CN212649124U - Over-discharge protection circuit for battery - Google Patents

Over-discharge protection circuit for battery Download PDF

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Publication number
CN212649124U
CN212649124U CN202021158264.7U CN202021158264U CN212649124U CN 212649124 U CN212649124 U CN 212649124U CN 202021158264 U CN202021158264 U CN 202021158264U CN 212649124 U CN212649124 U CN 212649124U
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battery
resistor
unit
switch
voltage
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CN202021158264.7U
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Chinese (zh)
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王然然
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Suzhou Langshirun Electronic Co ltd
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Suzhou Langshirun Electronic Co ltd
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Abstract

The utility model relates to a battery overdischarge protection circuit, including voltage comparison unit, voltage reference unit, the control unit, switch unit. The voltage comparison unit is connected with the battery and used for outputting a protection trigger signal when the voltage of the battery is reduced to a set reference voltage along with the discharge of the battery. The voltage reference unit is connected with the voltage comparison unit and used for providing reference voltage for the voltage comparison unit. The control unit is connected with the voltage comparison unit and used for outputting a corresponding control signal when receiving the protection trigger signal. The switch unit is respectively connected with the battery, the load and the control unit and used for disconnecting the battery and the load when receiving the control signal. The utility model discloses the circuit is simple, difficult breaking down, and is with low costs, can cross put the battery and play that better protection is used.

