A Passive LC Filter Based Harmonic Compensation for Multilevel Cascaded Inverters under Unbalanced DC Sources Using NVM Control Technique
T.MANOHAR REDDY, B.YELLA REDDY
Harmonic injection, multilevel cascaded inverters (MLCIs), neutral voltage modulation (NVM), phase-shifted (PS) modulation, space vector pulse width modulation (PWM) (SVPWM).
This paper proposes passive lc filter network based multilevel cascaded inverters with pulse width-modulation strategy to achieve balanced line-to- line output voltages and to maximize the modulation index in the linear modulation range where the output voltage can be linearly adjusted in the multilevel cascaded inverter (MLCI) operating under unbalanced dc-link conditions. A neutral voltage modulation strategy is proposed to achieve output voltage balancing as well as to extend the linear modulation range up to the maximum reachable point in theory. In the proposed method, too large of a dc-link imbalance precludes the balancing of the output voltages. The simulations for a seven-level phase-shifted modulated MLCI for electric vehicle traction motor drive show that the proposed method is able to balance line-to-line output voltages as well as to maximize the linear modulation range under the unbalanced dc-link conditions.