Battery protection circuit, battery and electronic equipment

Abstract

The utility model relates to a battery protection circuit, a battery and electronic equipment. The battery protection circuit comprises a main charging loop and a secondary charging loop which are used for being connected with the positive electrode and the negative electrode of a battery cell respectively, and the main charging loop and the secondary charging loop are connected in parallel. The battery protection circuit further comprises a first-stage protection unit and a second-stage protection unit, the first-stage protection unit is connected with the main charging loop, the second-stage protection unit is connected with the secondary charging loop, the first-stage protection unit comprises a thermosensitive device connected in series in the main charging loop, and the second-stage protection unit comprises a second-stage protection unit connected in series in the secondary charging loop. And the secondary protection unit comprises a load resistor connected in series in the secondary charging loop, and the load resistor is adjacent to the thermosensitive device and is used for heating the thermosensitive device under the overcharge test. And the battery cell heats the thermosensitive device through the load resistor under the overcharge test so as to disconnect the main discharge loop, so that the problem that a secondary PTC protection design scheme in the prior art cannot meet the safety standard authentication is solved.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and particularly to a battery protection circuit, a battery, and an electronic device. Background Art

[0002] With the development of intelligent terminals, the requirements for battery capacity, charging and discharging are getting higher and higher. A common scenario is that in order to achieve fast charging for large-capacity batteries, the battery charging current is getting larger and larger. For example, currently, some intelligent terminal batteries adopt a 30W - 50W fast charging scheme. In order to reduce costs, the original two-stage IC + MOS protection scheme is changed to: the primary protection is still an IC + MOS design, and the secondary protection is changed to a PTC design. However, the changed secondary PTC protection design scheme is difficult to pass the relevant safety standard certification in abnormal charging scenarios, and there are certain safety hazards in the protection design. Summary of the Utility Model

[0003] This application provides a battery protection circuit, a battery, and an electronic device to solve the problem that the existing secondary PTC protection design scheme cannot meet the safety standard certification.

[0004] In a first aspect, this application provides a battery protection circuit. The battery protection circuit includes a main charging circuit and a secondary charging circuit respectively used to connect the positive and negative electrodes of the battery cell, and the main charging circuit is in parallel with the secondary charging circuit; the battery protection circuit further includes a primary protection unit and a secondary protection unit. The primary protection unit is connected to the main charging circuit, and the secondary protection unit is connected to the secondary charging circuit. The primary protection unit includes a thermosensitive device connected in series in the main charging circuit, and the secondary protection unit includes a load resistor connected in series in the secondary charging circuit. The load resistor is adjacent to the thermosensitive device and is used to heat the thermosensitive device and the battery cell under overcharge testing.

[0005] Optionally, the primary protection unit further includes a first protection switch, a first protection chip, and an overcurrent detection resistor. The first protection switch and the overcurrent detection resistor are connected in series in the main charge and discharge circuit, and the first protection chip is respectively connected to the first protection switch, the overcurrent detection resistor, and the positive electrode of the battery cell.

[0006] Optionally, the secondary protection unit includes a second protection switch and a second protection chip. The first end of the second protection switch is respectively connected to the first end of the thermosensitive device and the positive electrode of the battery cell through the load resistor. The second end of the second protection switch is connected in series in the secondary charging circuit, and the third end of the second protection switch is connected back to the secondary charging circuit through the second protection chip.

[0007] Optionally, the second protection chip detects the battery voltage during overcharge testing, and outputs a high-level signal to the second protection switch when the battery voltage reaches the overcharge protection threshold of the second protection chip. The second protection switch conducts according to the high-level signal output by the second protection chip and provides a discharge current for the load resistor. The load resistor increases the ambient temperature of the thermosensitive device according to the discharge current, and the thermosensitive device disconnects when the ambient temperature reaches the temperature threshold.

[0008] Optionally, the secondary charging circuit further includes a first current-limiting resistor and a first filter capacitor. The first end of the first current-limiting resistor is connected to the positive electrode of the battery cell, and the second end of the first current-limiting resistor is respectively connected to the first end of the first filter capacitor and the power supply terminal of the second protection chip. The second end of the first filter capacitor is respectively connected to the negative electrode of the battery cell, the ground terminal of the second protection chip, and the sampling terminal of the second protection chip.

[0009] Optionally, a connector is further provided on the main charge and discharge circuit, and the connector is connected between the thermosensitive device and the first protection switch.

