Time optimal and loss minimizing deadbeat-direct torque and flux control for interior permanent magnet synchronous machines

Abstract

This paper presents time optimal control of an interior permanent magnet synchronous machine (IPMSM) in voltage- and current- limited conditions using deadbeat-direct torque and flux control (DB-DTFC). A commanded air-gap torque and flux can be achieved by the end of each PWM period using DB-DTFC. However, it may take several PWM periods to achieve a desired torque that is physically infeasible in one step when operating near the voltage limit. The large torque command can be shaped as a feasible trajectory so that the deadbeat torque and flux is achieved for every sample time instant (switching period) along the trajectory. In this paper, the feasible trajectory is dynamically optimized to achieve a large torque command in the shortest time during voltage- and current-limited operation. Loss minimizing stator flux linkage is used during steady state operation to reduce computational complexity of the dynamic optimization and to operate the IPMSM at the loss minimizing condition. The voltage- and current-limited operation of IPMSM drives is evaluated in both simulation and experiment in this paper.