基于三相PWM整流器的无死区空间矢量调制策略

THE NON-DEAD-TIME SPACE-VECTOR-MODULATION STRATEGY BASED ON THREE-PHASE PWM RECTIFIERS

与常规的连续空间矢量调制 (SVM )相比 ,不连续空间矢量调制可使器件的平均频率低于采样频率 ,因而可降低变换器的开关损耗。该文分析了不连续SVM二种形式———单一零矢量SVM和分区零矢量的工作原理、实现方式及开关损耗的计算方法。这种不连续SVM可使平均开关频率降低约 1/ 3。通常电压型PWM变换器上下桥臂间的换流死区不仅增加谐波含量 ,并降低了电压利用率和可靠性。该文在分析了电压型整流器换流过程的基础上提出了电压型整流器的无死区控制策略 ,改善了这类变换器的工作性能。并与分区零矢量SVM的调制方式相结合 ,提出了无死区的分区零矢量不连续SVM控制策略。实验结果证实了所提控制策略的可行性及其在改善相应PWM变换效率方面的优越性。

Comparing with normal space-vector modulation (SVM) scheme, the novel space-ve ctor modulation (NSVM) discussed in this paper can reduce the average switching frequency greatly, so that the switching loss can also be reduced. In this paper the operation principles, realization methods, as well as the calculation of th e switching loss of two types of NSVM schemes, the single zero-vector ar rangement scheme (SVZ) and distributing zero-vector arrangement scheme (DZV), a r e discussed in detail. It shows that the average switching frequency of such NSV M schemes can be reduced as much as 1/3.It is well known that the dead-time of the switching conversion in voltage type SPWM converter increases the harmonic component of output voltage, and decreases the maximum output voltage and the reliability of the converter. On the basis o f analyzing the conversion process of the voltage type SPWM rectifier a novel st rategy of non-dead-time control is proposed in this paper, which improves the op eration performance obviously. Cooperating its principle with DZV scheme the nov el non-dead-time DZV scheme is developed.Experiment results are given to verify the reliability of the proposed control s cheme. The advantage of the improved efficiency of the proposed converter is als o verified.