[0010] Optionally, at least one filter capacitor is further connected in parallel with the connector.

[0011] In a second aspect, the present application provides a battery, which includes a battery cell and the battery protection circuit as described in any one of the above.

[0012] In a third aspect, the present application provides an electronic device, which includes the above battery.

[0013] In the structure provided by the embodiments of the present application, the battery protection circuit includes a main charging circuit and a secondary charging circuit respectively used to connect the positive and negative electrodes of the battery cell, and the main charging circuit is connected in parallel with the secondary charging circuit; the battery protection circuit further includes a primary protection unit and a secondary protection unit, the primary protection unit is connected to the main charging circuit, the secondary protection unit is connected to the secondary charging circuit, the primary protection unit includes a thermosensitive device connected in series in the main charging circuit, the secondary protection unit includes a load resistor connected in series in the secondary charging circuit, and the load resistor is adjacent to the thermosensitive device and is used to heat the thermosensitive device during overcharge testing. During overcharge testing, the thermosensitive device is heated by the load resistor to disconnect the main charge and discharge circuit so as to successfully pass the safety standard certification, thereby solving the problem that the existing secondary PTC protection design scheme cannot meet the safety standard certification. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0016] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the drawings in the figures do not constitute a proportional limitation.

[0017] Figure 1 Structural schematic diagram of the battery protection circuit provided for the embodiments of the present application;

[0018] Figure 2 Structural schematic diagram of the primary protection unit provided for the embodiments of the present application;

[0019] Figure 3 Structural schematic diagram of the battery protection circuit provided for the embodiments of the present application. Detailed implementation manners

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0021] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0022] In one embodiment, Figure 1 For the flowchart of a battery protection circuit in one embodiment, refer to Figure 1, a battery protection circuit is provided. The battery protection circuit includes a main charging circuit and a secondary charging circuit respectively used to connect the positive and negative electrodes of the battery cell. The main charging circuit is connected in parallel with the secondary charging circuit. The battery protection circuit further includes a primary protection unit 210 and a secondary protection unit 220. The primary protection unit 210 is connected to the main charging circuit, and the secondary protection unit 220 is connected to the secondary charging circuit. The primary protection unit 210 includes a thermosensitive device connected in series in the main charging circuit, and the secondary protection unit 220 includes a load resistor connected in series in the secondary charging circuit. The load resistor is adjacent to the thermosensitive device and is used to heat the thermosensitive device under overcharge test.

[0023] Specifically, Figure 1 In [reference], A indicates the main charge and discharge circuit, B indicates the secondary charging circuit, F1 indicates the thermosensitive device, R5 indicates the load resistor, cell indicates the battery cell. The main charge and discharge circuit is used to provide charge and discharge functions for the battery, and the secondary charging circuit is used to provide a discharge function for the battery. There is a common line between the main charge and discharge circuit and the secondary charging circuit. The primary protection unit 210 is located on the main charge and discharge circuit and is used for overvoltage protection, overcurrent protection, and short-circuit protection. The secondary protection unit 220 is located on the secondary charging circuit and is used to provide overcharge protection. Conducting a safety standard certification is to conduct an overcharge test. The overcharge test is to charge the battery to determine whether the battery protection circuit can timely disconnect the charging current when an overcharge phenomenon occurs, that is, to determine whether the battery protection circuit can prevent the battery from further overcharging.

[0024] The load resistor is arranged adjacent to the thermosensitive device, that is, the spatial distance between the load resistor and the thermosensitive device is a preset distance. The preset distance refers to the distance at which the thermosensitive device can sense the temperature change of the load resistor. The thermosensitive device will protect and disconnect when the ambient temperature is higher. That is, the load resistor in the secondary protection unit 220 will heat the thermosensitive device in the primary protection unit 210 under overcharge test. The thermosensitive device is disconnected from the main charge and discharge circuit by being heated and melted. Once the main charge and discharge circuit is disconnected, the battery cannot be charged continuously, thereby preventing the battery from overcharging and successfully passing the safety standard certification.

[0025] In one embodiment, the primary protection unit 210 further includes a first protection switch, a first protection chip, and an overcurrent detection resistor. The first protection switch and the overcurrent detection resistor are connected in series in the main charge and discharge circuit, and the first protection chip is respectively connected to the first protection switch, the overcurrent detection resistor, and the positive electrode of the battery cell.

