Comparative performance evaluation of fixed and adaptive hysteresis band delta modulation techniques for UPS

The problem in a fixed hysteresis band delta modulation technique is a variation of switching frequency over the fundamental period of the modulation signal. This causes more subharmonics and higher load current ripple when compared to the fixed PWM switching frequency. A simple constant switching frequency delta modulator with adaptive hysteresis band is proposed in this paper. This research work contributes to comparative performance evaluation of proposed and conventional delta modulation techniques in order to be applied to a UPS. Also, the appropriate filter design is given.