A special flux-weakening control scheme of pmsm - incorporating and adaptive to wide-range speed regulation

This paper presents a special flux-weakening control scheme for permanent magnet synchronous machines (PMSM) over wide speed range. In contrast to conventional two-loop (d-, q-axis) control methods, the proposed control scheme achieves both flux-weakening and speed control simultaneously using only one speed/flux-weakening controller. The controller automatically generates both the required demagnetizing and torque-producing currents based on the crossing-coupling effects between d- and q-axes. Additional futures of the proposed controller include 1) not requiring knowledge of motor parameters and dc bus voltage of power inverter, and 2) preventing saturation of the current regulators under any load conditions. Therefore, this scheme is adaptive to the variation of motor parameters and load levels. The effectiveness of the proposed control scheme is verified by both computer simulation and experimental results