Lithium battery charging and discharging management circuit with protection function

Abstract

The utility model relates to a lithium battery charging and discharging management circuit with a protection function, which comprises a charging input filtering unit, a power adjusting unit, a battery protection unit, a feedback control unit, a logic switching unit and an output interface unit, and is characterized in that the charging input filtering unit suppresses input interference through a symmetrical inductor and a multistage decoupling capacitor; the power adjusting unit is used for converting the input energy into a target charging parameter; the battery protection unit works cooperatively with the protection chip through the back-to-back double MOSFET array, so that overvoltage / undervoltage quick turn-off is realized; the feedback control unit compares the voltage division sampling signal with an adjustable reference by using a dual-comparator network to generate a PWM closed-loop adjusting signal; and the logic switching unit constructs a logic AND circuit through a multi-channel MOSFET switch group, and responds to a protection signal to forcibly cut off a power path. And dynamic adjustment and multiple protection mechanisms are fused through modular design, so that the charging and discharging efficiency and the system safety are remarkably improved, and the method is suitable for a high-reliability lithium battery management system.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery management technical field especially relates to lithium battery charge -discharge management circuit with protection function. BACKGROUND

[0002] With the wide application of lithium battery in consumer electronics, electric vehicles and energy storage system, the safety and efficiency of its charge -discharge management circuit become the key problem.The traditional lithium battery management scheme generally has the following defects:

[0003] 1. The protection mechanism is imperfect: the conventional protection circuit adopts unidirectional MOSFET or relay control charge -discharge loop, and there are problems such as reverse current cannot be blocked, slow turn-off speed, especially when the battery pack is overvoltage / undervoltage, a single switching device is easy to cause secondary breakdown due to residual current, and safety hazards are caused.

[0004] 2. The dynamic regulation precision is insufficient: the existing power regulation unit mostly adopts open loop or simple feedback control, and cannot compensate input voltage fluctuation and load change in real time.

[0005] 3. Poor anti-interference ability: the traditional filter circuit adopts single-stage inductance or capacitance structure, and the high-frequency noise suppression is insufficient.

[0006] 4. Logic control response lag: the logic switching unit relies on a single switching device to realize protection turn-off, and when multiple faults occur, the response is delayed, and there is lack of multi-signal cooperative processing mechanism, and it is difficult to realize fast and accurate power path switching.

[0007] Therefore, an integrated lithium battery management circuit with high-precision regulation, fast protection response and multiple anti-interference mechanisms is needed to improve system reliability and energy efficiency. INVENTION CONTENTS

[0008] In view of the problems existing in the above-mentioned technology, the utility model provides a lithium battery charge -discharge management circuit with protection function.

[0009] The utility model provides a lithium battery charge -discharge management circuit with protection function, which comprises:

[0010] The charging input filter unit comprises a positive input terminal V+, a detection terminal D and a negative input terminal V-, and forms an input filter loop through a first inductor and a second inductor.

[0011] The power regulation unit is connected to the output terminal of the charging input filter unit and is used to convert input energy into target charging parameters.

[0012] The battery protection unit is connected to the output terminal of the power regulation unit and the battery pack and is used to monitor the overvoltage / undervoltage state of the battery in real time.

[0013] a feedback control unit, having an input end connected to the voltage and current signals of the charging input filter unit and the power regulation unit, and an output end connected to the control end of the power regulation unit, for generating a closed-loop regulation signal through a comparator network;

[0014] a logic switching unit, receiving the output signal of the feedback control unit and the status signal of the battery protection unit, for controlling the on-off of the power path through a logic gate circuit;

[0015] an output interface unit, connected to the output end of the power regulation unit, for outputting stable power P+ / P- to the load end.

[0016] Preferably, the power regulation unit comprises:

[0017] a first power switch tube, having an input end connected to the output end of the charging input filter unit, and an output end connected to the battery protection unit through a freewheeling diode;

[0018] a drive control circuit, comprising a first drive transistor and a second drive transistor connected in series, the base of the first drive transistor being connected to the output signal of the feedback control unit, the emitter being connected to ground through a current sampling resistor, and the collector of the second drive transistor being connected to the control pole of the first power switch tube;

[0019] a dynamic compensation network, comprising an RC circuit connected in parallel between the control pole of the first power switch tube and the input end;

[0020] an adjustable reference source U2, having a reference end connected to the emitter of the second drive transistor through a voltage dividing resistor network, and an output end for generating a reference voltage signal;

[0021] wherein the anode of the freewheeling diode is connected to the output end of the first power switch tube, and the cathode is connected to the battery protection unit through a third inductor, forming a freewheeling energy recovery path.

