| 摘要 |
Disclosed is a pulse width modulation method of a three-level inverter comprising a pair of condensers connected in series to each other, having a neutral point, and a plurality of switching devices. The method comprises the steps of obtaining effective offset voltages within an established control cycle of the inverter; calculating a switching loss in the switching devices according to each effective offset voltage supplied to the inverter; calculating a current flowing at the neutral point within the control cycle when each effective offset value is supplied; normalizing the calculated switching loss and the current flowing at the neutral point; and adding a predetermined weight to at least one of the normalized switching loss and the normalized neutral point current to select the offset voltage where the sum of the normalized switching loss and the normalized neutral point current is maximized. With this method, the voltage balance of the DC terminals may be appropriately maintained, and a switching loss may be reduced, thereby decreasing an electric loss of the inverter.
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