Predictive Control of Low-Cost Three-Phase Four-Switch Inverter-Fed Drives for Brushless DC Motor Applications

In this paper, an efficient control strategy for three-phase four-switch inverter-fed Brushless DC Motor (BLDCM) drives with trapezoidal back Electromotive Force (EMF) is proposed. In the proposed approach, the outer control loop for adjusting the motor speed is designed using Model Predictive Control (MPC) while the inner control loop based on a hysteresis controller regulates the BLDC phase currents. To effectively adjust the current of the uncontrolled phase in the four-switch inverter, efficient switching strategies for motor and generator modes are suggested. The proposed control scheme achieves favorably low torque ripples and improves the speed transient response in terms of tracking error and speed overshoot/undershoot. Therefore, it can be an ideal candidate for low-cost low-power BLDCM applications. Also, the MPC-based speed control loop is tuned by solving a suitable cost function in an offline manner to minimize the real-time computational effort. Using the foregoing technique, it is shown that the implementation of the proposed MPC-based controller becomes as simple as the PI controller while the MPC-based controller achieves superior control performance. The proposed BLDCM drive scheme is experimentally verified in a Hardware-in-the-Loop (HiL) test setup with a 1200W BLDCM and dSPACE1104 development board. The experimental results demonstrate the benefits of the proposed drive system.