[frankie-eight-days]

Hi all!

A little context for the project: I'm a senior electrical engineering student on a student design team. Every year we participate in the SpaceX Hyperloop Student Design Competition where we design and race protoype hyperloop vehicles.

In our previous design we used one Permanent Magnet Synchronous Motor (PMSM) with peak power output of 410W (You can see a video of our dyno testing here). In the interest of safety (we were ripping an 800V pack) and better vehicle design (lowering and centring our center of gravity) we are planning on using two PMSM motors with two smaller controllers. Hopefully being able to output up to 300kW each.

So my question is: can two PMSM motors be used on the same shaft? Would the controller completely poof out? I'm leaning towards yes (because BLDCs can do this). Would there be some wild magic happening in the controller that wouldn't make this possible?

I also read in some places that the same controller could be used with both motors in parallel if both motors were used together on the same shaft? Then the output could be paralleled? This could also be possible because we are using a pretty beefy controller (PM250DZ from cascadia motion).

Has anybody had any experience with this? Would love to hear what you guys think!

 

[brian_]

Yes, you can certainly use two (or more) motors (of any kind) on the same shaft. Sharing one controller (with the two synchronous motors on the same shaft) might be possible if the motors are connected to the shaft matched in phase (depending on whether or not imperfect current splitting in the parallel motor connection causes problems) but there is rarely a reason to do this because it's rare to have such a large controller/inverter.

I suggest asking Cascadia about this, both because they made the controller, and because their motor division has lots of experience with two Remy/BorgWarner HVH motor cores on the same shaft (which they sell as a factory-assembled dual-core motor)... always, as far as I have seen, using two controllers.

 

[brian_]

See this thread for an example of two motors on a common shaft, driven by Cascadia's inverters... and driving the rear wheels of a race car:
2019 Pikes Peak Racecar
https://www.diyelectriccar.com/forums/#/topics/200633?page=2
There's actually a third motor and inverter... but driving a separate shaft for the front axle.

 

[frodus]

Due to the difficulty of having two motors fed from one inverter and timing, alignment, etc, Cascadia Motion (where I currently work as Sr Sales and Applications Engineer), we can only recommend using 1 inverter per stator/rotor. If you have a second stator/rotor, we'd drive it with a second inverter.

In the end, the motor would need to come here to be tuned and parameterized. If you're using 2 motors that already has had tuning done, and use 2 inverters, there should not be a problem. Using a second parallel stator could change the tuning by a significant amount, even if you could ensure they're aligned.

Our 2019 PPIHC car, the D2EV, had 3 motors. 1 HVH250-115-DOM motor and PM250DZ inverter going to the front differential. The 2nd motor was a dual stack HVH250-115-DOM on the same shaft with 2 encoders and 2 PM250DZ inverters.

 

[brian_]

Due to the difficulty of having two motors fed from one inverter and timing, alignment, etc, Cascadia Motion (where I currently work as Sr Sales and Applications Engineer), we can only recommend using 1 inverter per stator/rotor. If you have a second stator/rotor, we'd drive it with a second inverter.

In the end, the motor would need to come here to be tuned and parameterized. If you're using 2 motors that already has had tuning done, and use 2 inverters, there should not be a problem. Using a second parallel stator could change the tuning by a significant amount, even if you could ensure they're aligned.

Excellent - the answer and you didn't even need to ask!

Our 2019 PPIHC car, the D2EV, had 3 motors. 1 HVH250-115-DOM motor and PM250DZ inverter going to the front differential. The 2nd motor was a dual stack HVH250-115-DOM on the same shaft with 2 encoders and 2 PM250DZ inverters.

For anyone who didn't catch this from the other thread, "PPIHC" is the Pike's Peak hillclimb, and the D2EV is the car discussed in that thread...

See this thread for an example of two motors on a common shaft, driven by Cascadia's inverters... and driving the rear wheels of a race car:
2019 Pikes Peak Racecar
https://www.diyelectriccar.com/forums/#/topics/200633?page=2

Thanks for the motor and inverter details.