This paper proposes a new antiwindup strategy for PI speed controller to suppress the undesired side effect known as integrator windup when large set-point changes are made. When the speed control mode is changed from P control to PI control, an appropriate initial value for the integrator is assigned. This value then restricts the overshoot. In addition, the proposed method guarantees the designed performance independent of the operating conditions, i.e., different set-point changes and load torques, and can be easily implemented with existing PI controllers. In SIMULINK/MATLAB-based comparative simulations and experiments for a permanent-magnet synchronous motor speed controller, the proposed method shows a superior control performance compared with the existing well-known antiwindup methods, such as conditional integration and tracking back calculation.

An estimation algorithm for identifying the moment of inertia, which is essential for the design of a high performance controller for a motor drive system, is presented. The proposed algorithm finds the moment of inertia by observing the position error signal generated by the speed observer, which contains error information on the moment of inertia. The proposed algorithm is easy to realise in an observer-based speed detection method. Simulation and experimental results are presented to confirm the performance of the moment of inertia estimation method, and show that the moment of inertia converges to an actual value within several speed changes. As a result, the speed control responses and designed speed controller performance match well.

To reduce voltage overshoot at the motor terminal, RLC filters are used at the inverter side with an objective of increasing the rise time, while RC filters are used at the motor side as a means of reducing the load impedance at high frequency. However, no clear optimal method for determining the filter parameters has appeared. In this work, we propose filter design methods that fully utilize given conditions such as cable length, cable inductance, cable capacitance, and the reflection coefficient at the inverter side. For determining the parameters of the RLC filter, the filter transfer function is utilized to make the rise time long enough to achieve desirable overshoot level at motor terminals. In choosing the parameters of the RC filter, the reflection coefficient is regarded as a transfer function between the incident and reflected voltages, and the capacitance is chosen so that cancellation occurs between the reflected voltage and its resulting incident voltage. The validity of the proposed design method is supported by simulation results, which are also compared with the experimental results.