A charging management circuit and charger

Abstract

This invention discloses a charging management circuit and charger, including a flyback converter, a first sampling feedback module, a second sampling feedback module, and an optocoupler. The first sampling feedback module includes a comparator, a first switching unit, a thermistor voltage divider unit, and a current sampling resistor. It controls the duty cycle of the PWM chip via the optocoupler to achieve constant current charging in the first charging stage. The thermistor voltage divider unit increases its resistance as the temperature rises, automatically reducing the charging current and achieving temperature adaptive protection. When the charging current decreases to a preset value, the second sampling feedback module takes over control of the optocoupler to achieve constant voltage charging in the second charging stage. This invention enables two-stage constant current and constant voltage charging, and features automatic temperature-adjusted charging current, effectively preventing charger overheating in high-temperature environments and protecting the charger and battery safety.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power conversion, and in particular to a charging management circuit and a charger. Background Technology

[0002] Lead-acid batteries are widely used in electric vehicles, UPS uninterruptible power supplies, and energy storage systems due to their advantages such as low cost, high safety, and ability to discharge at high currents. Lead-acid batteries require charging during use, and the performance of the charger directly affects the battery's lifespan and safety.

[0003] Currently, most lead-acid battery chargers on the market use a constant current and constant voltage charging method. This means that the battery is first charged with a constant current, and then switched to constant voltage charging once the battery voltage reaches a set value, until charging is complete. However, existing chargers still have the following problems in practical applications:

[0004] Chargers generate a significant amount of heat during high-current charging, especially in high-temperature environments. Excessive internal temperature can degrade or even damage electronic components, impacting the charger's lifespan and reliability. Current chargers lack effective temperature-adaptive regulation mechanisms and cannot automatically adjust the charging current based on ambient or internal temperatures. Summary of the Invention

[0005] The main technical problem solved by the embodiments of the present invention is to provide a charging management circuit and charger that can solve at least some of the defects of existing lead-acid battery chargers.

[0006] In a first aspect, embodiments of the present invention provide a charging management circuit, comprising: a flyback converter, including a PWM chip and a transformer T1 connected to the PWM chip, the transformer T1 being used to connect to a battery to provide a charging voltage to the battery; a first sampling feedback module, including a comparator U3D, a first switching unit, a thermistor voltage divider unit, and a current sampling resistor Rm, the thermistor voltage divider unit being connected to a first input terminal of the comparator U3D, the current sampling resistor Rm being connected in series in the battery charging circuit and connected to a second input terminal of the comparator U3D, and the control terminal of the first switching unit being connected to the output terminal of the comparator U3D; a second sampling feedback module connected to the battery; an optocoupler U2, the primary side of which is connected to the output terminals of the first sampling feedback module and the second sampling feedback module, and the secondary side being connected to the PWM chip; the first sampling feedback module is configured to control the switching of the optocoupler U2 to cycle through, so as to output high and low levels to the PWM chip through the optocoupler U2. The M chip is used to adjust the duty cycle of the PWM signal output to the flyback converter according to the received high and low levels to control the battery in the first charging stage. The thermistor voltage divider unit is configured to increase its resistance when the temperature rises, and when the resistance increases, the voltage divider signal fed back to the first input terminal of the comparator U3D decreases, thereby changing the switching frequency of the high and low levels of the comparator U3D output to adjust the switching frequency of the optocoupler U2, thereby reducing the duty cycle of the PWM signal to reduce the charging current in the first charging stage. When the charging current decreases to a first preset current value, the first switching unit remains off to disconnect the control of the optocoupler U2 by the first sampling feedback module. The second sampling feedback module is used to control the switching of the optocoupler U2 cyclically according to the battery voltage to output high and low levels to the PWM chip. The PWM chip is used to adjust the duty cycle of the PWM signal output to the flyback converter according to the received high and low levels to control the battery in the second charging stage.

[0007] In a second aspect, embodiments of the present invention provide a charger, including: the charging management circuit as described in the first aspect.

[0008] The beneficial effects of the embodiments of the present invention are as follows: Unlike the prior art, the embodiments of the present invention can realize constant current and constant voltage two-stage charging, and have the function of automatically adjusting the charging current according to temperature, effectively preventing the charger from overheating in high temperature environment and protecting the safety of the charger and battery. Attached Figure Description

[0009] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0010] Figure 1 This is a schematic diagram of a charging management circuit provided in an embodiment of the present invention;

[0011] Figure 2 This is a circuit schematic diagram of a flyback converter in a charging management circuit provided by an embodiment of the present invention;

[0012] Figure 3 This is a circuit diagram of the first sampling feedback module and the second sampling feedback module in a charging management circuit provided by an embodiment of the present invention;

[0013] Figure 4 This is a circuit diagram of a charging management circuit with an added fan control circuit provided by an embodiment of the present invention;

[0014] Figure 5 This is a circuit diagram of a charging management circuit with an added charging indicator circuit provided by an embodiment of the present invention;

[0015] Figure 6 This is a circuit diagram of a charging management circuit that simultaneously includes a fan control circuit and a charging indicator circuit, provided by an embodiment of the present invention.

[0016] Figure 7 This is another circuit schematic diagram of a charging management circuit that simultaneously includes a fan control circuit and a charging indicator circuit, provided by an embodiment of the present invention;

[0017] Figure 8 This is a circuit diagram of a charging management circuit with an added charging switch module provided by an embodiment of the present invention;

[0018] Figure 9 This is a complete circuit diagram of a charging management circuit with an added reverse connection protection module provided by an embodiment of the present invention. Detailed Implementation

[0019] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "bottom," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0021] Please see Figures 1 to 3 This invention provides a charging management circuit. The charging management circuit includes a flyback converter 100, a first sampling feedback module 200, a second sampling feedback module 300, and an optocoupler U2. The flyback converter 100 converts an AC input power supply 40 into a DC voltage to provide a charging voltage for the battery. The first sampling feedback module 200 and the second sampling feedback module 300 interact with the flyback converter 100 via the optocoupler U2 to achieve closed-loop control of the battery charging process.

[0022] Understandably, the flyback converter 100 includes a PWM chip U1 and a transformer T1 connected to the PWM chip U1. The output terminal of the transformer T1 is used to connect to a battery. Specifically, the first terminal of the primary winding of the transformer T1 is connected to the positive terminal BAT+ of the battery, and the second terminal of the primary winding is connected to the reference ground GND to provide a charging voltage for the battery. The PWM chip U1 is used to output a PWM signal to control the operating state of the flyback converter 100. By adjusting the duty cycle of the PWM signal, the charging voltage and charging current output by the transformer T1 can be adjusted.

[0023] In some embodiments of this application, reference is made to Figure 3The first sampling feedback module 200 includes a comparator U3D, a first switching unit 210, and a thermistor voltage divider unit 220. The thermistor voltage divider unit 220 is connected to the first input terminal of the comparator U3D and provides a temperature-varying voltage divider signal to the comparator U3D. The second input terminal of the comparator U3D is connected to a battery. Specifically, the second input terminal of the comparator U3D is connected to a current sampling resistor Rm connected to the battery. The current sampling resistor Rm is used to convert the charging current into a voltage signal and feed it back to the second input terminal of the comparator U3D. The control terminal of the first switching unit 210 is connected to the output terminal of the comparator U3D, and the output terminal of the first switching unit 210 is connected to the primary side of the optocoupler U2.

[0024] Combined with reference Figure 2 and Figure 3 The second sampling feedback module 300 is connected to the battery and is used to collect the battery's charging voltage. The output terminal of the second sampling feedback module 300 is connected to the primary side of the optocoupler U2, and together with the first sampling feedback module 200, it feeds a signal to the PWM chip U1 through the optocoupler U2.

[0025] In some embodiments of this application, the optocoupler U2 serves as an isolation and signal transmission device between the flyback converter 100 and the sampling feedback module. The primary side of the optocoupler U2 is connected to the output of the first sampling feedback module 200 and the output of the second sampling feedback module 300, while the secondary side of the optocoupler U2 is connected to the PWM chip U1. The optocoupler U2 achieves electrical isolation between the primary and secondary sides while simultaneously transmitting the sampling feedback signal to the PWM chip U1.

[0026] It is understandable that the charging process of the charging management circuit is divided into a first charging stage and a second charging stage. The first charging stage is a constant current charging stage, and the second charging stage is a constant voltage charging stage. In different charging stages, different sampling feedback modules control the optocoupler U2, thereby realizing different charging control strategies.

