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 voltageboosting 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.