroller and have an "advanced" controller with just four chips.
But of course, any microcontroller adds the challenge of programming
and testing with very close attention to detail: software bugs could
make the car do something unexpected, or burn out the motor.
A3938 version connectors.
There are three header strip connectors on the PC board. All have
ground and Vcc as the first two pins. (I haven't decided the best
voltage for Vcc - probably I'll settle on either +9V or +12V.) One
connects to the magnet sensors in the motor, and a second one connects
the operator controls at the front of the car or other control point.
A third connector provides various statuses and readings.
Since the battery voltage is the only really important reading, and
since it can be obtained from the heater wiring to the front of the
car, this connector is optional. It also has a PWM input from an
external source, and it can also be used in conjunction with the second
connector to provide external computerized control over the motor if
this is desired.
MOTOR CONNECTOR (5 pins, matching 5 pin rubber trailer lights
2. Power (+8 v to +12 v for hall effect sensors, comes through a
resistor (eg 100 ohms) to prevent damage in the event of a short
3. Sensor A
4. Sensor B
5. Sensor C
6. Motor Temperature Sensor (to separate 2-pin rubber connector if used)
eg, AD590, LM335, thermistor. I prefer the first two, either yielding
This is the same as for the MC33033 controller except for the addition
of the 6th pin to the header to optionally connect a temperature sensor.
OPERATOR CONTROLS CONNECTOR (8 pins - to controls at front of
2. Logic Supply (+8 to +12V)
(An Output for external use.)
3. Motor *ON/OFF
Motor is enabled by LOW
on A3932/A3938 chip - has pull-down res.
5. Gas Pedal Pot - wiper
3 leeds to potentiometer
6. Gas Pedal Pot - top end "Vref"
(pot. bottom end goes to ground)
8. Brake Pedal Pot -
for regen braking)
The first 6 pins are the same as the MC33033 version, but
the motor on/off switch sense is reversed, and the Vref for the
potentiometer(s) is a lower voltage.
differences in usage are
owed to differences in the controller chips themsleves. ("It's not my
fault!" - Han Solo)
"brake switch" input, if used, can connect directly to the brake
lights of the car, and must be grounded if not used. I suggest not
using it on a car system as it provides a fixed, heavy braking, and
there's no safety if the driver mosfets overheat. Pin 8 is only a
theoretical input - it's not connected. Essentially, pins 7 and 8 are
intended for some hypothetical future version of the controller that
adds regenerative braking with connections to the brake pedal. (The
wisdom of such additions is doubtful - the world is full of extra
'reserved' connector pins that are never used... like the old DB-25 for
serial communication that needed only 3 - 7 wires. However, pin 7 is in
fact usable for some applications, and the 8 pin plug can't be confused
with the 6 pin one to the motor.)
OPERATOR/MICROCONTROLLER DISPLAYS/INFO CONNECTOR (Optional), 10
pins - may be used in conjunction
with above connector to provide computerized control of the motor.)
2. +12 volts
3. Opto A (Hall switch A)
for tachometer, microcontroller
4. Opto B (Hall switch B)
5. Opto C (Hall switch C)
(two or three are needed to sense motor direction)
6. Motor Temperature
(10mV/degree K for LM335, AD590)
7. Battery Voltage Sense
Onboard resistor divider, B+ / 10 V
8. Motor Current Sense
(0 - 100 mV at 0 - max. current - for some
9. A3932/A3938 Fault output status (low = normal, high = fault)
10. External PWM
can be used with the A3932, but must be supplied
(Some might prefer to simply monitor battery voltage with a voltmeter
connected to the heater cable, so this instrumentation isn't essential
for basic car operation.)
Schematic diagram of the motor controller, excluding the power
mosfets with their filter capacitors and fuses
My old Eagle files of the Schematic and PCB layout are below. Note that
the DIP version of the MC33033 is apparently no longer available. There
appear to be problems with the board layout - it's not the same as the
picture below, and I can't find the original. The user will have to do
some editing to recreate a usable board.
The astute may notice that the "high" outputs of the
MC33033 go to the
"low" inputs of the IRS2003 half-bridge MOS driver chips (and vise
versa). By some quirk, those are both inverted, while the MC33033 "low"
outputs and the half-bridge "high" inputs are both not inverted.
Furthermore, the MC33033 pulse width modulates the "low"
where it seems more logical to me to modulate the "high" sides.
Proof is in the pudding: the controller works.
In practice, the motor *should* run the same with highs to
lows to lows -- but only because the half-bridges are internally
protected from having both outputs turn on at once.
Circuit Board. (Version 2009/07/06)
Note that the MOSFETs/heatsink wiring assembly and the
filters and motor connections aren't shown here as they aren't on the
PC board. The heatsink mounted components are in the schematic below.
pad wires are wired to the heatsink components as indicated by the
pinout, except that "G" goes to chassis ground. (It should be wired and
not left to the bolt to make the connection.)
The wiring box components - spike filters and motor
connection terminal blocks - are shown in the hand-drawn "Heavy Wiring"
schematic in chapter 5, "Mounting the Components in the Wiring Box".
