Zone fault detection method and system for electric vehicle charging systems

Patent metadata

Field	Value
Publication number	US-9841451-B2
Application number	US-201314774872-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A system for detecting faults in an electric vehicle charging system includes an electric vehicle supply equipment (EVSE) coupled to an electric vehicle via a cable. The EVSE includes a first charging circuit interrupting device (CCID) configured to detect faults at let-go levels between an ungrounded conductor in the cable and an external (or unintended) ground. The first CCID is also configured to detect faults above leakage current levels between a chassis of the vehicle and a power storage device of the vehicle. A second CCID is included in the cable or the vehicle to detect faults at let-go levels between an ungrounded conductor in the cable and the chassis. The system maintains grounding continuity between the electric vehicle and ground. The system thus provides protection at let-go levels while allowing a leakage current in the vehicle to be detected at a higher level for nuisance trip avoidance.

First claim

What is claimed is:

1. A system for detecting faults in an electric vehicle charging system, the system comprising:
an electric vehicle supply equipment (EVSE);
a cable for electrically coupling the EVSE to a power storage device located in an electric vehicle, the cable including a first ungrounded cable conductor and a second ungrounded cable conductor each conducting a respective current between the EVSE and the power storage device to charge the power storage device, the cable further including a grounded cable conductor for conducting electrical current from the vehicle to a ground at the EVSE; and
a first charging circuit interrupting device (CCID) at the EVSE, the first CCID being configured to monitor a current differential between the current conducted on the first ungrounded cable conductor, the current conducted on the second ungrounded cable conductor, and a first portion of the current conducted on the grounded cable conductor, the EVSE being configured such that a second portion of the current conducted on the grounded cable conductor bypasses the first CCID.

2. The system of claim 1 , wherein the EVSE includes a first grounded EVSE conductor and a second grounded EVSE conductor electrically coupled to the grounded cable conductor of the cable, the first portion of the current on the grounded cable conductor being conducted to ground via the first grounded EVSE conductor, the second portion of the current on the grounded cable conductor being conducted to ground via the second grounded EVSE conductor, the first grounded EVSE conductor being in electrical communication with the first CCID such that the first portion of the current on the grounded cable conductor is monitored by the first CCID, wherein the second portion of the current on the grounded cable conductor being conducted to ground via the second grounded EVSE conductor bypasses the first CCID.

3. The system of claim 2 , wherein the first CCID is configured to cause an interruption of current on at least one of the first ungrounded cable conductor or the second ungrounded cable conductor in response to the current differential being greater than a threshold limit.

4. The system of claim 3 , wherein the first grounded EVSE conductor and the second grounded EVSE conductor have respective impedances configured such that a leakage current conducted from the vehicle to the ground on the grounded cable conductor does not cause the first CCID to interrupt the current on the first ungrounded cable conductor and the second ungrounded cable conductor.

5. The system of claim 4 , wherein the threshold limit is approximately 5 mA.

6. The system of claim 5 , wherein the leakage current is between just above the threshold limit to approximately 15 mA.

7. The system of claim 1 , wherein the grounded cable conductor is electrically coupled to a chassis of the vehicle.

8. The system of claim 7 , further comprising a ground monitoring device configured to determine whether the grounded cable conductor is coupled to the ground and, if the grounded cable conductor is determined to not be coupled to ground, to cause an interruption of current on the first ungrounded cable conductor and the second ungrounded cable conductor.

9. The system of claim 1 , further comprising a second CCID located in the cable.

10. The system of claim 9 , further comprising a first control pilot circuit located at the EVSE and a second control pilot circuit located at the vehicle, the first control pilot circuit being communicatively coupled to the second control pilot circuit via a control pilot conductor in the cable and the grounded cable conductor in the cable, the second CCID being configured to monitor a current differential between the first ungrounded cable conductor, the second ungrounded cable conductor, the grounded cable conductor, and the control pilot conductor.

11. The system of claim 10 , wherein the second CCID is configured to cause the control pilot conductor to be shorted to the grounded cable conductor to cause the EVSE to interrupt the current on the first ungrounded cable conductor and the second ungrounded cable conductor.

12. The system of claim 10 , wherein the second CCID is configured to cause the grounded cable conductor to be coupled via a resistor to at least one of the first ungrounded cable conductor or the second ungrounded cable conductor to cause the EVSE to interrupt the current on the first ungrounded cable conductor and the second ungrounded cable conductor.

13. The system of claim 1 , further comprising a second CCID located in the vehicle.

14. The system of claim 1 , further comprising a power source configured to provide one of a 120 V AC , a 240 V AC , and a three-phase power to the EVSE.

15. A method of providing zone fault detection for an electric vehicle being charged by an electric vehicle supply equipment (EVSE), the method comprising:
conducting an electrical current from an EVSE to a power storage device of an electric vehicle via a cable coupled to the EVSE to charge the power storage device;
detecting whether a first fault has occurred in a first zone by a first charging circuit interrupting device (CCID) at the EVSE, the first zone being between the power storage device and a chassis of the electric vehicle;
detecting whether a second fault has occurred in a second zone by a second CCID, the second zone being between an ungrounded conductor in the cable and the chassis of the vehicle;
detecting whether a third fault has occurred in a third zone by the first CCID, the third zone being between the ungrounded conductor in the cable and a ground external to the EVSE, the cable, and the vehicle; and
interrupting the conduction of electrical current from the EVSE to the power storage device in response to an occurrence of at least one of the first fault, the second fault, or the third fault being detected.

16. The method of claim 15 , wherein the first CCID is configured to cause the interruption of electrical current in response to the first fault being greater than approximately 15 mA, the first CCID being further configured to cause the interruption in response to the third fault being greater than approximately 5 mA, and the second CCID is configured to cause the interruption in response to the second fault being greater than approximately 5 mA.

17. The method of claim 15 , wherein the first CCID is configured to cause the interruption of electrical current in response to the first fault being greater than a maximum leakage current level, the first CCID being further configured to cause the interruption in response to the third fault being greater than a let-go level, and the second CCID is configured to cause the interruption in response to the second fault being greater than the let-go level.

18. The method of claim 15 , further comprising:
conducting electrical current in response to the first fault from the chassis to a ground at the EVSE via a grounded conductor in the cable coupled to the chassis;
conducting a first portion of the electrical current in response to the first fault to the ground through the first CCID; and
conducting a second portion of the electrical current in response to the first fault to bypass the first CCID to the ground.

19. The method of claim 15 , wherein the first CCID includes two first charging circuit interrupting devices, the method further comprising:
monitoring, via one of the two first charging circuit interrupting devices, a current differential between the current conducted on a plurality ungrounded conductors in the cab

Assignees

• Schneider Electric Usa Inc

Inventors

• Reid Paul Andrew
• Sharp Jeffrey Owen

Classifications

• G01R31/52

  Testing for short-circuits, leakage current or ground faults · CPC title

• B60L58/15

  Preventing overcharging · CPC title

• Y04S30/14

  Details associated with the interoperability, e.g. vehicle recognition, authentication, identification or billing · CPC title

• B60L53/18

  Cables specially adapted for charging electric vehicles · CPC title

• B60L2200/18

  Buses · CPC title