Charging protection circuit, charging and discharging system and electric equipment

Abstract

The utility model relates to a charging protection circuit, a charging and discharging system and electric equipment, and the circuit comprises an input end which is used for connecting an input power supply and comprises a positive electrode end and a negative electrode end; the output end is used for connecting to-be-charged equipment; the diode module comprises a field effect transistor and a controller, the field effect transistor is connected with the positive electrode end and the output end, and the controller is connected with the field effect transistor and the negative electrode end; and the controller is suitable for controlling the on-off of the field effect transistor according to the voltage of the input end and the output end. The utility model has the effects of reducing the power loss of forward conduction and improving the charging utilization rate of the input power supply.

Description

Technical Field

[0001] The present application relates to the technical field of charging protection, and in particular to a charging protection circuit, a charging and discharging system, and an electrical device. Background Art

[0002] At present, in the battery management system (BMS), when charging, the BMS generally only activates the set protection function for some charging faults such as overcurrent and overvoltage. If the charging port is reversely connected, the charging port is connected to a load, the charging voltage is insufficient, the charging voltage is transient, etc., the body diode in the charging circuit is turned on, and the circuit will have a reverse current from the battery end to the input end, and the BMS cannot provide protection.

[0003] In the related art, reverse current blocking and reverse polarity protection are generally performed by connecting a diode in series at the input end, but the forward voltage drop of the diode will produce a large power loss. Utility Model Content

[0004] The present application is proposed to solve the above-mentioned problem. According to one aspect of the present application, a charging protection circuit is provided, wherein the circuit comprises: an input end, wherein the input end is used to connect an input power supply, and the input end comprises a positive terminal and a negative terminal; an output end, wherein the output end is used to connect a device to be charged; a diode module, wherein the diode module comprises a field effect transistor and a controller, wherein the field effect transistor is connected to the positive terminal and the output terminal, and the controller is connected to the field effect transistor and the negative terminal; and the controller is suitable for controlling the on and off of the field effect transistor according to the voltage between the input terminal and the output terminal.

[0005] Exemplarily, the gate of the field effect tube is connected to the controller, and the source of the field effect tube is connected to the positive terminal; when the voltage at the input terminal is greater than a first threshold, the controller is suitable for driving the gate of the field effect tube to turn on the field effect tube.

[0006] Exemplarily, the field effect transistor also includes a body diode, and when the positive and negative poles of the input power supply are respectively connected to the positive terminal and the negative terminal, the body diode is turned on; when the positive and negative poles of the input power supply are respectively connected to the negative terminal and the positive terminal, the body diode is turned off to disconnect the field effect transistor.

[0007] Exemplarily, a charge pump is provided in the controller, and the first threshold is a start-up threshold of the charge pump.

[0008] Exemplarily, the controller is also used to detect the current value of the reverse current. When the current value is greater than the reverse current threshold, the controller is suitable for driving a pull-down current between the gate and the source of the field effect transistor to turn off the field effect transistor and block the reverse current flowing from the output end to the input end.

[0009] Exemplarily, the controller is also suitable for adjusting the gate-source voltage according to the load current of the field effect tube, wherein the gate-source voltage is the voltage difference between the gate and the source of the field effect tube, and when the field effect tube is turned on, the gate-source voltage is greater than the threshold voltage of the field effect tube.

[0010] Exemplarily, the controller is adapted to drive the gate of the field effect transistor to reduce the gate-source voltage when the load current is less than a standard load current.

[0011] Exemplarily, the circuit further includes at least two transient voltage suppressors, and two ends of the transient voltage suppressor are respectively connected to the positive terminal and the negative terminal.

[0012] Exemplarily, the field effect transistor is an N-channel field effect transistor.

[0013] According to another aspect of the present application, a charging and discharging system is provided, the system comprising the above-mentioned charging protection circuit.

[0014] According to another aspect of the present application, an electrical device is provided, wherein the electrical device includes the above-mentioned charging and discharging system.

