# US 12,009,682 B2 · Load access detection method, switch circuit, and battery management system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,682 B2 - Document ID: US12009682B2 - Status: Granted - Kind: B2 - Application number: 17/479,505 - Filed: 2021-09-20 - Published: 2022-01-06 - Granted: 2024-06-11 - Earliest claimed: 2020-04-09 - Assignees: Contemporary Amperex Technology Co., Limited - Applicants: Contemporary Amperex Technology Co., Limited - Inventors: Xu Zhang; Hang Ma; Xingchang Wang - Web page: https://patentgrep.com/patent/US12009682B2 ## CPC - H02J 7/80: including monitoring or indicating arrangements - B60L 3/0046: {relating to electric energy storage systems, e.g. batteries or capacitors} - B60L 3/0069: {relating to the isolation, e.g. ground fault or leak current} - B60L 3/04: Cutting off the power supply under fault conditions (protective devices and circuit arrangements in general H01H; H02H) - B60L 3/12: Recording operating variables {; Monitoring of operating variables} - B60L 50/66: {Arrangements of batteries} - B60L 58/12: responding to state of charge [SoC] - G01R 31/3835: involving only voltage measurements - H02J 7/345: {using capacitors as storage or buffering devices} - H02J 7/62: against overcurrent - H02J 7/855: {with circuits adapted for supplying loads from the battery} - H02J 7/96: in response to battery voltage - B60L 2240/547: Voltage - B60L 2240/549: Current - Y02T 10/70: Energy storage systems for electromobility, e.g. batteries - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A load access detection method, a switch circuit, and a battery management system, relating to the field of circuit technology. The load access detection method includes: detecting a voltage at a first detection point; detecting a voltage at a second detection point; if a voltage difference between the voltage at the first detection point and the voltage at the second detection point is less than or equal to a preset voltage threshold, controlling a switch circuit to enter a pre-charging mode, and pre-charging a load capacitor in the load circuit through the battery pack, where a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode. ## Claims ### Claim 1 A load access detection method, comprising: detecting a voltage at a first detection point, wherein the first detection point is electrically connected to a positive electrode of a battery group in a battery pack through a bridging resistor; detecting a voltage at a second detection point, wherein the second detection point is short-circuited with the first detection point when the battery pack is connected to a load circuit; and under a voltage difference between the voltage at the first detection point and the voltage at the second detection point being less than or equal to a preset voltage threshold condition, controlling a switch circuit to enter a pre-charging mode, and pre-charging a load capacitor in the load circuit through the battery pack, wherein a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode. ### Claim 2 (depends on 1) The load access detection method according to claim 1, wherein the under a voltage difference between the voltage at the first detection point and the voltage at the second detection point being less than or equal to a preset voltage threshold condition, controlling a switch circuit to enter a pre-charging mode, and pre-charging a load capacitor in the load circuit through the battery pack comprises: under the voltage difference between the voltage at the first detection point and the voltage at the second detection point being less than or equal to the preset voltage threshold within a first preset period condition, controlling the switch circuit to enter the pre-charging mode, and pre-charging the load capacitor in the load circuit through the battery pack. ### Claim 3 (depends on 2) The load access detection method according to claim 2, wherein the switch circuit comprises a first switch, a second switch, and a third switch, and the method comprises: turning off the second switch, turning on a charging direction of the first switch, and turning on a charging direction of the third switch, so as to form the charging mode of the switch circuit; and turning off the first switch, turning on a charging direction of the second switch, and turning on the charging direction of the third switch, so as to form the pre-charging mode of the switch circuit; wherein the first switch is connected in parallel with the second switch; the first switch is connected in series with the third switch; and the second switch is connected in series with the third switch through at least one resistor. ### Claim 4 (depends on 1) The load access detection method according to claim 1, wherein the switch circuit comprises a first switch, a second switch, and a third switch, and the method comprises: turning off the second switch, turning on a charging direction of the first switch, and turning on a charging direction of the third switch, so as to form the charging mode of the switch circuit; and turning off the first switch, turning on a charging direction of the second switch, and turning on the charging direction of the third switch, so as to form the pre-charging mode of the switch circuit; wherein the first switch is connected in parallel with the second switch; the first switch is connected in series with the third switch; and the second switch is connected in series with the third switch through at least one resistor. ### Claim 5 (depends on 1) The load access detection method according to claim 1, wherein the controlling a switch circuit to enter a pre-charging mode, and pre-charging a load capacitor in the load circuit through the battery pack comprises: controlling the switch circuit to maintain the pre-charging mode within a second preset period, and pre-charging the load capacitor through the battery pack. ### Claim 6 (depends on 1) The load access detection method according to claim 1, further comprising: determining that an access fault occurs under the voltage difference between the voltage at the first detection point and the voltage at the second detection point being greater than the voltage threshold condition. ### Claim 7 A battery management system, comprising: a detection unit, configured to detect a voltage at a first detection point, wherein the first detection point is electrically connected to a positive electrode of a battery group in a battery pack through a bridging resistor; the detection unit is further configured to detect a voltage at a second detection point, wherein the second detection point is short-circuited with the first detection point when the battery pack is connected to a load circuit; and a processing unit, configured to control a switch circuit to enter a pre-charging mode, and pre-charge a load capacitor in the load circuit through the battery pack when a voltage difference between the voltage at the first detection point and the voltage at the second detection point is less than or equal to a preset voltage threshold, wherein a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode. ### Claim 8 (depends on 7) The battery management system according to claim 7, wherein the processing unit is configured to control the switch circuit to enter the pre-charging mode, and pre-charge the load capacitor in the load circuit through the battery pack when the voltage difference between the voltage at the first