Field-weakening in high-performance PMSM drives: a comparative analysis

A comparative analysis of field-weakening (FW) in vector controlled and DTC permanent magnet synchronous motor drives is performed. Following the description of the fundamentals of these drives, the results of simulations and a comprehensive set of experiments are given. The possibility of unstable operation in the high-speed region using DTC is emphasised. The present paper also highlights some important differences between DTC and vector drives in FW, such as quickness of torque response, torque/flux/current ripple content and implementation aspects. For this purpose two types of DTC drives are implemented, a classical DTC and also a DTC scheme with torque ripple reduction.