[0022] Preferably, the battery protection unit comprises:

[0023] a monitoring chip, having a voltage detection pin VC connected to the midpoint of the battery pack through a current limiting resistor, for real-time acquisition of the voltage signal of the series-connected battery;

[0024] a dual-MOSFET switch array, comprising a first MOSFET and a second MOSFET connected back-to-back;

[0025] a drive isolation circuit, comprising a drive resistor connected in series between the control end of the monitoring chip and the gate of the MOSFET, and a transient suppression element and a filter capacitor connected in parallel between the gate and the source;

[0026] a midpoint voltage stabilizing circuit, comprising a filter capacitor connected across the midpoint of the battery pack and the voltage detection pin of the monitoring chip.

[0027] The monitoring chip controls the on-off of the double-MOSFET switch array according to the battery pack voltage signal, and when overvoltage / undervoltage is detected, the MOSFET array is turned off by driving the isolation circuit to cut off the charging and discharging circuit.

[0028] Preferably, the feedback control unit comprises:

[0029] A double-comparator integrated circuit IC, a non-inverting input terminal of a first comparator of the double-comparator integrated circuit IC is connected to a voltage division sampling network, and an inverting input terminal is connected to ground through an RC filter network, and an inverting input terminal of a second comparator is connected to an adjustable reference network;

[0030] The voltage division sampling network is composed of a first voltage division resistor, a second voltage division resistor and a third voltage division resistor connected in series at an input terminal of the output interface unit, and a sampling node is connected to a non-inverting input terminal of the first comparator;

[0031] The adjustable reference network comprises a threshold adjustment branch composed of an adjustable resistor and a fixed voltage division resistor, and outputs a reference signal to an inverting input terminal of the second comparator;

[0032] The dynamic compensation circuit comprises a compensation capacitor connected across the input terminals of the double comparator and a temperature compensation resistor connected between the output terminal and the inverting input terminal of the second comparator.

[0033] Preferably, the logic switching unit comprises:

[0034] The MOSFET switch group comprises a fourth MOSFET, a fifth MOSFET and a sixth MOSFET arranged in parallel, wherein:

[0035] A gate of the fourth MOSFET is connected to an output terminal of the feedback control unit, and a drain is connected to a reference voltage terminal through a current limiting resistor;

[0036] A gate of the fifth MOSFET is connected to a comparator output terminal (IC-U1A) of the feedback control unit, and a drain is connected to another reference voltage terminal through a resistor;

[0037] A gate of the sixth MOSFET is connected to an enable signal terminal of the battery protection unit through a current limiting resistor, and a drain is connected to sources of the fourth MOSFET and the fifth MOSFET;

[0038] The acceleration capacitor group comprises a first capacitor connected in parallel between the gate and the source of the fourth MOSFET, a second capacitor connected in parallel between the gate and the source of the fifth MOSFET, and a third capacitor connected in parallel between the gate and the source of the sixth MOSFET Q6, for improving the switching response speed.

[0039] The technical effect of the lithium battery charge-discharge management circuit with the protection function is that: through the back-to-back double MOSFET switch array and the monitoring chip cooperative control, the bidirectional current blocking of the battery pack charge-discharge loop is realized, the overvoltage, undervoltage and reverse current impact are effectively prevented, the shutdown response time is shortened to the microsecond level, and the protection blind area caused by the unidirectional switch or the mechanical relay in the traditional scheme is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Figure 1 is a block diagram of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application;

[0042] Figure 2 is a principle diagram of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application;

[0043] Figure 3 is a structure diagram of the charge input filter unit of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application;

[0044] Figure 4 is a structure diagram of the power regulation unit of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application;

[0045] Figure 5 is a structure diagram of the feedback control unit and the logic switching unit of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application;

[0046] Figure 6 is a structure diagram of the battery protection unit and the output interface unit of the lithium battery charge-discharge management circuit with the protection function of the embodiment of the present application.

