A charging protection circuit and a charging protection control method

Abstract

This application relates to a charging protection circuit and a charging protection control method. The charging protection circuit includes a main control module, a power input module, a voltage sampling module, and a voltage detection module. The power input module includes a voltage input terminal, a voltage output terminal, a resistor-capacitor voltage divider unit, and a controllable switch unit. The resistor-capacitor voltage divider unit is coupled between the voltage input terminal and the voltage output terminal. The controllable switch unit is turned on to increase the voltage at the voltage output terminal. The voltage sampling module is connected to the voltage input terminal and outputs a detected voltage signal. The voltage detection module includes a first comparison unit and a second comparison unit. The first comparison unit receives the detected voltage signal and outputs a comparison signal. The main control module receives the comparison signal and outputs a control signal. The second comparison unit receives the control signal and issues a command signal. The controllable switch unit turns off after receiving the command signal. This application can continuously protect the downstream auxiliary charging module when a line voltage is mistakenly connected.

Description

Technical Field

[0001] This application relates to the technical field of charger protection, and in particular to a charging protection circuit and a charging protection control method. Background Technology

[0002] With the advent of the new energy era, more and more fields have developed mobile devices or equipment powered by batteries. Examples include electric trucks, electric forklifts, high-power mobile power supplies, and mobile robots. Batteries, as energy storage carriers, are typically charged by chargers.

[0003] When charging a battery using a charger, the charger contains various protection components to protect the auxiliary charging module inside. These components ensure the auxiliary charging module can output the set voltage while also providing good protection for the battery when fully charged or when the charger is in an abnormal voltage environment. Currently, when a charger is mistakenly connected to a high voltage (such as line voltage) or when there are positive or negative surge voltages in the charging power supply, a TVS (Transient Voltage Suppressor) is typically used to absorb the surge power, or a MOSFET Q1 (Metal-Oxide-Semiconductor Field-Effect Transistor) is used to directly shut down the circuit, thereby protecting the downstream circuitry.

[0004] Regarding the aforementioned technologies, existing charging protection circuits typically use disconnection to ensure the safety of downstream charging components when the charger is connected to an abnormally high voltage or a circuit environment with high surges. This results in the charger being unable to continue charging. Summary of the Invention

[0005] In order to ensure the safety of the back-end charging components and maintain the continuous charging of the charger, this application provides a charging protection circuit and a charging protection control method.

[0006] This application provides a charging protection circuit, which adopts the following technical solution:

[0007] A charging protection circuit, comprising:

[0008] The main control module, wherein the power supply terminal of the main control module is used to connect to the auxiliary charging module;

[0009] A power input module includes a voltage input terminal, a voltage output terminal, a resistor-capacitor voltage divider unit, and a controllable switch unit. The resistor-capacitor voltage divider unit is coupled between the voltage input terminal and the voltage output terminal. The controllable switch unit is turned on to increase the voltage at the voltage output terminal. The voltage input terminal is used to connect to mains power, and the voltage output terminal is used to connect to an auxiliary charging module.

[0010] A voltage sampling module is connected to the voltage input terminal, and the voltage sampling module outputs a detection voltage signal;

[0011] The voltage detection module includes a first comparison unit and a second comparison unit. The first comparison unit receives the detected voltage signal and outputs a comparison signal. The main control module receives the comparison signal and outputs a control signal. The second comparison unit receives the control signal and issues a command signal. The controllable switch unit receives the command signal and then turns off.

[0012] By adopting the above technical solution, when the circuit is first connected to mains power, the presence of the resistor-capacitor voltage divider ensures that the voltage output at the voltage output terminal is the voltage value after the power supply voltage has been divided by the resistor-capacitor unit. This ensures that the input voltage to the auxiliary charging module will not be too high, preventing damage. When the auxiliary charging module is activated, it supplies power to the main control module, voltage sampling module, and voltage detection module. Voltage sampling and detection analysis determines whether the power supply voltage is abnormal. If the voltage is abnormally high, a command signal is output through two comparisons by the first and second comparison units, controlling the controllable switch unit to turn off, thus protecting the voltage output terminal by maintaining the divided power supply voltage. If the voltage is normal, the controllable switch unit is turned on, restoring the voltage output terminal to the normal power supply voltage, thereby ensuring that the auxiliary charging module can continuously output power.

