A high-power lithium ion battery overdischarge protection circuit

Abstract

The utility model discloses a kind of overdischarge protection circuit of high-power lithium ion battery, including lithium ion battery group, sampling and comparison circuit, discharging switch and driving circuit, the sampling comparison circuit is connected with the lithium ion battery group, the discharging switch and driving circuit are connected with the anode of the lithium ion battery group, the sampling and comparison circuit connection.The utility model adopts the mode of automatically changing the reference input voltage of comparator to set overdischarge protection threshold value and overdischarge protection recovery threshold value, when battery group is discharged to discharge protection threshold value at high power, close discharging switch, so that battery group stops discharging, battery group voltage rapidly rises, while the reference input voltage of comparator is low, battery group voltage cannot reach overdischarge protection recovery threshold value, solve the problem of overdischarge protection repeated action of high-power battery group, design method is simple and easy to understand, engineering is easy to realize.

Description

Technical Field

[0001] This utility model relates to the field of aerospace power technology, specifically to an over-discharge protection circuit for a high-power lithium-ion battery. Background Technology

[0002] Satellites have increasingly higher power demands, leading to greater discharge currents in lithium-ion battery packs. The lithium-ion battery pack is a crucial component of the power subsystem, serving as the satellite's energy heart. During sunlight periods, it receives charging from solar cells, and during shadow periods, it provides energy storage power to onboard equipment. Over-discharge of the battery is a direct cause of premature battery damage or failure, and it also directly affects the overall lifespan of the satellite. To protect the battery from over-discharge damage, a battery discharge termination voltage must be set according to the load conditions to protect the battery and extend its lifespan. When the battery pack discharges at high power and reaches the discharge voltage protection threshold, disconnecting the discharge switch, the battery voltage recovers to a higher level than the discharge voltage protection threshold due to internal resistance and other issues. The discharge switch then reopens. However, because of the high-power discharge, the battery voltage quickly returns to the discharge voltage protection threshold, disconnecting the discharge switch again. This cycle of repeated discharge switch activation can cause the discharge switch to repeatedly trip. Summary of the Invention

[0003] This utility model provides an over-discharge protection circuit for high-power lithium-ion batteries, which solves the problem of repeated over-discharge protection activation in high-power battery packs. The specific technical solution is as follows:

[0004] A high-power lithium-ion battery over-discharge protection circuit, the circuit including a lithium-ion battery pack, a sampling and comparison circuit, a discharge switch and a drive circuit;

[0005] The lithium-ion battery pack is used to provide energy storage power.

[0006] The sampling and comparison circuit is connected to the lithium-ion battery pack and is used to collect the voltage of the lithium-ion battery pack and output an over-discharge judgment signal to the discharge switch and drive circuit.

[0007] The sampling and comparison circuit is also connected to an external voltage Verf, which serves as an input reference voltage.

[0008] The sampling and comparison circuit is also connected to a 12V external voltage, which serves as the power supply and pull-up voltage for the output drive. The discharge switch and drive circuit are connected to the positive terminal of the lithium-ion battery pack and the sampling and comparison circuit, and are used to control the discharge of the lithium-ion battery pack.

[0009] Preferably, the sampling and comparison circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, capacitor C1, transistor Q1, and comparator U1.

[0010] One end of resistor R4 is connected to the positive terminal of the lithium-ion battery pack, and the other end is connected to resistor R5 and the inverting input terminal of comparator U1. The other end of resistor R5 is grounded.

[0011] One end of resistor R1 is connected to the external voltage Verf, and the other end is connected to capacitor C1, resistor R2, resistor R3 and the non-inverting input of comparator U1. The other ends of capacitor C1 and resistor R2 are grounded, and the other end of resistor R3 is connected to the collector of transistor Q1. The emitter of transistor Q1 is grounded.

[0012] One end of resistor R6 is connected to the power input terminal of comparator U1 and the external 12V voltage, and the other end is connected to the output terminal of comparator U1, resistor R7, and resistor R8. The other end of resistor R8 is connected to the base of transistor Q1, and the other end of resistor R7 is connected to the discharge switch and drive circuit.

[0013] Furthermore, resistors R4 and R5 in the sampling and comparison circuit are connected to the lithium-ion battery pack to provide feedback on the real-time voltage of the lithium-ion battery pack.

[0014] Furthermore, the negative input terminal of comparator U1 in the sampling and comparison circuit acquires the output voltage of the lithium-ion battery pack. and the reference voltage connected to the non-inverting input of comparator U1 Compare and monitor the voltage status of lithium-ion battery packs in real time.