Description

Over-discharge protection circuit for battery
Technical Field
The utility model relates to a battery control technology field, concretely design battery overdischarge protection circuit.
Background
With the development of technology, rechargeable batteries are becoming more popular with users due to their convenience and low price. The most widely used rechargeable battery is, as far as present, a lithium battery. The lithium battery charging and discharging process is the process of lithium ion intercalation and deintercalation. Since the stored electric energy inside the lithium battery is realized through a reversible chemical change, excessive discharge can cause the chemical change to generate an irreversible reaction, and further cause the problems of battery failure, even scrapping and the like. Therefore, how to protect the rechargeable battery before the voltage of the rechargeable battery is too low is a problem to be solved at present.
The traditional industry at present adopts relay and singlechip and integrated circuit control's battery overvoltage crowbar more, and the circuit volume of relay control is great to be unfavorable for the assembly, and software bug appears easily in the circuit of singlechip control, because will write software so can increase development cost, and integrated circuit control not only light but also easy design, but the cost is higher.
Disclosure of Invention
The utility model aims at providing a simple, difficult battery overdischarge protection circuit that breaks down and with low costs of circuit.
In order to achieve the above purpose, the utility model adopts the technical scheme that:
a battery over-discharge protection circuit disposed between a battery and a load, the battery over-discharge protection circuit comprising:
the voltage comparison unit is connected with the battery and used for outputting a protection trigger signal when the voltage of the battery is reduced to a set reference voltage along with the discharge of the battery;
the voltage reference unit is connected with the voltage comparison unit and is used for providing the reference voltage for the voltage comparison unit;
the control unit is connected with the voltage comparison unit and used for outputting a corresponding control signal when receiving the protection trigger signal;
and the switch unit is respectively connected with the battery, the load and the control unit and is used for disconnecting the battery and the load when receiving the control signal.
The voltage comparison unit comprises a comparator, the positive electrode of the comparator is connected with the positive electrode of the battery, the negative electrode of the comparator is connected with the control unit and outputs the protection trigger signal, and the control electrode of the comparator is connected with the voltage reference unit.
The voltage reference unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a first capacitor, the first resistor, the second resistor and the third resistor are connected in series and connected between the anode and the cathode of the battery, the first capacitor is connected in parallel with the first resistor and the two ends of the second resistor, the fourth resistor is connected in parallel with the two ends of the third resistor, and the connection node of the second resistor and the third resistor is connected with the voltage comparison unit.
The control unit comprises a first switch device which is controlled by the protection trigger signal to be conducted and outputs an intermediate control signal, and a second switch device which is controlled by the intermediate control signal to be conducted and outputs the control signal, wherein the first switch device is respectively connected with the voltage comparison unit, the battery and the second switch device, and the second switch device is connected with the battery and the switch unit.
The first switch device adopts a control MOS tube, the second switch device adopts a triode, the grid electrode of the control MOS tube is connected with the voltage comparison unit, the drain electrode of the control MOS tube is connected with the anode of the battery and the base electrode of the triode, the source electrode of the control MOS tube is connected with the cathode of the battery, the emitting electrode of the triode is connected with the anode of the battery, and the collecting electrode of the triode is connected with the switch unit and outputs the control signal.
The voltage comparison unit is connected with the grid electrode of the control MOS tube through an input divider resistor; the drain electrode of the control MOS tube is connected with the anode of the battery through a fifth resistor and a sixth resistor which are connected in series, and the base electrode of the triode is connected with the connection node of the fifth resistor and the sixth resistor; the collector of the triode is connected with the switch unit through an output divider resistor; and a seventh resistor is connected between the grid of the control MOS tube and the cathode of the battery.
An eighth resistor, a ninth resistor and a tenth resistor are further connected in series between the positive electrode and the negative electrode of the battery, a connection node of the eighth resistor and the ninth resistor is connected with the base electrode of the triode, and second capacitors are connected in parallel at two ends of the tenth resistor.
The switch unit comprises a switch MOS tube, the grid electrode of the switch MOS tube is connected with the control unit, and the drain electrode and the source electrode of the switch MOS tube are connected between the load and the negative electrode of the battery.
And a parallel resistor is connected between the grid and the source of the switch MOS tube.
Because of the application of the technical scheme, compared with the prior art, the utility model has the following advantages: the utility model discloses the circuit is simple, difficult breaking down, and is with low costs, can cross put the battery and play that better protection is used.
Drawings
Fig. 1 is a schematic diagram of the battery overdischarge protection circuit of the present invention.
Detailed Description
The invention will be further described with reference to examples of embodiments shown in the drawings.
The terms "first," "second," and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The first embodiment is as follows: as shown in fig. 1, a battery overdischarge protection circuit provided between a (charged) battery (pack) BT and a load includes a voltage comparison unit, a voltage reference unit, a control unit, and a switching unit.
