Direct current power supply device, motor driving device, air conditioner, and refrigerator

摘要

A direct-current power supply device includes a rectifier connected to a power supply, a charge storage unit configured by a first capacitor and a second capacitor connected in series, a switching unit configured by a first switching element 4a and a second switching element connected in series and backflow preventing elements that suppress a backflow of electric charges from the charge storage unit, a reactor, a control unit that controls operations of the first switching element and the second switching element, and a direct-current-voltage detecting unit that detects a first both-end voltage, which is a voltage across the first capacitor, and a second both-end voltage, which is a voltage across the second capacitor. The control unit detects, on the basis of a voltage difference between the first both-end voltage and the second both-end voltage, a short-circuit failure of one of the first switching element and the second switching element.

主权项

1. A direct-current power supply device comprising:
a rectifier connected to an alternating-current power supply; a charge storage unit including a first capacitor and a second capacitor connected in series; a switching unit including a first switching element and a second switching element connected in series and backflow preventing elements that suppress a backflow of electric charges from the charge storage unit; a control unit that controls operations of the first switching element and the second switching element; a direct-current-voltage detecting unit that detects a first both-end voltage, which is a voltage across the first capacitor, and a second both-end voltage, which is a voltage across the second capacitor, wherein the control unit detects, on the basis of a voltage difference between the first both-end voltage and the second both-end voltage, a short-circuit failure of one of the first switching element and the second switching element, and a short-circuit-current detecting unit that detects a short-circuit current flowing from the alternating-current power supply, wherein the control unit detects, before a start of a switching operation of the switching unit, on the basis of whether the short-circuit current is detected in a state in which one of the first switching element and the second switching element is turned on and the other switching element is turned off, whether a short-circuit failure of the other switching element has occurred; the direct-current power supply device further comprising a connection control unit that switches disconnection or connection of a first middle point, which is a middle point between the first switching element and the second switching element, and a second middle point, which is a middle point between the first capacitor and the second capacitor, wherein when detecting the short-circuit failure, the control unit instructs the connection control unit to disconnect the first middle point and the second middle point and operates in a state in which the switching element in which the short-circuit failure has not occurred of the first switching element and the second switching element is turned off.