Patent ID: 9362840
Filing Date: 2016-06-07
CPC Classification: G01R,H02M

Claim Text:
1. A power conversion device comprising: a 3-level power conversion circuit having a plurality of semiconductor switching elements and a plurality of flyback diodes, for converting DC voltage to voltage having three potentials of positive voltage, negative voltage, and zero voltage; a current detection section for detecting a current value inputted to or outputted from a terminal having the three potentials of the 3-level power conversion circuit; a voltage detection section for detecting the DC voltage; and a control section for performing ON/OFF control for the plurality of semiconductor switching elements of the 3-level power conversion circuit based on a voltage command value, wherein four semiconductor switching elements per phase are connected in series in the 3-level power conversion circuit, the 3-level power conversion circuit has a first diode connected between a neutral point and a connecting point between two semiconductor switching elements connected to a high potential side and a second diode connected between the neutral point and a connecting point between the two semiconductor switching elements connected to a low potential side for each phase, and the control section calculates ON voltage error caused due to ON voltage drop including ON voltage drop in the first diode or the second diode when current flows in the plurality of semiconductor switching elements and the plurality of flyback diodes, based on time ratios of the three potentials in a predetermined certain period and the current value from the current detection section, corrects the voltage command value by a voltage correction amount for correcting the ON voltage error, and performs ON/OFF control for the plurality of semiconductor switching elements of the 3-level power conversion circuit based on the corrected voltage command value.