无刷直流电机三电平直接转矩控制系统

Three-level Direct Torque Control System for the Brushless DC Motor

由于无刷直流电机本身的特点,转矩脉动问题大大限制了无刷直流电机的性能表现。直接转矩控制方法以电机转矩为系统决策出发点,能够有效降低电机的转矩脉动。无刷直流电机直接转矩控制系统一般是两电平控制系统,定子磁链运行轨迹为正六边形。在分析了传统两电平无刷直流电机直接转矩控制方案后,提出了三电平直接转矩控制方案,将定子磁链轨迹由正六边形改为正十二边形,减少了电机运行中磁链幅值的变化,从而进一步降低电机转矩的脉动。通过仿真试验证明了系统方案的正确性和可行性。

The performance of the brushless DC (BLDC) motor is much limited because of the torque ripple attributable to its own characteristics. The direct torque control (DTC) method could reduce its torque ripple by taking motor torque as the starting point of system decision. The BLDC DTC system is usually a two-level control system, with its stator flux trajectory being regular hexagon. Following an analysis of the DTC approach for the traditional two-level BLDC motor, this paper proposed a three-level DTC scheme with the stator flux trajectory in the form of regular dodecagon instead of regular hexagon. Fluctuation of flux amplitude was thus reduced during motor operation, so that torque ripple of the motor was further reduced. Simulation tests indicated that the proposed system scheme was correct and feasible.