[0015] The charging protection circuit in the present application has a diode module consisting of a field effect tube and a controller connected to the input end to simulate an ideal diode. The controller controls the conduction and disconnection of the field effect tube based on the voltage at the input and output ends. On the one hand, it can perform reverse polarity protection when the input power is reversed, and on the other hand, it can block reverse current. Compared with the solution of using a diode for charging protection, it can greatly reduce the power loss of forward conduction and improve the charging utilization rate of the input power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0017] FIG. 1( a ) and FIG. 1( b ) are schematic diagrams of a charging circuit in the related art.

[0018] Figure 2 A schematic diagram of a charging protection circuit in an embodiment of the present application is shown.

[0019] Figure 3 A circuit diagram of a charging and discharging system in an embodiment of the present application is shown.

[0020] Figure 4 A structural block diagram of an electrical device in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0022] As shown in Figure 1(a) and Figure 1(b), it is a schematic diagram of the charging circuit in the related art. The INPUT and OUTPUT in the figure respectively represent the input end and the output end connected by the diode, and C+ represents the input power supply. The circuit protection is performed by connecting a diode in series at the input end. When the input power supply is connected in the forward direction, the battery (CELL) can be charged smoothly through the diode. Because the diode is unidirectional, it can block the reverse current. When the input power supply is reversed or reverse current appears in the circuit, the diode can provide protection. However, because the diode will have a power loss that is not negligible when it is forward-conducted, on the one hand, it will cause the energy loss of the input power supply, and on the other hand, it will generate more heat, and an additional heat sink is required for heat dissipation, which ultimately causes energy loss and increased costs.

[0023] like Figure 2 As shown, an embodiment of the present application provides a charging protection circuit, which includes: an input end, an output end, and a diode module.

[0024] The input end is used to connect the input power supply, and the input end includes a positive terminal and a negative terminal; the output end is used to connect the device to be charged; the diode module includes a field effect tube and a controller, the field effect tube is connected to the positive terminal and the output end, and the controller is connected to the field effect tube and the negative terminal; the controller is suitable for controlling the on and off of the field effect tube according to the voltage of the input end and the output end.

[0025] The charging protection circuit in the present application has a diode module consisting of a field effect tube and a controller connected to the input end to simulate an ideal diode. The controller controls the conduction and disconnection of the field effect tube based on the voltage at the input and output ends. On the one hand, it can perform reverse polarity protection when the input power is reversed, and on the other hand, it can block reverse current. Compared with the solution of using a diode for charging protection, it can greatly reduce the power loss of forward conduction and improve the charging utilization rate of the input power supply.

[0026] like Figure 3As shown, it is a circuit diagram of the charging circuit in the embodiment of the present application. The two ports C+ and C- in the figure respectively represent the positive terminal and the negative terminal in the input terminal. During normal use, the positive pole of the input power supply is connected to the positive terminal C+, and the negative pole of the input power supply is turned on to the negative terminal C-, so that charging is performed through the input power supply. The controller 2 and the field effect tube 1 together form a diode module. The field effect tube 1 is connected between the output terminal and the positive terminal C+, and the output terminal is connected to the charging control circuit, so that the device to be charged is charged through the charging control circuit. The controller 2 is connected between the gate and the negative terminal C- of the field effect tube 1, and controls the on and off of the field effect tube 1 by driving the gate.

[0027] Exemplarily, the field effect transistor 1 is an N-channel MOS transistor, and the source of the field effect transistor 1 is connected to the positive terminal C+. In addition, the field effect transistor 1 also includes a body diode. When the positive and negative poles of the input power supply are respectively connected to the positive terminal C+ and the negative terminal C-, the body diode is turned on; when the positive and negative poles of the input power supply are respectively connected to the negative terminal C- and the positive terminal C+, the body diode is disconnected to disconnect the field effect transistor 1. The body diode is a parasitic diode of the field effect transistor 1. Under the premise that the body diode is not turned on, the reverse connection of the input power supply to the input terminal will not cause the generation of reverse current. In some embodiments, the field effect transistor 1 can use a P-channel MOS tube, which can be adjusted according to the actual usage.

