CONTROL METHOD OF NEUTRAL POINT POTENTIAL ON SINGLE-PHASE NPC INVERTER

摘要

PROBLEM TO BE SOLVED: To control neutral point potential of a DC voltage on a single-phase NPC inverter in a manner not to alter switching timing.SOLUTION: Plural carrier patterns A and B are formed, which segments a triangular wave carrier signal at every 1/2 cycle and at a timing when the triangular wave carrier signals cross each other. A carrier pattern in a direction where the neutral point potential is balanced is selected from the plural carrier patterns A and B based on an upper arm DC voltage detection value Ea, a lower arm DC voltage detection value Eb and output current detection value Iout. An ON/OFF signal for each switch is generated by performing a PWM processing to compare the selected carrier pattern and an output voltage command Vref.SELECTED DRAWING: Figure 4