Patent ID: 9287820
Filing Date: 2016-03-15
CPC Classification: F24F,F25B,H02M,H02P

Claim Text:
1. A motor control device comprising: a current detecting element connected to a direct current side of an inverter circuit including a plurality of switching elements connected into a three-phase bridge configuration, the switching elements being configured to be on-off controlled according to a predetermined PWM signal pattern so that the inverter circuit converts direct current to three-phase alternating current, the current detecting element generating a signal corresponding to a current value; a rotor position determination unit configured to determine a rotor position based on phase currents of an electric motor driven by the inverter circuit; a PWM signal generation unit configured to generate a three-phase PWM signal pattern so that the pattern follows the rotor position; a current detection unit configured to detect the phase currents based on a signal generated by the current detecting element and the PWM signal pattern, wherein the PWM signal generation unit is configured to increase/decrease a duty in both directions of phase lag side and phase lead side with reference to any phase of the carrier-wave period regarding a first phase of the three-phase PWM signal pattern; wherein the PWM signal generation unit is configured to increase/decrease a duty in one of the directions of phase lag side and phase lead side with reference to any phase of the carrier-wave period regarding a second phase of the three-phase PWM signal pattern; wherein the PWM signal generation unit is configured to increase/decrease a duty in a direction opposite to the direction of the second phase with reference to any phase of the carrier-wave period regarding a third phase of the three-phase PWM signal pattern; and wherein the current detection unit has a timing point adjusting unit configured to detect two-phase currents at timing points fixed in the carrier-wave period of the PWM signal and to adjust a detection timing point so that the current is detectable at a variable timing point according to a magnitude of an output voltage supplied to the inverter circuit regarding at least one phase when the two-phase currents become undetectable at the fixed timing points.