In the AC servo system, the output voltage is restricted by inverter output limitations. Voltage saturation occurs as a result of these limitations. The settling time of the current and speed increases because of voltage saturation. This paper proposes a new control system for improving the transient response of the surface permanent magnet synchronous motor (SPMSM) by using the proposed flux-weakening control based on the current differential signal. Because the current differential signal is taken into consideration, the suppression of voltage saturation is achieved with a smaller d-axis current in a transient state. Finally, this paper proposes a new combination method of flux-weakening control and an inverter modulation scheme, which makes it possible to improve the voltage utilization on condition of flux-weakening region. The proposed speed control system achieves a quick and stable speed and current response. The effectiveness of the proposed control methods is confirmed by both the numerical simulation results and the experimental results.
2015 The Institute of Electrical Engineers of Japan