[0013] Optionally, the voltage input terminal includes a live wire connection terminal and a neutral wire connection terminal, the resistor-capacitor voltage divider unit includes a first capacitor C1, a second capacitor C2 and a first resistor R1, the first resistor R1, the first capacitor C1 and the second capacitor C2 are connected in series between the live wire connection terminal and the neutral wire connection terminal, the voltage output terminal is the two ends of the second capacitor C2; the first resistor R1 and the first capacitor C1 are connected in series and then connected in parallel with the controllable switch unit.

[0014] By adopting the above technical solution, the first capacitor C1, the second capacitor C2, and the first resistor R1 are connected in series between the live wire connection terminal and the neutral wire connection terminal, and voltage division is achieved through the first capacitor C1, the second capacitor C2, and the first resistor R1. Furthermore, the voltage output terminal is set across the two ends of the second capacitor C2. When power is first connected, the input voltage of the downstream charging module is the voltage across the second capacitor C2, ensuring the safety of the downstream charging module. By connecting the controllable switch unit in parallel with the series-connected first resistor R1 and the first capacitor C1, the voltage across the second capacitor C2 can be increased when the controllable switch unit is turned on, thereby increasing the voltage value at the voltage output terminal.

[0015] Optionally, the power input module further includes a common-mode filter unit, which is connected in series between the voltage input terminal and the resistor-capacitor voltage divider unit.

[0016] By adopting the above technical solution, a common-mode filtering unit is used to filter out common-mode interference signals in the circuit, so as to ensure that the auxiliary charging module at the back end is free from interference.

[0017] Optionally, the first comparison unit includes a first operational amplifier U1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, and a fourth capacitor C4; the second resistor R2 and the third capacitor C3 are connected in parallel between the inverting input terminal of the first operational amplifier U1 and ground; the third resistor R3 is connected in series between the voltage sampling module and the inverting input terminal of the first operational amplifier U1; the fourth resistor R4 and the fifth resistor R5 are connected in series to form a voltage divider circuit; the fourth resistor R4 is used to connect with the output of the auxiliary charging module. The power supply terminal is connected, the fifth resistor R5 is connected to the ground wire, and the fourth capacitor C4 is connected in parallel with the fifth resistor R5; the non-inverting input terminal of the first operational amplifier U1 is connected to the series node between the fourth resistor R4 and the fifth resistor R5, and the two ends of the sixth resistor R6 are respectively connected to the non-inverting input terminal and the output terminal of the first operational amplifier U1; one end of the seventh resistor R7 is connected to the output terminal of the first operational amplifier U1, and the other end of the seventh resistor R7 is used to connect to the power supply terminal of the auxiliary charging module; the output terminal of the first operational amplifier U1 outputs a comparison signal.

[0018] By employing the above technical solution, a filter circuit is formed using the second resistor R2 and the third capacitor C3 to filter out interference signals at the inverting input of the first operational amplifier U1. Similarly, a filter circuit is formed using the fourth capacitor C4 and the fifth resistor R5 to filter out interference signals at the non-inverting input of the first operational amplifier U1. Furthermore, a voltage divider circuit is formed between the fourth resistor R4 and the fifth resistor R5 to provide a reference voltage for the non-inverting input of the first operational amplifier U1. When the current output by the voltage sampling module passes through the second resistor R3 and enters the first operational amplifier U1, it begins to be compared with the reference voltage and outputs a high-level or low-level comparison signal.

[0019] Optionally, the second comparison unit includes a second operational amplifier U2, an eighth resistor R8, and a ninth resistor R9; the inverting input of the second operational amplifier U2 is connected to the non-inverting input of the first operational amplifier U1; the eighth resistor R8 is connected in series between the non-inverting input of the second operational amplifier U2 and the main control module, the non-inverting input of the second operational amplifier U2 is connected to the output of the first operational amplifier U1, and the non-inverting input of the second operational amplifier U2 receives the control signal from the main control module; one end of the ninth resistor R9 is connected to the output of the second operational amplifier U2, and the other end of the ninth resistor R9 is used to connect to the power supply terminal output by the auxiliary charging module; the output of the second operational amplifier U2 outputs a command signal.