To drive single mosfets, the six gate resistors might be
ohms each. Doubled-up mosfets: 15 ohms. Tripled: 10 ohms. To reduce
spikes, use larger resistors. To get faster switching (and hence reduce
power dissipation in the mosfets during switching), use smaller ones.
Another way to reduce switching losses is to reduce the PWM frequency.
Some alternate component values for Different Motors.
(Beware!, some of these are only estimates,
educated guesses, or wild guesses!)
MOSFETs (I've really only looked at International Rectifier MOSFET
24 volts: How about IRFP4004, or IRLS3034-7P (40 v, 240 a, .001 ohms ON
(Say, these look even better than the 3206s!)
up to ~140 amps - single MOSFETs
up to ~280 amps - doubles
up to ~420 amps - triples (These are just guesses.)
36 volts: IRFP3206 (rated 60 v, 120 a, .0024 ohms ON)
up to ~70 amps motor - single MOSFETs
up to ~140 amps - doubles
up to ~210 amps - triples
36 volts with doubled IRFP3206s is what I'm actually
using. The nice
thing about these low voltages is that people aren't likely to be
electrocuted, even if it's damp. The heavy cables to the motor add up
to nine feet of wire, max, plus a few more feet of battery cable wire.
Fatter wire for these short bits in order to use a low voltage is
*very* cheap life insurance! And, the lower voltage MOSFETs have much
lower ON resistances and will generate less heat in the controller. In
a car, I wouldn't go above around 40 volts or so, which value nominally
36 volt batteries can aproach. Above this the IRFP3206s are also
reaching their safe limit, considering transient inductive spikes of 10
or 15 volts, and a higher voltage MOSFET should be chosen.
48 volts or 60 volts: IRFP4310 (100 v, 120 a, .0048 ohms ON)
about the same as above: 70, 140, 210 amps. Note the on resistance is
double so that twice as much heat per amp will be generated.
Such voltages are probably safe enough in a warm, dry location. But
even dry, over 60 volts, especially DC, is a serious hazard. If your
body forms part of a circuit, you can't let go, can't move, can't
breathe. You die silently of asphyxiation in about 7-8 minutes.
I've heard of a safety standard of 30 volts wet, 60 volts dry. (If I
become convinced it's important, I'll change the Electric Hubcap coils
to 30 or 24 volts and use even heavier wire.)
120 volts: IRFP4227 (rated 200 v, 65 a, .021 ohms ON)
(DRY INDOOR LOCATIONS ONLY for safety above ~40 volts!)
up to ~35 amps motor - single MOSFETS
up to ~70 amps - doubles
Note that the higher ON resistance of the higher voltage transistors
will result in much more heat per amp.
Fuses to suit phase currents. Where you could put one fuse of (eg) 180
amps in the DC line, you can instead put three individual phase fuses
of 120 amps. This has been my approach (so far). In fact, I've been
putting 60 amps on each MOSFET pair. I feel that's more likely to
protect the transistors and circuitry in the event of a problem. (I
dispensed with this once things seemed to be working reliably and now
simply put in four 40 A fuses in parallel on the supply bus in the 36
Common automotive fuses that insert into common spade lug
available up to 40 amps. They're called AGO or AGC. (I suspect
somebody just goofed one day typing out a hand written "AGO" and gave
"AGC", or vice-versa!)
Above that value, fuses are big, expensive, and hard to find when you
need to replace them. Thus, I prefer to parallel as many identical
AGO-25, -30 or -40 fuses as necessary to get the desired current rating.
Tip: If a MOSFET(s) blows (reads short circuit), its half-bridge driver
on the circuit board is also likely to be blown. If it's not dealt
with, it may blow the replacement transistors. (I think it may do this
by turning them both on at once. Perhaps it could be tested with a
small resistor in series with the power? I haven't properly tried this,
but I have protected the circuits with thin "electronics" aligator clip
test leads ("small resistors"). The thin wire limits the current and
they get hot and their insulation melts to indicate a lot of current is
If not for the fact that IC sockets are themselves an
of bad connections (corrosion), I'd socket the half-bridge chips, and
that may be wise anyway for developing a prototype motor design, where
one may expect to go through quite a few transistors (and drivers)
before determining workable component values for filters, etc.
Capacitors across the High Side Drain to the Low Side Source (B+ after
fuse[s] to VS-): 100uF/100V, one per pair of MOSFETs in close
proximity, and a 0.1uF ceramic in parallel to that. Theoretically this
is DC, but the spikes being filtered are enough to pop capacitors with
small physical size or too low a voltage/current rating, especially if
there aren't enough of them, eg just one per phase with doubled mosfets.
