Extended constant-torque and constant-power speed range control of permanent magnet machine using a current source inverter

High-performance interior permanent magnet (IPM) machine drives using a current source inverter (CSI) are being studied for hybrid electric vehicle applications. This paper focuses on extending the constant-torque and constant-power operation ranges of an IPM machine by utilizing the voltage-boosting capability of the CSI. An equivalent circuit model of the IPM machine, including the inverter AC filter capacitors and the motor core-loss resistor, is presented and used to ensure the tracking of the torque-producing current of the PM machine to the commanded value under all operating conditions. A novel control strategy is proposed to achieve both minimum system losses and high system performance over the entire operating range, including the field-weakening region. Simulation and experimental results are presented to validate the functionality of the boost mechanism, the effectiveness of the equivalent circuit model, and the proposed control scheme.