Electrical system with reverse current protection circuit

Patent metadata

Field	Value
Publication number	US-9973134-B1
Application number	US-201715451898-A
Country	US
Kind code	B1
Filing date	Mar 7, 2017
Priority date	Mar 7, 2017
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

An electrical system includes a direct current (DC) voltage bus, a power supply providing a supply voltage to the DC voltage bus, an electric machine connected to the power supply, a reverse current protection (RCP) circuit positioned between the power supply and the electric machine, the RCP circuit including an energy dissipating element, and a controller. As part of an associated method, the controller detects a reverse current condition in which a current flows from the electric machine toward the power supply when an induced voltage of the electric machine exceeds a voltage level of the voltage bus. The controller transmits a control signal to the RCP circuit to direct the electrical current through the energy dissipating element for a duration of the reverse current condition or for a predetermined duration equal to or greater than that of the reverse current condition.

First claim

What is claimed is:

1. An electrical system comprising:
a direct current (DC) voltage bus;
a power supply providing a supply voltage to the DC voltage bus;
an electric machine connected to the power supply via the DC voltage bus;
a reverse current protection (RCP) circuit positioned between the power supply and the electric machine, the RCP circuit including an energy dissipating element; and
a controller in communication with the RCP circuit that is configured to detect a reverse current condition of the electric system in which an electrical current flows from the electric machine toward the power supply when an induced voltage of the electric machine exceeds a voltage level of the DC voltage bus, wherein the controller is configured to transmit a control signal to the RCP circuit so as to direct the electrical current through the energy dissipating element for a duration of the reverse current condition.

2. The electrical system of claim 1 , further comprising a master switch configured to selectively connect or disconnect the power supply to the DC voltage bus, wherein the controller is programmed to open the master switch and thereby disconnect the power supply from the DC voltage bus for the duration of the reverse current condition.

3. The electrical system of claim 1 , wherein the energy dissipating element includes a resistor.

4. The electrical system of claim 1 , wherein the energy dissipating element includes a capacitor bank.

5. The electrical system of claim 1 , further comprising a polyphase power inverter module (PIM) that is electrically connected to the DC voltage bus and the electric machine, the polyphase PIM having a number of upper semiconductor switches and a number of lower semiconductor switches equal to a number of phases of the electric machine, wherein the electric machine includes phase windings and the energy dissipating element includes the phase windings of the electric machine along with the upper semiconductor switches or the lower semiconductor switches.

6. The electrical system of claim 5 , further comprising a plurality of OR logic gates each connected to a respective gate driver and a latching AND logic gate providing a voltage signal to each of the OR logic gates in response to detection of the reverse electrical current condition and a voltage level of the DC bus exceeding a predetermined overvoltage threshold, the voltage signal being configured to turn on all of the lower semiconductor switches to prevent the reverse current into the DC bus.

7. The electrical system of claim 6 , the RCP circuit including a Zener diode having an anode that is connected to the AND logic gate to detect when the induced voltage of the electric machine exceeds a predetermined overvoltage threshold.

8. The electrical system of claim 1 , wherein the controller is a microcontroller connected to a respective gate driver of each of the semiconductor switches of the PIM, and wherein the microcontroller is configured to turn on the upper semiconductor switches and turn off the lower semiconductor switches of the PIM in response to the detection of the reverse electrical current condition when the induced voltage of the electric machine exceeds a voltage level of the DC voltage bus.

9. The electrical system of claim 1 , further comprising a DC power connector, wherein the RCP circuit is packaged within the DC power connector.

10. The electrical system of claim 9 , wherein the RCP circuit includes, as the energy dissipating device, a semiconductor switch in series with a power resistor, and further includes one of: a Zener diode and an operational amplifier, wherein the semiconductor switch has a gate connected to an anode of the Zener diode or an output of the operational amplifier.

11. The electrical system of claim 9 , wherein the RCP circuit includes a metal-oxide-varistor as the energy dissipating element.

12. The electrical system of claim 9 , wherein the RCP circuit includes an ultra-capacitor as the energy dissipating element.

13. The electrical system of claim 1 , wherein the electric machine is connected to a drive axle of a vehicle and configured to generate torque at a level suitable for propelling the vehicle.

14. The electrical system of claim 1 , wherein the electric machine is connected to a hydraulic brake boost system of a vehicle, and is configured to generate a braking force at a level suitable for slowing the vehicle during a braking maneuver.

15. A method for protecting an electrical system from a reverse current condition, the electric system having a direct current (DC) voltage bus, a power supply providing a supply voltage to the DC voltage bus, an electric machine connected to the power supply via the DC voltage bus, and a reverse current protection (RCP) circuit positioned between the power supply and the electric machine that includes an energy dissipating element, the method comprising:
detecting, via a controller, a reverse current condition of the electric system in which an electrical current flows from the electric machine toward the power supply when an induced voltage of the electric machine exceeds a voltage level of the DC voltage bus sensed by an overvoltage detection circuit with a predetermined overvoltage threshold;
opening a master switch to selectively disconnect the power supply from the DC voltage bus for a duration of the detected reverse current condition; and
transmitting a control signal to the RCP circuit via the controller to direct a flow of the electrical current, via operation of the RCP circuit, through the energy dissipating element for a duration of the reverse current condition.

16. The method of claim 15 , wherein the energy dissipating element includes a bleeding resistor or a capacitor bank, and wherein transmitting the control signal to the RCP circuit includes transmitting the control signal to a logic gate of a semiconductor switch.

17. The method of claim 15 , wherein the electrical system further includes a polyphase power inverter module (PIM) that is electrically connected to the DC voltage bus and the polyphase electric machine, the PIM having a plurality of upper semiconductor switches and a plurality of lower semiconductor switches, wherein transmitting the control signal to the RCP circuit includes transmitting the control signal to a corresponding logic gate of the upper or lower switches such that the corresponding upper or lower switches act as the energy dissipating elements in conjunction with windings of the polyphase electric machine.

18. The method of claim 17 , wherein transmitting the control signal to the RCP circuit includes transmitting the control signal to a corresponding logic gate of each of the upper switches to short the machine windings via the lower switches while the upper switches remain off.

19. The method of claim 17 , wherein transmitting the control signal to the RCP circuit includes transmitting the control signal to a corresponding logic gate of each of the lower switches to short the machine windings via the upper switches while the lower switches remain off.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Namuduri Chandra S
• Vyas Rajeev
• Gopalakrishnan Suresh
• Rychlinski Mark J
• Demmerle Markus
• Sadekar Varsha K

Classifications

• H02H3/18 Primary

  responsive to reversal of direct current · CPC title

• H02H7/12

  for static converters or rectifiers {(for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981)} · CPC title

• H02H7/097

  against wrong direction of rotation · CPC title

• B60L7/18

  Controlling the braking effect (B60L7/12, B60L7/14, B60L7/16 take precedence) · CPC title

• B60L7/22

  Dynamic electric resistor braking, combined with dynamic electric regenerative braking · CPC title