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Old 04-17-2015, 09:02 AM
eldis eldis is offline
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Lightbulb Any AC motor with any inverter - UMC Drive 2.0

Hi guys!

Some might remember my prototype of the universal AC motor controller, designed to be compatible with Toyota Prius inverters. I've been busy with making it a bit more interesting, by adding support of new inverters and making it as universal as possible. I ended up completely redesigning everything, making it more robust and safe for automotive use.

The idea is, that we all can now get powerful and cheap power electronics from our favourite car manufacturer. The market is flooded with them, and since they are generally well designed and water cooled, they don't break - therefore currently there is no market for them.

Of course you could try to reverse engineer the whole drivetrain from a pure electric car, like the Leaf - but there are only few of those, compared to the availability of hybrid cars. Unfortunately their drivetrains are integrated with the combustion engine control units, so you cannot just use the Volt inverter with the Volt motor. Well, now you can

Short summary:
- Possibility to drive any three phase motor (induction, BLDC, weird hybrid designs etc)
- Both sensor as well as sensorless capabilities
- Drive by wire dual output accelerator support
- Isolated CAN interface
- Isolated USB interface
- Very robust input protection
- Compatible with all Toyota / Lexus stuff, Chevrolet Volt inverters and several others

One of the very interesting things is a dual motor support. Yes, if you take a Chevy Volt inverter, you can use something like 2x 100kW motors. With peaks going even higher.

I've just sent the UMC Drive V2.0 in the production, this is how it will look like:



As you can see, everything is doubled. Two motor, fully differential PWM 3 phase control, measurement of 6 phase voltages, all currents, Vbus voltage, two throttle inputs, two temperature sensors, two encoder interfaces, several inputs and outputs.. one CAN

As with the prototype, you can easily run a calibration routine and teach it your own specific motor, or use configuration that someone else already made.

In terms of algorithms, I'm using InstaSPIN from Texas Instruments. This is currently the most advanced motor controller library, for both sensor as well as sensorless applications. The controller consists of two parts - the main carrier board, with all analog and digital signal conditioning, and an MCU board.

I've talked with several forum members having some interesting motors/projects, and they were willing to help me with the initial testing and verification of this controller on different motors.
They are going to get this controller, once the first batch comes from production If everything goes well, and tests are successful, I can offer it to other people.

Even though I'm not going to publish all the schematics and source code now, everyone who will buy it will get them. Eventually I can make it completely open source. I'm not sure, if this model might work (colleagues are telling me that it's a stupid idea), but I'm willing to risk it

What are your thoughts? What would you expect from such motor controller? What would you use it for? Any feedback welcomed!

Last edited by eldis; 04-17-2015 at 09:16 AM.
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Old 04-17-2015, 09:22 AM
Moltenmetal Moltenmetal is offline
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Sounds very exciting! If it does what you promise, it would unlock a huge re-use potential for OEM electric vehicle components that is currently more or less completely untapped. As to your strategy, or design etc., I can't knowledgeably comment but do wish you the best of luck!
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Old 04-17-2015, 11:06 AM
Tomdb Tomdb is online now
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Are the drives for the end stages, igbt/mosfet/whatever intergrated on the board? More specificaly, what kind of signals are used to control the high voltage side, as in what voltage. Since you mention prius, so 12v PWM?
Also current measurement input levels, 0-5 volts?

Also any idea on pricing for a board?
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Old 04-17-2015, 11:42 AM
eldis eldis is offline
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Quote:
Originally Posted by Tomdb View Post
Are the drives for the end stages, igbt/mosfet/whatever intergrated on the board? More specificaly, what kind of signals are used to control the high voltage side, as in what voltage. Since you mention prius, so 12v PWM?
Also current measurement input levels, 0-5 volts?

Also any idea on pricing for a board?
Yes, idea is to reuse as much from the original inverter as possible. Therefore the IGBT drivers are reused as well. As you correctly noted, Prius uses 12V signalling, and only one signal per half bridge, while for example Chevy uses 5V and needs full differential PWM drive.

