Modulation strategy for single phase PWM inverters

A novel pulse width modulation (PWM) strategy that closely approximates the harmonic performance of the off-line harmonic minimised PWM technique for single phase PWM inverters is presented. The proposed on-line PWM technique digitally reproduces the characteristics of hysteresis band modulation for which the switching frequency is directly controlled by adapting the width of the hysteresis band. The software implementation is achieved using the conventional equations for regular-sampled PWM, combined with the pulse-position modulation (PPM) function characteristic of hysteresis band modulation