[0027] In the charging management circuit, during the first charging stage, the first sampling feedback module 200 is configured to control the switching of the optocoupler U2. Specifically, the comparator U3D compares the voltage divider signal provided by the thermistor voltage divider unit 220 with the current sampling signal provided by the current sampling resistor Rm, and outputs a high or low level to the control terminal of the first switching unit 210. The first switching unit 210 turns on or off according to the output signal of the comparator U3D, thereby controlling the on / off state of the primary side of the optocoupler U2. The secondary side of the optocoupler U2 outputs corresponding high or low levels to the PWM chip U1 according to the on / off state of the primary side. The PWM chip U1 adjusts the duty cycle of the PWM signal output to the flyback converter 100 according to the received high or low levels to control the battery in a constant current charging state during the first charging stage.

[0028] By way of example and not limitation, the thermal voltage divider unit 220 is configured to increase its resistance as the temperature rises. When the resistance of the thermal voltage divider unit 220 increases, the voltage divider signal fed back to the first input terminal of comparator U3D decreases, thereby changing the switching frequency of the high and low levels of the comparator U3D output to adjust the switching frequency of optocoupler U2. The change in the switching frequency of optocoupler U2 affects the feedback signal received by PWM chip U1, thereby reducing the duty cycle of the PWM signal and lowering the charging current in the first charging stage. In this way, the charging management circuit can automatically adjust the charging current according to temperature changes, automatically reducing the charging current in high-temperature environments, and realizing temperature adaptive protection.

[0029] In the charging management circuit, as the charging process progresses, the battery voltage gradually increases and the charging current gradually decreases. When the charging current decreases to a first preset current value, the first switching unit 210 remains off, thereby disconnecting the control of the optocoupler U2 by the first sampling feedback module 200. It can be understood that after the first switching unit 210 remains off, the first sampling feedback module 200 no longer feeds signals to the PWM chip U1 through the optocoupler U2, and the charging process transitions from the first charging stage to the second charging stage.

[0030] In the charging management circuit, during the second charging phase, the second sampling feedback module 300 controls the switching of the optocoupler U2 according to the battery voltage to output high and low levels to the PWM chip U1. The PWM chip U1 adjusts the duty cycle of the PWM signal output to the flyback converter 100 based on the received high and low levels to control the battery in a constant-voltage charging state during the second charging phase. During the second charging phase, the second sampling feedback module 300 dynamically adjusts the state of the optocoupler U2 according to changes in the battery voltage, maintaining the charging voltage near a preset constant voltage value until the battery is fully charged.

[0031] Understandably, through the coordinated operation of the first sampling feedback module 200 and the second sampling feedback module 300, the charging management circuit can automatically switch between the constant current charging stage and the constant voltage charging stage to meet the charging requirements of lead-acid batteries. Simultaneously, the temperature adaptive function of the thermistor voltage divider unit 220 can automatically reduce the charging current in high-temperature environments, effectively preventing the charger from overheating and improving the charger's safety and reliability.

[0032] Please see Figure 2 , Figure 2 This is a circuit diagram of a flyback converter in a charging management circuit according to an embodiment of the present invention. The flyback converter 100 includes a rectifier filter circuit, a PWM chip U1, a switching transistor Q1, and a transformer T1.

[0033] In one embodiment, the rectifier-filter circuit includes a rectifier bridge DB1, an inductor LC1, an electrolytic capacitor EC1, and a capacitor C2. The two ends of the AC input power supply 40 are connected to the two AC input terminals of the rectifier bridge DB1. The positive and negative output terminals of the rectifier bridge DB1 are connected to the positive and negative terminals of the electrolytic capacitor EC1 through the inductor LC1. The negative terminal of the electrolytic capacitor EC1 is grounded. Capacitor C2 is connected in parallel across the electrolytic capacitor EC1. The rectifier bridge DB1 converts the AC voltage into a pulsating DC voltage. Capacitor C2 is used for primary filtering. The inductor LC1 and the electrolytic capacitor EC1 constitute an LC filter circuit for further filtering the pulsating DC voltage, outputting a smooth DC voltage.

[0034] The PWM chip U1 is a current-mode PWM control chip. The first pin of the PWM chip U1 is the compensation pin COMP, the second pin is the feedback pin VFB, the third pin is the current detection pin ISENSE, the fourth pin is the timing pin RT / CT, the fifth pin is the ground pin GND, the sixth pin is the output pin OUTPUT, the seventh pin is the power supply pin VCC, and the eighth pin is the reference voltage pin VREF.

[0035] The transformer T1 includes a first primary winding on the primary side, a second primary winding on the primary side, a first primary winding on the secondary side, and a second secondary winding on the secondary side. Specifically, the first primary winding includes a first pin and a second pin, the second primary winding includes a third pin and a fourth pin, the first primary winding includes a fifth pin and a sixth pin, and the second secondary winding includes a seventh pin and an eighth pin.

[0036] In some embodiments of this application, the flyback converter 100 further includes an RCD snubber circuit. The RCD snubber circuit includes a capacitor C1, resistors R3 and R4, and a diode D2. The first terminal of capacitor C1 is connected to the cathode of diode D2, and the anode of diode D2 is connected to the second pin of the first primary winding and the drain of switching transistor Q1. The second terminal of capacitor C1 is connected to the first terminals of resistors R3 and R4, and the first pin of the first primary winding. The second terminals of resistors R3 and R4 are connected to the cathode of diode D2. The RCD snubber circuit is used to absorb the voltage spikes generated by the leakage inductance of transformer T1 when switching transistor Q1 is turned off, protecting switching transistor Q1.

[0037] In one embodiment, the flyback converter further includes a diode D3, a resistor R7, and a resistor R15. The first terminal of resistor R7 is connected to the first pin of the first primary winding, and the fourth pin of the second primary winding of transformer T1 is connected to the second terminal of resistor R7 and the first terminal of resistor R15 via diode D3. The second terminal of resistor R15 is connected to the power supply pin VCC of the PWM chip U1. The third pin of the second primary winding is grounded.

[0038] In one embodiment, the charging management circuit further includes a resistor R11 and a capacitor C3. The first end of resistor R11 is connected to the reference voltage pin VREF of the PWM chip U1, and the second end of resistor R11 is connected to the timing pin RT / CT of the PWM chip U1. Capacitor C3 is connected between the timing pin RT / CT and ground. Resistor R11 and capacitor C3 are used to set the oscillation frequency of the PWM signal output by the PWM chip U1.

[0039] In one embodiment, the charging management circuit further includes a resistor R22, a capacitor C6, and a capacitor C4. The first end of resistor R22 is connected to the compensation pin COMP of the PWM chip U1, and the second end of resistor R22 is connected to the feedback pin VFB. The first end of capacitor C6 is connected to the feedback pin VFB, and the second end of capacitor C6 is grounded.

[0040] In this embodiment, the switching transistor Q1 is connected to the first primary winding and the PWM chip U1. The AC input power supply 40 is converted by a rectifier and filter circuit to provide DC voltage to the first primary winding of the primary side of the transformer T1. The first primary winding provides the operating voltage for the PWM chip, which is used to control the switching on and off of the switching transistor Q1. The first primary winding provides the charging voltage for the battery charging process. Specifically, when the switching transistor Q1 is closed, the first primary winding stores energy. When the switching transistor Q1 is open, the first primary winding outputs energy to the second primary winding of the primary side of the transformer, the first primary winding of the secondary side of the transformer, and the second secondary winding of the secondary side of the transformer.

[0041] In one specific embodiment, the switching transistor Q1 is an N-channel MOSFET. The gate of the switching transistor Q1 is connected to the output pin OUTPUT of the PWM chip U1 through resistor R14, the drain of the switching transistor Q1 is connected to the second pin of the first primary winding, and the source of the switching transistor Q1 is grounded through resistor R28. Resistor R20 is connected between the gate and source of the switching transistor Q1 to provide a discharge path for the gate when the switching transistor Q1 is turned off. Resistor R29 is connected in parallel across resistor R28.

