Modulated Model Predictive Current Control of Four-Switch Voltage Source Inverter-fed Brushless DC Motor

In this paper, a modulated model predictive current control(MPCC) method is proposed to improve the control performance of the three phase four-switch voltage source inverter(FSVSI)-fed brushless dc motor(BLDCM). The feature of this topology is that phase-A is connected at the midpoint of the dc-link capacitors, which leads to the current in phase-A cannot be controlled directly. Based on the traditional two-phase conduction mode, the proposed method realizes the control of each phase current by modulating four switches separately. First, the operating principles are analyzed in detail. According to whether phase-a participates in conduction or commutation period, the operation modes in one cycle are divided into three types. The equivalent current predictive models are established in the light of different operating modes. Then the duty ratio of each switch is calculated directly according to the optimization function under different modes. Simulation results verify the correctness and effectiveness of the proposed method.