Patent ID: 9742339
Date: 2017-08-22
CPC Classifications: G01R,H02M,H02P

Claim:
1. An apparatus for controlling an inverter employed in an inverter system, the apparatus comprising: a first determining unit configured to determine a frequency of an input voltage to an electric motor when an input power is reduced below a rated power, and to determine a magnitude, a phase and a frequency of the input voltage to the electric motor at the time of restarting if the input power is restored; a second determining unit configured to determine an command voltage to apply it to the inverter in a restart section after the time of restarting until an output voltage from the inverter reaches a predetermined output voltage; at least one power cell driving the electric motor; and a control unit controlling the inverter in response to at least an output of the second determining unit, by applying a voltage to the power cell wherein the second determining unit is further configured to determine a command frequency at the time when an appropriate torque is generated based on the frequency of the input voltage to the electric motor when the input power is reduced below the rated power, the frequency of the input voltage to the electric motor at the time of the restarting and a compensation value which is a time period required for generating the appropriate torque, and to determine a phase of the command voltage in the restart section based on the phase of the input voltage to the electric motor at the time of the restarting and the command frequency.