Current Limiting Sense Resistors: With each rating of motor, a
value of sense resistor needs to be chosen to cut off the drive when a
certain current limit is reached. Current limiting may be part of
normal operation and shouldn't be skipped. Shutting off the mosfet gate
drives at 0.1 volts, PWM cycle by cycle, it keeps the motor and the
controller from burning out if the motor is jammed or is running too
slowly with a "too heavy"
load. For the 36 volt Electric Hubcap motor, I read steady state "run"
current with a heavy load at about 75 amps on one phase, so presumably
112.5 amps from the battery. Setting the limit at about 135 amps [but
is 75 A the PEAK current? is 135 A reasonable?], just a copper wire is
used as the "sense resistor", eg:
0.1v / 135a = .0007407 ½
#12 AWG wire = .0016 ½/Ft (approximate - rises with temperature)
.0007407 ½ / .0016 ½/Ft * 12 In/Ft= 5.6 Inches (roughly)
Or, #10 wire at .001 ½/Ft would be 8.9 inches. (This is what I've used.)
* .1v * 135 a = 13.5 watts: the sense resistor (or wire) must handle it
without getting too hot.
* The resistance of a hot copper wire is greater than for a cold one,
eg by 20%.
* the wire should be as close to a straight line as possible
to minimize inductance. (Don't coil it!)
The sense resistor (or wire) goes between chassis ground ("B-")
and the source pins of the low side mosfets, VS-
(labelled V- on the PC board). Thus the mosfet/motor power
circuits operate across B+ to VS- ('almost ground') rather than from B+
to "B-", ground.
An idea to save the 13.5 extra watts and reduce heat in
might be to make chassis ground at the batteries. One fat line of the
desired sense resistance goes straight from the battery, B-, to the
mosfets. A separate line goes straight from the batteries to chassis
ground and the logic board ground. This can be thinner as it carries no
heavy currents. (Of course, the wiring box should be separately
grounded to the car frame with a heavy wire.) The heavy lead to the
mosfets then becomes its own sense resistor, which will already be
dropping the 0.1 volts and dissipating the 13.5 watts anyway. For the
135 amps Electric Hubcap, it's about 1.9 feet of #6 or 3.1 feet of #4
In that current limiting circuit, the MC33033 datasheet shows a 100 ohm
resistor [R9] and a 0.1 uF capacitor [C13] as a filter to prevent false
triggering on spikes. I'm wondering if that's going to prevent it from
reacting to a short circuit fast enough to protect the mosfets on a big
motor, and if, eg, 0.01uF might be better.
For the Electric Hubcap motors (36V - 135A), the
capacitors wired in delta between the motor coil lines should be around
7uF motor RUN capacitors (these are generally found at motor shops, not
electronics stores.) I decline to guess at suitable values for other
motors and other voltages.
For 36 volts, the varistors (or 'metal oxide varistors' or
soldered onto the motor capacitors in parallel with them are about
P36Z80's. The next size down, P33Z70, burns up after a short while of
operation. The next size up offers less spike protection to the
MOSFETs, becoming more highly conductive considerably above their 60
volts maximum rating. The 36V80 is still under voltage for a 36 volt
supply as recommended by the manufacturer, yet not as conductive as
desired at 60 volts. If they pop eventually, the next size up should be
chosen. Parallelling them for better spike protection is also possible.
The letters between the numbers seem to vary by brand, eg:
The Control Circuits/PCB [Old Version]
Theoretically most of this is just here for "historic"
reasons, but at least
the following paragraphs are still instructive. But note the "Power
Mosfets - Heatsink" portion of the schematic isn't repeated in the new
writeup, being unchanged.
In broad outline and working backwards, the motor
controller has spike
filter components to protect the output transistors, power MOSFET
output transistors rated to source or sink up to 240 amps to or from
each of the three motor coil wires, a mosfet gate driver chip (MGD)
that supplies the floating voltages and high transient currents
required to drive the mosfets, and electronics that decides what coils
are to go on and off moment by moment, based on the operator controls
and the optical commutator.
The system is so simple that simply feeding the
outputs directly to the inputs of the MGD chip will spin the motor.
Turning the light emitting diodes (LED)s rapidly on and off modulates
the motor power via pulse width modulation (PWM).
There are disadvantages to using the LEDs for PWM. First,
it makes it
hard to use the FT signals for a tachometer and to tell if the motor is
turning, and also daylight reaching the FTs defeats the PWM and
protection circuit as well as the timing. That means blown transistors
and fuses in the motor controller, just because, eg, the cover isn't on
the motor. It would be preferable to modulate the motor power within
the logic circuits, but unfortunately neither the IR2130 MGD chip nor
the quad XOR gate has any single disable/enable input to use for PWM.
(An IR2130 type driver with PWM and Fwd/Rev inputs would be awesome!)
The optics are thus the only place to turn the power on
and off without
adding an extra chip or a microcontroller. (I show it with the extra
"7400" chip in one schematic below.
The control electronics and the MGD circuit are mounted on
printed circuit board (PCB). Two motor controller control circuit
variants are available or planned:
1. a "basic logic"
controller made with common standard electronics
components: no microcontroller, no programming. (4 [or 5] chips, quite
a few resistors, capacitors & diodes.) Circuit boards for this will
be one of TEL's first priorities.
2. an "advanced logic"
controller where most of the electronics is
replaced by a microcontroller "brain". (2 chips, fewer extra
Some variants of the basic controller version with added
* Operates better in some
Anyone who has designed a circuit they think is better is welcome
to submit it. Please be aware that your submission will, if accepted,
be made available to the public as a blessed contribution to the common
cause. It may or may not become a feature of future Turquoise Energy
PCBs and controllers. Don't submit it if you want to retain control
over your intellectual property. Turquoise Energy Limited will assume
no obligation to pay for any designs it receives, even if it uses them.
