Calculate DC current for AC-motor

I know the nominal AC current of a three phase AC motor, but because I intend to use a drive system with central AC-DC converter and then DC-AC units for each motor, I was interested in how to calculate the DC current that corresponds with the nominal AC current.

At least current rating of motor * 1,42. I don't have experience with systems with central AC-DC converters, but it is logical as it is essentially PWM, and highest value will be the one I'v mentioned. There is also question of start because in that moment the current is much higher.

This is not necessarily a straightforward question. The answer depends on several factors, some of which are how fast the motor is turning, the efficiency of the drive connected to the motor and total bus utilization (which affect average bus voltage). But the most direct method of doing this is to calculate the output power of the motor at the speed of interest, add in losses due to inefficiency to determine power requirement from the bus, then divide by bus voltage. That will give you a reasonable idea of bus current requirement for that axis. This is not necessarily the same as the current required from the power supply since other axes may be generating at the time.

Keith

I'd just use full rated KW of motor(s) divided by the target DC Link voltage. Then multiply by a safety factor, say 125%.