Electric braking of machinery with a plurality of inverter-fed motors

• US 20080079373A1
• Filed: 09/29/2006
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Baldor Electric Company (ABB Limited)
• Original Assignee: Reliance Electric Technologies LLC (ABB Limited)
• Inventors: Melfi, Michael J.
• Granted Patent: US 7,511,438 B2
• Time in Patent Office: Days
• US Class Current: 318/63
• CPC Class Codes: H02P 3/18 for stopping or slowing an ac motor
• CPC Class Codes: H02P 3/24 by applying dc to the motor
• CPC Class Codes: H02P 5/74 controlling two or more ac dynamo-electric motors H02P5/46, H02P5/60 take precedence

Abstract

A system and method are provided whereby at least two motors driven by an inverter coupled to a DC bus are configured to alternate between regenerative and injection braking such that at least one motor is placed in regenerative braking mode and at least one motor is placed in motoring mode. Energy is simultaneously placed on and removed from the DC bus in a manner allowing a large current to flow in as many motors as possible, for fast stoppage of load inertia. At least one motor may be placed in regenerative braking mode and at least one motor in DC injection mode, such that energy is simultaneously placed onto and removed from the DC bus, respectively. Further, a single motor may be is alternated between regenerative braking and DC injection braking, such that energy is alternately placed onto and removed from the DC bus, respectively.

Claims

1. A method for controlling electric motors coupled to an inertial load, the method comprising:

controlling a first motor via a first inverter drive in an injection braking regime; and

controlling a second motor via a second inverter drive in a regenerative braking regime;

wherein the first and second motor drives are coupled to a common DC bus, and the injection braking regime and the regenerative braking regimes are regulated based upon energy drawn from the DC bus by injection braking and energy fed to the DC bus by regenerative braking.

2. The method of claim 1, further comprising sensing voltage on the DC bus and regulating the injection braking regime and the regenerative braking regime based upon the DC bus voltage.

3. The method of claim 2, wherein the injection braking regime and the regenerative braking regime are regulated to maintain a substantially constant DC bus voltage.

4. The method of claim 2, wherein the injection braking regime and the regenerative braking regime are regulated to maintain the DC bus voltage below a predetermined voltage.

5. The method of claim 4, wherein the predetermined voltage is a voltage at which one or both of the inverter drives would trip.

6. The method of claim 1, wherein the regenerative braking regime includes intermittently regeneratively braking the second motor.

7. The method of claim 1, wherein the first and second motors are disposed on opposite sides of a vehicle, and either the injection braking regime, or the regenerative braking regime, or both are regulated to control tracking of the vehicle.

8. The method of claim 1, comprising alternatively controlling the first and second motors in injection braking and regenerative braking regimes.

9. A method for controlling electric motors coupled to an inertial load, the method comprising:

simultaneously controlling a first motor in a regenerative braking regime and motoring a second motor via first and second inverter drives, respectively;

wherein the first and second motor drives are coupled to a common DC bus, and wherein the first and second motors are coupled to an inertial load.

10. The method of claim 9, wherein control of the first and second motors is alternated between the regenerative braking regime and the motoring regime, whereby energy resulting from regenerative braking of one motor is dissipated by the other motor operated in the motoring regime.

11. The method of claim 10, wherein the first and second motors are disposed on opposite sides of a vehicle and the regenerative braking regime is applied to the first and second motors to control tracking of the vehicle.

12. The method of claim 9, wherein application of the regenerative braking regime is regulated to maintain a voltage of the DC bus below a predetermined voltage.

13. The method of claim 12, wherein the predetermined voltage is a voltage at which one or both of the inverter drives would trip.

15. A method for controlling an electric motor coupled to an inertial load, the method comprising:

sensing voltage of a DC bus coupled to an inverter drive that controls the motor;

intermittently applying a regenerative braking regime via the inverter drive to brake the motor while maintaining the DC bus voltage below a predetermined voltage.

16. The method of claim 15, wherein the predetermined voltage is a voltage at which the inverter drive would trip.

17. The method of claim 15, comprising storing energy in a capacitive element coupled to the DC bus during regenerative braking.

18. The method of claim 15, comprising applying an injection braking regime during periods when the regenerative braking regime is not applied to the motor.

19. A system braking an inertial load comprising:

first and second electric motors;

first and second inverter drives coupled to the first and second motors, respectively; and

a common DC bus providing electrical power to both inverter drives;

wherein the first motor drive is configured to apply an injection braking regime to the first electric motor and the second motor drive is configured to apply a regenerative braking regime to the second electric motor when the first motor drive is applying the injection braking regime to the first electric motor.

20. The system of claim 19, comprising a sensor for sensing the voltage of the DC bus, and wherein the regenerative braking regime is regulated based upon the DC bus voltage.

21. The system of claim 19, wherein the first and second inverter drives are configured to alternatively provide injection and regenerative braking regimes to their respective electric motors.

22. A system for braking an inertial load, the system comprising:

first and second electric motors;

first and second inverter drives coupled to the first and second motors, respectively; and

a common DC bus providing electrical power to both inverter drives;

wherein the first and second inverter drives are configured to apply a regenerative braking regime to the first motor and a motoring regime to the second motor, respectively.

23. The system of claim 22, wherein control of the first and second motors is alternated between the regenerative braking regime and the motoring regime, whereby energy resulting from regenerative braking of one motor is dissipated by the other motor operated in the motoring regime.

24. The system of claim 23, wherein the first and second motors are disposed on opposite sides of a vehicle and the regenerative braking regime is applied to the first and second motors to control tracking of the vehicle.

25. The system of claim 22, wherein the first and second inverter drives are configured to regulate application of the regenerative braking regime to maintain the voltage on the DC bus below a predetermined voltage.

26. A system for controlling an electric motor coupled to an inertial load, the system comprising:

an inverter drive coupled to the motor for controlling operation of the motor,

a DC bus coupled to the inverter drive to provide power to the inverter drive; and

a sensor for sensing voltage of a DC bus;

wherein the inverter drive is configured to intermittently apply a regenerative braking regime to brake the motor while maintaining the DC bus voltage below a predetermined voltage.

27. The system of claim 26, wherein the predetermined voltage is a voltage at which the inverter drive would trip.

28. The system of claim 26, comprising a capacitive element coupled to the DC bus for storing energy from the motor during regenerative braking.

29. The system of claim 26, wherein the inverter drive is configured to apply an injection braking regime during periods when the regenerative braking regime is not applied to the motor.