(I've worked for three years for free to develop the Electric Hubcap
and motor controller, better batteries and wave power designs, and I've
published it all for anyone's personal use, which is why you're able to
read about this.)
* Takes fewer parts.
* Adds regenerative braking.
* Adds "charge batteries while driving on gas".
* Adds lights or alarms
for overheat, low batteries or other problems.
* Links two motors
Below are some schematics for the basic version. Of course, the
circuits shown will all be on one small printed circuit board (PCB).
The MGD portion of the circuit is the same for both versions. Indeed
within broad limits, the only changes required for various PMSM motors
of different RPM, voltage and current ratings are the values for the
underspeed protection resistors and the number and ratings of the power
mosfets used to drive the motor.
First we'll consider the power for the logic board. The
IR2130 needs 10
to 20 volts to operate. 12 to 15 volts is ideal, and I was tapping off
12 volts from the first battery of the 36 volts, but this means an
extra battery connection, extra power switch contacts and extra power
relat contacts in order to shut the logic power off with the motor
Since the logic board currents are trivial compared with
I decided it was preferrable to reduce the 36 volts to 12 volts (and 5
V if needed) with a voltage regulator(s) on the logic board and thus
need only a
single 36 volt supply. The circuit for this is in the MC33033 based
After the power, first in line from the optical commutator
on the motor
is the forward/reverse drive circuit. To reverse the motor direction,
the FT signals simply need to be inverted. So it's just 3 exclusive-or
gates of a four gate chip. I used a 4070. A 74AC86 would also work.
But, use CMOS and not TTL (eg, 74LS86, 74ALS86) as the phototransistor
outputs won't drive much - note the pull-up resistors are 39K½. (Hmm...
or would the LS chip eliminate the need for pull-up resistors?) In
large measure, the low drive of the FTs is a result of their
considerable distance from the LEDs. (I'm using an optical slot can
with thinner walls for the next unit. The LEDs & FTs can be spaced
closer together.) I've been using 4000 series logic as it will run on
12 volts, though a 5 volt supply and 5 volt logic is probably
Forward/Reverse drive logic: three XOR gates of a four gate chip and
Also seen is the schematic of the optical commutator, mounted on the
Motor Speed Sense Circuit
Next is the motor low/high speed sensing circuit, used to
PWM to protect the motor and controller from the high currents caused
by saturation of the iron in the coil cores at low RPMs or stopped.
With the LED's flickering on and off for PWM, the
outputs do likewise where there's a slot, and the only steady voltage
that can be counted on is "off" (high) where there's a solid.
Furthermore, any one or two phototransistors can be high. This means
that all three of them have to be sampled and only if any one of them
is staying "high" is the motor not rotating.
Thus, the three outputs feed a three input NOR gate via a
circuit. Each output discharges the sample capacitor when it goes low,
and the capacitor slowly recharges when the phototransistor output
stays high. Only when the motor is rotating are all of the outputs
driven "low" at times and charging of the sampling capacitors is
Then the output, which I call "Motor Speed Sense" (MSS)
goes high. When
it's low, PWM pulse width is limited to 50% duty cycle and the pulse
rate is slowed to 10Hz or less. When it's high, normal 1-99% duty cycle
at a higher frequency is obtained and the motor runs at full power.
The motor speed sense (MSS) circuit. Chip would be CMOS for sure -
74HC27, 74AC27, or 4025, shown in its "negative NAND" sense rather than
(The two diodes shown on the output are for the prototype PWM. Only
one, reversed, diode is used for the 555 based PWM circuit that
follows, and it's shown on that schematic as D3.)
(I can't help but think this circuit has more components
than it should
need, but I've been unable to devise a simpler one. Theoretically the
NOR gate should have hysteresis (schmidt trigger) inputs, but such a
NOR gate isn't available, and it's not really a concern. It would also
be possible to use three schmidt trigger inverters, eg 3/6 of a 74HC14
hex inverter chip, and AND their outputs together with another chip or
with three diodes.)
It occurrs to me (much later) that instead of the inputs
directly from the phototransistors, they could come from the outputs of
the XOR gates, which have more drive. In that case, the 22K resistors
might be dropped, eliminating three components.
This PWM isn't the one used in the prototype, so be warned
hasn't yet been tested as drawn. It's a modified version of a 555 timer
based PWM circuit shown at DPRG, and it has about 1/2 as many parts
(resistors, capacitors & diodes) as the LM339 version PWM currently
in the prototype.
