Comparisons of Space-Vector Modulation and Carrier-Based Modulation of Multilevel Inverter

This paper studies the relations of space-vector modulation (SVM) and carrier-based pulse-width modulation (PWM) for multilevel inverter. The PWMs´ generation of SVM can be achieved by carrier-based PWM scheme, but the modulated wave of SVM is acquired by vectors´ calculations and switching-states´ selection. Based on different selection of redundant switching-states, there are many types of SVM modulated waves, some of which can function equivalently through proper selection of common-mode injections in the case of carrier-based PWM, the others have more freedoms in switching-states´ selection than carrier-based PWM. Selection of more switching-states in SVM is propitious to optimize the output voltage, balance the dc power and so on. Then an improved PWM scheme is proposed based on the modulation waves of three-level SVM, which reserves the main advantages of SVM, and can be achieved easily. Finally, a five-level test circuit is built to verify this PWM scheme.