Abstract: To provide a power supply device which can reduce energy loss caused due to the forward-direction voltage of a flywheel diode. In a load circuit for subjecting an electronic switch T1 provided between a DC power supply VB and a motor M1 to the PWM control to thereby drive the motor M1, a MOSFET (T2) is provided in parallel to the motor M1. A parasitic diode Dp of the MOSFET (T2) is provided in a manner that its forward direction is in opposite to the flowing direction of a load current ID. The MOSFET (T2) is turned on during a part of a period during which the electronic switch T1 is placed in an off state to thereby flow a circulation current flowing through the motor M1 into the MOSFET (T2). Thus, the energy loss can be remarkably reduced as compared with the case of using the flywheel diode.

Abstract: To provide a power supply device which can reduce energy loss caused due to the forward-direction voltage of a flywheel diode. In a load circuit for subjecting an electronic switch T1 provided between a DC power supply VB and a motor M1 to the PWM control to thereby drive the motor M1, a MOSFET (T2) is provided in parallel to the motor M1. A parasitic diode Dp of the MOSFET (T2) is provided in a manner that its forward direction is in opposite to the flowing direction of a load current ID. The MOSFET (T2) is turned on during a part of a period during which the electronic switch T1 is placed in an off state to thereby flow a circulation current flowing through the motor M1 into the MOSFET (T2). Thus, the energy loss can be remarkably reduced as compared with the case of using the flywheel diode.