[0020] By adopting the above technical solution, the inverting input terminal of the second operational amplifier U2 is connected to the reference voltage between the fourth resistor R4 and the fifth resistor R5, while the non-inverting input terminal of the second operational amplifier U2 is connected to the power supply through the seventh resistor R7. Therefore, upon power-on, the output terminal of the second operational amplifier U2 outputs a high level to control the controllable switching unit to conduct, ultimately increasing the voltage across the second capacitor C2. When the first operational amplifier U1 outputs a low level, the level at the non-inverting input terminal of the second operational amplifier U2 is pulled low, causing the output terminal of the second operational amplifier U2 to output a low level, thereby disconnecting the controllable switching unit. The voltage at the voltage output terminal is the voltage division value across the second capacitor C2, thus protecting the safety of the downstream circuit.

[0021] Optionally, the controllable switching unit includes an electromagnetic relay K1, a MOSFET Q1, an optocoupler switch K2, a tenth resistor R10, and an eleventh resistor R11. The electromagnetic relay K1 and the MOSFET Q1 are connected in series. The end of the electromagnetic relay K1 away from the MOSFET Q1 is used to connect to the auxiliary charging module, and the end of the MOSFET Q1 away from the electromagnetic relay K1 is grounded. One end of the tenth resistor R10 is connected to the first input terminal of the optocoupler switch K2, the second input terminal of the optocoupler switch K2 is grounded, and the other end of the tenth resistor R10 is connected to the second comparison unit to receive command signals. The first switching terminal of the optocoupler switch K2 is used to connect to the power supply terminal output by the auxiliary charging module, and the eleventh resistor R11 is connected in series between the second switching terminal of the optocoupler switch K2 and the gate of the MOSFET Q1. The electromagnetic relay K1, the first resistor R1 connected in series, and the first capacitor C1 are connected in parallel.

[0022] By employing the above technical solution, the tenth resistor R10 is used to receive the high-level command signal output from the second comparator unit, thereby turning on the optocoupler switch K2. The conduction of optocoupler switch K2 increases the gate voltage of the MOSFET, triggering the MOSFET to conduct, ultimately causing the electromagnetic relay K1 to close and short-circuit the first resistor R1 and the first capacitor C1. By short-circuiting the first resistor R1 and the first capacitor C1, the second capacitor C2 is no longer subjected to voltage division, and the overall voltage output is the power supply voltage.

[0023] Optionally, the voltage sampling module includes an impedance unit and a sampling chip, the impedance unit being connected in series between the voltage input terminal and the sampling chip, and the sampling chip outputting a detection voltage signal.

[0024] By adopting the above technical solution, the power supply voltage is divided using an impedance unit, enabling the sampling chip to directly sample the divided voltage.

[0025] This application also discloses a charging protection control method, which is applied to the charging protection circuit described in the above scheme, and the method protects the following steps:

[0026] Connect the power supply module to the mains circuit to provide the voltage required for charging by voltage division;

[0027] Obtain the preset circuit operating voltage output by the back-end auxiliary charging module;

[0028] Based on the preset circuit operating voltage, power is supplied to the main control module, controllable switching unit, voltage acquisition module and voltage detection module.

[0029] Acquire the detected voltage signal output by the voltage acquisition module and determine whether the detected voltage signal exceeds the threshold.

[0030] If not, continue to judge and control the second comparison unit to output a high-level command signal; if yes, control the second comparison unit to output a low-level command signal.

[0031] The controllable switching unit is turned off based on the low-level command signal output.

[0032] Voltage division output is achieved by turning off the controllable switching unit.

[0033] By adopting the above technical solution, the voltage output terminal is output through voltage division, ensuring that the auxiliary charging module at the back end will not be damaged due to excessive power supply voltage when first connected to the power supply. When the back end charging module is activated, it supplies power to the main control module, voltage sampling module, and voltage detection module. The voltage sampling module samples and analyzes the power supply voltage to determine if it exceeds the normal range. If the voltage is normal, the second comparison unit outputs a high-level command signal, turning on the controllable switch unit and restoring the voltage output terminal to the normal power supply voltage, thus ensuring that the back end charging module can continuously output power. If the voltage is abnormally high, a command signal is output through two comparisons by the first and second comparison units, controlling the controllable switch unit to turn off, thus protecting the voltage output terminal through voltage division protection and protecting the auxiliary charging module at the back end.

