Electric vehicle battery test
First Claim
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1. An electric vehicle comprising:
- a motor coupled to one or more wheels of the electric vehicle;
an inverter coupled to the motor;
a first power bus coupled to the inverter; and
a first battery string having an output that is coupled to the first power bus through a first switch,a second battery string different from the first battery string having an output that is coupled to the first power bus through a second switch different from the first switch;
for each of the first and second battery string;
a first test load with a known impedance connected to a positive node of the respective battery string and a second test load with a known impedance connected to a negative node of the respective battery string; and
a battery management circuit coupled to at least the first switch and the second switch, the battery management circuit configured to selectively and independently control the open or closed state of the first switch and the second switch, the battery management circuit further configured to perform isolation fault testing by;
performing testing steps including;
during a first predetermined time window of a timeframe, determining an isolation status of the first battery string, during a second predetermined time window of the timeframe, determining an isolation status of the second battery string, calculating a new time window value based on the isolation status of the first battery string, and setting the first predetermined time window to the new time window value; and
repeating the testing steps;
wherein the isolation status of each of the first and second battery strings is determined by;
comparing a first voltage measurement across the first test load between the positive node and a chassis ground of the electric vehicle with a first expected voltage based on the impedance of the first test load; and
comparing a second voltage measurement across the second test load between the negative node and the chassis ground of the electric vehicle with a second expected voltage based on the impedance of the second test load.
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Abstract
An adaptive and adjustable isolation fault testing of a multi-string battery of an electric vehicle is disclosed. The isolation fault testing can be performed in an adjustable or predetermined loop having dedicated time windows for respective battery strings in compliance with the system requirements, specification, and regulatory regime.
17 Citations
17 Claims
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1. An electric vehicle comprising:
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a motor coupled to one or more wheels of the electric vehicle;
an inverter coupled to the motor;
a first power bus coupled to the inverter; anda first battery string having an output that is coupled to the first power bus through a first switch, a second battery string different from the first battery string having an output that is coupled to the first power bus through a second switch different from the first switch; for each of the first and second battery string; a first test load with a known impedance connected to a positive node of the respective battery string and a second test load with a known impedance connected to a negative node of the respective battery string; and a battery management circuit coupled to at least the first switch and the second switch, the battery management circuit configured to selectively and independently control the open or closed state of the first switch and the second switch, the battery management circuit further configured to perform isolation fault testing by; performing testing steps including;
during a first predetermined time window of a timeframe, determining an isolation status of the first battery string, during a second predetermined time window of the timeframe, determining an isolation status of the second battery string, calculating a new time window value based on the isolation status of the first battery string, and setting the first predetermined time window to the new time window value; andrepeating the testing steps; wherein the isolation status of each of the first and second battery strings is determined by; comparing a first voltage measurement across the first test load between the positive node and a chassis ground of the electric vehicle with a first expected voltage based on the impedance of the first test load; and comparing a second voltage measurement across the second test load between the negative node and the chassis ground of the electric vehicle with a second expected voltage based on the impedance of the second test load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of testing a plurality of battery strings in an electric vehicle comprising:
performing a battery test, the battery test steps comprising; disconnecting a first battery string from a power bus of the electric vehicle; during a first predetermined time window within a timeframe, determining an isolation status of the first battery string by performing an isolation fault test on the first battery string; reconnecting the first battery string to the power bus; while the first battery string remains connected to the power bus, disconnecting a second battery string from the power bus of the electric vehicle; during a second predetermined time window within the timeframe, determining an isolation status of the second battery string by performing an isolation fault test on the second battery string; calculating a new time window value different from the first predetermined time window based on the isolation status of the first battery string; setting the first predetermined time window to the new time window value; and repeating the steps of the battery test; wherein performing the isolation fault test on each tested battery string comprises; comparing a first voltage measurement across a first test load between a positive node of the tested battery string and a chassis ground of the electric vehicle with a first expected voltage based on a known impedance of the first test load; comparing a second voltage measurement across a second test load between a negative node of the tested battery string and the chassis ground of the electric vehicle with a second expected voltage based on a known impedance of the second test load. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
Specification