SYSTEMS AND METHODS FOR DISCHARGING BUS VOLTAGE USING SEMICONDUCTOR DEVICES

• US 20110133546A1
• Filed: 12/07/2009
• Published: 06/09/2011
• Est. Priority Date: 12/07/2009
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: STANCU, CONSTANTIN C., TANG, DAVID, YOUNG, RONALD W., JANG, SEOK-JOO
• Granted Patent: US 8,378,528 B2
• Time in Patent Office: Days
• US Class Current: 307/9.1
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 3/003 relating to inverters
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: H02M 1/322 Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
• CPC Class Codes: H02M 7/53871 with automatic control of output voltage or current
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

Systems and methods are provided for discharging a voltage bus. An electrical system comprises a first switch coupled to a first voltage rail, a second switch coupled between the first switch and a second voltage rail, and a control system coupled to the first switch and the second switch. The control system is configured to alternately activate the first switch and the second switch such that an energy potential between the first voltage rail and the second voltage rail is dissipated through the first switch and the second switch.

Claims

1. An electrical system comprising:

a first switch coupled to a first voltage rail;

a second switch coupled between the first switch and a second voltage rail; and

a control system coupled to the first switch and the second switch, wherein the control system is configured to alternately activate the first switch and the second switch such that an energy potential between the first voltage rail and the second voltage rail is dissipated through the first switch and the second switch.

2. The electrical system of claim 1, further comprising:

a third switch coupled to the first voltage rail; and

a fourth switch coupled between the third switch and the second voltage rail, wherein the control system is coupled to the third switch and the fourth switch, wherein;

the control system is configured to alternately activate the third switch and the fourth switch such that the energy potential is dissipated through the third switch and the fourth switch;

the third switch and the first switch are activated synchronously; and

the fourth switch and the second switch are activated synchronously.

3. The electrical system of claim 2, wherein:

each of the first switch, the second switch, the third switch, and the fourth switch comprises a transistor; and

the control system is configured to;

apply a first voltage pulse having a first duration to the first switch, wherein the second switch does not conduct current while the first voltage pulse is applied;

apply a second voltage pulse having the first duration to the third switch concurrently with the first voltage pulse, wherein the fourth switch does not conduct current while the second voltage pulse is applied;

apply a third voltage pulse having a second duration to the second switch after applying the first voltage pulse to the first switch, wherein the first switch does not conduct current while the third voltage pulse is applied; and

apply a fourth voltage pulse having the second duration to the fourth switch concurrently with the third voltage pulse, wherein the third switch does not conduct current while the fourth voltage pulse is applied.

4. The electrical system of claim 3, the first duration and the second duration being equal, wherein the first duration and the second duration are each greater than or equal to a minimum amount of time required for the first switch to transition from an OFF state to an ON state.

5. The electrical system of claim 3, wherein the control system is configured to apply the third voltage pulse and the fourth voltage pulse a dead time after applying the first voltage pulse and the second voltage pulse, the dead time corresponding to a minimum amount of time required for the first switch to transition from an ON state to an OFF state.

6. The electrical system of claim 5, wherein the control system is configured to:

apply a fifth voltage pulse having the first duration to the first switch the dead time after applying the third voltage pulse, wherein the second switch does not conduct current while the fifth voltage pulse is applied; and

apply a sixth voltage pulse having the first duration to the third switch concurrently with the fifth voltage pulse, wherein the fourth switch does not conduct current while the sixth voltage pulse is applied.

7. The electrical system of claim 1, wherein the control system is configured to:

apply a first voltage pulse to the first switch, the first voltage pulse having a first duration corresponding to an amount of time required for the first switch to transition from an OFF state to an ON state, wherein the second switch is in an OFF state while the first voltage pulse is applied;

apply a second voltage pulse having the first duration to the second switch a dead time after applying the first voltage pulse to the first switch, the dead time corresponding to an amount of time required for the first switch to transition from an ON state to an OFF state, such that the first switch is in an OFF state while the second voltage pulse is applied;

apply a third voltage pulse having the first duration to the first switch the dead time after applying the second voltage pulse to the second switch such that the second switch is in an OFF state while the third voltage pulse is applied; and

apply a fourth voltage pulse having the first duration to the second switch the dead time after applying the third voltage pulse to the first switch such that the first switch is in an OFF state while the fourth voltage pulse is applied.

8. The electrical system of claim 1, wherein the control system is configured to identify a discharge condition, wherein the control system alternately activates the first switch and the second switch in response to the discharge condition.

9. The electrical system of claim 8, further comprising:

a bus comprising the first voltage rail and the second voltage rail;

an energy source; and

a switching arrangement coupled between the bus and the energy source, wherein the control system is configured to open the switching arrangement to decouple the energy source from the bus in response to identifying the discharge condition.