[0034] In summary, this application includes at least one of the following beneficial technical effects:

[0035] 1. When the power supply voltage is mistakenly connected to the line voltage or there is a high surge voltage in the circuit, it can continuously protect the auxiliary charging module at the back end, while also maintaining the continuous charging output of the auxiliary charging module at the back end.

[0036] 2. The first comparison unit is used as the signal trigger for the main control module; the first comparison unit and the second comparison unit are used to compare twice to output the command signal to control the controllable switch unit to turn on or off, which can maintain the state of the controllable switch unit and improve the safety in circuits with surge voltage.

[0037] 3. It can accurately sample the power supply voltage, which makes it easier for the main control module to judge whether the power supply voltage is abnormal. Attached Figure Description

[0038] Figure 1 This is a system block diagram of a charging protection circuit according to an embodiment of this application.

[0039] Figure 2This is a schematic diagram of the power access module in a charging protection circuit according to an embodiment of this application.

[0040] Figure 3 This is a schematic diagram of a voltage sampling module in a charging protection circuit according to an embodiment of this application.

[0041] Figure 4 This is a schematic diagram of a voltage detection module in a charging protection circuit according to an embodiment of this application.

[0042] Figure 5 This is a schematic diagram of the main control module in a charging protection circuit according to an embodiment of this application.

[0043] Explanation of reference numerals in the attached diagram: 1. Main control module; 2. Power input module; 21. Voltage input terminal; 22. Voltage output terminal; 23. RC voltage divider unit; 24. Controllable switch unit; 25. Common mode filter unit; 3. Voltage sampling module; 31. Impedance unit; 32. Sampling chip; 4. Voltage detection module; 41. First comparison unit; 42. Second comparison unit; Detailed Implementation

[0044] The present application will be further described in detail below with reference to the accompanying drawings.

[0045] Example 1

[0046] This application discloses a charging protection circuit. (Refer to...) Figure 1 The charging protection circuit includes a main control module 1, a power input module 2, a voltage sampling module 3, and a voltage detection module 4. The voltage sampling module 3 is used to obtain the voltage value of the connected power supply, and the voltage detection module 4 and the main control module 1 are used to determine whether the power supply voltage is abnormal. Then, the power input module 2 is controlled to output an appropriate voltage to supply power to the downstream auxiliary charging module.

[0047] The power access module 2 includes a voltage input terminal 21, a voltage output terminal 22, a resistor-capacitor voltage divider unit 23, and a controllable switch unit 24. The resistor-capacitor voltage divider unit 23 divides the voltage of the voltage input terminal 21 by voltage division so that the voltage of the voltage output terminal 22 is less than the voltage of the voltage input terminal 21. This prevents the power access module 2 from being mistakenly connected to the line voltage and protects the auxiliary charging module subsequently connected to the voltage output terminal 22.

[0048] When the auxiliary charging module connected later starts working, it outputs various voltage values ​​to power the voltage sampling module 3, voltage detection module 4, and main control module 1. After the main control module 1 is powered on and initialized, if the voltage detection module 4 determines that the detected signal is within the normal range, the main control module 1 controls the controllable switch unit 24 to turn off, thereby reducing the voltage division value of the resistor-capacitor voltage divider unit 23 to ensure that the voltage output terminal 22 and the voltage input terminal 21 are consistent. If the voltage detection module 4 determines that the detected signal is outside the normal range, the main control module 1 controls the controllable switch unit 24 to turn on, thereby causing the resistor-capacitor voltage divider unit 23 to continue dividing the power supply voltage to ensure that the voltage output terminal 22 is less than the voltage input terminal 21, thus protecting the downstream auxiliary charging module. In this embodiment, the auxiliary charging module is an existing rectifier and filter charging module, and the auxiliary charging module can output multiple commonly used DC voltage values, such as 3.3V, 5V, 9V and 12V, which will not be described in detail here.