[0042] Please refer to the reference. Figures 2 to 9The feedback pin VFB of PWM chip U1 is connected to the secondary side of optocoupler U2. The collector of the secondary side of optocoupler U2 is connected to the power supply pin VCC of PWM chip U1 through resistor R25, and the emitter of the secondary side of optocoupler U2 is connected to the feedback pin VFB of PWM chip U1 through resistor R30. Resistor R31 is connected between the emitter of the secondary side of optocoupler U2 and ground. Capacitor C4 is connected between the collector of the secondary side of optocoupler U2 and ground. When the primary side of optocoupler U2 is turned on, the secondary side of optocoupler U2 is also turned on, pulling the voltage of feedback pin VFB low. PWM chip U1 adjusts the duty cycle of the output PWM signal according to the voltage of feedback pin VFB.

[0043] Please see Figure 3 , Figure 3 This is a circuit diagram of the first sampling feedback module and the second sampling feedback module in a charging management circuit provided by an embodiment of the present invention.

[0044] The thermal voltage divider unit 220 is used to provide a temperature-varying reference voltage divider signal to the comparator U3D. The first switching unit 210 is used to control the on / off state of the optocoupler U2 according to the output signal of the comparator U3D.

[0045] The thermistor voltage divider unit 220 includes a thermistor RT1 and a resistor R34. The first terminal of the thermistor RT1 is connected to a first reference voltage, and the second terminal of the thermistor RT1 is connected to the first terminal of the resistor R34 and then to the inverting input of the comparator U3D. The second terminal of the resistor R34 is grounded. The thermistor RT1 and the resistor R34 form a series voltage divider circuit. After the first reference voltage is divided by the thermistor RT1 and the resistor R34, a divided voltage signal is output at the connection point of the thermistor RT1 and the resistor R34 to the inverting input of the comparator U3D.

[0046] Specifically, the first reference voltage is +3.3V. The +3.3V reference voltage is provided by the voltage regulator circuit of the charging management circuit, which is used to provide a stable reference voltage for the thermistor voltage divider unit. After the +3.3V reference voltage is divided by the thermistor RT1 and resistor R34, it generates a voltage divider signal of about 0.05V at room temperature, which serves as the reference signal for the inverting input of comparator U3D.

[0047] Specifically, the thermistor RT1 is either a negative temperature coefficient thermistor or a positive temperature coefficient thermistor. In this embodiment, the thermistor RT1 is configured to increase its resistance as the temperature rises. When the ambient temperature rises, the resistance of the thermistor RT1 increases, the voltage division ratio of the thermistor RT1 in the voltage divider circuit increases, and the voltage division signal fed back to the inverting input of the comparator U3D by the resistor R34 based on the first reference voltage decreases.

[0048] In some embodiments of this application, the non-inverting input of comparator U3D is connected to the battery via a current sampling resistor Rm. The current sampling resistor Rm is connected in series in the battery's charging circuit. When the charging current flows through the current sampling resistor Rm, a voltage drop is generated, which is used as a current sampling signal input to the non-inverting input of comparator U3D. The resistance value of the current sampling resistor Rm is relatively small to minimize its impact on the charging circuit.

[0049] Understandably, comparator U3D compares the current sampling signal at the non-inverting input with the voltage divider signal at the inverting input. When the voltage at the non-inverting input is greater than the voltage at the inverting input, comparator U3D outputs a high level; when the voltage at the non-inverting input is less than the voltage at the inverting input, comparator U3D outputs a low level.

[0050] Specifically, the first switching unit 210 includes a switching transistor Q2, resistors R27, R32, and R33. The control terminal of the switching transistor Q2 is connected to the output terminal of the comparator U3D through resistor R32, which limits the current flowing into the control terminal of the switching transistor Q2. Resistor R33 is connected between the control terminal of the switching transistor Q2 and ground, and is used to pull the control terminal of the switching transistor Q2 low when the comparator U3D outputs a low level, ensuring that the switching transistor Q2 is reliably turned off. The collector of the switching transistor Q2 is connected to the primary side of the optocoupler U2 through resistor R27, which limits the current flowing through the primary side of the optocoupler U2. The emitter of the switching transistor Q2 is grounded.

[0051] In some embodiments of this application, the switching transistor Q2 is an NPN transistor. When the comparator U3D outputs a high level, the high-level signal is applied to the base of the switching transistor Q2 through resistor R32, turning on Q2. The primary side of the optocoupler U2 forms a current path with the switching transistor Q2 through resistor R27, turning on U2. When the comparator U3D outputs a low level, the base voltage of the switching transistor Q2 is pulled low by resistor R33, turning off Q2. The primary side current path of the optocoupler U2 is broken, turning off U2.

[0052] Understandably, during the first charging phase, as the charging current changes, the voltage drop across the current sampling resistor Rm changes accordingly, and the output state of comparator U3D switches accordingly, thereby controlling the switching cycle of optocoupler U2. When the temperature rises, the resistance of the thermistor RT1 increases, the voltage divider signal at the inverting input decreases, and the threshold for comparator U3D to output a high level decreases. This allows comparator U3D to output a high level even with a smaller charging current, thereby reducing the charging current during the first charging phase and achieving temperature adaptive protection.

[0053] In some embodiments of this application, the second sampling feedback module 300 includes a voltage divider resistor network 310, a resistor R23, and a three-terminal Zener diode U4. The voltage divider resistor network 310 is used to acquire the charging voltage of the battery and perform voltage division. The three-terminal Zener diode U4 is used to control the on / off state of the optocoupler U2 according to the voltage division signal.

[0054] Specifically, the voltage divider resistor network 310 includes resistors R2, R12, and R24. The first terminal of resistor R2 is connected to the positive terminal BAT+ of the battery. The second terminal of resistor R2 is connected to the first terminal of resistor R12. The second terminal of resistor R12 is connected to the first terminal of resistor R24 ​​and the reference terminal of the three-terminal regulator U4. The second terminal of resistor R24 ​​is connected to the anode of the three-terminal regulator U4 and grounded. Resistors R2, R12, and R24 form a series voltage divider circuit to divide the battery's charging voltage.

[0055] As is understood, the three-terminal Zener diode U4 includes a cathode, an anode, and a reference terminal. The reference terminal of the Zener diode U4 is connected to the junction of resistors R12 and R24, and is used to receive the voltage divider signal. The anode of the Zener diode U4 is connected to the second terminal of resistor R24 ​​and grounded. The cathode of the Zener diode U4 is connected to the primary side of the optocoupler U2 through resistor R23. Resistor R23 is used to limit the current flowing through the primary side of the optocoupler U2.

[0056] In some embodiments of this application, the three-terminal Zener diode U4 has an internal reference voltage. When the voltage at the reference terminal is lower than the internal reference voltage, the three-terminal Zener diode U4 is turned off, no current flows through the primary side of the optocoupler U2, and the optocoupler U2 is turned off. When the voltage at the reference terminal is higher than the internal reference voltage, the three-terminal Zener diode U4 is turned on, and the primary side of the optocoupler U2 forms a current path through the resistor R23 and the three-terminal Zener diode U4, and the optocoupler U2 is turned on.

[0057] Specifically, the voltage divider resistor network 310 is used to acquire the battery charging voltage and feed the voltage divider signal back to the reference terminal of the three-terminal regulator U4. As the battery charging voltage increases, the voltage divider signal output by the voltage divider resistor network 310 increases accordingly. When the voltage divider signal is greater than the turn-on voltage of the three-terminal regulator U4, the three-terminal regulator U4 turns on to control the optocoupler U2. The optocoupler U2 transmits the feedback signal to the PWM chip U1, which reduces the duty cycle of the PWM signal, thereby reducing the charging voltage. When the voltage divider signal is less than the turn-on voltage of the three-terminal regulator U4, the three-terminal regulator U4 turns off, the optocoupler U2 turns off, and the PWM chip U1 increases the duty cycle of the PWM signal, thereby increasing the charging voltage. Through the above negative feedback control, the charging voltage is stabilized near a preset constant voltage value.

[0058] It is understandable that the battery charging voltage is determined by the parameters of the voltage divider resistor network 310 and the three-terminal Zener diode U4. The formula for calculating the battery charging voltage is:

[0059] V_battery = V_Ref × (1 + (R2 + R12) / R24)

[0060] Where V_Ref is the reference voltage of the three-terminal Zener diode U4, and R2, R12, and R24 are the resistance values ​​of the voltage divider network 310. By adjusting the resistance values ​​of resistors R2, R12, and R24, different battery charging voltages can be set to accommodate lead-acid batteries of different specifications.