[0047] The drawings are as follows: charge input filter unit-10; power regulation unit-20; battery protection unit-30; feedback control unit-40; logic switching unit-50; output interface unit-60 DETAILED DESCRIPTION

[0048] Clearly, the described embodiments are merely a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0049] Please refer to Figure 1 and Figure 2 The lithium battery charging and discharging management circuit with protection function comprises a charging input filter unit 10, a power regulation unit 20, a battery protection unit 30, a feedback control unit 40, a logic switching unit 50 and an output interface unit 60. The power regulation unit 20 is connected to the output end of the charging input filter unit 10, and is used to convert input energy into target charging parameters. The battery protection unit 30 is connected to the output end of the power regulation unit 20 and the battery pack B1 / B2, and is used to monitor the overvoltage / undervoltage state of the battery in real time. The input end of the feedback control unit 40 is connected to the voltage and current signals of the charging input filter unit 10 and the power regulation unit 20, and the output end is connected to the control end of the power regulation unit 20, so as to generate a closed-loop adjustment signal through a comparator network. The logic switching unit 50 receives the output signal of the feedback control unit 40 and the state signal of the battery protection unit 30, and controls the on-off of the power path through a logic gate circuit. The output interface unit 60 is connected to the output end of the power regulation unit 20, and is used to output stable power P+ / P- to the load end.

[0050] As shown in Figure 3 The charging input filter unit 10 comprises a positive input end V+, a detection end D and a negative input end V-, and an input filter loop. The detection end D is connected to the battery B+ through a detection resistor R5. The input filter loop comprises a first inductor L1 and a second inductor L4. One end of the first inductor L1 is connected to the positive input end V+, and one end of the second inductor L4 is connected to the negative input end V- and the other end is grounded. Between the common end of the first inductor L1 and the positive input end V+ and the common end of the second inductor L4 and the negative input end V-, there are filter capacitors C1 and C2. Between the common end of the detection resistor R5 and the detection end D and the common end of the second inductor L4 and the negative input end V-, there are filter capacitors C7 and C8.

[0051] As shown in Figure 4As shown, the power regulation unit 20 includes: a first power switch Q1, whose input terminal is connected to the output terminal of the first inductor L1 of the charging input filter unit 10, and the output terminal of the first power switch Q1 is connected to the battery protection unit 30 through a freewheeling diode D3. The drive control circuit of the power regulation unit 20 includes a first drive transistor Q3 and a second drive transistor Q7 connected in series. The base of the first drive transistor Q3 is connected to the output signal of the feedback control unit 40, and its emitter is grounded through a current sampling resistor R18. The collector of the second drive transistor Q7 is connected to the control electrode of the first power switch Q1. The dynamic compensation network of the power regulation unit 20 is composed of an RC circuit (C4, R1) connected in parallel between the control electrode and the input terminal of the first power switch Q1. The adjustable reference source U2 (model TL431) of the power regulation unit 20 has its reference terminal connected to the emitter of the second drive transistor Q7 through a voltage divider resistor network R25, R27, and R28, and its output terminal generates a reference voltage signal. The positive terminal of the freewheeling diode D3 is connected to the output terminal of the first power switch Q1, and the negative terminal is connected to the battery protection unit 30 through the third inductor L3, forming a freewheeling energy recovery path.

[0052] like Figure 5 As shown, the feedback control unit 40 includes: a dual comparator integrated circuit IC (LM2903), wherein the non-inverting input of the first comparator is connected to a voltage divider sampling network, the inverting input is grounded through an RC filter network, and the inverting input of the second comparator is connected to an adjustable reference network; the voltage divider sampling network consists of a first voltage divider resistor R19, a second voltage divider resistor R21, and a third voltage divider resistor R22 connected in series at the input of the output interface unit 10, and the sampling node is connected to the non-inverting input of the first comparator; the adjustable reference network includes a threshold adjustment branch consisting of an adjustable resistor R11 and fixed voltage divider resistors R13 and R14, and outputs a reference signal to the inverting input of the second comparator; the dynamic compensation circuit includes a compensation capacitor C13 connected across the input of the dual comparators and a temperature compensation resistor R16 connected between the output of the second comparator and the inverting input.

