Dual slope integrator type delta modulator for high performance voltage source inverters

The integrator of the modulator in a delta modulated (DM) inverter control scheme greatly affects the voltage waveform patterns, fundamental voltage and spectral components. The performance of DM with different types of filters suffers from low fundamental voltage. Previous schemes could not provide a fundamental voltage equal to the supply voltage and pulse dropping phenomena occurs as the modulating frequency is increased. To overcome these problems, a dual slope integrating (DSI) filter is proposed in this paper. The introduction of a DSI filter in the DM loop gives a fundamental voltage equal to the supply voltage at 100% modulation index. The number of pulses per fundamental period can be maintained constant in the modified DSI-DM scheme. The performance of this modulator is better than other DM schemes so far reported. Simulations and experimental results are presented to justify the claims of the paper.