PWM technique for inverter with sinusoidal output current

A sinusoidal pulse width-modulation (PWM) technique suitable for single-chip microprocessor-based control is described. The scheme can be regarded as a digital alternative of the analog subharmonic method (SHM) in the sense that online real-time PWM control is possible and synchronization between carrier wave and signal wave is unnecessary. The maximum output voltage is 15% larger and the number of switchings is 30% less than those obtained by SHM. The PWM pulse creation principle is explained. As the calculation of the optimal PWM pattern needs only three multiplications, it can be executed online with a minimum ROM capacity using a conventional microprocessor. Experimental results are reported demonstrating the validity of the proposed scheme.<
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