[0061] Understandably, during the second charging phase, the first switching unit 210 remains off, and the first sampling feedback module 200 no longer controls the optocoupler U2. The second sampling feedback module 300 controls the switching state of the optocoupler U2 based on the battery's charging voltage to achieve constant voltage charging control. As the charging process progresses, the battery voltage gradually stabilizes, and the charging current gradually decreases until the battery is fully charged.

[0062] Please see Figure 4 , Figure 4 This is a circuit diagram of a charging management circuit with an added fan control circuit 20 provided by an embodiment of the present invention.

[0063] In some embodiments of this application, the charging management circuit further includes a fan control circuit 20. The fan control circuit 20 includes a comparator U3B, a first voltage divider unit 400, a second switching unit 500, and a cooling fan Fan. The fan control circuit 20 is used to automatically control the start and stop of the cooling fan Fan according to the magnitude of the charging current. During high-current charging, the cooling fan Fan is activated for heat dissipation, and during low-current charging or when charging is complete, the cooling fan Fan is turned off to save energy.

[0064] Combined with reference Figure 2 and Figure 4 The first voltage divider unit 400 is connected to the secondary winding of transformer T1 to provide a second voltage divider signal to the inverting input of comparator U3B. The voltage output from the secondary winding is processed by the first voltage divider unit 400 to generate a stable reference voltage divider signal, which serves as the comparison reference for comparator U3B.

[0065] Specifically, the first voltage divider unit 400 includes a voltage regulator unit 410 and a resistor voltage divider unit 420. The voltage regulator unit 410 is used to convert the voltage output from the secondary winding of transformer T1 into a stable reference voltage. The resistor voltage divider unit 420 is used to divide the reference voltage to generate a second voltage divider signal.

[0066] The voltage regulator unit 410 includes resistors R1 and R6, and a Zener diode DZ1. The first terminal of resistor R1 is connected to the eighth pin of the secondary winding of transformer T1, and the seventh pin of the secondary winding is grounded. The second terminal of resistor R1 is connected to the first terminal of resistor R6 and the cathode of Zener diode DZ1 to provide a reference voltage. The second terminal of resistor R6 and the anode of Zener diode DZ1 are grounded.

[0067] Understandably, the voltage output from the secondary winding of transformer T1 is current-limited by resistor R1 and then regulated by Zener diode DZ1. The cathode voltage of Zener diode DZ1 is clamped at its regulated value, forming a stable reference voltage. Resistor R6 is connected in parallel with Zener diode DZ1 to provide bias current, ensuring that Zener diode DZ1 operates in its regulated region.

[0068] Specifically, the resistor divider unit 420 includes resistors R5, R8, and R19. The first terminal of resistor R5 is connected to a reference voltage, which is the common connection point connecting the second terminal of resistor R1, the first terminal of resistor R6, and the cathode of Zener diode DZ1. Resistors R5, R8, and R19 are connected in series, with the second terminal of resistor R19 grounded. The connection point of resistors R8 and R19 outputs a second voltage divider signal to the inverting input of comparator U3B.

[0069] In some embodiments of this application, the reference voltage is divided in series by resistors R5, R8, and R19, generating a second voltage divider signal at the connection point of resistors R8 and R19. The voltage value of the second voltage divider signal is determined by the ratio of the reference voltage to the resistance values ​​of resistors R5, R8, and R19. By selecting appropriate resistor values, the voltage value of the second voltage divider signal can be set, thereby setting the current threshold for starting and stopping the cooling fan.

[0070] In some embodiments of this application, the Zener diode DZ1 has a Zener voltage of 12V, and the reference voltage output by the voltage regulator unit 410 is +12V. The +12V reference voltage is divided by the resistor divider unit 420, generating a second voltage divider signal at the connection point of resistors R8 and R19. The voltage value of the second voltage divider signal is 0.05V, which serves as the comparison reference for comparator U3B.

[0071] Specifically, the second preset current value is 0.5A. When the charging current is greater than 0.5A, the voltage drop across the current sampling resistor Rm is greater than 0.05V, comparator U3B outputs a high level, controlling the cooling fan Fan to operate. When the charging current is less than 0.5A, the voltage drop across the current sampling resistor Rm is less than 0.05V, comparator U3B outputs a low level, and the cooling fan Fan stops operating. Specifically, the output terminal of comparator U3B is connected to the control terminal of the second switching unit 500. Figure 2The output terminal of the second switching unit 500 is connected to the first terminal of the cooling fan Fan, and the second terminal of the cooling fan Fan is connected to the primary winding of the transformer T1. The primary winding provides power to the cooling fan Fan. When the second switching unit 500 is turned on, the primary winding, the cooling fan Fan, and the second switching unit 500 form a current loop, and the cooling fan Fan is energized and operates.

[0072] Understandably, the primary winding of transformer T1 powers the cooling fan Fan. The sixth pin of the primary winding is connected to the first terminal of resistor R35 via rectifier diode D5, the fifth pin of the primary winding is grounded, and the second terminal of resistor R35 is connected to the second terminal of the cooling fan Fan. Rectifier diode D5 rectifies the AC voltage output from the primary winding. Resistor R35 limits the current flowing through the cooling fan Fan. When switch Q3 is turned on, the primary winding, rectifier diode D5, resistor R35, cooling fan Fan, and switch Q3 form a current loop, energizing the cooling fan Fan.

[0073] In some embodiments of this application, when the battery charging current is greater than the second preset current value, the voltage drop across the current sampling resistor Rm is larger, and the voltage at the non-inverting input of comparator U3B is greater than the second voltage divider signal at the inverting input. Comparator U3B then outputs a high level. This high-level signal controls the second switching unit 500 to conduct, thereby controlling the cooling fan Fan to operate and dissipate heat from the charging management circuit.

[0074] Understandably, when the battery charging current is less than the second preset current value, the voltage drop across the current sampling resistor Rm is small. The voltage at the non-inverting input of comparator U3B is less than the second voltage divider signal at the inverting input, causing comparator U3B to output a low level. This low-level signal controls the second switching unit 500 to turn off, stopping the cooling fan Fan from working.

[0075] Specifically, the first preset current value is greater than the second preset current value. The first preset current value is the current threshold for switching between the first and second charging stages, and the second preset current value is the current threshold for starting and stopping the cooling fan. By setting the first preset current value to be greater than the second preset current value, the cooling fan is kept in operation for most of the constant current charging stage, providing sufficient heat dissipation capacity.

[0076] In some embodiments of this application, the first preset current value is 5A. When the charging current reaches 5A, the voltage drop across the current sampling resistor Rm makes the voltage at the non-inverting input of comparator U3D equal to the voltage at the inverting input; this is the set current value for constant current charging. The set current value for constant current charging can be changed by adjusting the resistance values ​​of the thermistor RT1 and resistor R34.

[0077] In some embodiments of this application, the second switching unit 500 includes a switching transistor Q3, a diode D6, a resistor R36, and a resistor R37. The anode of diode D6 is connected to the output terminal of comparator U3B, and the cathode of diode D6 is connected to the first terminal of resistor R36. Diode D6 is used to prevent current from flowing back into the output terminal of comparator U3B, thus protecting comparator U3B.

[0078] It is understandable that the second terminal of resistor R36 is connected to the first terminal of resistor R37 and the control terminal of switch Q3, while the second terminal of resistor R37 is grounded. Resistors R36 and R37 form a voltage divider circuit, which divides the high level output of comparator U3B and applies it to the control terminal of switch Q3. Resistor R37 is also used to pull low the control terminal of switch Q3 when comparator U3B outputs a low level, ensuring that switch Q3 is reliably turned off.

[0079] Specifically, the switching transistor Q3 is an NPN transistor. The collector of Q3 is connected to the first terminal of the cooling fan, and the emitter is grounded. When comparator U3B outputs a high level, the high-level signal passes through diode D6 and resistor R36, and is then divided by resistors R36 and R37. The divided voltage is applied to the base of switching transistor Q3, turning it on. Figure 2 After the switching transistor Q3 is turned on, the primary winding of transformer T1, the cooling fan Fan, and the switching transistor Q3 form a current loop, and the cooling fan Fan is energized and starts to work.

[0080] In some embodiments of this application, when the comparator U3B outputs a low level, the base voltage of the switching transistor Q3 is pulled low by the resistor R37, the switching transistor Q3 is turned off, the current loop of the cooling fan Fan is disconnected, and the cooling fan Fan stops working.

