Method and apparatus for high voltage isolation monitor for a vehicle

• US 9,341,665 B2
• Filed: 04/18/2012
• Issued: 05/17/2016
• Est. Priority Date: 04/18/2012
• Status: Active Grant

• Current Assignee: Lear Corporation
• Original Assignee: Lear Corporation
• Inventors: Kaminski, George, Hampo, Richard J.
• Primary Examiner(s): Nguyen, Tung X
• Assistant Examiner(s): SHAH, NEEL D
• Application Number:
  US13/449,665
• Publication Number:
  US 20130278272A1
• Time in Patent Office: 1,490 Days
• Field of Search: 324500-513, 324/523, 324/525, 324/522, 324/551, 324691-713, 702/91, 702/93, 361/42, 701/31.4, 701/34.4, 701/36, 701/102, 701/22, 701/29.6, 701/33.9, 701/29.1
• US Class Current: 1/1
• CPC Class Codes: B60L 3/0069 relating to the isolation, e.g. ground fault or leak current
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: G01R 27/18 Measuring resistance to earth , i.e. line to ground
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/14 Circuits therefor , e.g. for generating test voltages, sensing circuits G01R31/1209 - G01R31/1227 take precedence; for testing switches G01R31/327
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

An apparatus for monitoring a high voltage isolation in a vehicle. The apparatus comprising a power conversion device for receiving a high voltage on a power bus. The power conversion device is configured to control a first switch for enabling a first known resistance to receive the high voltage and to measure a first voltage between a first node and a ground in response to the first known resistance receiving the high voltage. The power conversion device is further configured to measure a second voltage between a second node and the ground in response to the first known resistance receiving the high voltage and to determine a first leakage resistance between the first node and the ground based on at least the first voltage and the second voltage. The first leakage resistance indicating whether the high voltage is isolated from the ground.

Claims

1. An apparatus for monitoring a high voltage isolation in a vehicle, the apparatus comprising:

a power conversion device for receiving a high voltage on a power bus, the power bus including a first node and a second node, the power conversion device being configured to;

control a first switch to close to enable a first known resistance to receive the high voltage;

initiate a timer in response to controlling the first switch to close;

measure a first voltage between the first node and a ground in response to the first known resistance receiving the high voltage after the timer has expired;

measure a second voltage between the second node and the ground in response to the first known resistance receiving the high voltage after the timer has expired; and

determine a first leakage resistance between the first node and the ground based on at least the first voltage and the second voltage, the first leakage resistance being indicative of whether the high voltage is isolated from the ground, wherein the power conversion device includes a relay to enable the high voltage to pass through the first switch when the power conversion device is in a normal operating mode and to prevent a voltage to pass through the first switch when the power conversion device is exposed to a hi-pot test, wherein the power conversion device is powered off when the hi-pot test is executed and the relay prevents the voltage from passing through the first switch when the hi-pot test is executed, and wherein the hi-pot test corresponds to electrically-over stressing the power conversion device.

2. The apparatus of claim 1 wherein the power conversion device is further configured to control a second switch for enabling a second known resistance to receive the high voltage and to measure a third voltage between the first node and the ground in response to the second known resistance receiving the high voltage.

3. The apparatus of claim 2 wherein the power conversion device is further configured to measure a fourth voltage between the second node and the ground in response to the second known resistance receiving the high voltage.

4. The apparatus of claim 3 wherein the power conversion device is further configured to determine a second leakage resistance between the second node and the ground based on at least the third voltage and the fourth voltage, the second leakage resistance also being indicative of whether the high voltage is isolated from the ground.

5. The apparatus of claim 1 wherein the first node of the power bus comprises a positive high voltage node.

6. The apparatus of claim 1 wherein the second node of the power bus comprises a negative high voltage node.

7. The apparatus of claim 1 wherein the ground is a chassis ground positioned in the vehicle.

8. A method for monitoring a high voltage isolation in a vehicle, the method comprising:

receiving, at a power conversion device, a high voltage on a power bus, the power bus including a first node and a second node;

controlling a first switch to close to enable a first known resistance to receive the high voltage;

initiating a timer in response to controlling the first switch to close;

measuring a first voltage between the first node and a ground in response to the first known resistance receiving the high voltage after the timer has expired;

a second voltage between the second node and the ground in response to the first known resistance receiving the high voltage after the timer has expired; and

determining a first leakage resistance between the first node and the ground based on at least the first voltage and the second voltage, the first leakage resistance being indicative of whether the high voltage is isolated from the ground;

enabling, with a relay, the high voltage to pass through the first switch in a normal operating mode;

powering off the power conversion device when a hi-pot test is executed;

preventing, with the relay, a voltage from passing through the first switch when the power conversion device is being exposed to the hi-pot test; and

wherein the hi-pot test corresponds to electrically-over stressing the power conversion device.

9. The method of claim 8 further comprising controlling a second switch for enabling a second known resistance to receive the high voltage and measuring a third voltage between the first node and the ground in response to the second known resistance receiving the high voltage.

10. The method of claim 9 further comprising measuring a fourth voltage between the second node and the ground in response to the second known resistance receiving the high voltage.

11. The method of claim 10 further comprising determining a second leakage resistance between the second node and the ground based on at least the third voltage and the fourth voltage, the second leakage resistance also being indicative of whether the high voltage is isolated from the ground.

12. The method of claim 8 wherein the first node of the power bus comprises a positive high voltage node.

13. The method of claim 8 wherein the second node of the power bus comprises a negative high voltage node.

14. The method of claim 8 wherein the ground is a chassis ground positioned in the vehicle.

15. An apparatus for monitoring a high voltage isolation in a vehicle, the apparatus comprising:

a power conversion device for receiving a high voltage on a power bus, the power bus including a positive node and a negative node, the power conversion device being configured to;

control a first switch to close to enable a first known resistance to receive the high voltage;

initiate a timer in response to controlling the first switch to close;

determine a first voltage between the positive node and a ground in response to the first known resistance receiving the high voltage after the timer has expired;

determine a second voltage between the negative node and the ground in response to the first known resistance receiving the high voltage after the timer has expired; and

determine a first leakage resistance between the positive node and the ground based on at least the first voltage and the second voltage, the first leakage resistance being indicative of whether the high voltage is isolated from the ground, wherein the power conversion device includes a relay to enable the high voltage to pass through the first switch when the vehicle is running and to prevent a voltage from passing through the first switch when the power conversion device is exposed to a hi-pot test, wherein the power conversion device is powered off when the hi-pot test is executed and the relay prevents the voltage from passing through the first switch when the hi-pot test is executed; and

wherein the hi-pot test corresponds to electrically-over stressing the power conversion device.