Running a motor at a higher voltage but the same power output.

[Jacobsmess]

Hi, will a motor run at a higher voltage but same power output have a lower temperature than one at a lower voltage and higher current or is it not that simple? Thanks

[johu]

This can't be answered in general terms.
In short, the inverter makes up for the difference in voltage required by the motor to output a certain torque at a certain speed (=power) and the battery voltage. An inverter running at low duty cycle is considered slightly less efficient, so at higher voltage and low to medium revs you will see slightly more inverter losses.

At higher speeds you can avoid field weakening longer which gets rid of field weakening currents and should therefor be more efficient.

Another way to look at it: if you can change your transmission ratio to run the motor at a higher speed, you can produce the same wheel torque with less motor torque. Less motor torque - lower motor current. Lower motor current - lower losses. Neglecting eddy currents and mechanical losses through the higher speeds.