IP Library › Granted Patent US 12665434
Granted Patent B2
US 12665434 · App. 18/051,248 · Granted Jun 23, 2026

Methods and systems for performing active discharge using an active discharge circuit and an auxiliary circuit

Inventors: Walter Kiefer (Perl, DE); Tillasthanam V. Sriram (Carmel, IN)
Assignee: Borg Warner Luxembourg Automotive Systems S.A.
H02J7/345H02J7/663H02J7/685H02J7/963B60L50/60
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Quick Facts
Patent No.
US 12665434
App. No.
18/051,248
Granted
Jun 23, 2026
Kind
B2
Abstract

A method may include receiving a discharge request to perform discharge of a capacitor of an electric vehicle; closing a first switch a first circuit provided in parallel with a second circuit of the electric vehicle; determining a voltage drop of the capacitor, based on closing the first switch; and closing a second switch of the second circuit to perform the discharge of the capacitor, based on the determining the voltage drop of the capacitor indicating that a battery of the electric vehicle is disconnected from the capacitor.

Claims (55)

1 . A method comprising:

receiving a discharge request to perform discharge of a capacitor of an electric vehicle;

closing a first switch of a first circuit provided in parallel with a second circuit of the electric vehicle;

determining a voltage drop of the capacitor, based on closing the first switch; and

closing a second switch of the second circuit to perform the discharge of the capacitor, based on the determining the voltage drop of the capacitor indicating that a battery of the electric vehicle is disconnected from the capacitor.

2 . The method of claim 1 , further comprising:

determining that the voltage drop of the capacitor is greater than a voltage drop threshold,

wherein closing the second switch comprises closing the second switch based on determining that the voltage drop is greater than the voltage drop threshold and determining that a timeframe of the voltage drop is less than a timeframe threshold.

3 . The method of claim 1 , further comprising:

determining that a timeframe of the voltage drop is less than a timeframe threshold,

wherein closing the second switch comprises closing the second switch based on determining that the voltage drop of the capacitor is greater than a voltage drop threshold and determining that the timeframe of the voltage drop is less than the timeframe threshold.

4 . The method of claim 1 , wherein the first circuit includes the first switch and a first resistor.

5 . The method of claim 1 , wherein the first circuit includes the first switch, a high voltage power supply, and a first resistor.

6 . The method of claim 1 , wherein the first circuit includes the first switch and a current source.

7 . The method of claim 1 , wherein the first circuit includes the first switch, a high voltage power supply, and a current source.

8 . The method of claim 1 , further comprising:

after closing the second switch, determining a second voltage drop of the capacitor; and

selectively opening the second switch after closing the second switch based on determining the second voltage drop of the capacitor.

9 . An electric vehicle comprising:

a first circuit;

a second circuit configured to perform discharge of a capacitor of the electric vehicle; and

a processor configured to:

receive a discharge request to perform the discharge of the capacitor of the electric vehicle;

close a first switch of the first circuit provided in parallel with the second circuit of the electric vehicle;

determine a voltage drop of the capacitor, based on closing the first switch; and

close a second switch of the first circuit to perform the discharge the capacitor, based on the determining the voltage drop of the capacitor indicating that a battery of the electric vehicle is disconnected from the capacitor.

10 . The electric vehicle of claim 9 , wherein the processor is further configured to:

determine that the voltage drop of the capacitor is greater than a voltage drop threshold,

wherein the processor, when closing the second switch, is configured to close the second switch based on determining that the voltage drop is greater than the voltage drop threshold and determining that a timeframe of the voltage drop is less than a timeframe threshold.

11 . The electric vehicle of claim 9 , wherein the processor is further configured to:

determine that a timeframe of the voltage drop is less than a timeframe threshold,

wherein the processor, when closing the second switch, is configured to close the second switch based on determining that the timeframe of the voltage drop is less than the timeframe threshold.

12 . The electric vehicle of claim 9 , wherein the first circuit includes the first switch and a first resistor.

13 . The electric vehicle of claim 9 , wherein the first circuit includes the first switch, a high voltage power supply, and a first resistor.

14 . The electric vehicle of claim 9 , wherein the first circuit includes the first switch and a current source.

15 . The electric vehicle of claim 9 , wherein the first circuit includes the first switch, a high voltage power supply, and a current source.

16 . The electric vehicle of claim 9 , wherein the processor is further configured to:

after closing the second switch, determine a second voltage drop of the capacitor; and

selectively open the second switch after closing the second switch based on determining the second voltage drop of the capacitor.

17 . A discharge device comprising:

a memory configured to store instructions; and

a processor configured to execute the instructions to:

receive a discharge request to perform discharge of a capacitor of an electric vehicle;

close a first switch of a first circuit provided in parallel with a second circuit of the electric vehicle;

determine a voltage drop of the capacitor, based on closing the first switch; and

close a second switch of the second circuit to perform the discharge the capacitor, based on the determining the voltage drop of the capacitor indicating that a battery of the electric vehicle is disconnected from the capacitor.

18 . The discharge device of claim 17 , wherein the processor is further configured to:

determine that the voltage drop of the capacitor is greater than a voltage drop threshold,

wherein the processor, when closing the second switch, is configured to close the second switch based on determining that the voltage drop is greater than the voltage drop threshold and determining that a timeframe of the voltage drop is less than a timeframe threshold.

19 . The discharge device of claim 17 , wherein the processor is further configured to:

determine that a timeframe of the voltage drop is less than a timeframe threshold,

wherein the processor, when closing the second switch, is configured to close the second switch based on determining that the voltage drop of the capacitor is greater than a voltage drop threshold and determining that the timeframe of the voltage drop is less than the timeframe threshold.

20 . The discharge device of claim 17 , wherein the processor is further configured to:

after closing the second switch, determine a second voltage drop of the capacitor; and

selectively open the second switch after closing the second switch based on determining the second voltage drop of the capacitor.