Current Regulation with Nearly Constant Losses for an Open-end Winding Traction IPM Motor Operating at Low Speeds

The thermal cycles are affecting the lifetime of the power electronics converters in traction drive. The rapid and repetitive change of the produced torque and temperature of the semiconducting devices results in the soldering cracks and bond wire lift-off. One of the special and hard modes is zero and low speed operation when temperature of the silicon follows close to the steady value and varies from maximum to minimum each revolution. An open-end winding motor has extra degree of freedom in current regulation. This paper proposes a current regulation strategy with nearly constant losses which is applicable to the open-end winding permanent magnet synchronous motors. It utilizes zero-sequence current injection, which does not produce torque but equalizes currents in all three phases. The simulation results show that the proposed thermal control strategy stabilizes the temperature and reduces its deviation in the semiconductor devices at low speeds.