Efficiency-Optimized Flux-Weakening Control of PMSM Incorporating Speed Regulation

This paper presents an efficiency-optimized flux-weakening control scheme for permanent magnet synchronous machines (PMSM) incorporating speed regulation. It is robust to variations of DC bus voltage and load level with optimized efficiency, especially under light load conditions. The developed speed/flux-weakening controller (SFWC) automatically generates the required demagnetizing current and produces torque component at high speeds based on the d-q current cross-coupling effect. By introducing a voltage constant adaptive to load level, the demagnetizing current can be optimized resulting in less copper losses and higher efficiency. Moreover, the proposed control scheme is able to achieve both flux-weakening and speed regulation simultaneously using only one regulator, in contrast to conventional two-loop (d-q-axis) control methods. Both computer simulation and experimental results are provided to verify its feasibility.