R1 sets the current to the three LEDs on the motor optics,
which are in
series. When the pulse output is high, the LEDs are energized. R3
charges the capacitors C3 and C4 to turn the output off if the gas
pedal potentiometer is disconnected. (If it is too large, something may
blow before the PWM goes to "off".) C1 and C2 are just power supply
C3 is the "regular" oscillator capacitor. (It really
should have been
drawn to the left of R2 & D4.) It charges when the output is high
through VR1 and D1. When it has charged to 2/3 of the supply voltage,
the output goes low. When the output is low, C3 discharges through the
other side of VR1 and D2, and when it hits 1/3 of Vcc, the output goes
high again to repeat the cycle. Thus, C3 oscillates between 1/3 and 2/3
of Vcc. Adjusting VR1 changes the rise time and fall time, increasing
one while decreasing the other, and hence the pulse width (duty cycle)
of the pulse changes to provide more or less average voltage to the
C4, R2, D3 and D4 are the low speed protection circuit.
When the motor
(car) speed is too low, MSS is low, grounding the "-" side of C4
through D3. C4 is a larger capacitor now essentially in parallel with
C3, and the frequency of the PWM is reduced from "whatever" to about
10Hz. C4 charges through D4 with no added delay, but it discharges
through R2. Being the same size as VR1, 10K½, R2 limits the "on" pulse
width to 50%.
Thus, the motor coil cores are driven on, but by the time
they start to
magnetically saturate the iron cores, they're switched off again,
allowing the magnetic field to collapse before the next pulse. As the
core approaches saturation, it reaches its maximum thrust. Thus,
repeating short bursts of up to full thrust, about 10 per second, get
the car to start moving.
When the motor is turning fast enough, MSS goes high
C4. As the 555 inputs trigger (TRG) and threshold (THR) draw almost no
current, the presence of R2 (also D4) in series becomes largely
irrelevant (unless R3 is too small).
PWM Circuit, modified 555 design.
A minor disadvantage of this PWM circuit is that it
doesn't go to
0% or 100% pulse width. There's always some tiny fraction of "on" or
"off". But it's very short.
(Setting R3 to about 18K would prevent the potentiometer
discharging the capacitor to 1/3 of the supply voltage at the extreme
10K½ end of its range, creating a 100% 'off' area. The output could be
inverted with a left over NOR gate and fed through a resistor and a
diode to TRG & THR to create a similar 100% 'on' range. R & C
values and varying oscillation frequencies would have to be considered.)
MOS Gate Driver Circuit
The schematic below encompasses the
forward/reverse XOR gates and
optional NAND gates for gating the PWM as well as the driver chip and
mosfet wiring. One could say it's the entire controller less the PWM
generator and low speed protection circuit, and the off-board spike
protection components: three 7uF motor "run" capacitors in parallel
with three varistors, wired in delta across the three motor power wires.
MOSFET wiring on right is valid for all versions including MC33033.
The 18 ohm resistors might be a bit big. That dampens
transients but means the mosfets dissipate more heat during switching,
as they have considerable capacitance and it takes them longer to turn
fully off and on. 15 or 12 ohms might be better, but it's probably a
fine point with low switching speeds.
I speak of the IR2130 MGD because it provides a simple
the least number of parts, but of course there are many other
solutions. First of course is three IR2110 single phase MGDs. Another
is to use buffered logic gates, with optical isolators and
diode/capacitor charge pumps to enable a floating high-side driver (as
shown in the IR2130 circuit).
Perhaps a word is in order about their operation. The
"ground" of the
floating high side driver is the output itself. When the output is
driven low, a fast diode (eg, UF4007) charges the capacitor (0.47uF) up
to Vcc, +12 volts. When the output is driven high, the "ground" rides
up to the mosfet supply voltage, + 36 volts, and the capacitor is
charged +12 volts with respect to that, ie 48 volts. Since the load,
the power mosfet gates, is entirely capacitive, the power drains out of
the capacitor only by the initial switching and then by stray leakage
currents. (IR specifies fast "ultra fast" diodes and a minimum
capacitance of 0.47uF in their application notes, AN947 and AN985,
which are on line.)
The capacitor is recharged when the output is switched low
the PWM circuit continually switching outputs on and off, and with the
rotation of the motor, the capacitors are repeatedly being charged.
(Hmm, is there any situation where they're not when the motor isn't
turning? Maybe - might explain occasional weird behavior! If the motor
has glitches, maybe a resistor, eg, 5K(?) could be attached from each
coils drive to ground, to ensure they pull low when they're not being
Note that the drivers must be able to drive the 18 ohm
over 1/2 an amp) in order to turn the power mosfets on and off quickly.
Slow power mosfet on/off times and thus long "partly on" times make for
high power dissipation in the transistors during switching. The
opto-isolator could drive a P channel/N channel mosfet totem pole
Important points are that the drives should default to
"off" if the
signals are disconnected and that turning on one driver should in some
way lock the other one out. Of course, for a microcontroller based
motor controller these things can be arranged in the controlling
Motor Speed Sense
After drawing the above circuit with NAND gates to gate
the PWM, I
realized that with steady LEDs, one XOR'ed FT signal can be used to
create the MSS signal. And furthermore, if the NAND gates are changed
to AND gates (which does nothing but reverse the sense of FWD/REV
input), the one optic signal MSS circuit (active high) can be made with
the two left-over gates from the XOR and AND chips. This reduces the
controller back to four chips, and also eliminates a half dozen
two-lead components, an overall saving, plus the non-PWM'ed optics
outputs can be used to derive the RPM. (Pulses/sec * 20 = RPM) As an
added bonus, the MSS signal, with its fixed capacitor charge "timeout"
times will start OFF at zero RPM and gradually tend towards 100% ON as
the RPM rises, becoming active on every transition of the optics output
until the timeout or until the motor is turning fast enough that the
timeout is never reached. (Using just one optics line's transitions
does mean that the phases will not be "fully ON" symetrically at
protected speeds, so the timout chosen must avoid overheating the "more
often ON" mosfets and coils: phase(s) "A", or "B" & "C". Which it
is depends on whether the 20¼ OFF period lies just before or just after
the transitions, which I haven't checked out yet.)