The voltage comparison unit is connected to the battery for outputting a protection trigger signal when the voltage of the battery BT decreases to a set reference voltage (e.g., 2.5V) as it discharges. The voltage comparison unit includes a comparator CJ431, the anode of the comparator CJ431 is connected with the anode of the battery BT, the cathode of the comparator CJ431 is connected with the control unit and outputs a protection trigger signal, and the control electrode of the comparator CJ431 is connected with the voltage reference unit.
The voltage reference unit is connected to a control electrode of the comparator CJ431 in the voltage comparison unit for providing a reference voltage to the comparator CJ431 in the voltage comparison unit. The voltage reference unit comprises a first resistor R11, a second resistor R15, a third resistor R8, a fourth resistor R14 and a first capacitor C8, wherein the first resistor R11, the second resistor R15 and the third resistor R8 are connected in series and connected between the positive pole and the negative pole of the battery BT, the first capacitor C8 is connected in parallel to two ends of a first resistor R11 and the second resistor R15, the fourth resistor R14 is connected in parallel to two ends of the third resistor R8, and the connection node of the second resistor R15 and the third resistor R8 is connected with the control pole of a comparator CJ431 in the voltage comparison unit.
The control unit is connected with the voltage comparison unit and used for outputting a corresponding control signal when receiving the protection trigger signal. The control unit comprises a first switching device which is controlled to be conducted by the protection trigger signal and outputs an intermediate control signal, and a second switching device which is controlled to be conducted by the intermediate control signal and outputs a control signal, wherein the first switching device is respectively connected with the voltage comparison unit, the battery BT and the second switching device, and the second switching device is connected with the battery BT and the switching unit.
Specifically, the first switching device adopts a control MOS transistor Q1, the second switching device adopts a triode Q2, the gate of the control MOS transistor Q1 is connected with the negative electrode of a comparator CJ431 in the voltage comparison unit, the drain of the control MOS transistor Q1 is connected with the positive electrode of the battery BT and the base of the triode Q2, the source of the control MOS transistor Q1 is connected with the negative electrode of the battery BT, the emitter of the triode Q2 is connected with the positive electrode of the battery BT, and the collector of the triode Q2 is connected with the switching unit and outputs a control signal.
The cathode of the comparator CJ431 of the voltage comparison unit is connected with the gate of the control MOS transistor Q1 through an input voltage-dividing resistor R4. The drain electrode of the control MOS transistor Q1 is connected with the positive electrode of the battery BT through a fifth resistor R5 and a sixth resistor R9 which are connected in series, and the base electrode of the triode Q2 is connected with the connection node of the fifth resistor R5 and the sixth resistor R9. The collector of the transistor Q2 is connected to the switch unit through an output divider resistor R6. And a seventh resistor R1 is connected between the grid electrode of the control MOS tube Q1 and the negative electrode of the battery BT. An eighth resistor R10, a ninth resistor R7 and a tenth resistor R3 are further connected in series between the positive electrode and the negative electrode of the battery BT, the connection node of the eighth resistor R10 and the ninth resistor R7 is connected with the base electrode of the triode Q2, and a second capacitor C1 is connected in parallel at two ends of the tenth resistor R3.
The switch unit is respectively connected with the battery BT, the load and the control unit and used for disconnecting the battery BT from the load when receiving the control signal. The switch unit comprises a switch MOS tube U1, and the switch MOS tube U1 adopts P-MOS NCE 4435. The grid electrode of the switching MOS tube U1 is connected with the collector electrode of a triode Q2 in the control unit through an output voltage-dividing resistor R6, the drain electrode and the source electrode of the switching MOS tube U1 are connected between a load and the negative electrode of the battery BT, and a resistor R12 is connected between the switching MOS tube U1 and the load. A parallel resistor R2 is connected between the grid and the source of the switching MOS tube U1.
The working principle of the battery over-discharge protection circuit is as follows:
during the discharging process of the battery BT, the electric quantity of the battery BT is gradually reduced along with the change of time, the voltage is reduced, when the voltage of the battery BT is reduced to the reference voltage (such as 2.5V) of the comparator CJ431, the circuit is started in a protection mode, at the moment, current flows to the control MOS tube Q1 from the comparator CJ431, Ug < Us is divided through the input voltage dividing resistor R4, the control MOS tube Q1 is conducted at the moment, the triode Q2 is also conducted, the grid voltage of the switch MOS tube U1 is lower than the source voltage through the voltage division of the output voltage dividing resistor R6, the switch MOS tube U1 is in a cut-off state, the whole circuit enters a battery protection state, and the load does not work any more. When the battery BT is fully charged, the circuit is restarted and enters a working mode.
Compared with the prior art, the voltage of the battery BT collected by the comparator CJ431 is compared with the reference voltage provided by the voltage reference unit, when the collected voltage is smaller than the reference voltage, the switch MOS tube U1 is controlled to be cut off, and the battery BT stops discharging, so that the battery (pack) is effectively protected from overdischarge, the battery (pack) is prevented from being permanently damaged due to overdischarge, and the service life of the battery (pack) is prolonged. In addition, the comparator of the design adopts a low-cost and micro-power consumption chip with a voltage reference, so that the cost is reduced, and the power consumption is saved; the electronic switch adopts a P-MOS field effect transistor and a triode, so that the loss is small, the response is fast, and the electronic switch is stable and reliable; the over-discharge protection circuit has the advantages of few devices, simple structure, small volume and convenient installation. Compared with a circuit controlled by a single chip microcomputer, the circuit has no software bug, and compared with a circuit controlled by an integrated circuit device, the circuit has lower cost.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose of the embodiments is to enable people skilled in the art to understand the contents of the present invention and to implement the present invention, which cannot limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.

