A lithium battery management circuit

Abstract

This application relates to the field of BMS circuits, and more particularly to a lithium battery management circuit, comprising: a sampling circuit, an equalization circuit, and a BMS; the BMS is electrically connected to several of the sampling circuits; the BMS is electrically connected to several of the equalization circuits; in this application, the sampling circuit transmits BAT voltage information to the BMS, the BMS calculates the SOC information of the BAT through the BAT voltage information, and then the equalization circuit discharges the BAT with a high SOC value to achieve passive equalization and prevent the battery from overcharging or over-discharging.

Description

Technical Field

[0001] This application relates to the field of BMS circuits, and more particularly to a lithium battery management circuit. Background Technology

[0002] With the increasing number of electric bicycles on the road, manufacturers are paying more and more attention to battery management systems. The main function of a lithium battery protection board is to intelligently manage and maintain each battery cell, preventing overcharging and over-discharging, extending battery life, and monitoring battery status. Overcharging and over-discharging are the biggest threats to lithium-ion batteries. Once overcharged or over-discharged, the battery will be damaged, its capacity reduced, and its lifespan shortened. In severe cases, it may even cause a fire or explosion, the impact of which on the electric bicycle is self-evident.

[0003] When batteries are used in groups, they are more prone to overcharging and over-discharging. The root cause is the inconsistency between the cells. If these differences are not properly controlled during charging and discharging, they will be further amplified, resulting in a serious shortening of the battery's lifespan. Utility Model Content

[0004] In view of the problems existing in the prior art, this application provides a lithium battery management circuit.

[0005] A lithium battery management circuit includes: a sampling circuit, an equalization circuit, and a BMS; the BMS is electrically connected to a plurality of the sampling circuits; the BMS is electrically connected to a plurality of the equalization circuits.

[0006] The sampling circuit includes: a first operational amplifier, a second operational amplifier, and a filter circuit;

[0007] In the first operational amplifier: the positive input terminal is connected to BAT+ and connected in series with resistor RK1, and the positive input terminal is also connected to BAT- and connected in series with resistor R1; the negative input terminal is connected to BAT+ and connected in series with resistors R2, RK2, and R3; the negative power supply terminal is connected to BAT-, the positive power supply terminal is connected to VCC+, and the output terminal is connected to the positive input terminal of the second operational amplifier.

[0008] In the second operational amplifier, the negative input terminal is connected to the output terminal, the positive power supply terminal is connected to one of the positive output terminals of the BMS and a capacitor C1 is connected in parallel, the other end of the capacitor C1 is grounded, the negative power supply terminal is grounded, and the output terminal is connected to the acquisition port of the BMS.

[0009] Furthermore, the filter circuit is provided in two parts, which are connected in parallel to the positive input circuit and the output circuit of the second operational amplifier, respectively.

[0010] Furthermore, the equalization circuit includes: an optocoupler, a transistor, and a discharge circuit;

[0011] in,

[0012] In the optocoupler, the light-emitting diode is powered by the BMS, with its collector connected to BAT+ and its emitter connected to BAT-.

[0013] Furthermore, a transistor Q1 is connected in the connection circuit between the first operational amplifier and the second operational amplifier. The collector of the transistor Q1 is connected to BAT+ and connected in series with resistors R2 and RK2. The base of the transistor Q1 is connected to the output terminal of the first operational amplifier and connected in series with resistor R4. The emitter of the transistor Q1 is connected to the positive input terminal of the second operational amplifier and connected in series with resistor R5 and diode D1.

[0014] Furthermore, the power supply circuit for VCC+ is as follows: BAT+ and BAT- are connected in parallel at the output terminal of VCC+, wherein a resistor RZ1 is connected in series between VCC+ and BAT+, and a Zener diode ZG1 is connected in series between VCC+ and BAT-.

