Drive System Design develops test rig for performing reliability testing of an ultra-high power density motor for Rimac Technology
EV technology company Rimac has engaged Drive System Design (DSD) to use its latest high-performance e-motor test rig at DSD’s facility in the UK carry out a test program to validate Rimac’s ultra-high power density 3-phase IPM motor for its OEM client base. DSD fully characterised the performance and efficiency of the motor to validate earlier simulation, including automotive standard tests for peak and continuous power output and mapping of MTPA (max torque per amp) and MTPV (max torque per volt).
Durability testing was carried out 24/7 for four weeks, using cycles accurately constructed from data collected during simulated high-speed laps of the Nürburgring track. DSD’s motor testing was thus effectively HIL (hardware in the loop) testing, with the test rig operating in a highly transient ‘path following’ mode.
The test rig can accommodate motors up to 450 Nm torque and 350 kW power output, running at up to 25,000 rpm. It can also be configured to test motors up to 1,000 Nm up to 9,000 rpm. The complete cell includes a gearbox, drive motor, battery emulator, coolant conditioning systems, HBM power analysis, HBM precision torque sensors, NI data acquisition and rig automation system.
The Inverter calibration is demanding and complex. It requires a very accurate setup for a motor that is delivering supercar levels of performance. It would normally take several months of fine-tuning to ensure the inverter accurately controls a motor over very dynamic drive cycles and during incredibly precise efficiency mapping. Still, DSD only had a couple of weeks.
DSD writes its inverter and rig control system software to tailor advanced features to the customers’ needs. For this application, software was implemented that allowed rapid, fully automated mapping of the inverter calibration and implementing a torque control structure capable of safely ‘driving’ the Nurburgring for hundreds of laps.