一种固定采样频率随机PWM调制策略研究

针对电压源型逆变器提出了一种新颖的随机PWM调制策略,其开关频率在允许的范围内随机变化,而采样频率固定不变.该方案保持了确定性PWM调速系统闭环控制器设计不变,而又使高幅值窄带高频谐波连续分布到一个相对较宽频带范围内,有效减小高频谐波幅值,从而能使系统声学噪音及机械振动得到有效抑制.为评价不同调制策略的谐波分布水平,引入了一个谐波分布因数的评价指标,对本文提出的方案进行了仿真和试验,结果证明了本文提出的随机PWM调制策略的正确性.

Study on a Novel Random PWM Modulation Strategy with Constant Sampling Frequency

This paper proposes a novel random PWM modulation strategy for voltage source inverter （VSI）, which sampling frequency is a constant value while switching frequency is random varied between allowable ranges. The strategy enables to maintain the design of close-loop controller of deterministic PWM while continuously spread the harmonics around the side-band of switching frequency and its times in a wide spectrum ranges, this mitigates the undesirable acoustic noise and mechanical vibration. A so-called Harmonic Spread Factor is proposed as a evaluation indicator to evaluate different PWM strategies harmonic spread level, simulations and experiment are done and the results proved the correctness of the proposed strategy.