[0081] Please see Figure 5 , Figure 5 This is a circuit diagram of a charging management circuit with an added charging indicator circuit 30 provided by an embodiment of the present invention.

[0082] In some embodiments of this application, the charging management circuit further includes a charging indicator circuit 30. The charging indicator circuit 30 includes a first voltage divider unit 400, comparator U3B, comparator U3C, a second voltage divider unit 600, a first display unit 700, and a second display unit 800. The charging indicator circuit 30 is used to indicate the charging status based on the magnitude of the charging current, allowing the user to understand the current charging progress. In some embodiments of this application, the Zener diode DZ1 has a Zener voltage of 12V, and the reference voltage output by the voltage regulator unit 410 is +12V.

[0083] In some embodiments of this application, the +12V reference voltage is divided in series by resistors R5, R8, and R19, generating a second voltage divider signal at the connection point of resistors R8 and R19. The voltage value of the second voltage divider signal is 0.05V, serving as the comparison reference for comparator U3B. The voltage value of the second voltage divider signal is determined by the ratio of the reference voltage to the resistance values ​​of resistors R5, R8, and R19. By selecting appropriate resistor values, the voltage value of the second voltage divider signal can be set, thereby setting the current threshold for switching the charging indication. Specifically, the output terminal of comparator U3B is connected to the inverting input terminal of comparator U3C and the first display unit 700. The output signal of comparator U3B serves simultaneously as the comparison input signal of comparator U3C and the drive signal of the first display unit 700.

[0084] In some embodiments of this application, the second voltage divider unit 600 is connected to the first voltage divider unit 400 to provide a third voltage divider signal to the non-inverting input of the comparator U3C. The second voltage divider unit 600 includes resistors R10 and R21. The first end of resistor R10 is connected to the reference voltage output of the first voltage divider unit 400, that is, the common connection point connecting the second end of resistor R1, the first end of resistor R6, and the cathode of the Zener diode DZ1. The second end of resistor R10 is connected to the first end of resistor R21 and outputs the third voltage divider signal to the non-inverting input of the comparator U3C. The second end of resistor R21 is grounded.

[0085] Understandably, the +12V reference voltage is divided in series by resistors R10 and R21, generating a third voltage divider signal at the connection point of R10 and R21. This third voltage divider signal has a value of 10V, serving as the comparison reference for the non-inverting input of comparator U3C. The value of the third voltage divider signal is determined by the ratio of the reference voltage to the resistance values ​​of resistors R10 and R21. The value of the third voltage divider signal is set higher than the voltage at which comparator U3B outputs a low level, ensuring that comparator U3C can output a high level when comparator U3B outputs a low level.

[0086] Specifically, the output of comparator U3C is connected to the second display unit 800. Comparator U3C compares the third voltage divider signal at the non-inverting input terminal with the output signal of comparator U3B at the inverting input terminal, and outputs a high or low level according to the comparison result to drive the second display unit 800.

[0087] In some embodiments of this application, the first display unit 700 includes a resistor R17 and a light-emitting diode (LED2). The first end of resistor R17 is connected to the output of comparator U3B, and the second end of resistor R17 is connected to the anode of LED2. The cathode of LED2 is grounded. Resistor R17 is used to limit the current flowing through LED2, protecting LED2.

[0088] Understandably, the second display unit 800 includes diode D4, resistor R16, resistor R18, and light-emitting diode LED1. The anode of diode D4 is connected to the reference terminal of the three-terminal Zener diode U4 through resistor R16. The cathode of diode D4 is connected to the first terminal of resistor R18 and the output terminal of comparator U3C. The second terminal of resistor R18 is connected to the anode of light-emitting diode LED1, and the cathode of light-emitting diode LED1 is grounded. Resistor R18 is used to limit the current flowing through light-emitting diode LED1, protecting it.

[0089] Specifically, when the battery charging current exceeds the second preset current value, the voltage obtained by converting the charging current through the current sampling resistor Rm is greater than the second voltage divider signal, and comparator U3B outputs a high level. This high-level signal drives LED2 to illuminate through resistor R17, and the first display unit 700 displays the first color. Simultaneously, the high-level signal output by comparator U3B is input to the inverting input of comparator U3C. At this time, the voltage at the inverting input of comparator U3C is greater than the third voltage divider signal at the non-inverting input, and comparator U3C outputs a low level. LED1 does not illuminate, and the second display unit 800 does not display anything.

[0090] In some embodiments of this application, when the battery charging current is less than a second preset current value, the voltage obtained by converting the charging current through the current sampling resistor Rm is less than the second voltage divider signal, and comparator U3B outputs a low level. The low-level signal cannot drive the light-emitting diode LED2 to conduct and emit light, and the first display unit 700 does not display anything. Simultaneously, the low-level signal output by comparator U3B is input to the inverting input of comparator U3C. At this time, the third voltage divider signal at the non-inverting input of comparator U3C is greater than the voltage at the inverting input, and comparator U3C outputs a high level. The high-level signal drives the light-emitting diode LED1 to conduct and emit light through resistor R18, and the second display unit 800 displays the second color.

[0091] Understandably, the first and second colors are different colors to distinguish different charging states. As an example, and not a limitation, the first color is red, indicating that the charger is performing high-current charging; the second color is green, indicating that the charging current has decreased and the battery is nearing or fully charged. Users can intuitively understand the current charging status by observing the display status of the first display unit 700 and the second display unit 800.

[0092] By way of example and not limitation, the charging indicator circuit 30 described above enables the charging management circuit to automatically switch the display state according to the magnitude of the charging current. During the high-current charging phase, the first display unit 700 displays a first color to indicate to the user that the charger is working. After the charging current decreases, the second display unit 800 displays a second color to indicate to the user that the battery is about to be fully charged or is fully charged. The charging indicator circuit 30 is simple and reliable, providing users with intuitive feedback on the charging status.

[0093] Please refer to the following: Figure 6 and Figure 7 , Figure 6 and Figure 7 This is a circuit diagram of a charging management circuit that includes both a fan control circuit 20 and a charging indicator circuit 30, provided by an embodiment of the present invention.

[0094] In some embodiments of this application, the charging management circuit includes both a fan control circuit and a charging indicator circuit 30. The fan control circuit 20 and the charging indicator circuit 30 share the first voltage divider unit 400 and the comparator U3B to simplify the circuit structure and reduce costs.

[0095] In some embodiments of this application, the output of comparator U3B is simultaneously connected to the control terminal of the second switching unit 500, the inverting input terminal of comparator U3C, and the first display unit 700. The output signal of comparator U3B is shared by the fan control circuit 20 and the charging indicator circuit 30.

[0096] Combination Figure 2 In terms of fan control, the output of comparator U3B is connected to the second switching unit 500 via diode D6. The second switching unit 500 includes a switching transistor Q3, diode D6, resistors R36 and R37. When comparator U3B outputs a high level, the high-level signal is divided by diode D6 and resistors R36 and R37, driving the switching transistor Q3 to conduct, thereby controlling the cooling fan Fan. The first terminal of the cooling fan Fan is connected to the collector of the switching transistor Q3, and the second terminal of the cooling fan Fan is connected to the primary winding of transformer T1.

[0097] Specifically, regarding the charging indication, the output of comparator U3B is connected to the first display unit 700 and the inverting input of comparator U3C. The first display unit 700 includes a resistor R17 and a light-emitting diode LED2. When comparator U3B outputs a high level, the high-level signal drives LED2 to conduct and emit light through resistor R17, displaying a first color.

[0098] Understandably, comparator U3C compares the third voltage divider signal at the non-inverting input with the output signal of comparator U3B at the inverting input. The output of comparator U3C is connected to the second display unit 800. When comparator U3B outputs a low level, the voltage at the non-inverting input of comparator U3C is greater than the voltage at the inverting input, causing comparator U3C to output a high level, driving LED1 to conduct and emit light, displaying the second color.

[0099] Specifically, when the battery charging current exceeds the second preset current value, the voltage obtained by the current sampling resistor Rm from the charging current is greater than the second voltage divider signal, and the comparator U3B outputs a high level. The high-level signal simultaneously performs the following functions: drives the second switching unit 500 to conduct, controlling the cooling fan Fan to work for heat dissipation; drives the LED2 of the first display unit 700 to light up, displaying the first color to indicate that the charger is performing high-current charging; and inputs to the inverting input of the comparator U3C, causing the comparator U3C to output a low level, and the LED1 of the second display unit 800 to turn off.

