Patent ID: 9595904
Date: 2017-03-14
CPC Classifications: H02M,H02P

Claim:
1. An apparatus for modifying voltage command for detecting output current in inverter, the apparatus comprising: a first determiner configured to determine a sector in a voltage hexagon that is output voltage vectors corresponding to switch states defined by the voltage hexagon, the sector having a PWM voltage command therein, by comparing each of 3-phase components in the PWM voltage command, and determine a maximum voltage, an intermediate voltage and a minimum voltage at a 3-phase PWM voltage command using the determination of the sector; a second determiner configured to determine an area, the area having the PWM voltage command, within a current detection disabled area by converting a minimum sampling time to a minimum sampling PWM and using the converted minimum sampling PWM, wherein the second determiner does not modify the PWM voltage command by determining that the area positioned with the PWM voltage command is a current detectable area, when a voltage deducted of a minimum sampling PWM from a maximum value of PWM triangular wave is greater than or equal to the intermediate voltage; and a command modification unit configured to determine an adjusting voltage and a restoring voltage using a minimum injection voltage based on the determined area and to modify the PWM voltage command, wherein the adjusting voltage is a modified voltage in an OFF sequence by deducing the minimum injection voltage from the PWM voltage command to move the PWM voltage command out of the current detection disabled area to a current detectable area within the voltage hexagon, the restoring voltage is a modified voltage in an ON sequence by adding the minimum injection voltage to the PWM voltage command to compensate for a difference of the adjusting voltage; and the minimum injection voltage is provided by using a geometry property in the voltage hexagon.