10. The electrical system of claim 1, further comprising:

a motor having a first winding coupled between the first switch and the second switch, wherein the control system comprises;

a controller configured to generate first command signals to operate the first switch and the second switch to deliver power to the motor;

a pulse generator configured to generate second command signals to toggle the first switch and the second switch to discharge the energy potential; and

gate drive circuitry configured to apply voltages to the first switch and the second switch to operate the first switch and the second switch, wherein;

the gate drive circuitry is initially coupled to the controller such that the gate drive circuitry applies voltages to the first switch and the second switch in accordance with the first command signals to operate the motor; and

in response to a discharge condition, the gate drive circuitry is coupled to the pulse generator, such that the gate drive circuitry applies voltages to the first switch and the second switch in accordance with the second command signals to alternately activate the first switch and the second switch such that the energy potential is dissipated.

11. An electrical system in a vehicle, the electrical system comprising:

a voltage bus;

a capacitive element coupled to the voltage bus;

an electric motor having one or more windings;

an inverter module coupled between the voltage bus and the electric motor, the inverter module including one or more inverter phase legs, wherein each inverter phase leg corresponds to a respective winding of the electric motor; and

a control system coupled to the inverter module, wherein the control system is configured to;

operate the one or more inverter phase legs to deliver power to the electric motor; and

in response to a discharge condition, toggle at least one of the inverter phase legs to dissipate energy potential on the voltage bus.

12. The electrical system of claim 11, the voltage bus comprising a positive rail and a negative rail, wherein:

each inverter phase leg includes a positive switch coupled between the positive rail and a respective winding of the electric motor and a negative switch coupled between the negative rail and the respective winding of the electric motor;

the control system is configured to toggle at least one of the inverter phase legs by alternating at least one inverter phase leg between a first state and a second state;

the positive switch conducts current and the negative switch does not conduct current in the first state; and

the negative switch conducts current and the positive switch does not conduct current in the second state.

13. The electrical system of claim 12, wherein the control system is configured to toggle the one or more inverter phase legs in concert, such that one or more positive switches of the one or more inverter phase legs are closed concurrently and one or more negative switches the one or more inverter phase legs are open in the first state and the one or more negative switches are closed concurrently and the one or more positive switches are open in the second state.

14. The electrical system of claim 11, the voltage bus comprising a positive rail and a negative rail, wherein:

the inverter module includes a first inverter phase leg having a positive switch coupled to the positive rail and a negative switch coupled to the negative rail; and

in response to the discharge condition, the control system is configured to toggle the first inverter phase leg with a switching period corresponding to a sum of an amount of time required for the positive switch to transition from an open state to a closed state, an amount of time required for the positive switch to transition from the closed state to the open state, an amount of time required for the negative switch to transition from an open state to a closed state, and an amount of time required for the negative switch to transition from the closed state to the open state.

15. A method for discharging an energy potential between a first conductive element and a second conductive element using an inverter module coupled to the first conductive element and the second conductive element, the inverter module including a first set of one or more switches coupled to the first conductive element and a second set of one or more switches coupled to the second conductive element, the method comprising:

identifying a discharge condition; and

in response to the discharge condition, alternately dissipating the energy potential through the first set of switches or the second set of switches, wherein the first set of switches and the second set of switches do not dissipate energy simultaneously.

16. The method of claim 15, the inverter module including a plurality of phase legs, each phase leg comprising a first switch of the first set of switches and a second switch of the second set of switches, the second switch being configured between the first switch and the second conductive element, wherein alternately dissipating the energy potential comprises toggling the plurality of phase legs in concert.

17. The method of claim 15, wherein toggling the plurality of phase legs comprises alternating between applying voltage to control terminals of the first set of switches and applying voltage to control terminals of the second set of switches.

18. The method of claim 15, wherein alternately dissipating the energy potential through the first set of switches or the second set of switches comprises:

closing the first set of switches, wherein the second set of switches do not conduct current while the first set of switches are closed; and

closing the second set of switches after closing the first set of switches, wherein the first set of switches do not conduct current while the second set of switches are closed.

19. The method of claim 18, wherein:

closing the first set of switches comprises applying voltage to control terminals of the first set of switches for a first duration equal to an amount of time required to close the first set of switches; and

closing the second set of switches comprises, a first dead time after applying voltage to the first set of switches, applying voltage to control terminals of the second set of switches for a second duration equal to an amount of time required to close the second set of switches, the first dead time corresponding to an amount of time required for the first set of switches to stop conducting current after applying voltage to the first set of switches.

20. The method of claim 19, wherein alternately dissipating the energy potential comprises repeating the steps of:

applying voltage to control terminals of the first set of switches for the first duration a second dead time after applying voltage to the second set of switches, the second dead time corresponding to an amount of time required for the second set of switches to stop conducting current after applying voltage to the second set of switches; and

applying voltage to control terminals of the second set of switches for the second duration the first dead time after applying voltage to the first set of switches.