A solar charging circuit

Abstract

The utility model relates to a solar charging circuit, including input voltage detection subcircuit, battery voltage management subcircuit and battery charging switch subcircuit, input voltage detection subcircuit is connected with the voltage output end of solar panel and the input of battery voltage management subcircuit respectively, battery voltage management subcircuit is connected with the output of input voltage detection subcircuit, the input of battery charging switch subcircuit and battery pack respectively, is used for the current voltage value of battery pack is less than second threshold value and exports high level, and is used for the current voltage value of battery pack is greater than third threshold value and exports low level, battery charging switch subcircuit is connected with the output of battery voltage management subcircuit, battery pack and the voltage output end of solar panel respectively, is used for when battery voltage management subcircuit exports high level, utilizes solar panel and charges battery pack. The prior art has solved the problem that battery pack frequently enters the charge -discharge cycle, shortens its service life.

Description

Technical Field

[0001] This utility model relates to the field of solar charging technology, and in particular to a solar charging circuit. Background Technology

[0002] Traditional curtain systems, such as fabric curtains and Venetian blinds, play an important role in regulating indoor lighting, ensuring privacy, and decorating spaces. With technological advancements, motorized curtains have become increasingly popular. They typically use municipal AC power as a power source and are driven by a motor to automatically open and close the curtains, improving ease of use.

[0003] However, these AC-powered motorized curtains have significant limitations. Firstly, when the AC power supply is interrupted, the entire system ceases to function, preventing the curtains from opening and closing properly. Secondly, installation often requires rewiring and reconnecting the power supply, increasing complexity and cost, especially in locations with limited wiring, such as rooftops and attics, where the workload is even greater, thus restricting their widespread application. Furthermore, some motorized curtains require manual operation after a power outage, which can lead to misalignment of curtain components, uneven opening and closing, and reduced lifespan. Lithium-ion battery curtains are suitable for the aftermarket, in situations where the curtain box lacks a pre-installed power outlet.

[0004] Currently, products integrating solar cells into curtains have appeared on the market, aiming to convert solar energy into electricity while providing shade. However, existing solar-charged curtain technology still faces challenges: for example, when solar panels are connected, voltage fluctuations in the battery pack cause the connected battery pack to frequently enter charge-discharge cycles. This frequent charge-discharge cycle state accelerates battery aging and shortens its lifespan. Utility Model Content

[0005] In view of this, it is necessary to provide a solar charging circuit to solve the problem in the prior art that the connected battery pack frequently enters charge and discharge cycles due to voltage fluctuations, thus shortening its service life.

[0006] This utility model provides a solar charging circuit, including an input voltage detection sub-circuit, a battery voltage management sub-circuit, and a battery charging switch sub-circuit; The input voltage detection sub-circuit is connected to the voltage output terminal of the solar panel and the input terminal of the battery voltage management sub-circuit, respectively, and is used to output a high level when the output voltage of the solar panel is greater than the first threshold. The battery voltage management sub-circuit is connected to the output of the input voltage detection sub-circuit, the input of the battery charging switch sub-circuit, and the battery pack, respectively. It outputs a high level when the current voltage value of the battery pack is less than the second threshold and outputs a low level when the current voltage value of the battery pack is greater than the third threshold. The battery charging switch sub-circuit is connected to the output terminal of the battery voltage management sub-circuit, the battery pack, and the voltage output terminal of the solar panel, respectively. It is used to charge the battery pack using the solar panel when the battery voltage management sub-circuit outputs a high level.

[0007] In some embodiments, the solar charging circuit also includes a reference voltage sub-circuit; The reference voltage sub-circuit is connected to the voltage detection sub-circuit, the battery voltage management sub-circuit, the battery charging switch sub-circuit, and the voltage output terminal of the solar panel, respectively, to provide a reference voltage.

[0008] In some embodiments, the input voltage detection subcircuit includes a first operational amplifier, resistors R1, R2, R3, and R4, with the output of the first operational amplifier serving as the output of the input voltage detection subcircuit.

[0009] In some embodiments, one end of resistor R1 is connected to the voltage output terminal of the solar panel, and the other end of resistor R1 is connected to the positive input terminal of the first operational amplifier; one end of resistor R2 is connected to the positive input terminal of the first operational amplifier, and the other end of resistor R2 is grounded; one end of resistor R3 is connected to the output terminal of the reference voltage sub-circuit, and the other end of resistor R3 is connected to the negative input terminal of the first operational amplifier; one end of resistor R4 is grounded, and the other end of resistor R4 is connected to the negative input terminal of the first operational amplifier; the positive power supply terminal of the first operational amplifier is connected to the output terminal of the reference voltage sub-circuit, and the negative power supply terminal of the first operational amplifier is grounded.