"New" Motor Controller Chip
As soon as I put the first version
of this manual on the web and mentioned it on a discussion board,
someone sent me a link to a chip that would appear to replace most of
the above circuits with considerable parts reduction, the MC33033
from ON Semiconductor.
It has all the logic I wished the IR2130 had: fwd/reverse,
PWM... and even on-chip PWM. But it's missing the great hi-side mosfet
drivers, and the easiest way to implement them is to use three small
"half-bridge" hi-low mosfet driver chips, eg IR2003. There are a number
of these 8-pin chips with the same pinout and varying specs.
The MC33033 also has inputs for magnet position sensors:
hall effect or "slotted optics". Since one possible configuration for
optics is, conveniently, the Electric Hubcap's Optical Commutator,
I didn't invent the idea first after all, though in trying to
figure out how to drive the motor I didn't previously find any sign of
such an arrangement on the web.
Another feature is cycle by cycle (PWM cycles) current
eliminates the need for my "underspeed protection" circuit. I thought
it would be silly to try to find a "current sense resistor" that
wouldn't burn out, of the tiny value a 150 amp motor would need to use.
Now I realize the 100mV would be dropped across around 6 inches of #12
wire, so that will be the 15 watt "sense resistor"!
There's now a design using the MC33033 in this version of
and a PCB has been layed out.
Soldering the circuit board
Making the motor controller is an easy or hard electronics
depending whether a printed circuit board (PCB) of the control circuit
is available, or if the circuit has to be created on a printed wiring
(Please let me know if you'd like a board for a
motor, or the gerber files to have one made. I'm not starting
"production", but I know the whole project is much more
difficult without a PC board for the controller. c r a i g @ s a e r s
. c o m )
Mounting the components in the wiring box
The Wiring Box with all components
& heavy cables
(Also see the wiring diagram of this at the end of the chapter)
This box goes behind the right rear wheel of the station wagon.
* The battery leeds + (+36V, red), and - (zero V, black) enter at the
bottom left. The red goes to the bolt-in side of the breaker (black,
left), and the two breakers (it's a double 100 amps house breaker) are
tied together in parallel. A green grounding wire comes through a
separate hole on the left. The left header connector goes to the motor
sensors and the right one to the operator controls at the front of the
* The ground, battery "-" and motor controller ground wires all tie
onto the one grounding lug bolt on the back cover of the box, seen
towards the left. The three-phase power from the controller, via filter
capacitors, and to the motor, ties into the copper triple terminal
* The power from the breaker comes out the plug-in connectors (normally
these are the input when it's mounted in a breaker box) to two pieces
of thick sheet metal that fit securely, and goes to one contact of the
"solenoid" relay. (I later put in a longer #10 wire so the relay could
be bypassed for testing.)
* The motor cables (three phase power and commutator optics) enter at
the lower right through a hole behind the capacitors.
* Lower right, at the front: three 7uF spike filters (motor "run"
capacitors from a motor shop) across the three phases (delta), also
with metal oxide varistors ("MOV"s - V36ZA80) soldered across them for
* Inside the "top" side (left or right side when mounted as convenient)
is the motor controller. "Above" the box are the aluminum "roofing
flashing" heat sink fins clamped on the outside of the cover.
The Motor End
5-pin "trailer lights" socket & plug for the motor optics, and the
Anderson "PowerPole" 75 amp connector (red) to the motor coils. The
"A.P.P." plug & socket are identical - one is simply flipped upside
down and they fit together. So far, these are the only suitable
connectors I've found. Prior to finding them, I had resorted to making
my own 'thin line' three-phase plugs and sockets! Note the holes that
allow bolting the socket onto something. I plan to fill the one on the
car with grease since they aren't intended for exposure to weather.
Main Power Switch or Circuit Beaker
There are a number of possibilities
for this switch. There
are battery switches that clip to the terminal post of an automotive
battery. One of those could be used and would be external to the wiring
box. There are also switches made for heavy battery loads that could be
mounted on or in the box.
But a circuit breaker offers protection if things go wrong
and is highly preferable.
I have used salvaged dual and triple 100 amps house main
breakers as switches. (And
they have never blown even when things went wrong in the controller.) A
breaker rated for 240 VAC should be able to handle up to about 40 VDC.
They are, however, physically large and really require a taller chassis
box than shown.
The best breaker-switches I've found are Blue Sea
Systems panel mount breakers, rated for 48 VDC and made for marine use.
