Battery protection circuit and mobile power supply

Abstract

The utility model relates to battery protection technical field, concretely relates to a battery protection circuit and portable power source. The battery protection circuit includes including switch unit, drive unit, discharge loop unit and at least one bidirectional gallium nitride switch tube, switch unit is located between the positive pole of battery group and the control end of every bidirectional gallium nitride switch tube, and the control end of switch unit is connected with drive unit, and discharge loop unit is connected between the control end and source electrode of every bidirectional gallium nitride switch tube, and the control end of discharge loop unit connects drive unit, and the source electrode of every bidirectional gallium nitride switch tube connects the negative pole of load, and the drain electrode connects the negative pole of battery group, and drive unit is used to drive switch unit and discharge loop unit to be connected or be disconnected. The application can avoid bidirectional gallium nitride switch tube damaging in the process of opening and disconnecting, prolong the service life of bidirectional gallium nitride switch tube, prolong the service life of the applied portable power source.

Description

Technical Field

[0001] This utility model relates to the field of battery protection technology, and in particular to a battery protection circuit and a mobile power supply. Background Technology

[0002] Currently, battery packs are widely used in energy storage power supplies, robotic vacuum cleaners, power tools, electric bicycles, drones, and other fields. Battery packs are usually equipped with a corresponding Battery Management System (BMS), which is mainly responsible for managing and maintaining the individual cells of the battery pack, monitoring the status of each cell, preventing overcharging or over-discharging of the battery pack, and extending the battery pack's lifespan.

[0003] In the battery protection circuit of a battery management system, two NMOS transistors are typically used, connected back-to-back with common source terminals. The drain side is used to block the output voltage, effectively using a combination of charging and discharging transistors to disconnect the battery pack in case of circuit malfunction. Because MOS transistors have PN junctions, their on-resistance is relatively high. The presence of two NMOS transistors further increases the overall internal resistance loss and heat generation. Therefore, some manufacturers use bidirectional gallium nitride (GaN) switches instead of two NMOS transistors to address the issues of high internal resistance loss and heat generation. However, bidirectional GaN switches are prone to damage during switching on and off, resulting in a short lifespan. Utility Model Content

[0004] This utility model provides a battery protection circuit and a power bank to solve the problem that the bidirectional gallium nitride switch in the battery protection circuit is easily damaged and has a short service life during the turn-on and turn-off process.

[0005] This utility model discloses a battery protection circuit disposed between a load and a battery pack. The battery protection circuit includes a switching unit, a driving unit, a discharge circuit unit, and at least one bidirectional gallium nitride (GaN) switching transistor. The switching unit is disposed between the positive terminal of the battery pack and the control terminal of each GaN switching transistor. The control terminal of the switching unit is connected to the driving unit. The discharge circuit unit is connected in series between the control terminal and the source of each GaN switching transistor. The control terminal of the discharge circuit unit is connected to the driving unit. The source of each GaN switching transistor is connected to the negative terminal of the load, and the drain is connected to the negative terminal of the battery pack. The driving unit is used to drive the switching unit and the discharge circuit unit to be turned on or off.

[0006] Optionally, the discharge circuit unit includes a first resistor, a first diode, and an NMOS transistor connected in series. The other end of the first resistor is connected to the switching unit and the control terminal of each of the bidirectional gallium nitride switches. The control terminal of the NMOS transistor is connected to the driving unit. The drain is connected to the negative terminal of the first diode, and the source is connected to the source of each of the bidirectional gallium nitride switches and the negative terminal of the load.

[0007] Optionally, the switching unit includes a PMOS transistor and a pull-up resistor. The pull-up resistor is connected in series between the control terminal of the PMOS transistor and the positive terminal of the battery pack. The control terminal of the PMOS transistor is connected to the driving unit, the source is connected to the positive terminal of the battery pack, and the drain is connected to the control terminal of each bidirectional gallium nitride switch and the other end of the first resistor.

