CONTROL SYSTEM, CONTROLLER, AND CONTROL METHOD FOR WOUND INDUCTION MACHINE

• US 20180278183A1
• Filed: 02/08/2018
• Published: 09/27/2018
• Est. Priority Date: 03/23/2017
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Energy Systems & Solutions Corporation (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Energy Systems & Solutions Corporation (Toshiba Corporation)
• Inventors: Hasegawa, Ryuta, Kageyama, Takahisa, Kusunoki, Kiyoshi, Ishizuki, Teruyuki, Shiozaki, Yuichi, Fujita, Takashi, Kaneda, Hironari
• Granted Patent: US 10,291,159 B2
• Time in Patent Office: Days
• CPC Class Codes: B60L 2220/12 Induction machines
• CPC Class Codes: H02H 7/06 for dynamo-electric generators; for synchronous capacitors
• CPC Class Codes: H02H 7/12 for static converters or rectifiers for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981
• CPC Class Codes: H02H 7/1222 responsive to abnormalities in the input circuit, e.g. transients in the DC input
• CPC Class Codes: H02H 9/002 limiting inrush current on switching on of inductive loads subjected to remanence, e.g. transformers
• CPC Class Codes: H02H 9/041 using a short-circuiting device
• CPC Class Codes: H02H 9/042 comprising means to limit the absorbed power or indicate damaged over-voltage protection device
• CPC Class Codes: H02P 2207/01 Asynchronous machines
• CPC Class Codes: H02P 27/05 using AC supply for both the rotor and the stator circuits, the frequency of supply to at least one circuit being variable
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 29/024 Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 6/005 Arrangements for controlling doubly fed motors
• CPC Class Codes: H02P 9/007 Control circuits for doubly fed generators

Abstract

According to one embodiment, a control system includes a chopper, a short-circuit unit, a voltage detector circuit, and a controller. The chopper reduces a direct current voltage between a converter connected to a stator in a wound induction machine and an inverter connected to a rotor in the wound induction machine. The short-circuit unit shorts a wire used for connection between the rotor and the inverter and the voltage detector circuit is to detect the direct current voltage. The controller causes driving the chopper and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when a voltage value exceeds a first predetermined value, and causes driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value.

Claims

1. A control system of a wound induction machine, comprising:

a chopper to reduce a direct current voltage between a converter connected to a stator in the wound induction machine and an inverter connected to a rotor in the wound induction machine;

a short-circuit unit to short a wire used for connection between the rotor and the inverter;

a voltage detector circuit to detect the direct current voltage; and

a controller to cause driving the chopper and, at the same time, outputting from the inverter an alternating current superimposed over a direct current component when a voltage value input from the voltage detector circuit exceeds a first predetermined value, and to cause driving the short-circuit unit and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value higher than the first predetermined value.

2. The control system according to claim 1, further comprising a current sensor to detect line current flowing through the wire, wherein

when one circuit breaker is connected between the stator and an electric power system, the controller causes the wound induction machine to halt after the current value of the line current falls below a predetermined current value, and

when any one of the multiple circuit breakers is connected between the stator and the electric power system, the controller causes the wound induction machine to continue operating after the current value falls below the predetermined current value.

3. The control system according to claim 2, wherein the controller temporarily increases the predetermined current value from the time at which both the chopper and the inverter are driven in accordance with the first predetermined value to the time at which the short-circuit unit is driven in accordance with the second predetermined value.

4. The control system according to claim 1, wherein the short-circuit unit includes a short-circuit switching element across the wire, and a current limit resistor series-connected to the short-circuit switching element.

5. The control system according to claim 1, wherein

the chopper includes a chopper switching element and a chopper resistor series-connected to the chopper switching element, and

the resistance of the chopper resistor is set to a value at which the voltage value does not exceed the second predetermined value.

6. A control method for a wound induction machine including a stator connected to an electric power system through at least one circuit breaker, and a rotor provided in the stator, the control method comprising:

detecting a direct current voltage between a converter connected to the stator and an inverter connected to the rotor;

driving a chopper to reduce the direct current voltage and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when the detected voltage value exceeds a first predetermined value; and

shorting a wire used for connection between the rotor and the inverter and, at the same time, halting the inverter when the voltage value exceeds a second predetermined value higher than the first predetermined value.

7. A controller for a wound induction machine including a stator connected to an electric power system through at least one circuit breaker, and a rotor provided in the stator, the controller comprising:

a determination unit to determine whether a voltage value corresponding to a direct current voltage between a converter connected to the stator and an inverter connected to the rotor exceeds a first predetermined value, and whether the voltage value exceeds a second predetermined value higher than the first predetermined value; and

a command unit to cause driving a chopper which reduces the direct current voltage and, at the same time, outputting from the inverter an alternating current over which a direct current component is superimposed when the determination unit determines that the voltage value exceeds the first predetermined value, and to cause driving a short-circuit unit which shorts a wire used for connection between the rotor and the inverter and, at the same time, halting the inverter when the determination unit determines that the voltage value exceeds the second predetermined value.