[0100] In some embodiments of this application, when the battery charging current is less than a second preset current value, the voltage obtained by the current sampling resistor Rm from the charging current is less than the second voltage divider signal, and the comparator U3B outputs a low level. The low-level signal simultaneously performs the following functions: turns off the second switching unit 500, stops the cooling fan Fan from working; turns off the light-emitting diode LED2 of the first display unit 700; and inputs it to the inverting input terminal of the comparator U3C, causing the comparator U3C to output a high level, driving the light-emitting diode LED1 of the second display unit 800 to light up, displaying a second color, indicating that the battery is close to fully charged or fully charged.

[0101] In some embodiments of this application, the reference voltage is +12V, the second voltage divider signal is 0.05V, the third voltage divider signal is 10V, and the second preset current value is 0.5A. The fan control circuit 20 and the charging indicator circuit 30 switch based on the same current threshold. When the charging current is greater than 0.5A, the cooling fan (Fan) operates and the first display unit 700 displays the first color; when the charging current is less than 0.5A, the cooling fan (Fan) stops and the second display unit 800 displays the second color.

[0102] Please see Figure 8 , Figure 8 This is a circuit diagram of a charging management circuit with an added charging switch module 900 provided by an embodiment of the present invention.

[0103] In some embodiments of this application, the charging management circuit further includes a charging switch module 900. The charging switch module 900 is used to automatically disconnect the charging circuit after the battery is fully charged to prevent overcharging, protect battery safety, and save energy.

[0104] Understandably, the charging switch module 900 includes a comparator U3A, a diode D1, a transient voltage suppressor diode TVS1, a resistor R43, a relay RLY1, a fourth voltage divider unit 910, and a fifth voltage divider unit 920. The comparator U3A compares the battery voltage with a preset full-charge voltage and outputs a control signal based on the comparison result. The relay RLY1 controls the on / off state of the battery charging circuit based on the output signal of the comparator U3A.

[0105] Specifically, the fourth voltage divider unit 910 is connected to a reference voltage source to provide a fourth voltage divider signal to the inverting input of comparator U3A. The fourth voltage divider unit 910 includes resistors R42 and R44. The first terminal of resistor R42 is connected to the reference voltage source, and the second terminal of resistor R42 is connected to the first terminal of resistor R44 and outputs the fourth voltage divider signal to the inverting input of comparator U3A. The second terminal of resistor R44 is grounded. After the reference voltage source is divided in series by resistors R42 and R44, the fourth voltage divider signal is generated at the connection point of resistors R42 and R44.

[0106] Combination Figures 4 to 7 The reference voltage source is provided by the voltage regulator unit 410 in the first voltage divider unit 400. The fourth voltage divider unit 910 is connected to the reference voltage output terminal of the voltage regulator unit 410, and generates a fourth voltage divider signal after dividing the reference voltage. The voltage value of the fourth voltage divider signal is determined by the ratio of the reference voltage and the resistance values ​​of resistors R42 and R44, and is used to set the threshold for judging the battery's fully charged voltage.

[0107] Combination Figure 2 The fifth voltage divider unit 920 is connected to transformer T1 and the battery to provide the fifth voltage divider signal to the non-inverting input of comparator U3A. The fifth voltage divider unit 920 includes resistors R45 and R46. The first terminal of resistor R45 is connected to the anode of diode D1 and the eighth pin of the secondary winding of transformer T1. The second terminal of resistor R45 is connected to the first terminal of resistor R46 and outputs the fifth voltage divider signal to the non-inverting input of comparator U3A. The second terminal of resistor R46 is connected to the negative terminal BAT- of the battery. The cathode of diode D1 is connected to the normally open contact of relay RLY1, and the normally closed contact of relay RLY1 is connected to the positive terminal BAT+ of the battery. The battery charging voltage is divided by resistors R45 and R46 in series, generating the fifth voltage divider signal at the connection point of resistors R45 and R46.

[0108] Specifically, the voltage value of the fifth voltage divider signal is proportional to the battery's charging voltage. As the charging process progresses, the battery voltage gradually increases, and the fifth voltage divider signal increases accordingly. By selecting appropriate values ​​for resistors R45 and R46, the battery's charging voltage can be proportionally converted into a fifth voltage divider signal suitable for the input range of comparator U3A.

[0109] In some embodiments of this application, the reference voltage output by the reference voltage source is +12V. The +12V reference voltage is divided by resistors R42 and R44 in series, generating a fourth voltage divider signal at the connection point of resistors R42 and R44. The voltage value of the fourth voltage divider signal is 2.5V, which serves as the comparison reference for the inverting input of comparator U3A.

[0110] Specifically, in the initial charging stage, the battery voltage is low. The fifth voltage divider signal, generated by the series voltage divider of resistors R45 and R46, is approximately 2.0V, which is lower than the fourth voltage divider signal of 2.5V. Comparator U3A outputs a low level, relay RLY1 is energized, and the charging circuit is connected. As charging progresses, the battery voltage gradually increases, and the fifth voltage divider signal increases accordingly. When the battery voltage reaches the preset full charge voltage, the fifth voltage divider signal rises to above 2.5V, comparator U3A outputs a high level, relay RLY1 is released, the charging circuit is disconnected, and charging stops.

[0111] In some embodiments of this application, comparator U3A compares the fourth voltage divider signal at the inverting input terminal and the fifth voltage divider signal at the non-inverting input terminal, and outputs a high level or a low level based on the comparison result. The output terminal of comparator U3A is connected to the first coil terminal of relay RLY1.

[0112] Understandably, the first terminal of resistor R43 is connected to a reference voltage source, and the second terminal of resistor R43 is connected to the second coil terminal of relay RLY1. Resistor R43 is used to provide drive current to the coil of relay RLY1. When comparator U3A outputs a low level, the reference voltage source forms a current loop through resistor R43, the coil of relay RLY1, and the output terminal of comparator U3A, energizing the coil of relay RLY1 and causing relay RLY1 to engage.

[0113] Specifically, the transient voltage suppressor diode TVS1 is connected across the coil of relay RLY1. The anode of TVS1 is connected to the first coil terminal of relay RLY1, and the cathode is connected to the second coil terminal of relay RLY1. TVS1 is used to absorb the reverse electromotive force generated in the coil of relay RLY1 at the moment of power failure, protecting comparator U3A and other circuit components from damage caused by voltage spikes.

[0114] Combination Figure 2When relay RLY1 is energized, its normally open contact closes, the battery charging circuit is activated, and the charging voltage output from the secondary winding of transformer T1 can charge the battery. When relay RLY1 is de-energized, its normally open contact opens, the battery charging circuit is disconnected, and charging of the battery stops.

[0115] Understandably, when the battery voltage is lower than the preset full charge voltage, the fifth voltage divider signal is less than the fourth voltage divider signal. The voltage at the non-inverting input of comparator U3A is less than the voltage at the inverting input, causing comparator U3A to output a low level. This low-level signal makes the output of comparator U3A present a low-impedance state. The reference voltage source forms a current loop through resistor R43, the coil of relay RLY1, and the output of comparator U3A. The coil of relay RLY1 is energized and closes, the normally open contact closes, the battery charging circuit is activated, and the charging management circuit charges the battery.

[0116] Specifically, when the battery voltage reaches the preset full charge voltage, the fifth voltage divider signal is greater than the fourth voltage divider signal. The voltage at the non-inverting input of comparator U3A is greater than the voltage at the inverting input, and comparator U3A outputs a high level. The high-level signal causes the output of comparator U3A to present a high-impedance state, breaking the coil current loop of relay RLY1. The coil of relay RLY1 is de-energized and released, the normally open contact opens, the battery charging circuit is disconnected, and the charging management circuit stops charging the battery.

[0117] In some embodiments of this application, the preset full-charge voltage is determined by the voltage division ratio of the fourth voltage divider unit 910. The formula for calculating the battery full-charge voltage is:

[0118] V_battery = V_Ref × (1 + R45 / R46) × (R44 / (R42+R44))

[0119] Where V_Ref is the voltage value of the reference voltage source, R42 and R44 are the resistance values ​​of the fourth voltage divider unit 910, and R45 and R46 are the resistance values ​​of the fifth voltage divider unit 920. By adjusting the resistance values ​​of resistors R42, R44, R45, and R46, different battery full-charge voltage thresholds can be set to accommodate lead-acid batteries of different specifications.

