Design and Integration of a Traction Inverter for a 150-kW Switched Reluctance Motor (SRM) Drive Unit in a Cadillac LYRIQ

Rare-earth permanent magnets (PMs) are heavily relied upon by modern electric vehicles for propulsion. In addition to a challenging supply chain, they exhibit environmental and technical challenges throughout their life cycle. Demand remains strong for PM motors despite these drawbacks, thus requiring a strong substitute. Switched reluctance motors (SRMs) have been proposed as an alternative owing to their simpler construction. Surpassing remaining hurdles to adopt SRM drives in automotive applications requires demonstration of power levels exceeding 135 kW, and successful implementation in an electric vehicle. This article details the design and integration of a traction inverter for driving a 150-kW SRM drive unit in a 2023 Cadillac LYRIQ. A system design framework for an SRM traction inverter capable of achieving over 100 kW of output power was established through detailed system architecture, power stage sizing, and DC-link bus bar design. A high-fidelity motor-inverter simulation model suitable for electro-thermal and motor control performance was created and used for peak performance evaluation. A prototype inverter was developed, and characterized using a dynamometer where it achieved peak power of 109.4 kW at 9,000 r/min. The inverter and SRM drive unit were integrated in the Cadillac LYRIQ and successfully used for system prototype demonstration.