[0008] Optionally, the driving unit includes a transistor and a pull-down resistor. The base of the transistor is used to receive a level signal. The pull-down resistor is connected in series between the base of the transistor and the negative terminal of the load. The collector of the transistor is connected to the control terminal of the PMOS transistor and the control terminal of the NMOS transistor, and the emitter is connected to the negative terminal of the load.

[0009] Optionally, the switching unit further includes a first current-limiting resistor, which is connected in series between the control terminal of the PMOS transistor and the collector of the transistor.

[0010] Optionally, the switching unit further includes a second current-limiting resistor and a third current-limiting resistor connected in series. The other end of the second current-limiting resistor is connected to the drain of the PMOS transistor, and the other end of the third current-limiting resistor is connected to the control terminal of each of the bidirectional gallium nitride switching transistors and the other end of the first resistor.

[0011] Optionally, the driving unit further includes a fourth current-limiting resistor, one end of which is used to receive a level signal, and the other end is connected to the base of the transistor.

[0012] Optionally, the battery protection circuit further includes a second diode, the positive terminal of which is connected to the positive terminal of the battery pack, and the negative terminal of which is connected to the switching unit.

[0013] Optionally, the battery protection circuit further includes an energy storage capacitor, which is connected in parallel between the positive terminal of the battery pack and the negative terminal of the load.

[0014] This utility model also discloses a portable power supply, including a battery pack, a load, and the aforementioned battery protection circuit. The battery protection circuit is disposed between the battery pack and the load. The switching unit of the battery protection circuit is disposed between the positive terminal of the battery pack and the control terminal of each of the bidirectional gallium nitride switching transistors. The source of the bidirectional gallium nitride switching transistors of the battery protection circuit is connected to the negative terminal of the load, and the drain is connected to the negative terminal of the battery pack.

[0015] The beneficial effects of the battery protection circuit and power bank provided in this utility model embodiment are as follows: By setting a switching unit between the positive terminal of the battery pack and the control terminal of each bidirectional gallium nitride (GaN) switch, the switching unit connects or disconnects the path between the positive terminal of the battery pack and the control terminal of the bidirectional GaN switch under the drive of the driving unit, so as to turn on or off the bidirectional GaN switch and realize the protection of the battery pack. The discharge circuit unit is connected in series between the control terminal and the source of each bidirectional GaN switch. The discharge circuit unit connects or disconnects under the drive of the driving unit, thereby forming a fast discharge circuit, avoiding damage to the bidirectional GaN switch during the opening and closing process, extending the service life of the bidirectional GaN switch, and extending the service life of the power bank used. Attached Figure Description

[0016] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0017] Figure 1 This is a structural block diagram of the battery protection circuit according to an embodiment of the present invention;

[0018] Figure 2 This is a circuit diagram of the battery protection circuit according to an embodiment of the present invention;

[0019] Figure 3 This is a structural block diagram of a portable power bank according to an embodiment of the present invention.

[0020] The labels for the attached figures are as follows:

[0021] 100. Battery protection circuit;

[0022] 110. Switching unit; 120. Drive unit; 130. Discharge circuit unit;

[0023] GaN1, bidirectional gallium nitride switch; R1, first resistor; D1, first diode; Q1, NMOS transistor; Q2, PMOS transistor; R2, pull-up resistor; R3, first current-limiting resistor; R4, second current-limiting resistor; R5, third current-limiting resistor; Q3, transistor; R6, pull-down resistor; R7, fourth current-limiting resistor; D2, second diode; C1, energy storage capacitor;

[0024] 200, load; 300, battery pack. Detailed Implementation

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0026] This utility model embodiment provides a battery protection circuit 100, which is disposed between the load 200 and the battery pack 300, such as Figure 1 and Figure 2 As shown, the battery protection circuit 100 includes a switching unit 110, a driving unit 120, a discharge circuit unit 130, and at least one bidirectional gallium nitride (GaN) switching transistor (GaN1). The switching unit 110 is located between the positive terminal BAT+ of the battery pack 300 and the control terminal of each bidirectional GaN switching transistor (GaN1). The control terminal of the switching unit 110 is connected to the driving unit 120. The discharge circuit unit 130 is connected in series between the control terminal and the source of each bidirectional GaN switching transistor (GaN1). The control terminal of the discharge circuit unit 130 is connected to the driving unit 120. The source of each bidirectional GaN switching transistor (GaN1) is connected to the negative terminal PACK- of the load 200, and the drain is connected to the negative terminal BAT- of the battery pack 300. The driving unit 120 is used to drive the switching unit 110 and the discharge circuit unit 130 to be turned on or off.