[0015] Furthermore, the sampling and comparison circuit is connected to an external voltage Verf, and through resistors R1 and R2, it provides a reference voltage for the over-discharge protection threshold. The expression for the battery pack over-discharge protection voltage threshold is as follows:

[0016] Furthermore, the sampling and comparison circuit is connected to an external voltage Verf, and through resistors R3 and R8 and transistor Q1, it provides a reference voltage for the over-discharge protection recovery threshold. The expression for the battery pack over-discharge protection voltage recovery threshold is as follows:

[0017]

[0018] Furthermore, capacitor C1 in the sampling and comparison circuit is used for filtering when the discharge protection state enters the discharge protection recovery state;

[0019] Preferably, the discharge switch and driving circuit include resistors R9, R10, R11, and R12, transistor Q2, transistor Q4, and MOSFET Q3;

[0020] One end of the resistor R12 is connected to the resistor R7 in the sampling and comparison circuit, and the other end is connected to the base of the transistor Q4, with the emitter of the transistor Q4 grounded.

[0021] One end of the resistor R9 is connected to the source of the MOSFET Q3 and the positive terminal of the lithium-ion battery pack, and the other end is connected to the resistor R10 and the gate of the MOSFET Q3. The other end of the resistor R10 is connected to the collector of the transistor Q2.

[0022] The drain of the MOS transistor Q3 is connected to the positive terminal of the external power supply Vo;

[0023] The emitter of transistor Q2 is grounded, and its base is connected to resistor R11 and the collector of transistor Q4. The other end of resistor R11 is connected to an external 12V voltage.

[0024] Compared with the prior art, the advantages of this utility model are as follows:

[0025] This invention uses an automatic change of the comparator's reference input voltage to set the over-discharge protection threshold and the over-discharge protection recovery threshold, in order to solve the problem of repeated operation of the discharge switch. When the battery pack reaches the discharge protection threshold during high-power discharge, the discharge switch is turned off, thereby stopping the battery pack from discharging. The battery pack voltage rises rapidly, while the comparator's reference input voltage decreases, and the battery pack voltage cannot reach the over-discharge protection recovery threshold. Therefore, the discharge switch will not be turned on again. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the over-discharge protection circuit for a high-power lithium-ion battery according to this utility model. Detailed Implementation

[0028] To better understand the above technical solution, the technical solution of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the utility model embodiments and the specific features in the embodiments are detailed descriptions of the technical solution of this utility model, rather than limitations on the technical solution of this utility model. In the absence of conflict, the technical features of this utility model and the embodiments can be combined with each other.

[0029] This embodiment provides an over-discharge protection circuit for a high-power lithium-ion battery, which solves the problem of repeated over-discharge protection action of a high-power battery pack. The circuit includes a lithium-ion battery pack, a sampling and comparison circuit, a discharge switch, and a drive circuit.

[0030] The lithium-ion battery pack is used to provide energy storage power.

[0031] The sampling comparison circuit is connected to the lithium-ion battery pack and is used to collect the voltage of the lithium-ion battery pack and output an over-discharge judgment signal to the discharge switch and drive circuit.

[0032] The sampling and comparison circuit is also connected to an external voltage Verf, which serves as the input reference voltage for the comparator.

[0033] The sampling and comparison circuit is also connected to a 12V external voltage, which serves as the power supply for the comparator and the pull-up voltage for the output drive.

[0034] The discharge switch and drive circuit are connected to the positive terminal of the lithium-ion battery pack and the sampling and comparison circuit, and are used to control the discharge of the lithium-ion battery pack.

[0035] Preferably, the sampling and comparison circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, capacitor C1, transistor Q1, and comparator U1.

[0036] One end of resistor R4 is connected to the positive terminal of the lithium-ion battery pack, and the other end is connected to resistor R5 and the inverting input terminal of comparator U1. The other end of resistor R5 is grounded.

[0037] One end of resistor R1 is connected to the external voltage Verf, and the other end is connected to capacitor C1, resistor R2, resistor R3 and the non-inverting input of comparator U1. The other ends of capacitor C1 and resistor R2 are grounded, and the other end of resistor R3 is connected to the collector of transistor Q1. The emitter of transistor Q1 is grounded.

[0038] One end of resistor R6 is connected to the power input terminal of comparator U1 and the 12V external voltage, and the other end is connected to the output terminal of comparator U1, resistor R7, and resistor R8. The other end of resistor R8 is connected to the base of transistor Q1, and the other end of resistor R7 is connected to the discharge switch and drive circuit.

