Capacitor electric leakage prevention circuit for lithium battery BMS (Battery Management System) board

Abstract

The utility model discloses a capacitor electric leakage prevention circuit for a lithium battery BMS board. The capacitor electric leakage prevention circuit comprises a chip power supply pin VCC, and a main power supply circuit and an auxiliary power supply circuit which are connected with the chip power supply pin VCC. The main power supply circuit is composed of a resistor R8 and is used for providing normal working current for the chip; the auxiliary power supply circuit is composed of a resistor R21, a diode D1 and a capacitor C9 so as to prevent electric leakage after the capacitor C9 is damaged. When the voltage of the main power supply circuit is stable, the auxiliary power supply circuit slowly charges the capacitor C9 through the resistor R21. When the voltage of the main power supply circuit drops suddenly, the capacitor C9 releases stored energy to the power pin of the chip VCC through the diode D1 so as to maintain the voltage stable. Through a two-path cooperative power supply structure and a high-resistance current-limiting design, the leakage current of the capacitor is limited to a microampere level while the stability of a chip power supply is maintained, and a battery pack is prevented from being scrapped due to long-term electric leakage.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery circuit technology, and in particular to a lithium battery BMS board anti-capacitor leakage circuit. Background Technology

[0002] With the rapid development of lithium-ion battery technology, lithium battery packs have been widely used in consumer electronics, electric vehicles, energy storage systems, and other fields due to their advantages such as high energy density and long cycle life. As the core management unit of a lithium battery pack, the battery management system (BMS) ensures the safe operation of the battery pack by monitoring parameters such as battery voltage, temperature, and current in real time and controlling the on / off state of the protection board.

[0003] Currently, the power supply pin VCC of the chip used in lithium battery pack BMS protection boards on the market typically uses one or more high-capacity capacitors, such as... Figure 1 (C9) is used to maintain stable chip operation. However, high-capacity capacitors have a drawback: they are easily damaged by various harsh external factors (such as external impacts, circuit board bending and deformation, moisture, severe vibration, drops, voltage surges, electrostatic discharge, etc.), causing varying degrees of leakage problems. Since the lithium battery BMS protection system is constantly powered by the lithium battery pack, capacitor damage and leakage will eventually deplete the lithium battery pack. When the voltage is too low, the lithium battery will suffer irreversible internal damage, ultimately causing the entire lithium battery pack to malfunction and become unusable. Utility Model Content

[0004] This invention addresses the shortcomings of existing technologies by providing a lithium battery BMS board anti-capacitor leakage circuit. Through a dual-path collaborative power supply structure and a high-resistance current limiting design, it maintains the stability of the chip power supply while limiting the capacitor leakage current to the microampere level, thus preventing the battery pack from being scrapped due to long-term leakage.

[0005] To solve the above-mentioned technical problems, this utility model provides a lithium battery BMS board anti-capacitor leakage circuit, comprising:

[0006] The chip's power supply pin VCC and the main power supply circuit and auxiliary power supply circuit connected to it;

[0007] The main power supply circuit consists of resistor R8, which is used to provide the chip with normal operating current.

[0008] The auxiliary power supply circuit consists of resistor R21, diode D1 and capacitor C9 to prevent leakage after capacitor C9 is damaged.

[0009] When the main power supply circuit voltage is stable, the auxiliary power supply circuit slowly charges capacitor C9 through resistor R21; when the main power supply circuit voltage suddenly drops, capacitor C9 releases stored energy to the chip's VCC power supply pin through diode D1 to maintain voltage stability.

[0010] In the above scheme, preferably, one end of the resistor R8 is connected to the positive terminal of the lithium battery pack, and the other end is connected to the chip power supply pin VCC.

[0011] In the above scheme, preferably, one end of the resistor R21 is connected to the positive terminal of the lithium battery pack, and the other end is connected to the positive terminal of the capacitor C9 through the diode D1. The negative terminal of the capacitor C9 is grounded, and the positive terminal of the capacitor C9 is also connected to the VCC power supply pin of the chip.

[0012] In the above scheme, preferably, the resistance value of the resistor R8 is in the range of 100Ω-10000Ω.

[0013] In the above scheme, preferably, the resistance value of the resistor R21 is in the megohm range, so that when the capacitor C9 is damaged and leaks current, the leakage current is limited to the microampere level.

[0014] In the above scheme, preferably, the anode of the diode D1 is connected to the resistor R21, and the cathode is connected to the positive terminal of the capacitor C9, forming a unidirectional conduction path, which is used to isolate the auxiliary power supply circuit from the main power supply circuit and prevent the current from flowing back into the main power supply circuit when the capacitor C9 is discharging.

[0015] In the above scheme, preferably, the resistance value of resistor R21 is ≥1MΩ, so as to limit the charging current of capacitor C9.

[0016] The beneficial effects of this utility model are:

[0017] 1. Leakage resistance: By limiting the current with megohm-level resistors, the leakage current is reduced to the microampere level, preventing the battery pack from being over-discharged due to capacitor leakage.

[0018] 2. Power supply stability: The two power supplies work together to ensure that the chip can still maintain stable operation when the main circuit is abnormal. Attached Figure Description

[0019] Figure 1 The capacitor power supply circuit for the VCC pin of the BMS chip in the prior art.

[0020] Figure 2 This utility model presents a schematic diagram of an anti-capacitor leakage circuit structure. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments: See below Figures 1-2 .