[0027] The battery protection circuit 100 of this application embodiment provides a switching unit 110 between the positive terminal BAT+ of the battery pack 300 and the control terminal of each bidirectional gallium nitride (GaN) switching transistor (GaN1). The switching unit 110, driven by the driving unit 120, connects or disconnects the path between the positive terminal BAT+ of the battery pack 300 and the control terminal of the bidirectional GaN switching transistor (GaN1) to turn the GaN1 on or off, thereby protecting the battery pack 300. A discharge circuit unit 130 is connected in series between the control terminal and the source of each bidirectional GaN switching transistor (GaN1). The discharge circuit unit 130, driven by the driving unit 120, connects or disconnects, forming a fast discharge circuit. This prevents damage to the bidirectional GaN switching transistor (GaN1) during the on / off process, extends the service life of the bidirectional GaN switching transistor (GaN1), and extends the service life of the applied power bank.

[0028] Specifically, when the switching unit 110 is turned on by the driving unit 120, the path between the positive terminal BAT+ of the battery pack 300 and the control terminal of the bidirectional gallium nitride switch GaN1 is connected, and the bidirectional gallium nitride switch GaN1 is turned on; when the switching unit 110 is turned off by the driving unit 120, the path between the positive terminal BAT+ of the battery pack 300 and the control terminal of the bidirectional gallium nitride switch GaN1 is disconnected, and the bidirectional gallium nitride switch GaN1 is turned off.

[0029] Among them, the bidirectional gallium nitride (GaN1) switch is one of the third-generation semiconductor power devices. It features bidirectional dual-drain single-gate operation and offers advantages such as high power, radiation resistance, smaller size, and lower internal resistance. The bidirectional GaN1 switch provides bidirectional protection for the 300 battery pack. Compared to using two NMOS transistors (Q1), it has lower on-resistance, occupies less circuit board space, is more efficient, generates less heat, and has more stable performance. The number of bidirectional gallium nitride (GaN) switches can be one, two, three, or more. The control terminal of each bidirectional GaN switch is connected to the switching unit 110, the source is connected to the negative terminal PACK- of the load 200, and the drain is connected to the negative terminal BAT- of the battery pack 300. That is, when multiple bidirectional GaN switches are set, they are connected in parallel. Setting multiple bidirectional GaN switches can distribute the total current flowing through each bidirectional GaN switch, thereby achieving higher current handling capacity, reducing overall on-resistance, reducing on-loss, and reducing the heat generated by each bidirectional GaN switch.

[0030] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the discharge circuit unit 130 includes a first resistor R1, a first diode D1, and an NMOS transistor Q1 connected in series. The other end of the first resistor R1 is connected to the control terminal of the switching unit 110 and each bidirectional gallium nitride switch GaN1. The control terminal of the NMOS transistor Q1 is connected to the driving unit 120. The drain is connected to the negative terminal of the first diode D1, and the source is connected to the source of each bidirectional gallium nitride switch GaN1 and the negative terminal PACK- of the load 200.