[0049] Reference Figure 2 The power input module 2 also includes a common-mode filter unit 25, which is connected between the voltage input terminal 21 and the resistor-capacitor voltage divider unit 23. The voltage input terminal 21 includes a live wire connection terminal and a neutral wire connection terminal. The power input terminal is used to connect to mains power, and the voltage output terminal 22 is used to connect to the auxiliary charging module. Mains power is connected through the power input terminal and passed through the resistor-capacitor voltage divider to provide power to the auxiliary charging module, facilitating battery charging. The common-mode filter unit 25 has a double-wire wound iron core structure, with its two coils connected to the branch containing the live wire and the branch containing the neutral wire, respectively. The resistor-capacitor voltage divider unit 23 includes a first capacitor C1, a second capacitor C2, and a first resistor R1. The first resistor R1, the first capacitor C1, and the second capacitor C2 are connected in series. The first resistor R1 is connected to the branch containing the live wire, and the second capacitor C2 is connected to the branch containing the neutral wire.

[0050] The first capacitor C1, the second capacitor C2, and the first resistor R1 together form a resistive-capacitive voltage divider structure, and the voltage output terminal 22 is the two ends of the second capacitor C2. The controllable switch unit 24, the first resistor R1, and the first capacitor C1 are connected in parallel. When the controllable switch unit 24 is off, the voltage output terminal 22 outputs the voltage value of the second capacitor C2; when the controllable switch unit 24 is on, the first resistor R1 and the first capacitor C1 are short-circuited, and the voltage output terminal 22 outputs the voltage value of the voltage input terminal 21.

[0051] The controllable switching unit 24 includes an electromagnetic relay K1, a MOSFET Q1, an optocoupler switch K2, a tenth resistor R10, and an eleventh resistor R11. The normally open contact of the electromagnetic relay K1 is connected in parallel with the first resistor R1 (connected in series) and the first capacitor C1. Therefore, when the electromagnetic relay K1 is energized, it short-circuits the first resistor R1 and the first capacitor C1, resulting in the voltage output at voltage output terminal 22 being the same as the voltage input at voltage input terminal 21. When the electromagnetic relay K1 is de-energized and open, the first resistor R1 and the first capacitor C1 act as a voltage divider, causing the voltage output at voltage output terminal 22 to be lower than the voltage input at voltage input terminal 21, thus protecting the auxiliary charging module connected to voltage output terminal 22.

[0052] In this embodiment, electromagnetic relay K1 and MOSFET Q1 are connected in series. The end of electromagnetic relay K1 furthest from MOSFET Q1 is connected to a 12V power supply, while the end of MOSFET Q1 furthest from electromagnetic relay K1 is grounded. When MOSFET Q1 is turned on, electromagnetic relay K1 is also energized and activated. One end of the tenth resistor R10 serves as CON5, used to connect to voltage detection module 4 to receive command signals. The other end of the tenth resistor R10 is connected to the first input terminal of optocoupler switch K2, and the second input terminal of optocoupler switch K2 is grounded. The first switching terminal of optocoupler switch K2 is connected to a 12V power supply, and the second switching terminal of optocoupler switch K2 is connected to the gate of MOSFET Q1 through eleventh resistor R11.

[0053] When a high-level command signal is received, the optocoupler switch K2 is turned on, which in turn turns on the MOSFET Q1, thereby controlling the electromagnetic relay K1 to be energized and engaged, causing the first resistor R1 and the first capacitor C1 to be short-circuited.

[0054] Reference Figure 3 The voltage sampling module 3 includes an impedance unit 31 and a sampling chip 32. The impedance unit 31 is connected between the voltage input terminal 21 and the sampling chip 32, reducing the voltage value connected to the sampling chip 32. Specifically, the impedance unit 31 is divided into two impedance branches, which are connected to the live wire connection terminal and the neutral wire connection terminal respectively. The sampling chip 32 is an LM258 dual operational amplifier chip. The input AC voltage is divided by the impedance unit 31 and sent to the input terminals of the two operational amplifiers, which isolate and amplify the positive and negative half-cycle signals respectively. The two operational amplifiers output half-waves proportional to the mains voltage. These half-waves are synthesized into a DC full-wave by the 29th resistor R29 connected to the 1st pin output terminal and the 28th resistor R28 connected to the 7th pin output terminal. The DC full-wave is then output as a detection voltage signal by the voltage follower formed by the third operational amplifier U3, and after low-pass filtering by the 31st resistor R31 and the 12th capacitor C12, the sampling signal is output by the CON2 terminal.

