正弦波逆变器SPWM调制教学研究

正弦波逆变器SPWM调制是电力电子技术教学中的重点和难点内容。通常,这部分的教学内容对于同学们如何厘清各种调制方式的优缺点以及如何得出结论,进而如何将SPWM调制信号(弱电)转化为正弦波逆变器输出电压(强电)并进行分析存在一定困难。鉴于此,本文在原有教学内容基础上进行了扩展分析,首先从SPWM调制的实际工程来源介绍了三种调制方式,对载波比为奇数以及3的倍数时波形具有良好的对称性进行了数学推导,并以此分析了三种调制方式的优缺点。接着,给出了基于桥式结构的正弦波逆变器基本变换单元,分析了其将SPWM调制信号转化为输出电压的桥梁作用,并延伸出了单相和三相桥式逆变器,给出了逆变器电压利用率计算方法,最后对其采用的倍频单极性难点问题进行了扩展分析。

Teaching Research of Sine Wave Inverter SPWM Modulation

Sine wave inverter SPWM modulation is the very important and difficult part in the teaching of power electronics technology. Usually, it is difficult for the students to clarify the advantages and disadvantages of various modulation methods and how to draw conclusions and then convert the SPWM modulation control into a sine wave inverter output signal and analyze it. In view of this, this paper conducts an extended analysis according to the original teaching part. Firstly, three modulation methods are introduced from the actual engineering applications, and waveform symmetry is mathematically derived when the carrier ratio is odd and multiples of 3, and the advantages and disadvantages of the three modulation methods are analyzed. Then, the basic conversion unit of the sine wave inverter based on the bridge structure is given, bridge function of converting the SPWM modulation signal into the output voltage is analyzed, and the single-phase and three-phase bridge inverters are extended according to this, the inverter voltage utilization calculation method is given. Finally, the difficult problems of double frequency unipolarity modulation is analyzed.