[0053] like Figure 5As shown, the logic switching unit includes a MOSFET switch group and an accelerating capacitor group. The MOSFET switch group includes a fourth MOSFET (Q4), a fifth MOSFET (Q5), and a sixth MOSFET (Q6) connected in parallel. The gate of the fourth MOSFET (Q4) is connected to the output of the feedback control unit, and its drain is connected to a reference voltage terminal (1V) through a current-limiting resistor R17. The gate of the fifth MOSFET (Q5) is connected to the comparator output (IC-U1A) of the feedback control unit, and its drain is connected to another reference voltage terminal through a resistor (R23). The gate of the sixth MOSFET (Q6) is connected to the enable signal terminal (U3-DO) of the battery protection unit through a current-limiting resistor R24, and its drain is connected to the sources of the fourth MOSFET (Q4) and the fifth MOSFET (Q5). The accelerating capacitor group includes a first capacitor C14 connected in parallel between the gate and source of the fourth MOSFET (Q4), a second capacitor C16 connected between the gate and source of the fifth MOSFET (Q5), and a third capacitor C17 connected between the gate and source of the sixth MOSFET (Q6), used to improve the switching response speed.

[0054] like Figure 6 As shown, the battery protection unit 30 includes: a monitoring chip U3 (model S-8252AAC), whose voltage detection pin (VC) is connected to the midpoint of the battery pack B1 / B2 through a current-limiting resistor R35, for real-time acquisition of the voltage signal of the series-connected batteries; a dual MOSFET switch array, including a first MOSFET (Q9A) and a second MOSFET (Q9B) connected back-to-back; a drive isolation circuit, including drive resistors R31 / R32 connected in series between the control terminal (DO / CO) of the monitoring chip U3 and the MOSFET gate, and transient suppression elements and filter capacitors C25 / C26 connected in parallel between the gate and source; and a midpoint voltage stabilization circuit, consisting of a filter capacitor C36 connected across the midpoint of the battery pack and the voltage detection pin of the monitoring chip U3; wherein, the monitoring chip U3 controls the on / off state of the dual MOSFET switch array according to the battery pack voltage signal, and when overvoltage / undervoltage is detected, it turns off the MOSFET array through the drive isolation circuit to cut off the charging and discharging circuit.

[0055] In this embodiment, the lithium battery charge / discharge management circuit with protection function

[0056] Diode reference models: D1 (MMSD914T1), D2 (MMSD914T1), D3 (MBRM120E), D4 (BAV99LT1)

[0057] Transistor reference models: Q1 (MJD45H11), Q2 (S8050LT1), Q3 (S8050LT1), Q4 (2N7002LT1), Q5 (2N7002LT1), Q6 (2N7002LT1), Q7 (S8550LT1), Q8 (2N7002LT1)

[0058] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A lithium battery charge / discharge management circuit with protection function, characterized in that, include: The charging input filter unit (10) includes a positive input terminal (V+), a detection terminal (D) and a negative input terminal (V-), and forms an input filter circuit through a first inductor (L1) and a second inductor (L4); The power adjustment unit (20) is connected to the output terminal of the charging input filter unit (10) and is used to convert the input energy into the target charging parameters; The battery protection unit (30) is connected to the output terminal of the power regulation unit (20) and the battery pack, and is used to monitor the overvoltage / undervoltage status of the battery in real time. The feedback control unit (40) has its input terminal connected to the voltage and current signals of the charging input filter unit (10) and the power regulation unit (20), and its output terminal connected to the control terminal of the power regulation unit (20). It generates a closed-loop regulation signal through a comparator network. The logic switching unit (50) receives the output signal of the feedback control unit (40) and the status signal of the battery protection unit (30), and controls the on / off state of the power path through logic gate circuits; The output interface unit (60) is connected to the output terminal of the power regulation unit (20) and is used to output stable electrical energy (P+ / P-) to the load terminal.