[0028] When the positive and negative poles of the input power supply are connected to the positive terminal C+ and the negative terminal C- respectively, the body diode of the field effect tube 1 will be turned on first, and then the controller 2 will determine the size of the input terminal voltage. When the voltage at the input terminal is greater than the first threshold, the controller 2 is suitable for driving the gate of the field effect tube 1 to make the field effect tube 1 turn on. Among them, a charge pump is configured in the controller 2, and the first threshold is the start threshold of the charge pump. Only when the voltage at the input terminal is greater than the start threshold of the charge pump, the controller 2 will control the field effect tube 1 to turn on, so as to conduct forward for the input power to charge the device to be charged. For example, Figure 3 As shown, the device to be charged can be a battery (CELL). Because the conduction and blocking in this application do not rely on diodes, but the controller 2 and the field effect tube 1 are used to simulate the ideal diode to achieve reverse polarity protection and reverse current blocking. When forward conducting, the voltage drop caused by the field effect tube 1 is significantly smaller than the voltage drop caused by the diode, so the power loss caused by it will be less, and there is no need to configure an additional heat sink for heat dissipation, reducing the heat dissipation cost and energy loss.

[0029] Furthermore, in the embodiment of the present application, the voltage drop is mainly caused by the internal resistance Rds(on) of the field effect tube 1, which is the intrinsic resistance between the source and the drain of the field effect tube 1 when the field effect tube 1 is in the on state. When selecting the field effect tube 1, a suitable internal resistance value can be selected according to the application requirements to ensure that the voltage drop of the field effect tube 1 when it is turned on meets the requirements, so as to further reduce the voltage drop in the forward conduction state and reduce energy loss.

[0030] The charging protection circuit in the embodiment of the present application can be disconnected to achieve reverse polarity protection when the input power is connected in reverse. It is smoothly turned on when the input power is connected in the forward direction and the input voltage is greater than the first threshold. This method can ensure that the device to be charged is charged only when the input power is stable and meets the requirements, avoiding the abnormality caused by charging due to an input power that does not meet the requirements (mainly refers to the input voltage is less than the first threshold). When the field effect tube 1 is smoothly turned on, the voltage drop it produces is smaller, which can reduce the power loss caused by the charging process and the heat generated by the voltage drop loss, and effectively improve the power utilization rate.

[0031] In the related art, there is a solution of directly using a metal oxide semiconductor field effect transistor (MOSFET), also known as a MOS tube, to replace a diode for charging protection. Generally, the MOS tube is connected in series to the input end or the output end, and the gate is connected to the other end for reverse polarity protection of the circuit. However, this method is difficult to completely block the reverse current. When the input voltage is lower than the output voltage (the voltage of the battery to be charged), the MOS tube will be turned on, resulting in a reverse current flowing from the output end to the input end, which may cause damage to the input power supply or the battery.

[0032] The field effect transistor 1 and the controller 2 in the embodiment of the present application are combined to form an ideal diode module, which, in addition to being used for reverse polarity protection, can also be used to completely block reverse current to ensure the safety of components.

[0033] In some embodiments, the controller 2 is configured with a forward comparator and a reverse comparator. When the controller 2 detects a reverse current (or detects that the voltage at the output terminal is greater than the voltage at the input terminal), the forward comparator is turned on and the reverse comparator is turned off. The controller 2 drives the gate to disconnect the field effect transistor 1, and the body diode of the field effect transistor 1 is used to block the reverse current.

[0034] In some embodiments, the controller 2 is also used to detect the current value of the reverse current. When the input power supply connected to the input end fails or short-circuits, the voltage at the output end is greater than the voltage at the input end. At this time, there will be a reverse current instantaneously flowing from the output end to the input end. The controller 2 will detect the current value of the reverse current. When the current value is greater than the reverse current threshold, the controller 2 is suitable for driving the gate and source of the field effect tube 1 to form a pull-down current to turn off the field effect tube 1 and block the reverse current flowing from the output end to the input end. Among them, the controller 2 is configured with a reverse comparator and a gate driver. The reverse comparator is used to compare the reverse current with the reverse current threshold. The gate driver is used to drive the gate so that a short circuit is formed between the gate and the source to generate the above-mentioned pull-down current to lower the gate-source voltage. When the gate-source voltage is lower than the threshold voltage of the field effect tube 1, the field effect tube 1 will be disconnected, blocking the reverse current to protect the components in the circuit. By blocking the reverse current in this way, on the one hand, it can deal with reverse currents with larger current values, and on the other hand, it can prevent the leakage current of the reverse current from flowing from the output end to the input end.