I got the 150 amps model, BSS7004. (BSS7048 has a nicer toggle handle
but costs more.) 150 amps is probably a bit larger than needed, but you
don't want it to trip when you floor the car! To mount this
requires cutting a large rectangular hole in the box. They sell a bezel
to cover inaccurate cutting. I used a file.
For vehicle use, I think at least an accessable manual
power switch is
indispensable so the car can drive on gas if there's an electric motor
or controller problem, without powering up the electric drive circuit.
A circuit breaker/switch seems to me to be much the best solution.
Mounting an ordinary "house" circuit breaker: two long bolts and a
piece of sheet metal for a clamp, plus a sized hole that fixes it in
position, are the key.
I used some #8 and even #6 jumper wires between components
chassis. I think I would now just use #10 wires unless they seem to
cause problems. They're short, so loss will be slight, and they're
considerably easier to work with. Very flexible wire is an asset,
especially to avoid stress to the wires to the motor controller, which
are attached to mechanically vulnerable components. Wire with many fine
strands is the most flexible.
Power Relay: "Solenoid" or "Contactor"
An inexpensive "solenoid" (the misleading name for 12 volt
coil contactor relays) for switching the power via the car key is
Tekonsha P/N 53536, available at RV stores. It's a little under spec on
nominal current rating (70 amps), but the motor (we trust) won't be
when it's switched on or off.
Cole-Hersee make "solenoids" with higher ratings, and I
recently found these, at a marine store. They seem rather costly.
Be sure to get one rated "continuous duty". The coil of
only made to be on for a moment (eg for a car starter motor) is likely
to burn out.
From the power disconnect breaker/switch (recommended) and
then the power "solenoid" relay (if
used), the power
line proceeds to the bus bar of the power mosfets. From here, each
phase goes through fuses to the power mosfet transistors, and their
associated filter capacitors. In the case of the
Electric HubcapTM, four common 30 amp AGO (= "AGC")
automotive fuses: 60
amps per transistor, 120 amps per phase. There is also a thin wire from
the bus bar to the circuit board to power the control logic.
Here the main battery power bus ends.
I confess to having bypassed the solenoid for testing so
far, as the
"ACC" circuit in my car doesn't seem to work, and the car won't be a
hybrid until the mechanical torque converter is working properly.
I originally used marette connectors
("wire nuts") to
tie together the heavy
wires between the motor controller, the motor drive cable, and the
spike filter components. It was a lot of work each time trying to fit
the three heavy wires into each marette.
I couldn't find suitable terminal blocks. I finally made
cube" connectors from a .5" x .75" copper bar. The holes for the wires
are first drilled right through the bar's 3/4" side. (IIRC, I used a
3/16" drill for #8 wires.) Then holes were drilled and tapped for #8-24
machine screws into the wire holes. Another #8-24 hole goes right
through the center to bolt down the cube. (Although only three wires
connect, I drilled four screw holes anyway except on the first block.)
After drilling, the piece was cut off the end of the bar, 3/4" long.
Finally, the cubes were
bolted onto a piece of dogwood, shaped and drilled as shown, via
another threaded hole at the center. (High temperature plastic would be
better - or maybe a sheet of
mylar between the copper and the wood.) The holes in the wood under the
recessed so the hold-in screws don't short to the wiring box. The
triangle pattern isn't for the benefit of the wires: it simply makes
for a firmer mounting to the box when it's screwed down.
In the first controllers, the wiring terminal blocks were in the
wiring box. They are better placed on the motor controller as shown
The base of the block, however, is angled so screwdriver handles don't
hit the other side of the box, avoiding considerable aggravation.
An alternative "brass pipe" connector block.
I also had an idea for an easier to make a unit using one
pieces of "1/8 inch" threaded brass pipe. (Actually, the inner diameter
is big enough for a #6 wire or two #8 wires.) Having thought of it, I
decided to try it and made one connector and a mounting block from a
piece of lilac wood.
I found the pipe tended to strip when the screws were
it seemed to work okay when I used a smaller than usual drill size to
ensure maximum metal in the threads. (It was hard threading the holes,
but I didn't break the threading tap.) The insides of the pipes are
bound to be corroded, whereas the copper cube holes, being freshly cut,
are clean. Cleaning inside the pipes - which I would want to do to
ensure good connections - might be more work than drilling the holes in
the copper cube.
Personally, I think the copper cubes is much the superior
system, though the pipe system is very compact and the piece of wood is
easier to make. There's lots of thread length in the cubes so the
screws won't strip with repeated insertions and removals, and being
screwed down, they can't rattle with car vibration.
I later found some commercial "bus connectors" in marine
supply stores, but they aren't as good or as compact as the cubes I
made. They generally tend to be long strips of screwdowns.
The varistors, which are pretty small, may be simply
screwed into the copper terminal blocks with the wires.
For those not familiar with metal oxide varistors ("MOV"s,
"varistors"), these interesting devices conduct exponentially more
current as the voltage rises, their resistance varying inversely with
the voltage. That helps to "short out" damaging higher voltage spikes.
The varistors I'm currently trying are "P36Z80". I tried the next
voltage rating down, "P33Z70", but a couple of them burned out during
regular motor tests. I want to use the lowest rating that lasts, to
help best protect the mosfets.
