Quick and stable speed control of SPMSM based on current differential signal and extension of DC-link voltage utilization in flux-weakening region

In the AC servo system, the output voltage is restricted by inverter output limitations. Voltage saturation occurs as a result of this limitation. The settling time of current and speed increases because of voltage saturation. This paper proposes a new control system for the rapid and stable speed response of surface permanent magnet synchronous motor (SPMSM) by using the proposed feedforward flux-weakening control based on current differential signal in the flux-weakening region. As a result of considering the current differential signal, the suppression of voltage saturation is realized with smaller d-axis current in a transient state. Finally, this paper proposes a new combination method of flux-weakening control and inverter modulation scheme, and it is possible to improve the voltage utilization on condition of the flux-weakening region. The proposed speed control system realizes the quick and stable speed and current response. The effectiveness of proposed control methods are confirmed by the experimental results under each load conditions.