[0035] For the diode module in the present application, its reverse current shutdown delay determines the response speed when facing reverse current, and the reverse current shutdown delay mainly includes two aspects, namely, reverse comparator delay and field effect tube shutdown delay. The former is the response speed of controller 2, and the latter is the speed at which controller 2 drives field effect tube 1. In order to reduce the reverse current shutdown delay, the controller 2 in the embodiment of the present application will also adjust the gate-source voltage according to the load current of field effect tube 1, wherein the gate-source voltage is the voltage difference between the gate and source of field effect tube 1, and when field effect tube 1 is turned on, the gate-source voltage is greater than the threshold voltage of field effect tube 1.

[0036] Specifically, the controller 2 controls the gate-source voltage to increase as the load current increases, and also decreases as the load current decreases. In the normal conduction state, when the load current of the field effect tube 1 is the standard load current, the gate-source voltage is higher than the threshold voltage (only when it is higher than the threshold voltage can the field effect tube 1 be smoothly turned on). When the circuit is under light load conditions, the load current is less than the standard load current. At this time, the controller 2 will drive the field effect tube 1, so that the gate-source voltage is reduced and closer to the threshold voltage. In this state, the internal resistance value of the field effect tube 1 will also increase compared to the standard value. Through this method of linear adjustment based on the load current, it is helpful to quickly disconnect the field effect tube 1 when the reverse current is detected, and reduce the reverse peak current as much as possible. For example: when it is in a light load state, if a reverse current occurs due to a fault, because the gate-source voltage at this time is lower than the gate-source voltage under the standard load, the process of adjusting the gate-source voltage at this time to less than the threshold voltage (the field effect tube 1 will be disconnected when it is less than the threshold voltage) is shorter and faster, and it can respond more quickly and reduce the reverse current shutdown delay.

[0037] Exemplarily, a transient voltage suppressor (TVS) is connected to the input terminal. TVS is also called an avalanche breakdown diode, which can prevent damage caused by electrostatic discharge, lightning strikes or other transient high-voltage spike pulses, thereby further protecting circuit components in extreme cases. There are two TVSs, and their two ends are respectively connected to the positive terminal C+ and the negative terminal C- of the input terminal, thereby providing protection for the circuit.

[0038] In summary, the charging protection circuit in the present application has a diode module composed of a field effect tube 1 and a controller 2 connected at the input end to simulate an ideal diode. The controller 2 controls the conduction and disconnection of the field effect tube 1 based on the voltage at the input and output ends. On the one hand, it can perform reverse polarity protection when the input power supply is reversed, and on the other hand, it can block the reverse current. Compared with the solution of using a diode for charging protection, it can greatly reduce the power loss of forward conduction and improve the charging utilization rate of the input power supply. In addition, the controller 2 can also linearly adjust the gate-source voltage of the field effect tube 1 based on the load current, thereby reducing its turn-off delay in response to the reverse current, and can respond to the reverse current more quickly, further improving the safety of the circuit elements.

[0039] like Figure 4 As shown, an embodiment of the present application further provides an electrical device and a charging and discharging system, wherein the electrical device includes the charging and discharging system for charging a battery and other devices of the electrical device.

