Algorithmic modelling of PWM solution sets for online control of inverters

It is demonstrated that by using accurate modeling techniques it is possible to define an analytic expression describing the law governing the commutation angles of an optimal pulse width modulation (PWM) strategy. The read-only-memory (ROM)-based approach is avoided by describing the law governing the switching angles of the harmonic elimination strategy by an analytical expression which is executable in real time. This expression is derived from accurate modeling of offline-prepared switching patterns, which provides for the elimination of the 5 th, 7 th, 11 th, and 13 th harmonics with control of the fundamental voltage component. A digital implementation method is described whereby three-phase generated PWM waveforms are obtained. Emphasis is placed on the quality of harmonic elimination and the speed of online execution of the pulse-width generation routines. The system allows for a wide operating frequency range without any modification to the hardware. The flexibility of the software controller is demonstrated