At Arrival, I contributed to the development of a 400 VDC mobile load rig for EMC testing of electric-vehicle inverters. The Arrival EMC facility RFQ compared the rig with Frankonia’s BlueBox Mobile Load Machine as a reference for the type of system.
Arrival inverter test rig, two 100 kW motor/inverter units coupled by a driveshaft
The rig used two motor/inverter units, each rated at 100 kW, coupled by a driveshaft. The Powertrain team supplied the production-vehicle motors and inverters. The rig was used as a mechanical load during inverter EMC testing in drive and regenerative conditions, with a physical motor connected to the inverter under test. The inverter under test sat on a table in a CISPR 25 setup.
I directed an external team that welded the frame, specified and sourced the driveshaft, and specified the high-voltage wiring, which a technician made. I also worked out the CAN control for the two motor/inverter units operating on a common shaft, an unusual use case.
For safety, the driveshaft was behind an acrylic door. I designed an interlock in which a magnetic switch detected whether the door’s locking pin was in place; the inverters could not be enabled without the pin. The HV power cables used two- and three-way Amphenol Powerlock connectors, whose HVIL (High Voltage InterLock) contacts formed part of the interlock loop.
The rig’s HV cables passed through chamber feedthroughs and were joined to the DUT’s HV cables outside the chamber before connection to an HV power supply. CAN communications were converted to optical and routed to a control PC outside the chamber. A chiller outside the chamber circulated conditioned water through the two motors and two inverters.
I estimated the rig’s round-trip efficiency at at least 80%, although I do not have a calculation or measurement record to confirm that figure.