[0040] Please refer to Figure 3 The charging and discharging system includes a charging and discharging circuit, and the charging and discharging circuit includes a charging end and a discharging end ( Figure 3 B+ and B- represent charging terminals, and P+ and P- represent discharging terminals), wherein the charging terminal is connected to the input terminal of the above-mentioned charging protection circuit for accessing the input power supply for charging, wherein the input power supply includes but is not limited to a charging gun. The charging and discharging circuit also includes a microcontroller chip 5, a first MOS tube 3 and a second MOS tube 4, wherein the first MOS tube 3 is connected to the charging terminal, and the second MOS tube 4 is connected to the discharging terminal, and the microcontroller chip 5 connects the first MOS tube 3 and the second MOS tube 4 for control. The microcontroller chip 5 includes an analog front end (Analog Front End, referred to as AFE) and a microcontroller unit (Microcontroller Unit, referred to as MCU), and the first MOS tube 3 and the second MOS tube 4 are controlled by the microcontroller chip 5 so that they are turned on during charging and discharging, respectively. Rsense in the figure represents a detection circuit, which is electrically connected to the microcontroller chip 5 for detecting the current and voltage drop in the circuit.

[0041] The charging and discharging system and electrical equipment in the present application include the above-mentioned charging protection circuit, a diode module consisting of a field effect tube 1 and a controller 2 connected at the input end, which is used to simulate an ideal diode. The controller 2 controls the conduction and disconnection of the field effect tube 1 based on the voltage at the input and output ends. On the one hand, it can perform reverse polarity protection when the input power supply is reversely connected, and on the other hand, it can block the reverse current; compared with the solution of using a diode for charging protection, it can greatly reduce the power loss of forward conduction and improve the charging utilization rate of the input power supply. In addition, the controller 2 can also linearly adjust the gate-source voltage of the field effect tube 1 based on the load current, thereby reducing its turn-off delay in response to the reverse current, and can respond to the reverse current more quickly, further improving the safety of the circuit elements.

[0042] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0043] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0044] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0045] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0046] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0047] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A charging protection circuit, characterized in that: The circuit comprises: An input terminal, the input terminal is used to connect an input power source, and the input terminal includes a positive terminal and a negative terminal; An output end, the output end is used to connect a device to be charged; A diode module, the diode module includes a field effect tube and a controller, the field effect tube is connected to the positive terminal and the output terminal, and the controller is connected to the field effect tube and the negative terminal; the controller is suitable for controlling the on and off of the field effect tube according to the voltage of the input terminal and the output terminal.

2. The circuit according to claim 1, characterized in that The gate of the field effect tube is connected to the controller, and the source of the field effect tube is connected to the positive terminal; when the voltage of the input terminal is greater than a first threshold, the controller is suitable for driving the gate of the field effect tube to turn on the field effect tube.

3. The circuit according to claim 2, characterized in that The field effect tube also includes a body diode. When the positive and negative poles of the input power supply are respectively connected to the positive terminal and the negative terminal, the body diode is turned on; when the positive and negative poles of the input power supply are respectively connected to the negative terminal and the positive terminal, the body diode is turned off to disconnect the field effect tube.

4. The circuit according to claim 2, characterized in that A charge pump is provided in the controller, and the first threshold is a start threshold of the charge pump.

5. The circuit according to claim 2, characterized in that The controller is also used to detect the current value of the reverse current. When the current value is greater than the reverse current threshold, the controller is suitable for driving the gate and source of the field effect tube to form a pull-down current to turn off the field effect tube and block the reverse current flowing from the output end to the input end.

6. The circuit according to claim 5, characterized in that The controller is also suitable for adjusting the gate-source voltage of the field effect tube according to the load current of the field effect tube. When the field effect tube is turned on, the gate-source voltage is greater than the threshold voltage of the field effect tube.

7. The circuit according to claim 6, characterized in that The controller is adapted to drive the gate of the field effect transistor to reduce the gate-source voltage when the load current is less than a standard load current.

8. The circuit according to any one of claims 1 to 7, characterized in that The circuit further includes at least two transient voltage suppressors, and two ends of the transient voltage suppressors are respectively connected to the positive terminal and the negative terminal.

9. The circuit according to any one of claims 1 to 7, characterized in that: The field effect transistor is an N-channel field effect transistor.

10. A charging and discharging system, characterized in that: The system comprises the charging protection circuit according to any one of claims 1-9.

11. An electrical device, characterized in that: The electrical equipment includes the charging and discharging system according to claim 10.

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