针对空间矢量脉宽调制(SVPWM)过调制算法复杂且涉及除法运算的问题,构建一种分裂式可变调制波,该调制波在调制度M∈[0,1]的线性区为正弦波,在M∈(1,4/π)的过调制区则分裂为两种以不同方式变化的正弦曲线段,相衔接构成一种调制波,其面积随M提升进一步扩大,直至方波.采用三角载波采样,在线性区改变调制波幅值即可线性地改变PWM基波值,在过调制区则减小两种正弦波曲线段间的分界角,继续提高PWM基波幅值大小,直至方波模式.经研究过调制区的PWM谐波影响与分界角初值的关系,得出最佳分界角初值.提出的PWM算法简单,线性区间的PWM电流总谐波畸变率(THD)与正弦脉宽调制(SPWM)一致;在M∈(1,1.2]过调制区其值仍延续低位.实验结果验证了该技术的有效性和优越性.%The existing SVPWM (space vector pulse width modulation) overmodulation algorithm is complex and involves division operation. Hence, a new type of splitting variable modulation waveform was developed. The modulation waveform is a sinusoidal wave in the linear range of modulation index M∈[0, 1], while in the M∈(1, 4/π) overmodulation range, the sine wave is split into two sinusoidal curves that can be changed independently. The two splitting curves are connected to form a new modulation waveform. The area of the new modulation waveform further expends with the increase of M until approaching the square waveform. In the linear range, through a triangle carrier waveform sampling, changing the modulating waveform height linearly changes PWM fundamental amplitude. In the overmodulation range, reducing the splitting angle further increases the fundamental amplitude till approaching a square waveform. The optimal splitting angle's initial value can be obtained by studying the relationship between the harmonics of PWM in overmodulation range and the initial value of splitting angle. The new PWM algorithm is simple. Compared to SPWM, its total harmonic current distortion THD is identical in the linear range; and it is still continuously lower atM∈(1, 1.2] overmodulation range. The experimental results had been confirmed the validity and superiority of the new technique.
展开▼