[0031] Specifically, when NMOS transistor Q1 is turned on by driving unit 120, current flows from the gate to the source of bidirectional gallium nitride (GaN) switch GaN1 through the path formed by the first resistor R1, the first diode D1, and NMOS transistor Q1. The charge between the gate and source is rapidly released through discharge circuit unit 130, the gate voltage drops rapidly, and bidirectional GaN switch GaN1 is quickly turned off. When NMOS transistor Q1 is turned off by driving unit 120, due to the turn-off of NMOS transistor Q1 and the reverse bias of the first diode D1, current cannot flow through discharge circuit unit 130, the gate charge of bidirectional GaN switch GaN1 remains stable, and bidirectional GaN switch GaN1 remains in the on state. Therefore, when the bidirectional gallium nitride (GaN) switch GaN1 needs to be turned off, the discharge circuit unit 130 provides a fast charge release path, ensuring that the gate charge of the bidirectional GaN switch GaN1 can be released quickly, thereby enabling the bidirectional GaN switch GaN1 to be turned off quickly. The rapid release of the gate charge can reduce gate voltage spikes and avoid device damage caused by voltage spikes. The circuit structure of the discharge circuit unit 130 is simple, reducing the complexity and cost of circuit design.

[0032] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the switching unit 110 includes a PMOS transistor Q2 and a pull-up resistor R2. The pull-up resistor R2 is connected in series between the control terminal of the PMOS transistor Q2 and the positive terminal BAT+ of the battery pack 300. The control terminal of the PMOS transistor Q2 is connected to the driving unit 120, the source is connected to the positive terminal BAT+ of the battery pack 300, and the drain is connected to the control terminal of each bidirectional gallium nitride switch GaN1 and the other end of the first resistor R1.

[0033] Specifically, when the control terminal of PMOS transistor Q2 receives a low-level signal, PMOS transistor Q2 turns on, connecting the positive terminal BAT+ of battery pack 300 with the control terminal of bidirectional gallium nitride (GaN) switch GaN1, driving GaN1 to turn on. When the control terminal of PMOS transistor Q2 receives a high-level signal, PMOS transistor Q2 turns off, disconnecting the connection between the positive terminal BAT+ of battery pack 300 and the control terminal of bidirectional GaN1, turning GaN1 off. The pull-up resistor R2 pulls the control terminal of PMOS transistor Q2 to a high level when it does not receive a signal, keeping PMOS transistor Q2 off and preventing false turn-on, thus improving the safety of the battery protection circuit 100. Furthermore, since the switching unit 110 is connected to the positive terminal BAT+ of battery pack 300, using PMOS transistor Q2 allows for a simpler driving circuit compared to using an NMOS transistor, reducing the overall circuit design complexity.

[0034] Further, refer to Figure 1 and Figure 2 The switching unit 110 also includes a first current-limiting resistor R3, which is connected in series between the control terminal of the PMOS transistor Q2 and the collector of the transistor Q3.

[0035] By setting the first current-limiting resistor R3, the current at the control terminal of PMOS transistor Q2 can be limited, ensuring that PMOS transistor Q2 operates within a safe current range, avoiding overcurrent damage to PMOS transistor Q2, and extending the service life of PMOS transistor Q2.

[0036] Further, refer to Figure 1 and Figure 2 The switching unit 110 also includes a second current-limiting resistor R4 and a third current-limiting resistor R5 connected in series. The other end of the second current-limiting resistor R4 is connected to the drain of the PMOS transistor Q2, and the other end of the third current-limiting resistor R5 is connected to the control terminal of each bidirectional gallium nitride switch GaN1 and the other end of the first resistor R1.

[0037] By setting a second current-limiting resistor R4 and a third current-limiting resistor R5 in series between the drain of PMOS transistor Q2 and the control terminal of bidirectional gallium nitride switch GaN1, the current in the circuit can be limited to prevent the current from exceeding the safe range, thereby protecting the components in the circuit from damage and further extending the service life of bidirectional gallium nitride switch GaN1.

[0038] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the driving unit 120 includes a transistor Q3 and a pull-down resistor R6. The base of the transistor Q3 is used to receive a level signal. The pull-down resistor R6 is connected in series between the base of the transistor Q3 and the negative terminal PACK- of the load 200. The collector of the transistor Q3 is connected to the control terminal of the switching unit 110 and the control terminal of the NMOS transistor Q1, and the emitter is connected to the negative terminal PACK- of the load 200.

