Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

[freebeard]

Just wondering why one would WANT a flywheel on an EV??

On one level, that was my point. One reason would be to retain the clutch. Why would anyone do that?

In that case, remove the ring gear's weight and embed the magnet in the flywheel proper.

Astro -- good point about the square-cut gears. There are aftermarket hi-torque starters for engines with super-high compression, but there goes reusing the existing parts.

Most of this goes right over my head, I'll go back to lurking now.

[e*clipse]

Originally Posted by MPaulHolmes

There is a shaft on back and front. The dang thing sticks out like 1 foot in both directions. haha. 0.875" near the motor, and it gets smaller. I forgot how much smaller. I'll measure it today. Also, way the heck away from the motor (like 8") the shaft has a right angle cut on it, with the other 3/4" of the circumference of a cross section still circular.

Well, it will seem pretty hokey, but probably work. - - The sensor I have is a quadrature sensor with an index pulse. The shaft diameter is 1/4" with a flat machined onto it.

I can make a shaft adapter; would you be able to make some 8" long bracket for the thing? I guess another way to approach it would be a timing belt...

E*clipse

[Astro]

Originally Posted by freebeard

On one level, that was my point. One reason would be to retain the clutch. Why would anyone do that?

In that case, remove the ring gear's weight and embed the magnet in the flywheel proper.

Astro -- good point about the square-cut gears. There are aftermarket hi-torque starters for engines with super-high compression, but there goes reusing the existing parts.

Most of this goes right over my head, I'll go back to lurking now.

Lurking around EV forums i get the impression there is a real mix of clutch and clutchless builds.
There is a long list of pros and cons for each.
If it were just about efficiency then clutchless, gearboxless would be the way to go.
But then you have to add in the builders abilities, skills, knowledge, access to tools etc, etc.
If i was using a DC motor then i would retain the clutch just for safety in case of a controller fail on situation.
For my AC motor conversion i have still retained the clutch, mainly because i will not be the only driver and so i am trying to keep the set up drivable by any driver with little to no instructions required. It is also my first conversion and i have this feeling that the less i change the less there is to muck up.
My father in-law is a machinist so if we decide at a later date to swap out the clutch and flywheel for a direct coupler then this should be possible.
If we went for a direct coupler initially and then later changed our minds then we would probably have to re-do the motor to gearbox spacing.
Also i know the slow gear changes would irk me. Even though gear changes should be much rarer in the EV than the ICE powered version.

I did a search and found an old thread clutch-vs-clutchless. but it was a very short thread mainly about getting the controller to match the motor speed to the gear for easier gear changes. Maybe the thread should be resurrected?

[freebeard]

You have been in the Hotrodding the Toyota MGR thread, haven't you? For me, that just sidesteps a whole lot of couplers, adapter plates and burnt clutch disks, with weight savings.

[Astro]

Originally Posted by freebeard

You have been in the Hotrodding the Toyota MGR thread, haven't you? For me, that just sidesteps a whole lot of couplers, adapter plates and burnt clutch disks, with weight savings.

It would be a nice option if i hadn't already bought a motor. Also i think tracking one down may be a challenge round here.
Maybe for the next EV.

[thingstodo]

Originally Posted by Astro

Lurking around EV forums i get the impression there is a real mix of clutch and clutchless builds.
There is a long list of pros and cons for each.

My list for 'I need a clutch' on my DC conversion is quite short:
- my skills barely make bolting the motor coupler to the clutch achievable.
- my motor is a bit too large for my car, so I may need the clutch to act as a 'mechanical fuse' if I get the settings on the controller too aggressive
- if my controller fails at full throttle, pushing in the clutch is my last resort.

First option is turning off the ignition (4 contactors would need to fail to keep power going to the controller).

Second option is a pull cord that trips a 200A, 125V breaker - should be OK for highway driving but won't open for sure if I am accelerating.

Last resort is pressing the clutch and letting the motor grenade - but I survive.

[cts_casemod]

Originally Posted by e*clipse

Just wondering why one would WANT a flywheel on an EV??

It's just added inertia - necessary on an ICE; useless - detrimental - for an electric motor.

If you need a crank angle sensor, there are lots of much lower inertia methods - for example Paul's last setup.

Paul - is there any possibility of ( in a useful way ) connecting your new motor to a much smaller shaft? Something like an exposed back shaft?

- E*clipse

That's a personal choice, E*clipse.
Some folks want to keep the clutch so that the car behaves just like a petrol and normal people can change gears effortlessly.

