Yong-feng Guo^1,, Xin-lei Ma¹, Ping Shi¹

Estimates of the lifespans of components in the power converter of electronic power steering (EPS) system are necessary for driving safety and comfort, and require accurate predictions of temperatures and power losses. Temperature profiles, including steady-state and transient conditions, are difficult to measure in actual vehicle operations. This study investigates a method to accurately calculate the power losses in the converter in an EPS system based on measured automobile steering cycles, the driving profile, and the currents and voltages of the semiconductor devices. In addition, the temperature variations in the electronic components are studied. This methodology is based on the relationship between temperature cycles and thermal resistance. The power loss and temperature model, which is implemented in MATLAB/Simulink, allows for the simulation of various power device losses, temperature and thermal resistances variations. The method is then verified for an EPS power converter. The power losses and temperature variations in the electronic components can be calculated, and these calculate values can be used to predict the reliability of the EPS system.

electronic power steering (EPS) system, power converter, lifespans, temperatures, power losses