[0015] Furthermore, in the discharge circuit of the equalization circuit, a transistor Q2 is also included in the connection circuit between BAT+ and BAT-. Specifically, the collector of transistor Q2 is connected in parallel in the connection circuit between BAT+ and the collector of the optocoupler. The emitter of the optocoupler is connected to the base of transistor Q2 and a resistor R7 is connected in series. The emitter of transistor Q2 is connected to BAT-. This avoids excessive current flowing through the optocoupler, which could cause it to overheat and be damaged.

[0016] The technical effects and advantages of this application are as follows:

[0017] In this application, the BAT voltage information is transmitted to the BMS through a sampling circuit. The BMS calculates the SOC information of the BAT through the BAT voltage information, and then discharges the BAT with a high SOC value through an equalization circuit to achieve passive equalization and prevent the battery from overcharging or over-discharging.

[0018] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description and the accompanying drawings. Attached Figure Description

[0019] Figure 1 The circuit diagram of the sampling circuit is shown;

[0020] Figure 2 The power supply circuit diagram for the first operational amplifier is shown;

[0021] Figure 3 The circuit diagram of the equalization circuit is shown; Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Furthermore, in the application, the terms "first," "second," and other similar words are not intended to imply any order, quantity, or importance, but are merely used to distinguish different elements, and the terms "upper," "lower," "left," "right," and other similar words are merely positional relationships in the accompanying drawings.

[0024] A lithium battery management circuit includes: a sampling circuit, an equalization circuit, and a battery management system (BMS); the BMS is electrically connected to a plurality of the sampling circuits, the number of the sampling circuits being equal to the number of individual batteries (BATs) in the battery pack and electrically connected in a one-to-one correspondence; the BMS is electrically connected to a plurality of equalization circuits, the number of the equalization circuits being equal to the number of individual batteries (BATs) in the battery pack and electrically connected in a one-to-one correspondence.

[0025] In this way, the sampling circuit can send the BAT voltage information to the BMS. The BMS can calculate the SOC information of the BAT through the BAT voltage information, and then discharge the BAT with a high SOC value through the equalization circuit to achieve passive equalization.

[0026] like Figure 1 As shown, the sampling circuit includes: a first operational amplifier, a second operational amplifier, and a filter circuit;

[0027] in,

[0028] In the first operational amplifier (model RS8031XF): the positive input terminal is connected to BAT+ and connected in series with resistor RK1 (200KΩ); the positive input terminal is also connected to BAT- and connected in series with resistor R1 (200KΩ); the negative input terminal is connected to BAT+ and connected in series with resistors R2 (100KΩ), RK2 (100KΩ), and R3 (200KΩ); the negative power supply is connected to BAT-, the positive power supply is connected to VCC+, and the output terminal is connected to the positive input terminal of the second operational amplifier.

[0029] In the second operational amplifier (model LM321), the negative input terminal is connected to the output terminal, the positive power supply terminal is connected to one of the positive output terminals of the BMS and a capacitor C1 is connected in parallel, the other end of the capacitor C1 is grounded, the negative power supply terminal is grounded, and the output terminal is connected to the acquisition port of the BMS.

[0030] There are two filter circuits, which are connected in parallel to the positive input circuit and the output circuit of the second operational amplifier, respectively.

[0031] The equalization circuit includes: an optocoupler, a transistor, and a discharge circuit;

[0032] in,

[0033] In the optocoupler, the light-emitting diode is powered by the BMS, with its collector connected to BAT+ and its emitter connected to BAT-.

[0034] In this way, the voltage information of multiple BATs is collected one by one through multiple sampling circuits and sent to BMS. BMS calculates the SOC information of BATs based on the voltage information through its built-in calculation program, and equalizes the SOC of each BAT through equalization circuit.

[0035] Specifically, the BMS sends an electrical signal to the optocoupler in the equalization circuit to connect BAT+ and BAT- to achieve discharge. BAT+ and BAT- are connected in series with R6 (resistance value of 150Ω).

[0036] In one embodiment of this application, a transistor Q1 (model MMBT5401) is also connected in the connection circuit between the first operational amplifier and the second operational amplifier. The collector of the transistor Q1 is connected to BAT+ and in series with resistors R2 and RK2. The base of the transistor Q1 is connected to the output terminal of the first operational amplifier and in series with resistor R4. The emitter of the transistor Q1 is connected to the positive input terminal of the second operational amplifier and in series with resistor R5 and diode D1.

