A power balance control strategy was developed to address the power imbalance issue inherent in the total harmonic distortion ( THD) minimization modulation strategy for typeⅡasymmetric cascaded H-bridge (ACHB) multilevel inverters with a DC-side source voltage ratio of 1∶2. In the proposed strate-gy

the phase voltage redundancy of the type Ⅱ ACHB multilevel inverter was utilized to perform an e-quivalent decomposition of the fundamental amplitude

ensuring that the output voltage amplitudes of the high-voltage and low-voltage units formed a periodic symmetrical waveform with a 1∶2 ratio

thereby a-chieving power balance across all H-bridge units within one output cycle. In addition

by comparing with the traditional selected harmonic elimination pulse width modulation ( SHEPWM) method

by the pro-posed method

the power balance of each unit is achieved and output phase voltage THD is smaller than that of the traditional SHEPWM method

which optimizes the power quality. Moreover

this approach a-voides the drawback of necessitating a reduction in the degrees of freedom for harmonic elimination when achieving power balance. Taking the two-unit seven-level type Ⅱ multilevel inverter as an example

the above-mentioned power balance control strategy was theoretically analyzed and verified by simulation. The experimental results verify the feasibility of the equilibrium strategy.