POWER CONVERSION SYSTEM AND CONTROL METHOD THEREOF

• US 20150229252A1
• Filed: 04/22/2015
• Published: 08/13/2015
• Est. Priority Date: 11/28/2012
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: TOBA, Akio
• Granted Patent: US 9,843,278 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02M 1/0067 Converter structures employing plural converter units, other than for parallel operation of the units on a single load
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: H02M 7/5387 in a bridge configuration
• CPC Class Codes: H02P 6/14 Electronic commutators

Abstract

Aspects of a power conversion system can include a capacitor which stores direct current power, an inverter, and a pair of direct current terminals of which are connected to two ends of the capacitor and to the alternating current terminals of which an alternating current motor acting as a load is connected. Also included can be an upper and lower arm portion of which the connection point of semiconductor switches connected in series is connected to the neutral point of the motor, a direct current power source connected in parallel to the upper and lower arm portion and a switch connected between one of the direct current terminals of the inverter and one end of the upper and lower arm portion. The other direct current terminal of the inverter can be connected to the other end of the upper and lower arm portion.

Claims

1. A power conversion system, comprising:

a power storage device which stores direct current power;

an inverter, between the positive and negative direct current terminals of which the power storage device is connected, and between a plurality of alternating current terminals of which a load having an inductance is connected;

a first upper and lower arm portion, configured by connecting first and second semiconductor switches in series, of which the connection point of the first and second semiconductor switches is connected to the neutral point of the load; and

a direct current power source connected in parallel to the first upper and lower arm portion, the power conversion system being characterized in that at least one pair of homopolar terminals, of pairs of homopolar terminals out of the positive and negative direct current terminals of the inverter and the positive and negative terminals of the first upper and lower arm portion, are connected by a switch, and the other pair of homopolar terminals are set at the same potential.

2. The power conversion system according to claim 1, wherein

only one pair of homopolar terminals, of pairs of homopolar terminals out of the positive and negative direct current terminals of the inverter and the positive and negative terminals of the first upper and lower arm portion, are connected by a switch, and the other pair of homopolar terminals are directly connected together.

3. The power conversion system according to claim 1, wherein

pairs of homopolar terminals, of the positive and negative direct current terminals of the inverter and the positive and negative terminals of the first upper and lower arm portion, are connected one pair by each switch.

4. The power conversion system according to claim 1, wherein

semiconductor switches configuring the inverter and the first and second semiconductor switches configuring the first upper and lower arm portion are each configured of a semiconductor switching element and a reflux diode connected in reverse parallel thereto.

5. The power conversion system according to claim 1, wherein

the load is an alternating current motor, and the inductance which the load has is a leakage inductance of the alternating current motor.

6. The power conversion system according to claim 1, wherein

by switching the plurality of semiconductor switches configuring the inverter in a condition in which the switch is turned on and the first and second semiconductor switches are turned off, an alternating current voltage is output from the inverter to drive the load.

7. The power conversion system according to claim 2, wherein

the switch is turned off, and all the semiconductor switches in the upper arm or lower arm of the inverter are turned on or off at the same time, thereby equivalently configuring a second upper and lower arm portion formed of the series circuit of third and fourth semiconductor switches, and that the first and second semiconductor switches are turned on and off, thereby causing a buck-boost chopper formed of the first upper and lower arm portion, the second upper and lower arm portion, and the inductance of the load to operate, thus charging and discharging the power storage device.

8. The power conversion system according to claim 3, wherein

in a condition in which one switch is constantly turned on, the other switch is turned off, and all the semiconductor switches in the upper arm or lower arm of the inverter are turned on or off at the same time, thereby equivalently configuring a second upper and lower arm portion formed of the series circuit of third and fourth semiconductor switches, and that the first and second semiconductor switches are turned on and off, thereby causing a buck-boost chopper formed of the first upper and lower arm portion, the second upper and lower arm portion, and the inductance of the load to operate, thus charging and discharging the power storage device.

9. The power conversion system according to claim 6, wherein

a switching pattern of the inverter for carrying out a buck-boost operation by the second upper and lower arm portion configures one portion of a switching pattern for outputting an alternating current voltage from the inverter to drive the load.

10. The power conversion system according to claim 8, wherein

a switching pattern of the inverter for carrying out a buck-boost operation by the second upper and lower arm portion configures one portion of a switching pattern for outputting an alternating current voltage from the inverter to drive the load.

11. The power conversion system according to claim 8, wherein

a switching pattern of the inverter for carrying out a buck-boost operation by the second upper and lower arm portion forms one portion of a switching pattern for outputting an alternating current voltage from the inverter to drive the load.