2. The lithium battery charge and discharge management circuit according to claim 1, characterized in that, The power regulation unit (20) includes: The first power switch (Q1) has its input terminal connected to the output terminal of the charging input filter unit (10), and its output terminal connected to the battery protection unit (30) through the freewheeling diode (D3). The drive control circuit includes a first drive transistor (Q3) and a second drive transistor (Q7) connected in series. The base of the first drive transistor (Q3) is connected to the output signal of the feedback control unit, and the emitter is grounded through the current sampling resistor (R18). The collector of the second drive transistor (Q7) is connected to the control electrode of the first power switch transistor (Q1). The dynamic compensation network consists of an RC circuit (C4, R1) connected in parallel between the control electrode and the input terminal of the first power switch (Q1); The adjustable reference source (U2) has its reference terminal connected to the emitter of the second driving transistor (Q7) through a voltage divider resistor network (R25, R27, R28), and its output terminal generates a reference voltage signal. The positive terminal of the freewheeling diode (D3) is connected to the output terminal of the first power switch (Q1), and the negative terminal is connected to the battery protection unit through the third inductor (L3), forming a freewheeling energy recovery path.

3. The lithium battery charge and discharge management circuit according to claim 1, characterized in that, The battery protection unit (30) includes: The monitoring chip (U3) has its voltage detection pin (VC) connected to the midpoint of the battery pack (B1 / B2) through a current-limiting resistor (R35) to collect the voltage signal of the series-connected batteries in real time. A dual MOSFET switch array comprising a first MOSFET (Q9A) and a second MOSFET (Q9B) connected back-to-back; The drive isolation circuit includes a drive resistor (R31 / R32) connected in series between the control terminal (DO / CO) of the monitoring chip (U3) and the gate of the MOSFET, and a transient suppression element and a filter capacitor (C25 / C26) connected in parallel between the gate and the source. The midpoint voltage stabilization circuit consists of a filter capacitor (C36) connected between the midpoint of the battery pack (B1 / B2) and the voltage detection pin of the monitoring chip (U3); The monitoring chip (U3) controls the switching of the dual MOSFET switch array according to the battery pack voltage signal, and when overvoltage / undervoltage is detected, it turns off the MOSFET array by driving the isolation circuit to cut off the charging and discharging circuit.

4. The lithium battery charge and discharge management circuit according to claim 1, characterized in that, The feedback control unit (40) includes: The dual comparator integrated circuit (IC) has a first comparator whose non-inverting input is connected to a voltage divider sampling network and whose inverting input is grounded through an RC filter network; and a second comparator whose inverting input is connected to an adjustable reference network. The voltage divider sampling network consists of a first voltage divider resistor (R19), a second voltage divider resistor (R21), and a third voltage divider resistor (R22) connected in series at the input of the output interface unit. The sampling node is connected to the non-inverting input of the first comparator. The adjustable reference network includes a threshold adjustment branch consisting of an adjustable resistor (R11) and fixed voltage divider resistors (R13, R14), and outputs a reference signal to the inverting input of the second comparator. The dynamic compensation circuit includes a compensation capacitor (C13) connected across the input terminals of the dual comparators and a temperature compensation resistor (R16) connected between the output terminal of the second comparator and the inverting input terminal.

5. The lithium battery charge and discharge management circuit according to claim 1, characterized in that, The logic switching unit (50) includes: The MOSFET switching group includes a fourth MOSFET (Q4), a fifth MOSFET (Q5), and a sixth MOSFET (Q6) connected in parallel, wherein: The gate of the fourth MOSFET (Q4) is connected to the output terminal of the feedback control unit (40), and the drain is connected to the reference voltage terminal (1V) through the current limiting resistor (R17). The gate of the fifth MOSFET (Q5) is connected to the comparator output terminal (IC-U1A) of the feedback control unit (40), and the drain is connected to another reference voltage terminal through a resistor (R23). The gate of the sixth MOSFET (Q6) is connected to the enable signal terminal (U3-DO) of the battery protection unit (30) through a current-limiting resistor (R24), and the drain is connected to the source of the fourth MOSFET (Q4) and the fifth MOSFET (Q5).

6. The lithium battery charge / discharge management circuit according to claim 5, characterized in that, The logic switching unit (50) further includes: The acceleration capacitor bank includes a first capacitor (C14) connected in parallel between the gate and source of the fourth MOSFET (Q4), a second capacitor (C16) connected between the gate and source of the fifth MOSFET (Q5), and a third capacitor (C17) connected between the gate and source of the sixth MOSFET (Q6), which is used to improve the switching response speed.

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