METHODS AND SYSTEMS FOR INDUCTIVE ENERGY MANAGEMENT

• US 20140265987A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Regal Beloit America, Inc.
• Original Assignee: Regal Beloit America, Inc.
• Inventors: Chretien, Ludovic Andre, Becerra, Roger C.
• Granted Patent: US 9,735,715 B2
• Time in Patent Office: Days
• US Class Current: 318/494
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 3/22 by short-circuit or resistive braking

Abstract

A controller configured to be coupled to an electric motor. The controller including a processor programmed to receive a signal indicating a stopping command of the electric motor, and control a current such that a capacitor coupled to the electric motor is not overcharged by regenerative energy when a stopping of the electric motor has commenced, wherein controlling the current includes one of the following: upon receiving the signal indicating the stopping command of the electric motor, ramping the current down below a threshold level, or upon receiving the signal indicating the stopping command of the electric motor, forcing the current to circulate in motor windings to prevent regeneration of energy in the capacitor.

Claims

1. A controller configured to be coupled to an electric motor, the controller comprising a processor programmed to:

receive a signal indicating a stopping command of the electric motor; and

control a current such that a capacitor coupled to the electric motor is not overcharged by regenerative energy when a stopping of the electric motor has commenced, wherein controlling the current comprises one of the following;

upon receiving the signal indicating the stopping command of the electric motor, ramping the current down below a threshold level;

or

upon receiving the signal indicating the stopping command of the electric motor, forcing the current to circulate in motor windings to prevent regeneration of energy in the capacitor.

2. A controller in accordance with claim 1, wherein the capacitor has a capacitance below 10 μ

F/kW.

3. A controller in accordance with claim 1, wherein a current below the threshold level enables the regenerated voltage to be below a maximum voltage rating of the capacitor.

4. A controller in accordance with claim 3, wherein ramping the current down below a threshold level comprises:

receiving an amplitude of the current;

determining the threshold level;

comparing the amplitude of the current with a maximum level of current based on the determined threshold level; and

ramping the current down below the determined threshold level.

5. A controller in accordance with claim 1, wherein the processor is further programmed to send a signal requesting an inverter to be in an off-state upon receiving the signal indicating the stopping of the electric motor.

6. A controller in accordance with claim 5, wherein the processor is further programmed to, prior to sending the signal to the inverter, ramping the current down below the threshold level.

7. A system comprising:

an electric motor;

a capacitor coupled to the electric motor through an inverter; and

a controller coupled to the electric motor, the controller comprising a processor programmed to;

receive a signal indicating a stopping command of the electric motor; and

control a current such that the capacitor is not overcharged by regenerative energy when the stopping of the electric motor has commenced, wherein controlling the current comprises one of the following;

upon receiving the signal indicating the stopping command of the electric motor, ramping the current down below a threshold level;

or

upon receiving the signal indicating the stopping command of the electric motor, forcing the current to circulate in motor windings to prevent regeneration of energy in the capacitor.

8. A system in accordance with claim 7, wherein the capacitor has a capacitance below 10 μ

F/kW.

9. A system in accordance with claim 7, wherein a current below the threshold level enables the regenerated voltage to be below a maximum voltage rating of the capacitor.

10. A system in accordance with claim 9, wherein ramping the current down below a threshold level comprises:

receiving an amplitude of the current;

determining the threshold level;

comparing the amplitude of the current with a maximum level of current based on the determined threshold level; and

ramping the current down below the determined threshold level.

11. A system in accordance with claim 7, further comprising an inverter coupled to the controller and the electric motor, and wherein the processor is further programmed to send a signal requesting the inverter to be in an off-state upon receiving the signal indicating the stopping of the electric motor.

12. A system in accordance with claim 11, wherein the processor is further programmed to, prior to sending the signal to the inverter, ramping the current down below the threshold level.

13. A system in accordance with claim 7, further comprising a voltage clamping device coupled the capacitor, the voltage clamping device configured to protect the capacitor from being overcharged by regenerative energy, the voltage clamping device configured to absorb the regenerative energy if the regenerated voltage reaches a maximum threshold.

14. A system in accordance with claim 13, wherein the voltage clamping device is at least one of a metal oxide varistor, a transient voltage suppressor, and a gas discharge tube

15. A method for controlling a current such that a capacitor coupled to an electric motor is not overcharged by regenerative energy when a stopping of the electric motor has commenced, the method comprising:

receiving a request to stop the electric motor; and

upon receiving the request, executing one of the following;

ramping the current down below a threshold level;

or

forcing the current to circulate in motor windings to prevent regeneration of energy in the capacitor.

16. A method in accordance with claim 15, wherein the capacitor has a capacitance below 10 μ

F/kW.

17. A method in accordance with claim 15, wherein a current below the threshold level enables the regenerated voltage to be below a maximum voltage rating of the capacitor.

18. A method in accordance with claim 17, wherein ramping the current down below a threshold level comprises:

receiving an amplitude of the current;

determining the threshold level;

comparing the amplitude of the current with a maximum level of current based on the determined threshold level; and

ramping the current down below the determined threshold level.

19. A method in accordance with claim 15, further comprising requesting an inverter to be in an off-state upon receiving the request to stop the electric motor.

20. A method in accordance with claim 19, further comprising, prior to requesting the inverter to be in an off-state, ramping the current down below the threshold level.

21. A method in accordance with claim 15, wherein forcing the current to circulate in motor windings to prevent regeneration of energy in the capacitor is performed until the electric motor has stopped or until the current decays below a threshold.