[0120] Please see Figure 9 , Figure 9 This is a complete circuit diagram of a charging management circuit with an added reverse connection protection module 1000 provided by an embodiment of the present invention.

[0121] In some embodiments of this application, the charging management circuit further includes a reverse connection protection module 1000. The reverse connection protection module 1000 is used to protect the charging management circuit and the battery from damage when the battery is connected in reverse. When the user accidentally reverses the positive and negative terminals of the battery, the reverse connection protection module 1000 can automatically activate to pull the positive terminal of the battery to protective ground, preventing reverse current from damaging the electronic components inside the charging management circuit.

[0122] Understandably, the reverse connection protection module 1000 includes transistor Q4, MOSFET Q5, resistors R13, R38, R39, R40, and R41. Transistor Q4 is used to detect the battery's connection polarity, and MOSFET Q5 is used to pull the battery's positive terminal to protective ground when the battery is reverse connected.

[0123] Specifically, transistor Q4 is an NPN transistor. The base of transistor Q4 is connected to the positive terminal BAT+ of the battery through resistor R13, and the base of transistor Q4 is also connected to the negative terminal BAT- of the battery through resistor R38. Resistors R13 and R38 constitute the bias circuit for the base of transistor Q4, used to determine the potential of the base of transistor Q4 according to the battery's connection polarity.

[0124] In some embodiments of this application, the emitter of transistor Q4 is connected to the positive terminal BAT+ of the battery, and the collector of transistor Q4 is connected to the gate of MOSFET Q5 and the first terminal of resistor R40 through resistor R39. Resistor R39 is used to limit the current at the collector of transistor Q4, the first terminal of resistor R40 is connected to the gate of MOSFET Q5, and the second terminal of resistor R40 is connected to the protective ground terminal PE. Resistors R39 and R40 constitute the bias circuit for the gate of MOSFET Q5.

[0125] Understandably, MOSFET Q5 is an N-channel enhancement-mode MOSFET. The drain of MOSFET Q5 is connected to the positive terminal BAT+ of the battery, and the source of MOSFET Q5 is connected to the protective ground PE. When MOSFET Q5 is turned on, the positive terminal BAT+ of the battery is connected to the protective ground PE through the drain and source of MOSFET Q5, forming a low-impedance path.

[0126] Specifically, resistor R41 is connected between the source and drain of MOSFET Q5. Resistor R41 provides a discharge path for the drain when MOSFET Q5 is off, and provides an initial bias for MOSFET Q5 when the circuit starts up.

[0127] In some embodiments of this application, when the battery is correctly connected, the potential of the positive terminal BAT+ is higher than the potential of the negative terminal BAT-. The base of transistor Q4 is connected to the positive terminal BAT+ through resistor R13 and to the negative terminal BAT- through resistor R38. Since the emitter of transistor Q4 is connected to the positive terminal BAT+, the voltage difference between the base and emitter potentials of transistor Q4 is insufficient to turn on transistor Q4, and transistor Q4 is in the off state.

[0128] Understandably, when transistor Q4 is off, its collector presents a high impedance state. The gate of MOSFET Q5 is connected to the protective ground (PE) via resistor R40, resulting in a low gate potential and the transistor being off. At this time, the reverse connection protection module 1000 does not operate, the battery charging circuit is normally connected, and the charging management circuit charges the battery normally.

[0129] Specifically, when the battery is connected in reverse, the potential of the negative terminal BAT- is higher than the potential of the positive terminal BAT+. In this case, the positive terminal BAT+ is actually connected to the negative terminal of the battery, and the negative terminal BAT- is actually connected to the positive terminal. The emitter of transistor Q4 is connected to the positive terminal BAT+ (actually the negative terminal, with a lower potential), and the base of transistor Q4 is connected to the negative terminal BAT- (actually the positive terminal, with a higher potential) through resistor R38.

[0130] In some embodiments of this application, when the battery is connected in reverse, the base potential of transistor Q4 is higher than the emitter potential, forming a forward bias voltage between the base and emitter, and transistor Q4 is turned on. After transistor Q4 is turned on, the collector potential of transistor Q4 is pulled down to near the emitter potential, that is, close to the potential of the positive terminal BAT+ of the battery.

[0131] Understandably, after transistor Q4 is turned on, its collector is connected to the gate of MOSFET Q5 through resistor R39. Since the collector potential of transistor Q4 is low, and the source of MOSFET Q5 is connected to the protective earth (PE), a voltage divider circuit is formed between the gate and source of MOSFET Q5 through resistors R39 and R40. The voltage at the negative terminal BAT- (actually the positive terminal) of the battery is applied to the gate of MOSFET Q5 after being divided by resistors R39 and R40, thus providing sufficient drive voltage to the gate of MOSFET Q5.

[0132] Specifically, when the gate voltage of MOSFET Q5 exceeds its turn-on voltage, MOSFET Q5 turns on. After MOSFET Q5 turns on, a low impedance state exists between its drain and source, and the battery's positive terminal BAT+ is pulled to the protective ground PE through MOSFET Q5. At this time, the potential of the battery's positive terminal BAT+ is clamped to a potential close to the protective ground PE, the reverse current is limited, and the electronic components inside the charging management circuit are protected.

[0133] In some embodiments of this application, the protective ground terminal PE is the protective ground of the charging management circuit, and is independent of the circuit's signal ground GND. By pulling the battery's positive terminal BAT+ to the protective ground terminal PE, reverse current can be effectively guided to the protective ground, preventing reverse current from flowing into other parts of the charging management circuit and protecting the circuit safety.

[0134] In some embodiments of this application, a charger is provided, which includes a charging management circuit as described in any of the above embodiments.

[0135] Understandably, the charger also includes a housing and connection terminals. The housing houses and protects the charging management circuitry. The connection terminals include AC input terminals and DC output terminals; the AC input terminals are used to connect to an AC power source, and the DC output terminals are used to connect to a battery.

[0136] Specifically, the charging management circuit is located inside the housing. The AC input terminal is connected to the input of the rectifier and filter circuit of the charging management circuit, used to introduce AC input power into the charging management circuit. The DC output terminal is connected to the positive terminal BAT+ and the negative terminal BAT- of the battery of the charging management circuit, used to transmit the charging voltage and charging current output by the charging management circuit to the battery.

[0137] By way of example and not limitation, by integrating the charging management circuit into the charger, the charger can achieve functions such as constant current and constant voltage two-stage charging, temperature-adaptive adjustment of charging current, automatic power-off when fully charged, charging status indication, and reverse connection protection of the battery, thereby meeting the charging needs of lead-acid batteries and improving charging safety and reliability.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this application as described above. For the sake of brevity, they are not provided in detail; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A charging management circuit, characterized in that, include: A flyback converter includes a PWM chip and a transformer T1 connected to the PWM chip. The transformer T1 is used to connect to a battery to provide a charging voltage to the battery. The first sampling feedback module includes a comparator U3D, a first switching unit, and a thermal voltage divider unit. The first input terminal and the second input terminal of the comparator U3D are respectively connected to the thermal voltage divider unit and the battery. The control terminal of the first switching unit is connected to the output terminal of the comparator U3D. The second sampling feedback module is connected to the battery; Optical coupler U2, the primary side of which is connected to the output terminal of the first sampling feedback module and the output terminal of the second sampling feedback module, and the secondary side is connected to the PWM chip; The first sampling feedback module is configured to control the switching of the optocoupler U2 in a cyclic manner, so as to output high and low levels to the PWM chip through the optocoupler U2. The PWM chip is used to adjust the duty cycle of the PWM signal output to the flyback converter according to the received high and low levels, so as to control the battery to be in the first charging stage. The thermistor voltage divider unit is configured to increase the resistance when the temperature rises, and when the resistance increases, the voltage divider signal fed back to the first input terminal of the comparator U3D decreases, thereby changing the switching frequency of the high and low levels of the comparator U3D output, so as to adjust the switching frequency of the optocoupler U2, thereby reducing the duty cycle of the PWM signal to reduce the charging current in the first charging stage. When the charging current decreases to a first preset current value, the first switching unit remains off to disconnect the control of the first sampling feedback module on the optocoupler U2. The second sampling feedback module is used to control the switching of the optocoupler U2 cyclically according to the voltage of the battery to output high and low levels to the PWM chip. The PWM chip is used to adjust the duty cycle of the PWM signal output to the flyback converter according to the received high and low levels to control the battery to be in the second charging stage. It also includes comparator U3B, first voltage divider unit, second switching unit and cooling fan; The first voltage divider unit is connected to the second winding of the transformer T1 to provide a second voltage divider signal to the inverting input of the comparator U3B. The non-inverting input of the comparator U3B is connected to the battery through a current sampling resistor Rm. The output of the comparator U3B is connected to the control terminal of the second switching unit. The output of the second switching unit is connected to the first end of the cooling fan. The second end of the cooling fan is connected to the first winding of the transformer T1. When the charging current of the battery is greater than the second preset current value, the voltage fed back to the non-inverting input of the comparator U3B by the current sampling resistor Rm is greater than the second voltage divider signal. The comparator U3B outputs a high level to control the second switching unit to turn on, thereby controlling the cooling fan to work; the first preset current value is greater than the second preset current value.