[0055] Reference Figure 4 and Figure 5 The voltage detection module 4 includes a first comparison unit 41 and a second comparison unit 42. The first comparison unit 41 receives the detected voltage signal output from the voltage sampling module 3. The first comparison unit 41 is connected to a reference voltage circuit, which uses the reference voltage to determine if the detected voltage signal is abnormal and outputs a comparison signal. The first comparison unit 41 is also connected to the main control module 1, inputting the comparison signal to the main control module 1 for analysis and processing, and then issuing a control signal. The second comparison unit 42 is connected to the main control module 1 and the reference voltage circuit. After receiving the control signal from the main control module 1, the second comparison unit 42 compares it with the reference voltage and issues a command signal, thereby controlling the on or off state of the optocoupler switch K2.

[0056] Specifically, the first comparison unit 41 includes a first operational amplifier U1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, and a fourth capacitor C4. The second resistor R2 and the third capacitor C3 are connected in parallel, and this parallel connection is then connected between the inverting input terminal of the first operational amplifier U1 and ground. The second resistor R2 and the third capacitor C3 form a filter circuit to filter out interference signals at the inverting input terminal of the first operational amplifier U1. The third resistor R3 is connected in series between the voltage sampling module 3 and the inverting input terminal of the first operational amplifier U1.

[0057] Similarly, the fourth capacitor C4 and the fifth resistor R5 are connected in parallel, and then connected between the non-inverting input of the first operational amplifier U1 and ground. The fourth resistor R4 and the fifth resistor R5 are connected in series, with the fourth resistor R4 also connected to the 3.3V power supply. The fourth resistor R4 and the fifth resistor R5 form a reference voltage circuit. The two ends of the sixth resistor R6 are connected to the non-inverting input and the output of the first operational amplifier U1, respectively. One end of the seventh resistor R7 is connected to the output of the first operational amplifier U1, and the other end of the seventh resistor R7 is connected to the 3.3V power supply.

[0058] The second comparator unit 42 includes a second operational amplifier U2, an eighth resistor R8, and a ninth resistor R9. The inverting input of the second operational amplifier U2 is connected to the non-inverting input of the first operational amplifier U1 to receive a reference voltage signal. The eighth resistor R8 is connected in series between the non-inverting input of the second operational amplifier U2 and the main control module 1 via the CON4 terminal. A low-level control signal output by the main control module 1 enters the non-inverting input of the second operational amplifier U2 through the eighth resistor R8. The second operational amplifier U2 is also connected to the output of the first operational amplifier U1. One end of the ninth resistor R9 is connected to the output of the second operational amplifier U2, and the other end of the ninth resistor R9 is connected to the 3.3V power supply.

[0059] The detection voltage signal output by the third operational amplifier U3 in voltage sampling module 3 enters the non-inverting input of the first operational amplifier U1 through the third resistor R3. When the power supply voltage is too high, causing the detection voltage signal to be abnormal, the voltage at the non-inverting input of the first operational amplifier U1 is lower than the voltage at the inverting input, causing the first operational amplifier U1 to output a low-level comparison signal. The low-level comparison signal is input to the main control module 1 through the CON3 terminal. When the main control module 1 detects the falling edge of the comparison signal, it starts outputting a low-level control signal from the CON4 terminal.

[0060] After receiving a low-level control signal at the non-inverting input of the second operational amplifier U2, the second operational amplifier U2 outputs a low-level command signal, and the low-level command signal is sent to the tenth resistor R10 connected to the optocoupler switch K2 through the CON5 terminal, thereby driving the electromagnetic relay K1 to disconnect. The voltage output by the voltage output terminal 22 is a voltage divider value, protecting the back-end auxiliary charging module.

[0061] When the power supply voltage is normal, the voltage at the non-inverting input of the first operational amplifier U1 is higher than the voltage at the inverting input, causing the first operational amplifier U1 to output a high-level signal. This high-level signal is also sent to the non-inverting input of the second operational amplifier U2, causing the second operational amplifier U2 to output a high-level signal. This signal then controls the optocoupler switch K2 to conduct via the CON5 terminal, thereby driving the electromagnetic relay K1 to close. Consequently, the voltage output from the voltage output terminal 22 is the power supply voltage, ensuring normal power supply.

