Inverter device and air conditioner

Patent metadata

Field	Value
Publication number	US-9490705-B2
Application number	US-201514612521-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Mar 6, 2014
Publication date	Nov 8, 2016
Grant date	Nov 8, 2016

Abstract

An inverter device includes: a rectifier circuit that converts an AC power supply into a DC power supply; a smoothing unit that is connected to a subsequent stage of the rectifier circuit; a short-circuit unit that short-circuits the AC power supply via a reactor that improves a power factor of the AC power supply; an inverter unit that converts a direct current from the smoothing unit into an alternating current; and a control unit that controls the inverter unit, wherein a gate drive circuit is connected to a gate terminal of each switching element in the inverter unit, the gate drive circuit includes a first gate voltage line and a second gate voltage line having a voltage value larger than a voltage value of the first gate voltage line, and the voltage value of the first gate voltage line is variable even during an operation of the inverter device.

First claim

What is claimed is:

1. An inverter device comprising:
a rectifier circuit that converts an AC power supply into a DC power supply;
a smoothing unit, including two capacitors, connected to a subsequent stage of the rectifier circuit;
a switch that connects the rectifier circuit to a node located between the two capacitors of the smoothing unit;
a short-circuit unit that short-circuits the AC power supply via a reactor that improves a power factor of the AC power supply;
an inverter unit that converts a direct current from the smoothing unit into an alternating current; and
a control unit including a control circuit configured to control the inverter unit, wherein
the inverter unit includes a gate drive circuit, the gate drive circuit includes:
a plurality of switching elements, each of the plurality of switching elements including a gate terminal connected to the gate drive circuit,
a plurality of resistors including a first resistor and a second resistor,
a capacitor,
a first gate voltage line that drives the gate terminal of each of the plurality of switching elements, and
a second gate voltage line, which drives the gate terminal of each of the plurality of switching elements, the second gate voltage line having a voltage value higher than a voltage value of the first gate voltage line, and the voltage value of the first gate voltage line is variable even during an operation of the inverter device, wherein
a resistance value of the first resistor and a resistance value of the second resistor are set to values that enable the gate drive circuit to operate.

2. The inverter device according to claim 1 , wherein the first gate voltage line is controlled according to a load current.

3. The inverter device according to claim 1 , wherein a voltage of the first gate voltage line is generated from the second gate voltage line.

4. An air conditioner comprising the inverter device according to claim 1 , wherein the inverter device drives a motor to rotate.

5. The inverter device according to claim 1 , further including:
a current detection unit that detects a bus current flowing in the inverter device; and
a voltage detection unit that detects the voltage across both the two capacitors of the smoothing unit, the two capacitors being connected in series, wherein
the current detection unit and the voltage detection unit each output a detected value to the control unit.

6. The inverter device according to claim 5 , further comprising
a bus current resistor electrically connected between the smoothing unit and the inverter unit, wherein
the current detection unit is configured to detect the bus current flowing in the inverter device via the bus current resistor.

7. The inverter device according to claim 1 , wherein a capacitance value of the capacitor of the gate drive circuit is set such that the product of the resistance value of the second resistor and the capacitance value of the capacitor is a predetermined time constant.

8. The inverter device according to claim 7 , wherein the predetermined time constant is greater than a turn-on time of each of the plurality of switching elements of the inverter circuit.

9. The inverter device according to claim 7 , wherein the predetermined time constant is about one to ten times greater than a turn-on time of each of the plurality of switching elements of the inverter circuit.

10. The inverter device according to claim 1 , wherein
the voltage value of the first gate voltage line is lowered to reduce a turn-on speed of each of the plurality of switching elements of the inverter circuit, and
the voltage value of the first gate voltage line is raised to increase a turn-on speed of each of the plurality of switching elements of the inverter circuit.

11. The inverter device according to claim 1 , wherein the controller is configured to vary the voltage value of the first gate voltage line in direct proportion to a load current of the inverter device so that noise generation of the inverter device varies in direct proportion to the load current.

12. The inverter device according to claim 1 , wherein the smoothing unit includes only the two capacitors.

13. The inverter device according to claim 1 , wherein a voltage of the first gate voltage line is generated from the second gate voltage line.

14. An inverter device comprising:
a rectifier circuit that converts an AC power supply into a DC power supply;
a smoothing unit, including two capacitors, connected to a subsequent stage of the rectifier circuit;
a short-circuit unit that short-circuits the AC power supply via a reactor that improves a power factor of the AC power supply;
an inverter unit that converts a direct current from the smoothing unit into an alternating current; and
a control unit including a control circuit configured to control the inverter unit, wherein
the inverter unit includes a gate drive circuit, the gate drive circuit includes:
a plurality of switching elements, each of the plurality of switching elements including a gate terminal connected to the gate drive circuit,
a plurality of resistors including a first resistor and a second resistor,
a capacitor,
a first gate voltage line that drives the gate terminal of each of the plurality of switching elements, and
a second gate voltage line, which drives the gate terminal of each of the plurality of switching elements, the second gate voltage line having a voltage value higher than a voltage value of the first gate voltage line, and the voltage value of the first gate voltage line is variable even during an operation of the inverter device, wherein
a resistance value of the first resistor and a resistance value of the second resistor are set to values that enable the gate drive circuit to operate, and
a capacitance value of the capacitor of the gate drive circuit is set such that the product of the resistance value of the second resistor and the capacitance value of the capacitor is a predetermined time constant.

15. The inverter device according to claim 14 , wherein the first gate voltage line is controlled according to a load current.

16. An air conditioner comprising the inverter device according to claim 14 , wherein the inverter device drives a motor to rotate.

17. The inverter device according to claim 14 , further including:
a current detection unit that detects a bus current flowing in the inverter device; and
a voltage detection unit that detects the voltage across both the two capacitors of the smoothing unit, the two capacitors being connected in series, wherein
the current detection unit and the voltage detection unit each output a detected value to the control unit.

18. The inverter device according to claim 17 , further comprising
a bus current resistor electrically connected between the smoothing unit and the inverter unit, wherein
the current detection unit is configured to detect the bus current flowing in the inverter device via the bus current resistor.

19. The inverter device according to claim 14 , wherein the predetermined time constant is greater than a turn-on time of each of the plurality of switching elements of the inverter circuit.

Assignees

• Mitsubishi Electric Corp

Inventors

• Ito Norikazu

Classifications

• H03K17/163

  Soft switching · CPC title

• H03K17/0412

  by measures taken in the control circuit · CPC title

• H02M5/458

  using semiconductor devices only · CPC title

• H03K17/0406 Primary

  in composite switches · CPC title

• Y02B70/126

  Cross-Sectional Technologies · mapped topic