Claims (9)

1. The utility model provides a battery overdischarge protection circuit, sets up between battery and load which characterized in that: the battery over-discharge protection circuit includes:
the voltage comparison unit is connected with the battery and used for outputting a protection trigger signal when the voltage of the battery is reduced to a set reference voltage along with the discharge of the battery;
the voltage reference unit is connected with the voltage comparison unit and is used for providing the reference voltage for the voltage comparison unit;
the control unit is connected with the voltage comparison unit and used for outputting a corresponding control signal when receiving the protection trigger signal;
and the switch unit is respectively connected with the battery, the load and the control unit and is used for disconnecting the battery and the load when receiving the control signal.
2. The battery over-discharge protection circuit of claim 1, wherein: the voltage comparison unit comprises a comparator, the positive electrode of the comparator is connected with the positive electrode of the battery, the negative electrode of the comparator is connected with the control unit and outputs the protection trigger signal, and the control electrode of the comparator is connected with the voltage reference unit.
3. The battery over-discharge protection circuit of claim 1, wherein: the voltage reference unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a first capacitor, the first resistor, the second resistor and the third resistor are connected in series and connected between the anode and the cathode of the battery, the first capacitor is connected in parallel with the first resistor and the two ends of the second resistor, the fourth resistor is connected in parallel with the two ends of the third resistor, and the connection node of the second resistor and the third resistor is connected with the voltage comparison unit.
4. The battery over-discharge protection circuit of claim 1, wherein: the control unit comprises a first switch device which is controlled by the protection trigger signal to be conducted and outputs an intermediate control signal, and a second switch device which is controlled by the intermediate control signal to be conducted and outputs the control signal, wherein the first switch device is respectively connected with the voltage comparison unit, the battery and the second switch device, and the second switch device is connected with the battery and the switch unit.
5. The battery over-discharge protection circuit of claim 4, wherein: the first switch device adopts a control MOS tube, the second switch device adopts a triode, the grid electrode of the control MOS tube is connected with the voltage comparison unit, the drain electrode of the control MOS tube is connected with the anode of the battery and the base electrode of the triode, the source electrode of the control MOS tube is connected with the cathode of the battery, the emitting electrode of the triode is connected with the anode of the battery, and the collecting electrode of the triode is connected with the switch unit and outputs the control signal.
6. The battery over-discharge protection circuit of claim 5, wherein: the voltage comparison unit is connected with the grid electrode of the control MOS tube through an input divider resistor; the drain electrode of the control MOS tube is connected with the anode of the battery through a fifth resistor and a sixth resistor which are connected in series, and the base electrode of the triode is connected with the connection node of the fifth resistor and the sixth resistor; the collector of the triode is connected with the switch unit through an output divider resistor; and a seventh resistor is connected between the grid of the control MOS tube and the cathode of the battery.
7. The battery over-discharge protection circuit of claim 6, wherein: an eighth resistor, a ninth resistor and a tenth resistor are further connected in series between the positive electrode and the negative electrode of the battery, a connection node of the eighth resistor and the ninth resistor is connected with the base electrode of the triode, and second capacitors are connected in parallel at two ends of the tenth resistor.
8. The battery over-discharge protection circuit of claim 1, wherein: the switch unit comprises a switch MOS tube, the grid electrode of the switch MOS tube is connected with the control unit, and the drain electrode and the source electrode of the switch MOS tube are connected between the load and the negative electrode of the battery.
9. The battery over-discharge protection circuit of claim 8, wherein: and a parallel resistor is connected between the grid and the source of the switch MOS tube.
CN202021158264.7U 2020-06-22 2020-06-22 Over-discharge protection circuit for battery Active CN212649124U (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202021158264.7U CN212649124U (en) 2020-06-22 2020-06-22 Over-discharge protection circuit for battery

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202021158264.7U CN212649124U (en) 2020-06-22 2020-06-22 Over-discharge protection circuit for battery

Publications (1)

Publication Number Publication Date
CN212649124U true CN212649124U (en) 2021-03-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202021158264.7U Active CN212649124U (en) 2020-06-22 2020-06-22 Over-discharge protection circuit for battery

Country Status (1)

Country Link
CN (1) CN212649124U (en)

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