Integrated Motor-Inverter Power Module for Electric Compressor (E-Compressor) in 48V Mild Hybrid Vehicles

Abstract

A three-leg MOSFET inverter power module is presented, which is designed to operate the electric compressor (e-Compressor) of 48V mild hybrid vehicles. The e-Compressor module is integrated with its motor. The motor-inverter integration and the voltage elevation to 48V have advantages over conventional 12V vehicle systems, but also enforce subsequent challenges in system assembly, electrical reliability, and thermal management. We tackle these challenges first by using MOSFET dies soldered on direct bond copper (DBC) substrates. The DBC-based module also incorporates high-power shunt resistors, SMD devices, air cooling, and ribbon bonding interconnections. Finite-element-method (FEM) simulations are tailored to represent practical e-Compressor operations. The simulations are conducted to minimize parasitic inductance/resistance, concentrated current density, and device temperatures. The designed e-Compressor module is manufactured and experimentally calibrated, notably decreasing stray inductance by ∼57% and consequently reducing overshoot voltage by ∼53%. It is confirmed that the module temperature is lower than the allowable MOSFET temperature.