Measuring isolated high voltage and detecting isolation breakdown with measures for self-detection of circuit faults
View Patent ↗A system for making high voltage measurements to measure a voltage of a battery pack and detect of an isolation fault. The system includes a first resistive divider comprising at least a first resistive element and a second resistive element. The system also includes a second resistive divider comprising the second resistive element and a third resistive element. The system also includes a plurality of switches comprising a first switch and a second switch coupled between the second resistive element and the battery pack. The system further includes a controller configured to control the plurality of switches to operate in first mode to measure the voltage of the battery pack based on a voltage produced by the first resistive divider, and to control the plurality of switches to operate in at least a second mode to detect an isolation fault based on a voltage produced by the second resistive divider.
1. A system for making high voltage measurements to measure a voltage of a battery pack and detect of an isolation fault, the system comprising:
a first resistive divider comprising at least a first resistive element and a second resistive element;
a second resistive divider comprising the second resistive element and a third resistive element;
a plurality of switches comprising a first switch and a second switch coupled between the second resistive element and the battery pack; and
a controller configured to control the plurality of switches to operate in first mode to measure the voltage of the battery pack based on a voltage produced by the first resistive divider, and to control the plurality of switches to operate in at least a second mode to detect an isolation fault based on a voltage produced by the second resistive divider.
2. The system of claim 1 , wherein the controller is configured to control the plurality of switches to operate in a third mode to verify operation of the plurality of switches.
3. The system of claim 1 , wherein the first and third resistive elements are connected to first and second terminals of the battery pack, respectively.
4. The system of claim 1 , wherein the first switch is connected between the first resistive element and the second resistive element and the second switch is connected between the second resistive element and the third resistive element.
5. The system of claim 1 , wherein the system is configured to measure the voltage of the battery pack by measuring a voltage across the second resistive element that is representative of the voltage of the battery pack.
6. The system of claim 5 , further comprising:
a second plurality of switches coupled to the second resistive element, wherein the controller is configured to sample the voltage across the second resistive element by turning on the second plurality of switches.
7. The system of claim 6 , further comprising a capacitor connected to the second plurality of switches to sample the voltage across the second resistive element.
8. The system of claim 1 , further comprising a third switch to connect the third resistive element to the second resistive element when the plurality of switches are controlled to operate in the second mode, wherein the controller is configured to make a first isolation fault measurement when the plurality of switches are controlled to operate in the second mode and the third switch is turned on.
9. The system of claim 8 , further comprising:
a fourth switch to connect the third resistive element or a fourth resistive element to the second resistive element when the plurality of switches are controlled to operate in the second mode, wherein the controller is configured to make a second isolation fault measurement when the plurality of switches are controlled to operate in the second mode and the fourth switch is turned on.
10. The system of claim 7 , further comprising a third plurality of switches in series with the second plurality of switches to couple the capacitor to a measurement circuit.
11. The system of claim 10 , wherein the controller is configured to control the system in a self-check mode to verify operation of the third plurality of switches, the second plurality of switches and/or the first plurality of switches.
12. The system of claim 1 , further comprising:
an analog to digital converter configured to receive a voltage produced by the first or second resistive divider and convert the voltage produced by the first or second resistive divider to a digital value.
13. The system of claim 12 , further comprising:
a self-check circuit connected to an input of the analog-to-digital converter to couple the analog-to-digital converter to at least one reference voltage.
14. The system of claim 13 , wherein the controller is configured to verify operation of the self-check circuit by coupling the input of the analog-to-digital converter to the at least one reference voltage to verify that the digital value produced by the analog-to-digital converter is indicative of the at least one reference voltage.
15. The system of claim 1 , wherein the controller is configured to determine a voltage across the isolation fault.
16. The system of claim 1 , wherein the controller is configured to determine the magnitude of the isolation fault.
17. The system of claim 16 , wherein the controller is configured to determine a degree of uncertainty with which the magnitude of the isolation fault is measured.
18. The system of claim 17 , wherein the controller is configured to make isolation measurements in a first mode with a first measurement timing and a second mode with a second measurement timing.
19. The system of claim 18 , wherein the first measurement timing and the second measurement timing are selected based on a desired measurement accuracy for the first mode, and the second mode, respectively.
20. The system of claim 1 , wherein the controller is configured to measure a capacitance in parallel with the isolation fault.
21. The system of claim 1 , wherein the controller is configured to temporarily disable cell measurements while isolation measurements are made.
22. The system of claim 1 , further additional resistors and switches to make additional high voltage measurements.
23. A system for measuring a voltage of a battery pack and a detecting of an isolation fault, the system comprising:
a plurality of resistive elements;
a plurality of switches connected to the plurality of resistive elements; and
a controller configured to control the plurality of switches to operate in first mode to measure the voltage of the battery pack based on a signal produced by coupling the plurality of resistive elements to the battery pack in a first configuration, and to control the plurality of switches to operate in at least a second mode to detect an isolation fault based on a signal produced by coupling the plurality of resistive elements to the battery pack in at least a second configuration.
24. The system of claim 23 , wherein the controller is configured to control the plurality of switches to operate in the second mode to couple the plurality of resistive elements to the battery pack in the second configuration to make a first isolation fault measurement, and to control the plurality of switches to operate in a third mode to couple the plurality of switches to the battery pack in a third configuration to make a second isolation fault measurement.
25. The system of claim 24 , wherein the controller is configured to detect an isolation fault based on the first and second isolation fault measurements.
26. The system of claim 24 , wherein the controller is configured to determine a magnitude of the isolation fault based on the first and second isolation fault measurements.
27. A system for measuring a magnitude of an isolation fault from a battery pack, the system comprising:
a first resistive divider comprising at least a first resistive element and a second resistive element;
a second resistive divider comprising the second resistive element and a third resistive element;
a plurality of switches coupled between the second resistive element and the battery pack; and
a controller configured to control the plurality of switches to operate in a first mode to make a first measurement using the first resistive divider, to make a second measurement using the second resistive divider, and to determine a magnitude of the isolation fault based on the first and second measurements.
28. The system of claim 27 , wherein the controller is configured to determine a voltage across the isolation fault.
29. The system of claim 27 , wherein the controller is configured to determine a degree of uncertainty with which the magnitude of the isolation fault is measured.
30. The system of claim 27 , wherein the controller is configured to measure a capacitance in parallel with the isolation fault.