[0062] The implementation principle of Example 1 is as follows: Before use, the voltage divider is started, and the voltage sampling module 3 sends the mains peak signal to the voltage detection module 4 for judgment. If the voltage peak is too high, the voltage detection module 4 sends the voltage detection signal to the main control module 1 for processing and controls the electromagnetic relay to turn off, so that the voltage at the voltage output terminal 22 is maintained in the voltage divider state. In the event of a power supply voltage mistakenly connected to the line voltage or a high surge voltage in the circuit, the auxiliary charging module at the back end can be continuously protected, while also maintaining the continuous charging output of the auxiliary charging module at the back end.

[0063] Example 2

[0064] This application also discloses a charging protection control method. The method includes the following steps.

[0065] S1. Connect the power supply module 2 to the mains circuit to provide the voltage required for charging in a voltage divider manner.

[0066] Among them, when the power supply module 2 is first connected to the power supply, it provides the voltage required for charging by using a voltage divider method. In case of accidental connection to high voltage or high surge voltage in the circuit, it can ensure the safety of the auxiliary charging module connected at the back end.

[0067] S2. Obtain the preset circuit operating voltage output by the back-end auxiliary charging module.

[0068] S3. Based on the preset circuit operating voltage, power is supplied to the main control module 1, the controllable switching unit 24, the voltage sampling module 3, and the voltage detection module 4.

[0069] The preset circuit operating voltage is a DC voltage value commonly used in daily circuit control systems, such as 3.3V, 5V, 9V, and 12V. When the auxiliary charging module is activated, the circuit operating voltage output by the auxiliary charging module powers the main control module 1, the controllable switching unit 24, the voltage sampling module 3, and the voltage detection module 4, ensuring normal circuit operation.

[0070] S4. Obtain the detection voltage signal output by the voltage acquisition module and determine whether the detection voltage signal exceeds the threshold.

[0071] S5. If not, continue to judge and control the second comparison unit 42 to output a high-level command signal; if yes, control the second comparison unit 42 to output a low-level command signal.

[0072] Among them, the use of a comparator to determine the voltage can output a high-level command signal or a low-level command signal in a timely and effective manner.

[0073] S6. Based on the low-level command signal output, control the turn-off of the controllable switch unit 24.

[0074] S7. The voltage output terminal 22 is divided and output according to the turn-off of the controllable switch unit 24.

[0075] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A charging protection circuit, characterized in that, include: The main control module (1) is used to connect the power supply terminal of the main control module (1) to the auxiliary charging module; The power access module (2) includes a voltage input terminal (21), a voltage output terminal (22), a resistor-capacitor voltage divider unit (23), and a controllable switch unit (24). The resistor-capacitor voltage divider unit (23) is coupled between the voltage input terminal (21) and the voltage output terminal (22). The controllable switch unit (24) is turned on to increase the voltage of the voltage output terminal (22). The voltage input terminal (21) is used to connect to the mains power, and the voltage output terminal (22) is used to connect to the auxiliary charging module. A voltage sampling module (3) is connected to the voltage input terminal (21), and the voltage sampling module (3) outputs a detection voltage signal; The voltage detection module (4) includes a first comparison unit (41) and a second comparison unit (42). The first comparison unit (41) receives the detected voltage signal and outputs a comparison signal. The main control module (1) receives the comparison signal and outputs a control signal. The second comparison unit (42) receives the control signal and issues a command signal. The controllable switch unit (24) turns off after receiving the command signal. The voltage input terminal (21) includes a live wire connection terminal and a neutral wire connection terminal. The resistor-capacitor voltage divider unit (23) includes a first capacitor C1, a second capacitor C2 and a first resistor R1. The first resistor R1, the first capacitor C1 and the second capacitor C2 are connected in series between the live wire connection terminal and the neutral wire connection terminal. The voltage output terminal (22) is the two ends of the second capacitor C2. The first resistor R1 and the first capacitor C1 are connected in series and then connected in parallel with the controllable switch unit (24).

2. The charging protection circuit according to claim 1, characterized in that: The power access module (2) further includes a common-mode filter unit (25), which is connected in series between the voltage input terminal (21) and the resistor-capacitor voltage divider unit (23).