2. The circuit according to claim 1, characterized in that, The thermistor voltage divider unit includes a thermistor RT1 and a resistor R34. The first end of the thermistor RT1 is connected to a first reference voltage. The second end of the thermistor RT1 is connected to the first end of the resistor R34 and connected to the inverting input of the comparator U3D. The second end of the resistor R34 is grounded. The non-inverting input of the comparator U3D is connected to the battery via a current sampling resistor Rm. The first switching unit includes a switching transistor Q2, resistors R27, R32, and R33. The control terminal of the switching transistor Q2 is connected to the output terminal of the comparator U3D via resistor R32, and resistor R33 is connected to the control terminal of the switching transistor Q2. The collector of the switching transistor Q2 is connected to the primary side of the optocoupler U2 via resistor R27. The emitter of the switching transistor Q2 and resistor R33 are grounded. When the ambient temperature rises, the resistance of the thermistor RT1 increases, and the voltage divider signal fed back to the inverting input of the comparator U3D by resistor R34 based on the first reference voltage decreases.

3. The circuit according to claim 1, characterized in that, The second sampling feedback module includes a voltage divider resistor network, resistor R23, and a three-terminal Zener diode U4; The voltage divider resistor network includes resistors R2, R12, and R24. The first end of resistor R2 is connected to the positive terminal of the battery. The second end of resistor R2 is connected to the first end of resistor R12. The second end of resistor R12 is connected to the first end of resistor R24 ​​and the reference terminal of the three-terminal Zener diode U4. The second end of resistor R24 ​​is connected to the anode of the three-terminal Zener diode U4. The cathode of the three-terminal Zener diode U4 is connected to the primary side of the optocoupler U2 through resistor R23. The voltage divider resistor network is used to collect the charging voltage of the battery and feed the voltage divider signal back to the three-terminal Zener diode U4. When the voltage divider signal is greater than the conduction voltage of the three-terminal Zener diode U4, the three-terminal Zener diode U4 is turned on to control the operation of the optocoupler U2.

4. The circuit according to claim 1, characterized in that, The second switching unit includes a switching transistor Q3, a diode D6, a resistor R36, and a resistor R37; The anode of diode D6 is connected to the output terminal of comparator U3B, the cathode of diode D6 is connected to the first terminal of resistor R36, the second terminal of resistor R36 is connected to the first terminal of resistor R37 and the control terminal of switch Q3, and the second terminal of resistor R37 is grounded; the collector of switch Q3 is connected to the second terminal of cooling fan, and the emitter of switch Q3 is grounded. When the comparator U3B outputs a high level, the resistors R36 and R37 divide the high level, turning on the switching transistor Q3 and thus controlling the cooling fan to work.

5. The circuit according to claim 1, characterized in that, The charging management circuit also includes a comparator U3C, a second voltage divider unit, a first display unit, and a second display unit; The output of comparator U3B is connected to the inverting input of comparator U3C and the first display unit; the second voltage divider unit is connected to the first voltage divider unit to provide a third voltage divider signal to the non-inverting input of comparator U3C; the output of comparator U3C is connected to the second display unit. When the charging current of the battery is greater than the second preset current value, the voltage obtained by the current sampling resistor Rm from the charging current is greater than the second voltage divider signal, and the comparator U3B outputs a high level to control the first display unit to display the first color; When the charging current of the battery is less than the second preset current value, the voltage obtained by the current sampling resistor Rm from the charging current is less than the second voltage divider signal, and the comparator U3B outputs a low level. At this time, the third voltage divider signal at the non-inverting input of the comparator U3C is greater than the voltage at the inverting input, and the comparator U3C outputs a high level to control the second display unit to display the second color.

6. The circuit according to claim 1, characterized in that, The first voltage divider unit includes a voltage regulator unit and a resistor voltage divider unit; The voltage regulator unit includes resistors R1 and R6 and a Zener diode DZ1. The first end of resistor R1 is connected to the first end of the second winding of transformer T1, and the second end of the second winding is grounded. The second end of resistor R1 is connected to the first end of resistor R6 and the cathode of Zener diode DZ1 to provide a reference voltage. The second end of resistor R6 and the anode of Zener diode DZ1 are grounded. The resistor voltage divider unit includes resistors R5, R8, and R19. The first end of resistor R5 is connected to the reference voltage. Resistors R5, R8, and R19 are connected in series. The connection point of resistors R8 and R19 outputs the second voltage divider signal to the inverting input of comparator U3B. The second end of resistor R19 is grounded.

7. The circuit according to any one of claims 1 to 5, characterized in that, The charging management circuit also includes a charging switch module; The charging switch module includes a comparator U3A, a diode D1, a transient suppression diode TVS1, a resistor R43, a relay RLY1, a fourth voltage divider unit, and a fifth voltage divider unit; The fourth voltage divider unit is connected to a reference voltage source to provide a fourth voltage divider signal to the inverting input of the comparator U3A; the fifth voltage divider unit is connected to the transformer T1, the anode of the diode D1, and the battery to provide a fifth voltage divider signal to the non-inverting input of the comparator U3A; the cathode of the diode D1 is connected to the normally open contact of the relay RLY1, and the normally closed contact of the relay RLY1 is connected to the negative terminal of the battery; the output of the comparator U3A is connected to the first coil terminal of the relay RLY1; the first terminal of the resistor R43 is connected to the reference voltage source; the second terminal of the resistor R43 is connected to the second coil terminal of the relay RLY1; and the transient suppression diode TVS1 is connected across the coil of the relay RLY1. When the battery voltage is lower than the preset full charge voltage, the fifth voltage divider signal is less than the fourth voltage divider signal, the comparator U3A outputs a low level, and the relay RLY1 is energized to conduct the battery charging circuit. When the battery voltage reaches the preset full charge voltage, the fifth voltage divider signal is greater than the fourth voltage divider signal, the comparator U3A outputs a high level, and the relay RLY1 is released to disconnect the battery charging circuit.

8. The circuit according to any one of claims 1 to 5, characterized in that, The charging management circuit also includes a reverse connection protection module; The reverse connection protection module includes transistor Q4, MOSFET Q5, resistor R13, resistor R38, resistor R39, resistor R40 and resistor R41; The base of transistor Q4 is connected to the positive terminal of the battery through resistor R13, and the base of transistor Q4 is connected to the negative terminal of the battery through resistor R38. The emitter of transistor Q4 is connected to the positive terminal of the battery. The collector of transistor Q4 is connected to the gate of MOSFET Q5 and the first terminal of resistor R40 through resistor R39. The drain of MOSFET Q5 is connected to the positive terminal of the battery, and the source of MOSFET Q5 and the second terminal of resistor R40 are connected to protective ground. Resistor R41 is connected between the source and drain of MOSFET Q5. When the battery is correctly connected, both transistor Q4 and MOSFET Q5 are cut off, and the reverse connection protection module does not work. When the battery is connected in reverse, the base of the transistor Q4 receives a forward bias voltage and turns on. The collector of the transistor Q4 outputs a low level, which causes the gate of the MOSFET Q5 to receive a driving voltage through the resistors R39 and R40 and turn on, pulling the positive terminal of the battery to protective ground.

9. A charger, characterized in that, include: The charging management circuit as described in any one of claims 1-8.

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