detection point and the voltage at the second detection point is less than or equal to the preset voltage threshold within a first preset period. ### Claim 9 (depends on 8) The battery management system according to claim 8, wherein the switch circuit comprises a first switch, a second switch, and a third switch, wherein the first switch is connected in parallel with the second switch; the first switch is connected in series with the third switch; and the second switch is connected in series with the third switch through at least one resistor; the processing unit is specifically configured to: turn off the first switch, turn on a charging direction of the second switch, and turn on a charging direction of the third switch, so as to form the pre-charging mode of the switch circuit; and the processing unit is specifically configured to: turn off the second switch, turn on a charging direction of the first switch, and turn on the charging direction of the third switch, so as to form the charging mode of the switch circuit. ### Claim 10 (depends on 7) The battery management system according to claim 7, wherein the switch circuit comprises a first switch, a second switch, and a third switch, wherein the first switch is connected in parallel with the second switch; the first switch is connected in series with the third switch; and the second switch is connected in series with the third switch through at least one resistor; the processing unit is specifically configured to: turn off the first switch, turn on a charging direction of the second switch, and turn on a charging direction of the third switch, so as to form the pre-charging mode of the switch circuit; and the processing unit is specifically configured to: turn off the second switch, turn on a charging direction of the first switch, and turn on the charging direction of the third switch, so as to form the charging mode of the switch circuit. ### Claim 11 (depends on 7) The battery management system according to claim 7, wherein the processing unit is configured to control the switch circuit to maintain the pre-charging mode within a second preset period, and pre-charge the load capacitor through the battery pack. ### Claim 12 (depends on 7) The battery management system according to claim 7, wherein the processing unit is further configured to determine that an access fault occurs when the voltage difference between the voltage at the first detection point and the voltage at the second detection point is greater than the voltage threshold. ### Claim 13 A switch circuit, comprising a first switch, a second switch, and a third switch; wherein the first switch is connected in parallel with the second switch, the first switch is connected in series with the third switch, and the second switch is connected in series with the third switch through at least one resistor; the switch circuit is configured to enter a pre-charging mode according to control of the battery management system; and the switch circuit is further configured to pre-charge a load capacitor in the load circuit through the battery pack, wherein a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode. ### Claim 14 (depends on 13) The switch circuit according to claim 13, wherein that the switch circuit is configured to enter the pre-charging mode according to control of the battery management system is specifically that: the first switch is configured to be turned off, a charging direction of the second switch is configured to be turned on, and a charging direction of the third switch is configured to be turned on, so as to form the pre-charging mode of the switch circuit. ### Claim 15 (depends on 14) The switch circuit according to claim 14, wherein the switch circuit is further configured such that: the second switch is configured to be turned off, a charging direction of the first switch is configured to be turned on, and the charging direction of the third switch is configured to be turned on, so as to form the charging mode of the switch circuit. ### Claim 16 (depends on 13) The switch circuit according to claim 13, wherein the switch circuit is further configured such that: the second switch is configured to be turned off, a charging direction of the first switch is configured to be turned on, and the charging direction of the third switch is configured to be turned on, so as to form the charging mode of the switch circuit. ### Claim 17 (depends on 13) A load access detection method, wherein the method is applied to the switch circuit according to claim 13, and the method comprises: entering, by the switch circuit, a pre-charging mode according to control of a battery management system; pre-charging, by the switch circuit, a load capacitor in a load circuit through a battery pack, wherein a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode; and the entering, by the switch circuit, a pre-charging mode according to control of a battery management system comprises: controlling, by the battery management system, the switch circuit to enter the pre-charging mode under a voltage difference between a voltage at a first detection point and a voltage at a second detection point being less than or equal to a preset voltage threshold condition; detecting, by the battery management system, the voltage at the first detection point, wherein the first detection point is electrically connected to a positive electrode of a battery group in a battery pack through a bridging resistor; and detecting, by the battery management system, the voltage at the second detection point, wherein the second detection point is short-circuited with the first detection point when the battery pack is connected to a load circuit. ### Claim 18 (depends on 17) The load access detection method according to claim 17, wherein the controlling, by the battery management system, the switch circuit to enter the pre-charging mode comprises: under the control of the battery management system, turning off, by the switch circuit, the first switch, and turning on a charging direction of the second switch and a charging direction of the third switch, so as to form the pre-charging mode of the switch circuit. ### Claim 19 (depends on 17) The load access detection method according to claim 17, wherein the method further comprises: under the control of the battery management system, turning off, by the switch circuit, the second switch, and turning on a charging direction of the first switch and the charging direction of the third switch, so as to form the charging mode of the switch circuit. ### Claim 20 (depends on 7) A load access detection system, comprising the battery management system according to claim 7, and the load access detection system further comprises: a switch circuit, comprising a first switch, a second switch, and a third switch; wherein the first switch is connected in parallel with the second switch, the first switch is connected in series with the third switch, and the second switch is connected in series with the third switch through at least one resistor; the switch circuit is configured to enter a pre-charging mode according to control of the battery management system; and the switch circuit is further configured to pre-charge a load capacitor in the load circuit through the battery pack, wherein a charging current of the switch circuit in the pre-charging mode is less than a charging current of the switch circuit in a charging mode.