带功率因数补偿的单相半控桥整流器(二)

Single-phase half-bridge rectifier with power factor correction

介绍了绘制正弦线电流的开关模式单相半控桥整流器,用它来获得功率因数补偿并保持直流环节电压的恒定。在该整流器中使用4个有源开关,以便在交流端电压上产生单极脉宽调制(PWM)电压波形。与中性点箝位变流器(NPC)相比,该整流器没有箝位二极管也能实现三点式PWM控制。控制电路采用两个控制回路:外部控制回路用比例积分电压控制器调整直流环节电压,采用相位闭环电路产生与电源电压同相的正弦波形来实现功率因数补偿。在内部控制回路中,用基于载波的电流控制器跟踪线电流信号。为补偿由于负载变化所引起的中点电压,控制电路采用中点电压补偿器。该整流器的交流侧可产生3个电压电平,并用计算机仿真与试验结果验证了控制算法的有效性。

A single-phase half-bridge switch mode rectifier is presented to draw a sinusoidal line current, to achieve power factor correction and to maintain the DC-link voltage constant.Four active switches are used in the proposed rectifier to generate a unipolar pulse width modulation（PWM） voltage waveform on the AC terminal voltage. There is no clamping diode in the proposed rectifier （as compared with the neutral point clamped （NPC） converter ）so as to achieve three-level PWM operation. Two control loops are used in the proposed control scheme. In the outer control loop, a proportional integral voltage controller is used to regulate the CD-link voltage. A phase lock loop circuit is adopted to generate a sinusoidal waveform in phase with main voltage to achieve power factor correction. In the inner control loop, a carder-based current controller is used to track the line current command. To compensate the neutral point voltage due to the load variation, a neutral point voltage compensator is used in the control scheme. Three voltage levels are generated on the AC terminal of the adopted recti tier. Computer simulations and experimental results are presented to verify the effectiveness of the proposed control algorithm.