[0010] In some embodiments, the battery voltage management subcircuit includes a second operational amplifier, a first dual transistor, resistors R6, R7, R8, R9, and R10. The first dual transistor has six pins. The second pin of the first dual transistor serves as the input terminal of the battery voltage management subcircuit and is connected to the output terminal of the first operational amplifier. The output terminal of the second operational amplifier serves as the output terminal of the battery voltage management subcircuit.

[0011] In some embodiments, the first pin of the first dual transistor is grounded, the fifth and sixth pins of the first dual transistor are connected, the fourth pin of the first dual transistor is connected to the battery pack, and the third pin of the first dual transistor is connected to one end of resistor R6; the other end of resistor R6 is connected to the negative input terminal of the second operational amplifier; one end of resistor R7 is connected to the negative input terminal of the second operational amplifier, and the other end of resistor R7 is grounded; one end of resistor R8 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R8 is grounded; one end of resistor R9 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R9 is connected to the output terminal of the reference voltage sub-circuit; one end of resistor R10 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R10 is connected to the output terminal of the second operational amplifier; the positive power supply terminal of the second operational amplifier is connected to the output terminal of the reference voltage sub-circuit, and the negative power supply terminal of the second operational amplifier is grounded.

[0012] In some embodiments, the battery charging switch sub-circuit includes a second dual transistor, resistors R11 and R12, and a field-effect transistor. The second dual transistor has six pins. The second pin of the second dual transistor serves as the input terminal of the battery charging switch sub-circuit and is connected to the output terminal of the second operational amplifier. The drain of the field-effect transistor is connected to the voltage output terminal of the solar panel, and the source of the field-effect transistor is connected to the battery pack.

[0013] In some embodiments, one end of resistor R11 is connected to the sixth pin of the second dual transistor, the other end of resistor R11 is connected to the gate of the field-effect transistor, one end of resistor R12 is connected to the gate of the field-effect transistor, and the other end of resistor R12 is connected to the drain of the field-effect transistor.

[0014] In some embodiments, the battery charging switch sub-circuit further includes a Zener diode Z1 and a diode D1. The positive terminal of the Zener diode Z1 is connected to the source of the field-effect transistor, and the negative terminal of the Zener diode Z1 is connected to the drain of the field-effect transistor. The positive terminal of the diode D1 is connected to the source of the field-effect transistor, and the negative terminal of the diode D1 is connected to the battery pack.

[0015] In some embodiments, the reference voltage subcircuit includes a connector, a voltage regulator, capacitors C1, C2, and C3. The first pin of the connector is connected to the input terminal of the voltage regulator, and the second pin of the connector is grounded. One end of capacitor C1 is connected to the input terminal of the voltage regulator, and the other end of capacitor C1 is grounded. One end of capacitor C2 is connected to the output terminal of the voltage regulator, and the other end of capacitor C2 is grounded. One end of capacitor C3 is connected to the output terminal of the voltage regulator, and the other end of capacitor C3 is grounded. The output terminal of the voltage regulator is the output terminal of the reference voltage subcircuit.

[0016] This utility model provides a solar charging circuit including an input voltage detection subcircuit, a battery voltage management subcircuit, and a battery charging switch subcircuit. Through the cooperation of these three subcircuits, the battery voltage management subcircuit outputs a high level only when the current voltage of the battery pack is less than a second threshold after the battery is fully charged. This prevents the battery pack from entering a charging state as soon as its charge level drops slightly, thus extending the battery pack's lifespan. It also solves the problem in existing technologies where voltage fluctuations in the battery pack easily lead to frequent charge-discharge cycles when a solar panel is connected, which accelerates battery aging and shortens its lifespan. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a solar charging circuit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of another solar charging circuit according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a voltage detection sub-circuit according to an embodiment of the present invention; Figure 4 This is a schematic diagram of another voltage detection sub-circuit according to an embodiment of the present invention; Figure 5 This is a schematic diagram of a battery voltage management sub-circuit according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a battery charging switch sub-circuit according to an embodiment of the present invention; Figure 7 This is a schematic diagram of a reference voltage sub-circuit 400 according to an embodiment of the present invention.

[0018] Figure reference numerals: 100, voltage detection sub-circuit; 200, battery voltage management sub-circuit; 300, battery charging switch sub-circuit; 400, reference voltage sub-circuit. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that when a component is said to be "set on" another component, it can be directly set on the other component or there may be an intervening component. When a component is considered to be "set on" another component, it can be directly set on the other component or there may be an intervening component. When a component is considered to be "fixed to" another component, it can be directly fixed to the other component or there may be an intervening component.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Please see Figure 1 This utility model provides a solar charging circuit, which includes an input voltage detection sub-circuit 100, a battery voltage management sub-circuit 200, and a battery charging switch sub-circuit 300.

