DC power-supply device and refrigeration-cycle application device including the same

Patent metadata

Field	Value
Publication number	US-9800077-B2
Application number	US-201315024393-A
Country	US
Kind code	B2
Filing date	Nov 26, 2013
Priority date	Nov 26, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The DC power-supply device includes a rectifier circuit rectifying an alternating current, a reactor connected to an input or output side of the rectifier circuit, a first capacitor and a second capacitor serially connected between output terminals to a load, and a charging unit that selectively charges one or both of the first capacitor and the second capacitor. A ratio, to a period obtained by combining a charging period and a non-charging period of a pair of the first capacitor and the second capacitor, of the non-charging period, is controlled according to an operating condition of the load, to change a charging frequency of the first capacitor and the second capacitor based on the ratio, at the time of controlling an output voltage to the load.

First claim

The invention claimed is:

1. A DC power-supply device that converts an alternating current into a direct current and supplies the direct current to a load while having a reactor on a conversion path thereof, the DC power-supply device comprising:
a first capacitor and a second capacitor serially connected between output terminals to the load;
a charging unit to selectively charge one or both of the first capacitor and the second capacitor; and
a control unit to control the charging unit to change, based on a ratio of a non-charging period to a period obtained by combining a charging period and the non-charging period when a pair of the first capacitor and the second capacitor is charged, a charging frequency that is an inverse number of the period obtained by combining the charging period and the non-charging period, and thereby to control an output voltage of the load, wherein
the control unit controls the charging unit such that the charging frequency becomes n times a frequency multiplied by the number of phases of the alternating current (n is a natural number).

2. The DC power-supply device according to claim 1 , wherein
the charging unit includes:
a first switching element to switch between charging and non-charging of the first capacitor;
a second switching element to switch between charging and non-charging of the second capacitor;
a first backflow prevention element to prevent backflow of a charged electric charge of the first capacitor to the first switching element; and
a second backflow prevention element to prevent backflow of a charged electric charge of the second capacitor to the second switching element.

3. The DC power-supply device according to the claim 2 , wherein
the control unit has
a full-wave rectifying mode in which the first switching element and the second switching element are in an off-controlled state, and
a boost mode in which the first switching element and the second switching element are alternately controlled to be on, and
in the boost mode, the control unit controls an output voltage to the load by changing an on-duty of the first switching element and the second switching element.

4. The DC power-supply device according to the claim 3 , wherein in an operating range by the boost mode, the control unit executes control such that the charging frequency in a state having neither a section in which the first switching element and the second switching element are simultaneously off nor a section in which the first switching element and the second switching element are simultaneously on is the lowest, and the charging frequency in an operating range having the section in which the first switching element and the second switching element are simultaneously off and the charging frequency in an operating range having the section in which the first switching element and the second switching element are simultaneously on are made higher.

5. The DC power-supply device according to the claim 3 , further comprising
a switch connected between a midpoint of a series circuit consisting essentially of the first switching element and the second switching element and a midpoint of a series circuit consisting essentially of the first capacitor and the second capacitor, wherein
when any of the first backflow prevention element, the second backflow prevention element, the first switching element and the second switching element has a short-circuit fault, the control unit controls the switch to be opened, and operates the DC power-supply device in the full-wave rectifying mode.

6. The DC power-supply device according to the claim 5 , wherein the switch is an electromagnetic contactor or a semiconductor switching element that does not include a flywheel diode.

7. The DC power-supply device according to claim 2 , wherein at least one of the first switching element, the second switching element, the first backflow prevention element and the second backflow prevention element is formed from a wide-bandgap semiconductor.

8. The DC power-supply device according to claim 7 , wherein the wide-bandgap semiconductor is silicon carbide, a gallium-nitride-based material, or diamond.

9. The DC power-supply device according to the claim 1 , wherein a voltage between opposite ends of a series circuit consisting essentially of the first capacitor and the second capacitor and a voltage at a midpoint of the series circuit are applied to the load.

10. The DC power-supply device according to the claim 9 , wherein the load is an inverter configured to have four switching elements that drive a two-phase motor.

11. The DC power-supply device according to the claim 9 , wherein the load is a three-level inverter.

12. The DC power-supply device according to the claim 1 , wherein the control unit is adapted to a plurality of types of frequencies of the alternating current and controls the charging unit such that the charging frequency becomes a least common multiple of the plurality of types of frequencies of the alternating current.

13. A refrigeration-cycle application device comprising the DC power-supply device according to claim 1 .

14. A DC power-supply device that converts an alternating current into a direct current and supplies the direct current to a load while having a reactor on a conversion path thereof, the DC power-supply device comprising:
a first capacitor and a second capacitor serially connected between output terminals to the load;
a charging unit to selectively charge one or both of the first capacitor and the second capacitor; and
a control unit to control the charging unit to change, based on a ratio of a non-charging period to a period obtained by combining a charging period and the non-charging period when a pair of the first capacitor and the second capacitor is charged, a charging frequency that is an inverse number of the period obtained by combining the charging period and the non-charging period, and thereby to control an output voltage of the load, wherein
a voltage between opposite ends of a series circuit consisting essentially of the first capacitor and the second capacitor and a voltage at a midpoint of the series circuit are applied to the load.

15. The DC power-supply device according to the claim 14 , wherein the load is an inverter configured to have four switching elements that drive a two-phase motor.

16. The DC power-supply device according to the claim 14 , wherein the load is a three-level inverter.

17. A refrigeration-cycle application device comprising the DC power-supply device according to claim 14 .

18. A DC power-supply device that converts an alternating current into a direct current and supplies the direct current to a load while having a reactor on a conversion path thereof, the DC power-supply device comprising:
a first capacitor and a second capacitor serially connected between output terminals to the load;
a charging unit to selectively charge one or both of the first capacitor and the second capacitor, the charging unit includes
a first switching element to switch between charging and non-charging of the first capacitor,
a second switching element to switch between charging and non-charging of the second capacitor,
a first backflow prevention element to prevent backflow of a charged electric charge of the first capacitor to the first switching element, and
a second backflow prevention element to prevent backflow of a charged electric charge of the second capacitor to the second switching element; and

a control unit to control the charging unit to change, based on a ratio of a non-chargin

Assignees

• Mitsubishi Electric Corp

Inventors

• Hatakeyama Kazunori
• Uemura Keisuke
• Shinomoto Yosuke

Classifications

• Y02B70/126

  Cross-Sectional Technologies · mapped topic

• H02M7/5387

  in a bridge configuration · CPC title

• H02M7/487

  Neutral point clamped inverters · CPC title

• H02J7/0072 Primary

  Electricity · mapped topic

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title