[0039] Preferably, the discharge switch and driving circuit include resistors R9, R10, R11, and R12, transistor Q2, transistor Q4, and MOSFET Q3;

[0040] One end of the resistor R12 is connected to the resistor R7 in the sampling and comparison circuit, and the other end is connected to the base of the transistor Q4, with the emitter of the transistor Q4 grounded.

[0041] One end of the resistor R9 is connected to the source of the MOSFET Q3 and the positive terminal of the lithium-ion battery pack, and the other end is connected to the resistor R10 and the gate of the MOSFET Q3. The other end of the resistor R10 is connected to the collector of the transistor Q2.

[0042] The drain of the MOS transistor Q3 is connected to the positive terminal of the external power supply Vo;

[0043] The emitter of transistor Q2 is grounded, and its base is connected to resistor R11 and the collector of transistor Q4. The other end of resistor R11 is connected to an external 12V voltage.

[0044] Resistors R4 and R5 in the sampling and comparison circuit are connected to the lithium-ion battery pack and are used to provide feedback on the real-time voltage of the lithium-ion battery pack.

[0045] The sampling and comparison circuit is connected to an external voltage Verf, and through resistors R1 and R2, it provides a reference voltage for the over-discharge protection threshold. The expression for the battery pack over-discharge protection voltage threshold is as follows:

[0046] The sampling and comparison circuit is connected to an external voltage Verf, and through resistors R3 and R8 and transistor Q1, it provides a reference voltage for the over-discharge protection recovery threshold. The expression for the over-discharge protection voltage recovery threshold of the lithium-ion battery pack is as follows:

[0047]

[0048] The capacitor C1 in the sampling and comparison circuit is used for filtering when the discharge protection state enters the discharge protection recovery state.

[0049] The specific implementation process of the high-power lithium-ion battery over-discharge protection circuit is as follows:

[0050] When the lithium-ion battery pack powers the entire satellite, the negative input terminal of comparator U1 in the sampling and comparison circuit acquires the output voltage of the lithium-ion battery pack. and the reference voltage connected to the non-inverting input of comparator U1 Compare and monitor the voltage status of lithium-ion battery packs in real time.

[0051] like Higher than When the over-discharge judgment signal output by comparator U1 is low, transistor Q4 is not turned on, transistor Q2 is turned on, and then MOSFET Q3 is turned on, so the lithium-ion battery pack generates electricity normally.

[0052] The output voltage of the lithium-ion battery pack continues to decrease, when Below When the comparator U1 outputs an over-discharge judgment signal, it is at a high level. At this time, transistor Q4 is turned on, the base voltage of transistor Q2 is 0, transistor Q2 is not turned on, and consequently MOSFET Q3 is also not turned on, and the lithium-ion battery pack stops discharging.

[0053] Transistor Q1 is turned on, and the reference voltage connected to the non-inverting input of comparator U1 is... Become At this point, the over-discharge protection threshold becomes the over-discharge protection recovery threshold, and the over-discharge protection circuit enters the over-discharge protection recovery monitoring state.

[0054] As the lithium-ion battery pack stops discharging, its voltage rises rapidly. Higher than Comparator U1 still outputs a high level, meaning MOSFET Q3 is off;

[0055] If charging begins at this point, the voltage of the lithium-ion battery pack will continue to rise. Higher than When the comparator U1 outputs a low level, transistor Q4 is not turned on, and the base voltage of transistor Q2 is not 0. Therefore, transistor Q2 is turned on, MOSFET Q3 is turned on, and the lithium-ion battery pack discharge switch is turned on.

[0056] Transistor Q1 is not conducting. At this time, the reference voltage connected to the non-inverting input of comparator U1 is... Become At this point, the over-discharge protection recovery threshold becomes the over-discharge protection threshold, and the over-discharge protection circuit re-enters the over-discharge protection monitoring state.

[0057] This invention enables the adjustment of the over-discharge voltage and over-discharge recovery voltage of lithium-ion batteries to meet the operating characteristics of high-power lithium-ion battery packs and achieve effective protection against over-discharge of the battery packs.

[0058] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention. Other changes and modifications made by those skilled in the art without departing from the spirit and scope of protection of the present invention are still included within the scope of protection of the present invention.

