Motor drive device and refrigerator employing same

Abstract

Motor drive device (30) includes brushless DC motor (5) that drives a load and speed controller (8) that decides a PWM ON ratio for performing PWM control on brushless DC motor (5). The motor drive device further includes PWM ON ratio increasing-reducing unit (9) that increases/reduces the PWM ON ratio in accordance with a driving speed of brushless DC motor (5) and drive unit (10) that performs PWM control for driving brushless DC motor (5) in accordance with the PWM ON ratio decided by PWM ON ratio increasing-reducing unit (9). PWM ON ratio increasing-reducing unit (9) sets the PWM ON ratio to a ratio equal to or lower than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed of brushless DC motor (5) is lower than a predetermined speed, and sets the PWM ON ratio to a ratio equal to or higher than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed is higher than the predetermined speed.

Dependencies are inferred from the claim text.