[0037] like Figure 2 As shown, the power supply circuit for VCC+ is as follows: BAT+ and BAT- are connected in parallel at the output terminal of VCC+, wherein a resistor RZ1 (with a resistance of 1KΩ) is connected in series between VCC+ and BAT+, and a Zener diode ZG1 (model BZX384C5V1) is connected in series between VCC+ and BAT-.

[0038] like Figure 3As shown in one embodiment of this application, in the discharge circuit of the equalization circuit, a transistor Q2 (model 8050 / SOT-23) is also provided in the connection circuit between BAT+ and BAT-. Specifically, the collector of transistor Q2 is connected in parallel in the connection circuit between BAT+ and the collector of the optocoupler, the emitter of the optocoupler is connected to the base of transistor Q2 and a resistor R7 (resistance value of 2.7KΩ) is connected in series, and the emitter of transistor Q2 is connected to BAT-. This avoids excessive current passing through the optocoupler, which could cause the optocoupler to overheat and be damaged.

[0039] Finally, it should be noted that the above description is only a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A lithium battery management circuit, characterized by, include: Sampling circuit, equalization circuit, BMS; The BMS is electrically connected to several of the sampling circuits; the BMS is electrically connected to several of the equalization circuits. The sampling circuit includes: a first operational amplifier, a second operational amplifier, and a filter circuit; In the first operational amplifier: the positive input terminal is connected to BAT+ and connected in series with resistor RK1, and the positive input terminal is also connected to BAT- and connected in series with resistor R1; the negative input terminal is connected to BAT+ and connected in series with resistors R2, RK2, and R3; the negative power supply terminal is connected to BAT-, the positive power supply terminal is connected to VCC+, and the output terminal is connected to the positive input terminal of the second operational amplifier. In the second operational amplifier, the negative input terminal is connected to the output terminal, the positive power supply terminal is connected to one of the positive output terminals of the BMS and a capacitor C1 is connected in parallel, the other end of the capacitor C1 is grounded, the negative power supply terminal is grounded, and the output terminal is connected to the acquisition port of the BMS.

2. The lithium battery management circuit of claim 1, wherein, The filter circuit has two components, which are connected in parallel to the positive input circuit and the output circuit of the second operational amplifier, respectively.

3. The lithium battery management circuit of claim 1, wherein, The equalization circuit includes: an optocoupler, a transistor, and a discharge circuit; in, In the optocoupler, the light-emitting diode is powered by the BMS, with its collector connected to BAT+ and its emitter connected to BAT-.

4. The lithium battery management circuit of claim 1, wherein, A transistor Q1 is also connected in the connection circuit between the first operational amplifier and the second operational amplifier. The collector of the transistor Q1 is connected to BAT+ and in series with resistors R2 and RK2. The base of the transistor Q1 is connected to the output terminal of the first operational amplifier and in series with resistor R4. The emitter of the transistor Q1 is connected to the positive input terminal of the second operational amplifier and in series with resistor R5 and diode D1.

5. The lithium battery management circuit of claim 1, wherein, The power supply circuit for VCC+ is as follows: BAT+ and BAT- are connected in parallel at the output terminal of VCC+, wherein a resistor RZ1 is connected in series between VCC+ and BAT+, and a Zener diode ZG1 is connected in series between VCC+ and BAT-.

6. The lithium battery management circuit of claim 1, wherein, In the discharge circuit of the equalization circuit, a transistor Q2 is also provided in the connection circuit between BAT+ and BAT-. Specifically, the collector of transistor Q2 is connected in parallel in the connection circuit between BAT+ and the collector of the optocoupler. The emitter of the optocoupler is connected to the base of transistor Q2 and a resistor R7 is connected in series. The emitter of transistor Q2 is connected to BAT-. This can prevent the optocoupler from overheating and being damaged due to excessive current passing through it.

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