Using 600kW reference inverter to drive a single motor in parallel mode

RobertH

My group is currently using the 300kW reference inverter (CRD300DA12E-XM3) to power a unit under test, and after some development we are now up against the performance limits of that inverter. We have a 600kW dual-channel reference inverter on hand (CRD600DA12E-XM3). Question is, the documentation only speaks to using the two sides of the 600kW unit to drive two separate motors. Is there any experience or theory towards using both sides of the 600kW unit in parallel to drive a single motor past the limits of a single side?

Thank you!

TBhatia

Hello, thank you for your message. A member of our technical team is looking into your questions and we will respond shortly. 

AustinC

Hi RobertH,

You can absolutely use both sides of the inverter in parallel to operate up to 600 kW.

Here are a few tips to make parallel operation simple and reliable:

1. Match the inductance between the output terminals. Fabricate bussing similar to the examples below to create a common connection point for the paralleled phases that is equidistant from each output terminal of the inverter. For the best connection, we recommend ordering the busbar design (STEP file attached) from a fabrication company such as Protolabs or Xometry to achieve this paralleled connection.

Parallel Busbar.zip

2. Use MMCX cable jumpers to short the PWM channels together rather than using the ePWM_SYNC function in the DSP. Due to the delay between the ePWM and Sync output, there is ~20 ns of difference between the channel outputs, which would lead to current sharing issues during turn-on and turn-off transitions of paralleled modules. Using the jumper cables results in < 1 ns of difference between channels and is the recommended approach.

Recommended Part Number: CCMX2-MM-RG178-6 (https://www.digikey.com/short/pdwr7783)

Best Regards,

Austin C.