Propulsion System Design of Cadillac Lyriq Electric Vehicle

The propulsion system design of GM-Cadillac’s first electric vehicle Lyriq uses an optimized drive unit comprising interior permanent magnet (IPM) motors and silicon traction inverters. The main objective behind the drive unit design was to minimize energy losses and cost while maximizing hardware consolidation, range, performance, power density, and scalability. Two IPM motors with different length and number of stator turns are designed, while their rotor design and stator-conductor profile are kept the same. A high-speed rotor is designed to achieve higher power density. AC winding effect at higher speeds is mitigated by using a bar-conductor with much smaller cross section. The rotor surface has a special notch design to minimize acoustic noise, without use of rotor or stator skew. Also, the traction inverters in the Lyriq EV are engineered with a significant emphasis on being scalable and adaptable for various vehicle architectures while considering a broad range of requirements.