The reader should be warned that they have been known to
Like the other electronic components, they should be mounted only
inside the metal wiring box.
Seeing the sparks that result from connecting and
batteries directly to the motor coils gives one a lot of respect for
the power of the transient energies of switching the coils on and off,
of the capacity of the filters and of the electronic components to
withstand such energies repeatedly and reliably, and why power mosfets
keep going up in sparks and flame until everything is relatively
Power Wiring General Connections.
Note: DO NOT USE the 7uF "motor run" capacitors in the drawing.
It works better
without them and the spikes coming back from the motor coils seem about
the same. (And the chassis has more room without them!)
Notes on the diagram:
1. The diagram of the motor shows the 3 sets of 3 coils in parallel.
Although it shows the phases together, the parallelled coils are the
ones physically 120 degrees apart from each other.
2. Doubled varistors V36ZA80 are shown. They are currently only single
and nothing has blown up - yet. It also remains to be seen whether they
will withstand long use or whether the next voltage up will need to be
3. I've bought an inexpensive "solenoid" relay for the power via the
car key as shown, Tekonsha, P/N 53536, but I haven't
got it hooked up yet. [May 18th 2009.] It's a little under spec on
current rating (70 amps), but the motor (we trust) won't be running
when it's switched on or off.
4. Battery switches are available from marine supply stores.
I much prefer a switch that's also a circuit breaker as a disconnect in
case of any short circuit. Besides electrical panel main breakers, I've
seen smaller breaker-switches on the web that look more suitable, eg
140 amps/48 volts, but I didn't order any (yet) or write down any part
Motor Controller Parts List
Circuit Board Parts List
1 - F1 - small 1 amp solder-on fuse
1 - Connector 1 - 8 pin single header strip, 0.1" pin spacing.
1 - Connector 2 - 10 pin single header strip, 0.1" pin spacing.
1 - IC1 - MC33033 brushless motor controller
3 - IC2,3,4 - IR2003 half bridge hi & low side MOS gate grivers (or
1 - Q1 - NPN power transistor, TO-220 case, 60+ volts BCE. (I used a
3 - R15,16,17 - 10,000 ohms
ZD1 - 12.6 V zenor diode
D1,2,3 - UF4003 (or UF4003, -04, -05, -06, UF4007 or equivalent fast
Cx all 0.1 uF except for a few of them
The .1 inch spacing header connectors I used are made by Mode
Electronics and these are their part numbers. (I think the "-2" on
the end is because there are two per display package.):
1 of: 37-6208-2 8-pin header strip
1 of: 37-608-2 8-position header plug body with 8 crimp-on wire
I haven't actually got the 10 position one yet as there were none in
the store (I just cheated and used the second 8 position set), but
three positions ones were 37-6203-2, so I presume the part numbers
1 of: 37-6210-2 10-pin header strip
1 of: 37-610-2 10 position socket & pins.
(Note: Evidently the 10 pin ones are "discontinued". ...should I try
for 11 pin???)
The advantage of this type over "generic" header strips is first that
they can't be accidentally plugged in one pin over from where they
should be and second that it takes a bit of force to bend the plastic
to separate them, so they are unlikely to eventually work their way off
due to car vibration. I soldered the crimp pins for the plug as my
"general purpose" crimping tool didn't tighten them very well.
...a bunch of resistors, etc, etc, etc.
Anyway, the parts are shown on the PCB layout and in the schematic.
Version 1, April 29th 2009:
* First preliminary manual
Version 2, May 20th 2009:
* Diagrams of heavy wiring and power mosfet layout/wiring, accidentally
omitted from V1.
* Mentions MC33033 Motor Controller chip.
* Gives make and model of a "solenoid" power relay.
* Moves "Soldering PC Board" section to the right place.
Version 3, June 2009 (not uploaded):
* New motor controller with MC33033 Brushless Motor Controller chip,
with schematic, PCB layout. (Should put in a link to the PCB gerber
files to e-mail the board design to a PCB maker.)
V 3: August 1st 2009 (MC33033 Based Controller) (uploaded)
Version 4, July 2009:
* Includes updated motor controller enclosure details - and fotos, now
that I've finally made the planned "production version" enclosure! 74A
Version 5, Sept. 18 2009:
* Included controller schematic and other images "dropped" by HTML
* New MOSFETs wiring schematic CAD (Eagle PCB) drawing
* Accompanying minor text changes for new drawing.
Version 6, December 30 2009
* New (BSS4007) circuit breaker. takes little room in chassis. (With
new photo of
chassis with it.)
* Misc. minor text edits.
(Coming soon: update to Motor Making Manual, with Hall Effect magnet
sensing switches instead of optical... Also see Turquoise Energy News
#22 for this.)
April 26th 2010
* Just a little note to leave out the 7uF "motor run" capacitors -
works better without them.
May 31st 2010
* Better description of a "brushless motor", odds and ends in the
intro, title, disclaimer.
* a few things... new connector pinout plans.
* Heavy wiring terminal blocks moved from back of box onto motor
controller side panel.