[PMSM]

With chopper driving, ideally, you want >10times the motor voltage, but is it better to do this with a higher voltage motor that has less coil current? Or is it better with a lower voltage motor with less coil resistance? For eg. I could get a 0.5A 12V motor and run it at, let's say 120V or something... or I could get a 2A 3V motor and run it at 30V. Is there a downside to having more current through the coils at higher speeds?

The reason I am asking is because my supply considerations are limited and at the moment, not yet designed.

Thank you,
Phil

[jeffs555]

You would have a hard time finding a drive that will handle 120 volts. The most inexpensive drives are only rated around 30 to 50 volts, and even the Gekos are only rated for 80 volts. Generally, the low voltage higher current drives are what you want for best speed.

[PMSM]

Yes, it was just for illustrative purposes.

I do have a followup though... I am using this system in an automotive app. and have 12V battery power. It is difficult to find somewhat inexpensive DC-DC converters that will handle a few amps that goto higher voltages that would make a chopper useful. I have found a few 48V supplies, I'm assuming they're using buck converting, but the amperage is still not enough. What is generally done in this situation? It seems like it would also be a problem using a switcher directly coupled to a highly inductive load but I feel my options are limited... But without chopper cktry, I will not get nowhere near the speed I desire out of the motor unless I triple the motor size by using a very coarse leadscrew.

Phil

[jeffs555]

In that situation, you might want to get the lowest voltage, lowest inductance motors you could find, and try using the 12 volts directly. You would have to be careful which drive you select, because many of them have a minimum voltage.