Regarding the encoder, the same applies for direct drive. Machine a plate with some slots and fit the sensor there.

Myself I used a back shaft encoder, which required machining the rotor shaft and removing the mechanical FAN. I installed electrical fans instead.

[cts_casemod]

I'm off to design a PCB to my inverter

Right now I have a high and a low voltage section and this is what I've included

Low Voltage:

Throttle Input - Current signal with broken wire detection
Tachometer Output - Optoisolated with 100mA Fuse. Goes into the cluster
Brake input - Throttle over-ride, hard regeneration and stop regeneration
e-Reverse input - Reverse gear switch input
Ignition power input - Electronics power
Ignition start input - To start the thing. Can also be done via RFID
12V battery monitoring - Voltage reading, DC-DC Power good signal
Battery indicator - Indicates when the DC-DC converter is not operational
Reverse light output - This drives the reverse bulbs and a buzzer

For the high voltage Side:

Battery voltage monitoring
Pre-Charge Control circuit (dedicated and on-board)
EVSE Communication
DC-DC Buck converter output (to 320V @ 1KW) and power output
Encoder Input (isolated)
Pre-Charge or IGBT output (With relay economizer, PWM, 2A, 500V, fused)
Optoisolated Fault inputs (2x)
AC-DC onBoard Power supply - Interlock for the inverter when charging, DC-DC control, Main Charger control.
OptoIsolated IGBT output - The gate drivers are in a separate PCB

Any suggestions on some stuff I should add?

[Astro]

Originally Posted by cts_casemod

I'm off to design a PCB to my inverter
...
Any suggestions on some stuff I should add?

Motor temperature monitor, scaling back output according to temperature. Maybe a PWM cooling system output to control water cooling pump or fans. Low duty cycle when IGBTs are cool and increasing to keep IGBTs temperature below the level where power output needs to be reduced.
That way the cooling system uses the least power possible and generates the least noise possible.

Some outputs for various features that only discovered to be needed long after the PCB is manufactured.
One output i can think of would be a load indicator. Used to indicate when the motor was working hard. Could be used to inhibit things that may put added load on the motor or the batteries.
For example, if the A/C compressor was running via a belt to the drive motor then disabling the A/C clutch during heavy acceleration would be handy.
Also if an electric heater element is used then this could also be disabled during heavy acceleration. Even the DC-to-DC converter. Basically any of the high power users that may put an unneeded demand on the traction system during acceleration.

That's all i can think of off the top of my head.

[cts_casemod]

Originally Posted by Astro

Motor temperature monitor, scaling back output according to temperature. Maybe a PWM cooling system output to control water cooling pump or fans. Low duty cycle when IGBTs are cool and increasing to keep IGBTs temperature below the level where power output needs to be reduced.
That way the cooling system uses the least power possible and generates the least noise possible.

Some outputs for various features that only discovered to be needed long after the PCB is manufactured.
One output i can think of would be a load indicator. Used to indicate when the motor was working hard. Could be used to inhibit things that may put added load on the motor or the batteries.
For example, if the A/C compressor was running via a belt to the drive motor then disabling the A/C clutch during heavy acceleration would be handy.
Also if an electric heater element is used then this could also be disabled during heavy acceleration. Even the DC-to-DC converter. Basically any of the high power users that may put an unneeded demand on the traction system during acceleration.

That's all i can think of off the top of my head.

Thanks,

The water pump is a good one, with the complementary temperature sensor input

Originally Posted by Astro

One output i can think of would be a load indicator. Used to indicate when the motor was working hard. Could be used to inhibit things that may put added load on the motor or the batteries.

Load indicator can be taken directly from the throttle, since the user commands torque. I think this would be better suited to the display PCB (I have one PCB on the front to interface with the gauges) while the controller itself could disable the auxiliary power and the DC-DC.
I'm planning to turn on the heater for rheostatic braking, if needed.
There will also be an input to throttle back the controller, for example BMS input.

I don't expect to support Air con, I will rather make a second unit to drive an auxiliary motor. This would allow variable compressor operation on demand, so much more efficient that the stock setup.

Originally Posted by Astro

Some outputs for various features that only discovered to be needed long after the PCB is manufactured.

I could do that. but at this point it starts to make sense to isolate the boards, perhaps. I want to have a relatively small board. This would allow the code to be changed as per user needs. Would 8 outputs and 8 inputs (digital) be enough?