I have here a 3 phase inverter and a PMSM, where I can measure the phase current of two phases and the input voltage of the DC supply. The PMSM is connected in star connection. I would like to estimate the current drawn by the DC power supply, but I don't know how to do this.
Since the PMSM is connected in star you can measure the phase current directly in one of the supply lines from the inverter to the PMSM. The input voltage of the DC supply (part of the inverter) can only be measured inside the inverter.
From the outside you can calculate the voltage as being the line voltage of the input times sqrt 2. Measuring the value of the current might be visible in the display of the inverter.