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This site seems to exclusively focus on the batteries. As important as the batteries are, what about the high power electronics that will pull all of this together? What are some of the challenges there? What is the progress? I reviewed the presentation by Steven Schultz that was posted. It seems that there needs to be a supplier base of automotive high power electronic components that needs to be put in place as well.

Thoughts?
 

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Traction Drive and Accessory Electronics

I was reviewing an article on some developmental military vehicles that were built on a serial hybrid platform. The traction drive was said to be built by the Allen-Bradley Company in Wisconsin.

The powerpoint presentation done by Shultz(?) (Torrance, CA engineer) had an image of the traction power module that looked alot like the Allen-Bradley development model.

I think that we need to move beyond the battery discussions to encompass more information on the other vehicle systems - like traction drives, accessories, interior climate control.

I would like to see integration of the on-board diagnostics and the capabilities of OnStar to communicate with the owner/driver/maintaining dealer/GM corporate engineers.

"This is your GM Volt calling to advise on the state of readiness..."

There are so many more things to discuss than just batteries.
 

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Engineer 101,
I'm still waiting for info on the motor as well. I just have to keep an eye on this forum. All we can talk about the battery in the past 7 month or so. I'm sooo bored with battery and price of the car. Come on GM toss a bone here. So we can complain. Times fly faster when people are complain.
 

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I wonder if the final selection for the electric motor, generator, climate controls, etc, have been selected yet?

That may be why GM is keeping mum on the subjects. I would imagine that all of that will come together after the Li-Ion powered mules have completed their tests....
 

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I wonder if the final selection for the electric motor, generator, climate controls, etc, have been selected yet?

That may be why GM is keeping mum on the subjects. I would imagine that all of that will come together after the Li-Ion powered mules have completed their tests....

There was either a blog post by Lyle or just a forum thread in the old forum where this topic was discussed. If I remember correctly, Lutz said they had to look into designing new components or finding manufacturers that developed low power drawing alternatives to the radio, speaker system and other electronic controls in order to minimize the drain on the battery. It was a brief comment that was quoted from Lutz and I couldn't find the post/thread, so I might be imagining it.
 

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There were discussions several weeks ago regarding the abbreviation for the motor technology mentioned in the Schultz briefing that occured in Austin, TX.

We all fumbled with the term "PMI", or was it "IPM"? This is a Permanant Magnet Induction motor.

This type of motor works well in traction applications when regeneration is used to decelerate the vehicle and to push power back into the battery. As long as the generated voltage is high enough, or phase-shifted to drive a current back through the drive electronics and that the battery is receptive.

Could GM also be considering the use of a reluctance type motor? They are very durable indeed. The stator field rotates in the same way as a poly-phase induction motor, but there is a intentional mismatch in the pole count of the stator and the salient pole rotor. The "trick" is in the power electronics and and the magnetic flux path through the rotor.

Does anyone have more information on this? Maybe the details are secret now due to patent license negotiations?
 

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BigRedFed:

I remember that as well. It was the big scream fest over the winshield wipers!!!

What I really meant was about the main drive electric motor. I can't remember anything about any specific manufacturer or model ever being mentioned. Same thing for the generator.
 

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Engineer_101 wrote: “Could GM also be considering the use of a reluctance type motor?”

Since nobody has responded to your question, let me try…
Yes, indeed. The switched reluctance type motor is cheaper to make than the PM type since it does not use exotic magnets in its rotor. You need high-power, high-speed switching semis and precision position sensors to make this type of motor. It is mechanically robust and thermally stable. Its power to weight ratio is better than the brushless DC type and same as or close to that of the PM type. Compared to the PM synchronous type its efficiency is said to be not as good, though. Maybe it is possible to improve its efficiency by attaching cheaper ceramic magnets on the rotor.* Other point is that its low-rpm torque delivery is not as smooth as other types.

*Magnets on the rotor make the motor more like the PM synchronous type, such as the one used for Prius. I think Prius motor has iron “reluctance“ poles between rotor magnets to utilize the added torque generated by them. One problem of this type of motor is the rotation of rotor (magnets) generates electricity in the field coil counter to the direction of the field exciter current, thereby limiting the max rpm and torque. To increase rpm either you decrease exciter current, increase field supply voltage or advancing the phase of the exciter current ahead of the self-generated current, any of which reduces efficiency. Because of the low torque and low efficiency nature of the PM synchronous motor at high rpm, I think Prius depends on the motor assist mostly in low rpm range or when accelerating from a slow speed. At higher speed it is not getting much assistance, I think. This means the Volt needs a motor or transmission mechanism that maintains power at wider vehicle speed range.
 

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current power electronic techology

The Volt's power electronics will basically convert battery and generator DC power to variable frequency/voltage AC power to drive the motor. This is a minor variation of standard industrial variable frequency drives (VFD's). They have become the standard speed controller technology for industrial motors, water pumps, HVAC fans, air conditioning compressors, etc. They are now sold by the millions in sizes from 1 HP to 1000's of HP. Quality and reliabilty is way up and they are now dirt-cheap.

Similar fixed-frequency power-electronic devices called inverters convert DC to 50 or 60 Hz AC and are used to connect the DC output from photovoltaic systems to the AC grid.

The batteries are the key unknown in the mixture - that's why they get the bulk of the engineering focus.
 

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HVACMAN,

Well done! Bravo. Your presentation on the types of motors available is welcome and informative. We have sucessfully taken this forum beyond the boggy mire of batteries.

However, I think the added information on excitation and running the reluctance motor above base speed by decreasing the field excitation is a bit off the mark. The reluctance motor does not have any ohmic connection to the rotor. The currents that are present in the rotor are induced across the air gap. Think of a reluctance motor as a variant of a stepping motor with a rotating magnetic field in the stator.

In general, the PWM (pulse-width modulation) drives run the motor in two modes. (1) Constant torque, and (2) Constant horsepower. There are also variable voltage requirements so that the motor flux paths conform to a constant volts/hertz relationship - magnetic saturation is not desireable. The reason that the torque falls off above a certain rotational speed is because the motor is being driven in a constant horsepower mode. Remember that HP=Torque * rotational speed. [units supressed for brevity]
 

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Re: Reluctance Motor
One thing I forgot about this type of motor...
Since its rotor is not magnetized, it cannot generate electricity when coasting. You will need other arrangements to recoup braking energy.
I think Toyota knows a thing or two about the automotive motor since Prius is using PM synchronous motor with added help from "reluctance" poles.
 
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