What is the optimum PWM inverter architecture when the pulse number is small?

The optimum pulsewidth-modulated (PWM) inverter architecture for voltage-stiff inverters with relatively small pulse number is investigated. The figures of merit are the following: higher harmonics content and the frequency of dominant residual harmonics; switching frequency in each of the switching devices; response in instantaneous voltage control; and simplicity in the power circuit configuration. A sufficient control range and a good control characteristic are required. Basic PWM inverter and modulation methods are considered. In the large-capacity region, the compromise between several items is discussed. From various points of view, PWM patterns and multi-unit inverter topologies are compared. The combination of multi-unit inverter and PWM inverter is proposed