Universal scheme of sliding pulse-width modulation of signals for voltage-fed AC drives

The paper presents sliding mode approach to realization of straightforward closed-form pulse-width modulation of line-to-line voltage of three-phase voltage source inverters for drive application. It is based on direct frequency representation of control (modulation) laws. There are some additional parameters in the scheme of modulation here, providing smooth continuous quasi-sliding variation of voltage waveform during the whole adjustment range. It is possible to realize different combined algorithms of modulation both scalar and vector on the base of the methodology of modulation worked out. There is presented an example of the typical control mode based on quasi-space vector modulation for the whole speed ratio, consisted from two different stages: for lower-middle output frequency zone and for higher subrange of output frequency.