PWM整流器的定频直接功率控制

直接功率控制(DPC)和常规的电压定向控制(VOC)是PWM整流器常用的控制技术。直接功率控制动态响应比电压定向控制要快,但其稳态特性不如电压定向控制,而且开关频率高且不固定,给滤波器的设计带来困难。在这两者的基础上提出了一种新的定频直接功率控制技术。该控制结构为直流输出电压外环,功率控制内环,无功功率参考值设为0以达到单位功率因数;同时用PWM调制模块代替滞环,得到定频的直接功率控制。分析了该控制结构的特性,并进行仿真研究。结果表明,所提出的控制技术有好的动静态性能,电流畸变量小,而且弥补了直接功率控制和电压定向控制的缺点。

Direct Power Control with Constant Switching Frequency of Three-phase PWM Rectifier

direct power control(DPC) system and conventional voltage oriented control(VOC) system are often used to control rectifiers.The dynamic performance of DPC is better than that of VOC,but the steady performance is not so good.And the switching frequency of DPC is changeable,and higher than it of VOC,and the higher switching frequency brings difficulties in designing the filters.So this paper proposes a new control method based on the two control systems.The new method uses closed-loop DC voltage control as outside control and closed-loop power control as internal control.Especially the new method uses a PWM voltage modulator to instead of the switching table to realize the control of constant switching frequency.Also this paper analyzes the new control strategy,and gets analyze result by Simulink software on the base of math model.It is shown that the new strategy exhibits less deviation of the current,and the dynamic performance of it is better compared with the VOC and DPC,as well as the steady performance.As a result,the new method can set off disadvantages of DPC and VOC.