[0026] Specifically, Figure 2Q1 in it indicates the first protection switch, U1 indicates the first protection chip, RS1 indicates the overcurrent detection resistor, and R4 is the current-limiting resistor connected between the first protection chip and the first protection switch. The overcurrent detection resistor is used to detect the charging current in the main charge and discharge loop and feed back the detection result of the charging current to the first protection chip. The first protection chip determines whether there are overvoltage, overcurrent, short circuit or other overcharging tests in the main charge and discharge loop according to the detection result of the charging current. If any of these situations occurs, it will output a corresponding control signal to the first protection switch to control it to disconnect, thus disconnecting the main charge and discharge loop and playing a protective role.

[0027] The first protection switch is a switching device composed of two MOS field effect transistors and two diodes. The first protection switch can also be other integrated circuits or devices with switching functions, such as current-type fully controlled devices (BJT, GTO), current-type semi-controlled devices (SCR), voltage-type fully controlled devices (P-MOSFET, IGBT, MCT, SIT), etc. The first protection chip is used to output a corresponding control signal to the first protection switch according to the voltage situation in the main charge and discharge loop, that is, to control the switching state of the first protection switch through the control signal. And the first protection switch is arranged on the main charge and discharge loop, so the on-off state of the main charge and discharge loop can be controlled through the first protection switch, thus playing a protective role.

[0028] In one embodiment, the secondary protection unit 220 further includes a second protection switch and a second protection chip. The first end of the second protection switch is connected to the first end of the thermosensitive device and the positive electrode of the battery cell respectively through the load resistor. The second end of the second protection switch is connected in series in the secondary charging loop. The third end of the second protection switch is connected back to the secondary charging loop through the second protection chip.

[0029] Specifically, Figure 3 Q2 in it indicates the second protection switch, U2 indicates the second protection chip, R5 indicates the load resistor, and F1 indicates the thermosensitive device. The thermosensitive device can specifically adopt semiconductor materials or components with a very large positive temperature coefficient, such as the thermistor PTC. The second protection chip is used to detect the battery voltage and control the conduction state of the second protection switch according to the battery voltage. The second protection switch is used to determine whether to provide current for the load resistor to conduct the secondary charging loop. When the secondary charging loop is connected, it will provide current for the load resistor. The load resistor has heat generation when the current flows through it. Since the load resistor is adjacent to the thermosensitive device, the load resistor continuously heats the thermosensitive device under overcharging tests. The thermosensitive device will protect and disconnect when the ambient temperature is higher, thus disconnecting the main charge and discharge loop and playing a protective role.

[0030] In one embodiment, the second protection chip detects the battery voltage under overcharge test, and outputs a high-level signal to the second protection switch when the battery voltage reaches the overcharge protection threshold of the second protection chip. The second protection switch conducts according to the high-level signal output by the second protection chip and provides a discharge current for the load resistor. The load resistor increases the ambient temperature of the thermosensitive device according to the discharge current, and the thermosensitive device disconnects when the ambient temperature reaches the temperature threshold.

[0031] Specifically, the overcharge test will cause a certain device without safety certification to fail, that is, it will cause the first protection chip in the primary protection unit 210 of the battery protection circuit to fail. Then, the battery is charged at 6V / 1C and 6V / 2C. The second protection chip detects the battery voltage under the overcharge test. If the battery voltage does not reach the overcharge protection threshold, it means that the battery has not experienced overcharge, and there is no need to control the second protection switch to conduct. At this time, the secondary charging circuit is in an open state. If the battery voltage reaches the overcharge protection threshold, it means that the battery has experienced overcharge, and then the second protection switch is controlled to conduct. At this time, the secondary charging circuit is connected, providing current for the load resistor. After receiving the current, the load resistor will heat up. Since the load resistor is close to the thermosensitive device, the load resistor can conduct heat to the thermosensitive device, causing the ambient temperature of the thermosensitive device to gradually increase until the protection disconnects when the ambient temperature reaches the temperature threshold of the thermosensitive device, thereby disconnecting the main charge and discharge circuit and preventing further overcharging of the battery due to continued charging of the battery.

[0032] In one embodiment, the secondary charging circuit further includes a first current-limiting resistor and a first filter capacitor. The first end of the first current-limiting resistor is connected to the positive electrode of the battery cell, and the second end of the first current-limiting resistor is respectively connected to the first end of the first filter capacitor and the power supply terminal of the second protection chip. The second end of the first filter capacitor is respectively connected to the negative electrode of the battery cell, the grounding terminal of the second protection chip, and the sampling terminal of the second protection chip.

