Stator flux oriented control for high performance interior permanent magnet synchronous machine drives

This paper proposes direct stator flux oriented control for high performance interior mounted permanent magnet brushless AC (IPM-BLAC) drives and compares it with conventional indirect stator flux vector controlled schemes which are generally referred to as direct torque control (DTC). Torque angle is controlled indirectly in conventional DTC drives through a torque control loop or a torque-axis current control loop. This results in slow torque response and variation of torque control bandwidth with operating conditions due to highly non-linear relations between torque and torque angle or between torque-axis current and torque angle. More importantly, indirect control of the torque angle is compounded by stability conditions which are dependent on machine parameters and flux observer accuracy. The proposed control scheme yields linear and decoupled torque control characteristic, and hence improved robustness and dynamic response ensuring stable operation. Superiority of the proposed control scheme when compared to the state-of-theart schemes has been illustrated by experimental results of a 10kW IPM machine prototype drive designed for traction applications.