[0039] Specifically, when the base of transistor Q3 receives a high level, transistor Q3 turns on, pulling down the control terminal of PMOS transistor Q2 in switching unit 110 and the control terminal of NMOS transistor Q1 in discharge circuit unit 130. PMOS transistor Q2 turns on, and the control terminal of bidirectional gallium nitride (GaN) switch GaN1 is pulled high by the positive voltage of battery pack 300, turning on GaN1. NMOS transistor Q1 turns off, and bidirectional GaN switch GaN1 remains on. When the base of transistor Q3 receives a low level, transistor Q3 turns off, pulling up the control terminal of PMOS transistor Q2 in switching unit 110 and the control terminal of NMOS transistor Q1 in discharge circuit unit 130 is pulled high. PMOS transistor Q2 turns off, bidirectional GaN switch GaN1 turns off, and NMOS transistor Q1 turns on, quickly releasing the charge on the gate of bidirectional GaN switch GaN1 and preventing damage to bidirectional GaN switch GaN1.

[0040] In practice, transistor Q3 is an NPN transistor.

[0041] Optionally, refer to Figure 1 and Figure 2 The drive unit 120 also includes a fourth current-limiting resistor R7. One end of the fourth current-limiting resistor R7 is used to receive the level signal, and the other end is connected to the base of the transistor Q3.

[0042] By setting the fourth current-limiting resistor R7, the current flowing into the base of transistor Q3 can be limited, ensuring that the current flowing through the base of transistor Q3 does not exceed its rated value, thereby protecting transistor Q3 from overcurrent damage.

[0043] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the battery protection circuit 100 further includes a second diode D2, the positive terminal of which is connected to the positive terminal BAT+ of the battery pack 300, and the negative terminal is connected to the switching unit 110.

[0044] The second diode D2 has unidirectional conductivity. Its positive terminal is connected to the positive terminal BAT+ of the battery pack 300, and its negative terminal is connected to the switching unit 110. This connection method can effectively prevent current from flowing from the switching unit 110 to the positive terminal BAT+ of the battery pack 300, prevent the generation of reverse current, and protect the battery pack 300 from damage.

[0045] refer to Figure 1 and Figure 2 In an optional embodiment of this application, the battery protection circuit 100 further includes an energy storage capacitor C1, which is connected in parallel between the positive terminal BAT+ of the battery pack 300 and the negative terminal PACK- of the load 200.

[0046] By setting the energy storage capacitor C1, the voltage output from the battery pack 300 to the load 200 can be smoothed, reducing the impact of voltage fluctuations on the load 200 and improving the stability and reliability of the overall circuit operation.

[0047] The battery protection circuit 100 of this application embodiment can be applied to mobile power supplies, outdoor energy storage products, etc., allowing the applied products to have greater power and discharge capacity, reducing costs and the heat generation temperature of the battery management system.

[0048] This utility model embodiment provides a portable power bank, see reference. Figures 1 to 3 The power bank includes a battery pack 300, a load 200, and a battery protection circuit 100 as described above. The battery protection circuit 100 is located between the battery pack 300 and the load 200. The switching unit 110 of the battery protection circuit 100 is located between the positive terminal BAT+ of the battery pack 300 and the control terminal of each bidirectional gallium nitride switch GaN1. The source of the bidirectional gallium nitride switch GaN1 of the battery protection circuit 100 is connected to the negative terminal PACK- of the load 200, and the drain is connected to the negative terminal BAT- of the battery pack 300.

[0049] In the portable power bank of this utility model embodiment, the battery protection circuit 100 provides a switching unit 110 between the positive terminal BAT+ of the battery pack 300 and the control terminal of each bidirectional gallium nitride (GaN) switching transistor (GaN1). The switching unit 110, driven by the driving unit 120, connects or disconnects the path between the positive terminal BAT+ of the battery pack 300 and the control terminal of the bidirectional GaN switching transistor (GaN1), thereby turning the bidirectional GaN switching transistor (GaN1) on or off and protecting the battery pack 300. A discharge circuit unit 130 is connected in series between the control terminal and the source of each bidirectional GaN switching transistor (GaN1). The discharge circuit unit 130, driven by the driving unit 120, connects or disconnects, forming a fast discharge circuit. This prevents damage to the bidirectional GaN switching transistor (GaN1) during the on / off process, extends the service life of the bidirectional GaN switching transistor (GaN1), and extends the service life of the portable power bank.