I get around the problem by using high voltage open collector drivers. Then on the output you have two resistors - depending on which one you populate, you either have 5V or 12V output drive

Current measurement is designed the same way as the input phase voltage measurement. You have an instrumentation amplifier, where you can modify both input scaling as well as apply offset (to support LEM sensors with a fixed offset, as well as current sensors that swings around 0V and goes negative). On all analog inputs there are TVS diodes clamping an overload between differential inputs as well as to GND and power rail. So it should be almost impossible to burn any op amp. I'll post more info on how this can be connected into inverters soon.

I do have all three current measurements for both motors (therefore up to 6 current sensors). Even though you need only two per motor, some inverters have three to have redundancy and to detect a short in the winding/case, so I'm doing the same thing.

No idea about the pricing yet, will know this once first batch is manufactured and assembled.

Last edited by eldis; 04-17-2015 at 12:56 PM.
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Old 04-17-2015, 12:14 PM
Tomdb Tomdb is online now
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Good to hear you are keeping it very open to almost all kinds of "expensive" bits, love toying with those parts of the electronics.

Becareful you do not call it an inverter, this will confuse alot of buyers to thinking they just need your kit/board to run motors.
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Old 04-17-2015, 01:07 PM
eldis eldis is offline
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Quote:
Originally Posted by Tomdb View Post
Good to hear you are keeping it very open to almost all kinds of "expensive" bits, love toying with those parts of the electronics.

Becareful you do not call it an inverter, this will confuse alot of buyers to thinking they just need your kit/board to run motors.
Good thinking, Tom - I modified it in the original text. This is a motor controller that is designed to work with widely available automotive inverters. In theory, you can build your own power stage - all you need are current sensors, IGBT/MOSFETs and drivers for them. It can be for a bicycle, motorcycle or a drag racer - controller doesn't care. All you have to do pick a reasonably scaled inverter, and adjust the scaling once and you're done.
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Old 04-17-2015, 03:29 PM
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Resolver excitation and decoding?
The Prius uses resolvers instead of encoders.

Very exciting. I look forward to the outcome.
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Old 04-17-2015, 04:33 PM
eldis eldis is offline
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Default Re: Any AC motor with any inverter - UMC Drive 2.0

Quote:
Originally Posted by jddcircuit View Post
Resolver excitation and decoding?
The Prius uses resolvers instead of encoders.

Very exciting. I look forward to the outcome.
Hi jddcircuit!
This is a very good question - I've spent quite a lot of time thinking how to solve this. Almost all motors that people are using are encoder based, while all the automotive motor-gearbox combos are using resolvers. (and I always go sensorless!

At the end I decided to go for the encoder option, as this microcontroller has two dedicated HW encoder interfaces (therefore not slowing down the critical part - two FOC cores running in parallel).



There is a very nice resolver chip - AD2S1205 (among others it is used on Chevy Volt inverters). It has an encoder emulation output - so you can have a simple daughter card that fits on these headers (that's why there is +5V and +12V available) and provides resolver to encoder interface.

There is a possibility of putting it on the motor controller directly - but it would make the board more expensive for people not using resolvers. I can make the daughter card later on and offer it for the price of components (it would be very small). Or maybe I'll put those two chips (two motors, two resolvers) directly onboard in the next manufacturing run.

What is your opinion?
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Old 04-17-2015, 05:31 PM
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Wow, I'm keen. One key interest I am currently looking at is reusing Lexus hybrid drives so this is exactly what I'm looking for.
What software interface is needed and how 'idiot proof'or user friendly would it be? I'm not a programmer or electrician or anything so totally new to me.
Thanks
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Old 04-17-2015, 05:32 PM
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Also, what link to bms would it have? What scope is there to operate the oem bms from this board or at least communicate between them to function as they are required to?
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