[0022] A lithium battery BMS board anti-capacitor leakage circuit includes a chip power supply pin VCC and a main power supply circuit and a secondary power supply circuit connected in parallel to the chip power supply pin VCC. The main power supply circuit is composed of a resistor R8, which is used to provide normal operating current to the chip. Specifically, one end of the resistor R8 is connected to the positive terminal of the lithium battery pack, and the other end is directly connected to the chip power supply pin VCC. The resistance value of the resistor R8 is in the range of 100Ω-10000Ω, which is used to provide continuous current to the chip under normal operating conditions.

[0023] The auxiliary power supply circuit consists of a resistor R21, a diode D1, and a capacitor C9 to prevent leakage after capacitor C9 is damaged. Specifically, one end of the resistor R21 is connected to the positive terminal of the lithium battery pack, and the other end is connected to the positive terminal of capacitor C9 through diode D1. The negative terminal of capacitor C9 is grounded, and the positive terminal of capacitor C9 is also connected to the VCC power supply pin of the chip.

[0024] The resistance value of the resistor R21 is in the megohm range. Specifically, the resistance value of the resistor R21 can be ≥1MΩ, thereby limiting the leakage current to the microampere level when the capacitor C9 is damaged and leaks current. It can also limit the charging current of the capacitor C9 during normal charging, so that it charges smoothly.

[0025] The anode of the diode D1 is connected to the resistor R21, and the cathode is connected to the positive terminal of the capacitor C9, forming a unidirectional conduction path. This path is used to isolate the auxiliary power supply circuit from the main power supply circuit and prevent the current from flowing back into the main power supply circuit when the capacitor C9 is discharging. The unidirectional conduction characteristic of the diode D1 isolates the main power supply circuit from the auxiliary power supply circuit and prevents the current from flowing back when the capacitor C9 is discharging.

[0026] When the main power supply circuit voltage is stable, the auxiliary power supply circuit slowly charges capacitor C9 through resistor R21; when the main power supply circuit voltage suddenly drops, capacitor C9 releases stored energy to the chip's VCC power supply pin through diode D1 to maintain voltage stability.

[0027] A method for using a lithium battery BMS board anti-capacitor leakage circuit as described above:

[0028] 1. Normal power supply mode: The main power supply circuit provides a stable current through the low-resistance resistor R8. Diode D1 is reverse-biased and cut off because the voltage of the main circuit is higher than that of the secondary circuit, thus avoiding current shunting.

[0029] 2. Voltage sag compensation mode: When the main circuit voltage drops (such as due to load change or battery transient response), diode D1 conducts in the forward direction, and capacitor C9 releases stored energy to the chip power supply pin VCC through a low impedance path to maintain chip power supply.

[0030] 3. Leakage protection mode: If capacitor C9 leaks due to damage, megohm-level resistor R21 will limit the total current of the leakage path to the microampere level, so that the capacity loss of the battery pack due to leakage is much lower than the self-discharge rate.

[0031] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A lithium battery BMS board anti-capacitor leakage circuit, characterized by: The application relates to a lithium battery protection circuit. The main power supply circuit and the auxiliary power supply circuit connected with the chip power pin VCC; The main power supply circuit is composed of a resistor R8 and used for providing normal working current for the chip; The auxiliary power supply circuit is composed of a resistor R21, a diode D1 and a capacitor C9 and used for preventing the capacitor C9 from leaking after being damaged; When the voltage of the main power supply circuit is stable, the auxiliary power supply circuit slowly charges the capacitor C9 through the resistor R21; when the voltage of the main power supply circuit suddenly drops, the capacitor C9 releases the stored energy to the chip VCC power pin through the diode D1 to maintain the voltage stability.

2. The lithium battery BMS board anti-capacitor leakage circuit according to claim 1, characterized in that: One end of the resistor R8 is connected with the positive pole of a lithium battery pack, and the other end is connected with the chip power pin VCC.

3. The lithium battery BMS board anti-capacitor leakage circuit according to any one of claims 1-2, characterized in that: One end of the resistor R21 is connected with the positive pole of the lithium battery pack, the other end is connected with the positive pole of the capacitor C9 through the diode D1, the negative pole of the capacitor C9 is grounded, and the positive pole of the capacitor C9 is also connected with the chip VCC power pin.

4. The lithium battery BMS board anti-capacitor leakage circuit according to claim 1, characterized in that: The resistor R8 has a resistance value in the range of 100-10000 ohms.

5. The lithium battery BMS board anti-capacitor leakage circuit according to claim 1, characterized in that: The resistor R21 has a resistance value in the range of mega-ohms, so that the leakage current of the capacitor C9 is limited to the micro-ampere level when the capacitor C9 is damaged and leaks.

6. The lithium battery BMS board anti-capacitor leakage circuit according to claim 1, characterized in that: The anode of the diode D1 is connected with the resistor R21, and the cathode is connected with the positive pole of the capacitor C9, so as to form a one-way conduction path and isolate the auxiliary power supply circuit from the main power supply circuit, thereby preventing the current from flowing reversely into the main power supply circuit when the capacitor C9 discharges.

7. The lithium battery BMS board anti-capacitor leakage circuit according to claim 4, characterized in that: The resistor R21 has a resistance value greater than 1M ohm, so as to limit the charging current of the capacitor C9.

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