[0050] It should be understood that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of this utility model.

Claims

1. A battery protection circuit, disposed between a load and a battery pack, characterized in that, The battery protection circuit includes a switching unit, a driving unit, a discharge circuit unit, and at least one bidirectional gallium nitride (GaN) switching transistor. The switching unit is located between the positive terminal of the battery pack and the control terminal of each GaN switching transistor. The control terminal of the switching unit is connected to the driving unit. The discharge circuit unit is connected in series between the control terminal and the source of each GaN switching transistor. The control terminal of the discharge circuit unit is connected to the driving unit. The source of each GaN switching transistor is connected to the negative terminal of the load, and the drain is connected to the negative terminal of the battery pack. The driving unit is used to drive the switching unit and the discharge circuit unit to be turned on or off.

2. The battery protection circuit according to claim 1, characterized in that, The discharge circuit unit includes a first resistor, a first diode, and an NMOS transistor connected in series. The other end of the first resistor is connected to the switching unit and the control terminal of each of the bidirectional gallium nitride switching transistors. The control terminal of the NMOS transistor is connected to the driving unit. The drain is connected to the negative terminal of the first diode, and the source is connected to the source of each of the bidirectional gallium nitride switching transistors and the negative terminal of the load.

3. The battery protection circuit according to claim 2, characterized in that, The switching unit includes a PMOS transistor and a pull-up resistor. The pull-up resistor is connected in series between the control terminal of the PMOS transistor and the positive terminal of the battery pack. The control terminal of the PMOS transistor is connected to the driving unit, the source is connected to the positive terminal of the battery pack, and the drain is connected to the control terminal of each bidirectional gallium nitride switch and the other end of the first resistor.

4. The battery protection circuit according to claim 3, characterized in that, The driving unit includes a transistor and a pull-down resistor. The base of the transistor is used to receive a level signal. The pull-down resistor is connected in series between the base of the transistor and the negative terminal of the load. The collector of the transistor is connected to the control terminal of the PMOS transistor and the control terminal of the NMOS transistor. The emitter is connected to the negative terminal of the load.

5. The battery protection circuit according to claim 3, characterized in that, The switching unit further includes a first current-limiting resistor, which is connected in series between the control terminal of the PMOS transistor and the collector of the transistor.

6. The battery protection circuit according to claim 5, characterized in that, The switching unit further includes a second current-limiting resistor and a third current-limiting resistor connected in series. The other end of the second current-limiting resistor is connected to the drain of the PMOS transistor, and the other end of the third current-limiting resistor is connected to the control terminal of each of the bidirectional gallium nitride switching transistors and the other end of the first resistor.

7. The battery protection circuit according to claim 4, characterized in that, The driving unit also includes a fourth current-limiting resistor, one end of which is used to receive a level signal, and the other end is connected to the base of the transistor.

8. The battery protection circuit according to claim 1, characterized in that, The battery protection circuit also includes a second diode, the positive terminal of which is connected to the positive terminal of the battery pack, and the negative terminal of which is connected to the switching unit.

9. The battery protection circuit according to any one of claims 1-8, characterized in that, The battery protection circuit also includes an energy storage capacitor, which is connected in parallel between the positive terminal of the battery pack and the negative terminal of the load.

10. A portable power bank, characterized in that, The device includes a battery pack, a load, and a battery protection circuit as described in any one of claims 1-9. The battery protection circuit is disposed between the battery pack and the load. The switching unit of the battery protection circuit is disposed between the positive terminal of the battery pack and the control terminal of each of the bidirectional gallium nitride switching transistors. The source of the bidirectional gallium nitride switching transistors of the battery protection circuit is connected to the negative terminal of the load, and the drain is connected to the negative terminal of the battery pack.

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