【摘要】 从脉宽调制的基本原理——冲量定理出发,针对1/4周期对称波形,根据分区内PWM波形与参考信号波形的重心相对位置,选三种典型多电平PWM方案,以五电平逆变器为例,研究并发现了在较低开关频率下输出电压谐波含量与基波控制精度随1/4周期内每个分区中PWM波重心位置的变化规律,以此为依据,提出了基于等面积法的数字化PWM控制的最优算法,可以同时实现高基波控制精度和低波形畸变系数。该PWM方法不受拓扑结构和电平数的约束,适用于所有的多电平逆变器,并且具有计算简单、易于编程和实现等优点,特别适用于对快速性、灵活性和输出波形质量有较高要求的应用场合。以五电平逆变器为例,对多电平逆变器的新型PWM方法进行了仿真和实验研究,结果证明了该PWM方法的有效性和实用性。更多还原

【Abstract】 According to the impulse principle and the relative location of baricenter of PWM signal and reference signal in a section, take an five-level inverter for example, three typical PWM schemes are investigated to examine the variation of harmonics contents and fundamental control precision with the location of the baricenter of the PWM waveform in a section at a low switching frequency for PWM method of quarter wave symmetry. Based on the investigation, a novel optimum digital PWM scheme is proposed. The advantages of the new PWM method include easiness for calculating and programming, high flexibility, high quality in output waveform, high precision in fundamental control and so on. The new PWM method is not restricted to the topology and number of output levels of the multilevel inverters, and can be used in all kinds of multilevel inverters. Take five-level inverter as an example, the new PWM method is investigated by simulation and experiment. The results agree with each other very well and prove the validity, advantages and practicability.更多还原