Direct current power supply device, motor driving device, air conditioner, and refrigerator
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 4 a 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.
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.
2. The direct-current power supply device according to claim 1 , 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 stops an operation of the switching unit.
3. The direct-current power supply device according to claim 2 , wherein, in a case in which the short-circuit failure is detected, when the switching element in which the short-circuit failure is not detected is on, the control unit instructs the connection control unit to disconnect the first middle point and the second middle point.
4. The direct-current power supply device according to claim 1 , wherein at least one of the first switching element, the second switching element, the backflow preventing elements, and rectifier elements configuring the rectifier is formed by a wide band gap semiconductor.
5. The direct-current power supply device according to claim 4 , wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.
6. A motor driving device that drives an electric motor, the motor driving device comprising:
the direct-current power supply device according to claim 1 ;
an inverter that controls the electric motor using a direct current supplied from the direct-current power supply device;
a current detecting unit that detects an electric current flowing to the electric motor; and
a driving control unit that controls the inverter on the basis of the electric current detected by the current detecting unit.
7. The motor driving device according to claim 6 , wherein
the driving control unit determines, on the basis of a load amount of the electric motor, a voltage of the direct current supplied to the inverter and indicates the determined voltage to the direct-current power supply device, and
the direct-current power supply device controls, on the basis of the indication from the driving control unit, the voltage of the direct current to be supplied to the inverter.
8. The motor driving device according to claim 6 , wherein the electric motor includes a permanent magnet composed of a material other than a rare-earth element.
9. The motor driving device according to claim 6 , wherein switching elements configuring the inverter are each formed by a wide band gap semiconductor.
10. The motor driving device according to claim 9 , wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.
11. An air conditioner comprising: the motor driving device according to claim 6 ; and
a compressor including an electric motor driven by the motor driving device.
12. A refrigerator comprising: the motor driving device according to claim 6 ; and a compressor including an electric motor driven by the motor driving device.
13. 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; 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.
14. The direct-current power supply device according to claim 13 , wherein at least one of the first switching element, the second switching element, the backflow preventing elements, and rectifier elements configuring the rectifier is formed by a wide band gap semiconductor.
15. The direct-current power supply device according to claim 14 , wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.
16. A motor driving device that drives an electric motor, the motor driving device comprising:
the direct-current power supply device according to claim 13 ;
an inverter that controls the electric motor using a direct current supplied from the direct-current power supply device;
a current detecting unit that detects an electric current flowing to the electric motor; and
a driving control unit that controls the inverter on the basis of the electric current detected by the current detecting unit.
17. The motor driving device according to claim 16 , wherein
the driving control unit determines, on the basis of a load amount of the electric motor, a voltage of the direct current supplied to the inverter and indicates the determined voltage to the direct-current power supply device, and
the direct-current power supply device controls, on the basis of the indication from the driving control unit, the voltage of the direct current to be supplied to the inverter.
18. An air conditioner comprising: the motor driving device according to claim 16 ; and a compressor including an electric motor driven by the motor driving device.
19. A refrigerator comprising: the motor driving device according to claim 16 ; and a compressor including an electric motor driven by the motor driving device.
20. The motor driving device according to claim 17 , wherein the electric motor includes a permanent magnet composed of a material other than a rare-earth element.
21. The motor driving device according to claim 16 , wherein switching elements configuring the inverter are each formed by a wide band gap semiconductor.
22. The motor driving device according to claim 21 , wherein the wide band gap semiconductor is silicon carbide, a gallium nitride-based material, or diamond.