3. The charging protection circuit according to claim 1, characterized in that: The first comparison unit (41) includes a first operational amplifier U1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, and a fourth capacitor C4; the second resistor R2 and the third capacitor C3 are connected in parallel between the inverting input terminal of the first operational amplifier U1 and the ground line, and the third resistor R3 is connected in series between the voltage sampling module (3) and the inverting input terminal of the first operational amplifier U1; the fourth resistor R4 and the fifth resistor R5 are connected in series to form a voltage divider circuit, and the fourth resistor R4 is used to connect with the auxiliary charging module. The output power supply terminal is connected, the fifth resistor R5 is connected to the ground wire, and the fourth capacitor C4 is connected in parallel with the fifth resistor R5; the non-inverting input terminal of the first operational amplifier U1 is connected to the series node between the fourth resistor R4 and the fifth resistor R5, and the two ends of the sixth resistor R6 are respectively connected to the non-inverting input terminal and the output terminal of the first operational amplifier U1; one end of the seventh resistor R7 is connected to the output terminal of the first operational amplifier U1, and the other end of the seventh resistor R7 is used to connect to the power supply terminal of the auxiliary charging module; the output terminal of the first operational amplifier U1 outputs a comparison signal.

4. The charging protection circuit according to claim 3, characterized in that: The second comparison unit (42) includes a second operational amplifier U2, an eighth resistor R8, and a ninth resistor R9; the inverting input of the second operational amplifier U2 is connected to the non-inverting input of the first operational amplifier U1; the eighth resistor R8 is connected in series between the non-inverting input of the second operational amplifier U2 and the main control module (1), the non-inverting input of the second operational amplifier U2 is connected to the output of the first operational amplifier U1, and the non-inverting input of the second operational amplifier U2 receives the control signal from the main control module (1); one end of the ninth resistor R9 is connected to the output of the second operational amplifier U2, and the other end of the ninth resistor R9 is used to connect to the power supply output of the auxiliary charging module; the output of the second operational amplifier U2 outputs a command signal.

5. The charging protection circuit according to claim 1, characterized in that: The controllable switch unit (24) includes an electromagnetic relay K1, a MOSFET Q1, an optocoupler switch K2, a tenth resistor R10, and an eleventh resistor R11. The electromagnetic relay K1 and the MOSFET Q1 are connected in series. The end of the electromagnetic relay K1 away from the MOSFET Q1 is used to connect to the auxiliary charging module, and the end of the MOSFET Q1 away from the electromagnetic relay K1 is grounded. One end of the tenth resistor R10 is connected to the first input terminal of the optocoupler switch K2, and the second input terminal of the optocoupler switch K2 is grounded. The other end of the tenth resistor R10 is connected to the second comparison unit (42) to receive command signals. The first switching terminal of the optocoupler switch K2 is used to connect to the power supply terminal output by the auxiliary charging module. The eleventh resistor R11 is connected in series between the second switching terminal of the optocoupler switch K2 and the gate of the MOS transistor Q1. The electromagnetic relay K1, the first resistor R1 connected in series, and the first capacitor C1 are connected in parallel.

6. The charging protection circuit according to claim 1, characterized in that: The voltage sampling module (3) includes an impedance unit (31) and a sampling chip (32). The impedance unit (31) is connected in series between the voltage input terminal (21) and the sampling chip (32). The sampling chip (32) outputs a detection voltage signal.

7. A charging protection control method, characterized in that, This method is applied to the charging protection circuit as described in any one of claims 1-6, and the method protects the following steps: Connect the power supply module (2) to the mains circuit to provide the voltage required for charging in a voltage divider manner; Obtain the preset circuit operating voltage output by the back-end auxiliary charging module; Based on the preset circuit operating voltage, the main control module (1), controllable switch unit (24), voltage acquisition module and voltage detection module (4) are powered. Acquire the detection voltage signal output by the voltage sampling module (3) and determine whether the detection voltage signal exceeds the threshold. If not, continue to judge and control the second comparison unit (42) to output a high-level command signal; if yes, control the second comparison unit (42) to output a low-level command signal. Based on the low-level command signal output, the controllable switch unit (24) is turned off; The voltage output of the voltage output terminal (22) is achieved by turning off the controllable switch unit (24).

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