Claims

1. A high-power lithium-ion battery overdischarge protection circuit, characterized in that, The over-discharge protection circuit includes a lithium-ion battery pack, a sampling and comparison circuit, a discharge switch, and a drive circuit. The lithium-ion battery pack is used to provide energy storage power. The sampling comparison circuit is connected to the lithium-ion battery pack and is used to collect the voltage of the lithium-ion battery pack and output an over-discharge judgment signal to the discharge switch and drive circuit. The sampling and comparison circuit is also connected to an external voltage Verf, which serves as an input reference voltage. The sampling and comparison circuit is also connected to a 12V external voltage, which serves as the power supply and pull-up voltage for the output drive. The discharge switch and drive circuit are connected to the positive terminal of the lithium-ion battery pack and the sampling and comparison circuit, and are used to control the discharge of the lithium-ion battery pack.

2. The overdischarge protection circuit for a high-power lithium-ion battery according to claim 1, wherein The sampling and comparison circuit includes resistors R1, R2, R3, R4, R5, R6, R7, R8, capacitor C1, transistor Q1, and comparator U1. One end of resistor R4 is connected to the positive terminal of the lithium-ion battery pack, and the other end is connected to resistor R5 and the inverting input terminal of comparator U1. The other end of resistor R5 is grounded. One end of resistor R1 is connected to the external voltage Verf, and the other end is connected to capacitor C1, resistor R2, resistor R3 and the non-inverting input of comparator U1. The other ends of capacitor C1 and resistor R2 are grounded, and the other end of resistor R3 is connected to the collector of transistor Q1. The emitter of transistor Q1 is grounded. One end of resistor R6 is connected to the power input terminal of comparator U1 and the 12V external voltage, and the other end is connected to the output terminal of comparator U1, resistor R7, and resistor R8. The other end of resistor R8 is connected to the base of transistor Q1, and the other end of resistor R7 is connected to the discharge switch and drive circuit. Resistors R4 and R5 in the sampling and comparison circuit are connected to the lithium-ion battery pack and are used to provide feedback on the real-time voltage of the lithium-ion battery pack. The capacitor C1 in the sampling and comparison circuit is used for filtering when the discharge protection state enters the discharge protection recovery state.

3. The overdischarge protection circuit for high-power lithium-ion batteries according to claim 1, characterized in that, The discharge switch and drive circuit include resistors R9, R10, R11, and R12, transistor Q2, transistor Q4, and MOSFET Q3; One end of the resistor R12 is connected to the resistor R7 in the sampling and comparison circuit, and the other end is connected to the base of the transistor Q4, with the emitter of the transistor Q4 grounded. One end of the resistor R9 is connected to the source of the MOSFET Q3 and the positive terminal of the lithium-ion battery pack, and the other end is connected to the resistor R10 and the gate of the MOSFET Q3. The other end of the resistor R10 is connected to the collector of the transistor Q2. The drain of the MOS transistor Q3 is connected to the positive terminal of the external power supply Vo; The emitter of transistor Q2 is grounded, and its base is connected to resistor R11 and the collector of transistor Q4. The other end of resistor R11 is connected to an external 12V voltage.

4. A high-power lithium-ion battery over-discharge protection circuit according to any one of claims 1 to 3, characterized in that, The over-discharge protection circuit solves the problem of repeated operation of the discharge switch by automatically changing the reference input voltage of the comparator to set the over-discharge protection threshold and the over-discharge protection recovery threshold. When the battery pack reaches the discharge protection threshold during high-power discharge, the discharge switch is turned off, thereby stopping the lithium-ion battery pack from discharging. The voltage of the lithium-ion battery pack rises rapidly, while the reference input voltage of the comparator decreases. The voltage of the lithium-ion battery pack cannot reach the over-discharge protection recovery threshold, so the discharge switch will not be turned on again.

5. The over-discharge protection circuit for a high-power lithium-ion battery according to claim 2, characterized in that, The negative input terminal of comparator U1 in the sampling and comparison circuit collects the output voltage of the lithium-ion battery pack. and the reference voltage connected to the non-inverting input of comparator U1 Comparisons are made to monitor the voltage status of lithium-ion battery packs in real time.

6. The over-discharge protection circuit for a high-power lithium-ion battery according to claim 2, characterized in that, The sampling and comparison circuit is connected to an external voltage Verf, and through resistors R1 and R2, it provides a reference voltage for the over-discharge protection threshold. The expression for the over-discharge protection voltage threshold of the lithium-ion battery pack is as follows:

7. The over-discharge protection circuit for a high-power lithium-ion battery according to claim 2, characterized in that, The sampling and comparison circuit is connected to an external voltage Verf, and through resistors R3 and R8 and transistor Q1, it provides a reference voltage for the over-discharge protection recovery threshold. The expression for the over-discharge protection voltage recovery threshold of the lithium-ion battery pack is as follows:

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