Power Balance Control Method Based on Carriers Freedom Degrees Control

Abstract

Although the traditional in-phase disposition (IPD) modulation method has excellent harmonic elimination performance when applied to CHB multilevel inverters, it has the problem of unbalanced power of cascaded units. In order to solve the power balance problem and take into account the harmonic elimination performance of the line voltage, based on the IPD method, the principle of carrier freedom control is deeply analyzed, and then the idea of controlling the carrier freedom to redistribute the output voltage of the cascade unit is proposed, and a new power balance modulation method is put forward. Based on the carrier of the IPD method, the method controls the carrier to perform a new cycle rotation at different carrier layers, which can realize the power balance of the cascaded unit within a shorter carrier rotation cycle, and retains the line voltage harmonic elimination performance of the IPD method. And on the premise of realizing the power balance of all levels of connected units, the time required for power balance is reduced. Finally, the correctness of the theory and the feasibility of the proposed method are verified by the simulation and experiments.