[0033] Specifically, the first current-limiting resistor is connected between the positive electrode of the battery and the first filter capacitor, and is used for current-limiting the battery voltage, while the first filter capacitor filters the battery voltage to avoid interference with the first protection chip caused by the battery voltage.

[0034] In one embodiment, a connector is further provided on the main charge and discharge circuit, and the connector is connected between the thermosensitive device and the first protection switch.

[0035] Specifically, referring to Figure 3 As shown, J1 indicates the connector, which is used to establish the connection relationship between the external device and the battery cell.

[0036] In one embodiment, at least one filter capacitor is also connected in parallel with the connector.

[0037] Specifically, as Figure 3 shown, two filter capacitors are connected in parallel with the connector, and these two capacitors are connected in series with each other, so as to filter the voltage supplied to the connector in the main charge and discharge circuit, and reduce the interference signals in the voltage supplied by the battery to the external device.

[0038] In one embodiment, a battery is provided, and the battery includes an electric cell and the battery protection circuit described in any one of the above embodiments that are electrically connected.

[0039] In one embodiment, an electronic device is provided, and the electronic device at least includes the battery described in the previous embodiment.

[0040] Those skilled in the art can understand that Figure 3 the structure shown in

[0041] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the electronic device to which the solution of the present application is applied. The specific electronic device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0042] It should be understood that the terms used in this document are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless otherwise clearly specified in the context, the singular forms "a", "an", and "the" as used in this document may also represent the plural form. The terms "include", "comprise", "contain", and "have" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The steps, processes, and operations of the battery protection circuit described in this document are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly specified. It should also be understood that additional or alternative

Claims

1. A battery protection circuit, characterized in that: The battery protection circuit includes a main charging circuit and a secondary charging circuit respectively used to connect the positive and negative electrodes of the battery cell, and the main charging circuit is connected in parallel with the secondary charging circuit; the battery protection circuit also includes a primary protection unit and a secondary protection unit, the primary protection unit is connected to the main charging circuit, and the secondary protection unit is connected to the secondary charging circuit, the primary protection unit includes a thermistor connected in series in the main charging circuit, and the secondary protection unit includes a load resistor connected in series in the secondary charging circuit, the load resistor is adjacent to the thermistor, and is used to heat the thermistor under a flooding test.

2. The battery protection circuit according to claim 1, characterized in that: The first-level protection unit also includes a first protection switch, a first protection chip, and an overcurrent detection resistor. The first protection switch and the overcurrent detection resistor are connected in series in the main charge and discharge circuit, and the first protection chip is respectively connected to the first protection switch, the overcurrent detection resistor, and the positive electrode of the battery cell.

3. The battery protection circuit according to claim 1, characterized in that: The secondary protection unit also includes a second protection switch and a second protection chip, the first end of the second protection switch is respectively connected to the first end of the thermistor and the positive electrode of the battery cell through the load resistor, the second end of the second protection switch is connected in series in the secondary charging circuit, and the third end of the second protection switch is connected back to the secondary charging circuit through the second protection chip.

4. The battery protection circuit according to claim 3, characterized in that: The second protection chip detects the battery voltage under the overcharge test, and outputs a high-level signal to the second protection switch when the battery voltage reaches the overcharge protection threshold of the second protection chip. The second protection switch is turned on according to the high-level signal output by the second protection chip and provides a discharge current for the load resistor. The load resistor increases the ambient temperature of the thermistor according to the discharge current, and the thermistor is disconnected when the ambient temperature reaches the temperature threshold.

5. The battery protection circuit according to claim 3, characterized in that: The secondary charging circuit also includes a first current limiting resistor and a first filter capacitor, the first end of the first current limiting resistor is connected to the positive electrode of the battery cell, the second end of the first current limiting resistor is respectively connected to the first end of the first filter capacitor and the power supply end of the second protection chip, and the second end of the first filter capacitor is respectively connected to the negative electrode of the battery cell, the ground end of the second protection chip, and the sampling end of the second protection chip.

6. The battery protection circuit according to claim 3, characterized in that: The main charge and discharge circuit is also provided with a connector, and the connector is connected between the thermal sensitive device and the first protection switch.

7. The battery protection circuit according to claim 5, characterized in that: The connector is also connected in parallel with at least one filter capacitor.

8. A battery, characterized in that: The battery comprises a battery cell and a battery protection circuit as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: The electronic device comprises the battery as claimed in claim 8.

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