BALANCE CONTROL METHOD OF THREE-LEVEL CIRCUIT NEUTRAL POINT VOLTAGE AND THREE-LEVEL CIRCUIT USING BALANCE CONTROL METHOD OF THREE-LEVEL CIRCUIT NEUTRAL POINT VOLTAGE

摘要

To provide a balance control method of neutral point voltages of a three-level circuit.SOLUTION: A balance control method of neutral point voltages of a neutral point clamp type three-level circuit comprises: acquiring neutral point voltages by sampling; and upon occurrence of an absolute value of the neural point voltage exceeding a threshold, adjusting a zero-level duty ratio of one phase to maintain balance of the neutral point voltage, and distributing a positive level duty ratio and a negative level duty ratio of the phase to cause output voltages of a bridge arm of the phase to have three levels, namely, a positive level, a negative level, and a zero-level in at least one switching period.SELECTED DRAWING: Figure 1A