[0023] The input voltage detection sub-circuit 100 is connected to the voltage output terminal of the solar panel and the input terminal of the battery voltage management sub-circuit 200, respectively. It outputs a high level when the output voltage of the solar panel (i.e., the input voltage of the input voltage detection sub-circuit 100) exceeds a first threshold. This first threshold can be set by connecting resistors in series or parallel within the input voltage detection sub-circuit 100. The battery pack is only charged when the output voltage of the solar panel exceeds a certain value, i.e., when the solar radiation intensity exceeds a certain value.

[0024] The battery voltage management subcircuit 200 is connected to the output of the input voltage detection subcircuit 100, the input of the battery charging switch subcircuit 300, and the battery pack. It outputs a high level when the current voltage of the battery pack is less than a second threshold and a low level when the current voltage is greater than a third threshold, where the second threshold is less than the third threshold. The second threshold can be set by connecting resistors in series or parallel within the battery voltage management subcircuit 200. After the battery is fully charged, when the current voltage of the battery pack is less than the second threshold, the battery voltage management subcircuit 200 outputs a high level, allowing the solar panel to charge the battery pack. This prevents the battery pack from entering charging mode as soon as its charge level drops slightly, thus extending the battery pack's lifespan. The third threshold is the full-charge voltage of the battery pack, i.e., the highest voltage limit allowed during charging. Once the battery voltage reaches this value, the charging process must stop or switch to trickle charging to prevent overcharging. The third threshold can also be set by connecting resistors in series or parallel within the battery voltage management subcircuit 200.

[0025] The battery charging switch sub-circuit 300 is connected to the output terminal of the battery voltage management sub-circuit 200, the battery pack, and the voltage output terminal of the solar panel, respectively. It is used to charge the battery pack using the solar panel when the battery voltage management sub-circuit 200 outputs a high level.

[0026] The solar charging circuit of this embodiment includes an input voltage detection subcircuit 100, a battery voltage management subcircuit 200, and a battery charging switch subcircuit 300. Through the cooperation of these three subcircuit components, the battery voltage management subcircuit 200 outputs a high level only when the current voltage of the battery pack is less than a second threshold after the battery is fully charged. This prevents the battery pack from entering a charging state as soon as its charge level drops slightly, thus extending the battery pack's lifespan. This solves the problem in the prior art where voltage fluctuations in the battery pack easily cause the connected battery pack to frequently enter charge-discharge cycles when a solar panel is connected, accelerating battery aging and shortening its lifespan.

[0027] In some of these embodiments, reference is made to Figure 2 The solar charging circuit also includes a reference voltage sub-circuit 400; the reference voltage sub-circuit 400 is connected to the voltage detection sub-circuit, the battery voltage management sub-circuit 200, the battery charging switch sub-circuit 300 and the voltage output terminal of the solar panel, respectively, and is used to provide a reference voltage.

[0028] refer to Figure 3The input voltage detection sub-circuit 100 includes a first operational amplifier U1A, resistors R1, R2, R3, and R4. The output terminal of the first operational amplifier U1A serves as the output terminal of the input voltage detection sub-circuit 100. One end of resistor R1 is connected to the voltage output terminal of the solar panel or the output terminal of the charger, that is, one end of resistor R1 is connected to the input voltage Vin, which is the input of the solar panel or the charger. The other end of resistor R1 is connected to the positive input terminal of the first operational amplifier U1A. One end of resistor R2 is connected to the positive input terminal of the first operational amplifier U1A, and the other end of resistor R2 is grounded. One end of resistor R3 is connected to the output terminal of the reference voltage sub-circuit 400, and the other end of resistor R3 is connected to the negative input terminal of the first operational amplifier U1A. One end of resistor R4 is grounded, and the other end of resistor R4 is connected to the negative input terminal of the first operational amplifier U1A. The positive power supply terminal of the first operational amplifier U1A is connected to the output terminal of the reference voltage sub-circuit 400, and the negative power supply terminal of the first operational amplifier U1A is grounded. The input voltage detection sub-circuit 100 is used to output a high level of the first operational amplifier U1A when the output voltage of the solar panel, that is, the input voltage of the input voltage detection sub-circuit 100, is greater than a first threshold. The voltage value at the negative input terminal of the first operational amplifier U1A can be calculated based on resistors R3 and R4 and the reference voltage Vref, denoted as V1. The voltage value at the positive input terminal of the first operational amplifier U1A can be denoted as V2. When V2 is greater than V1, the first operational amplifier U1A outputs a high level. The first threshold is calculated based on the voltage value at the positive input terminal of the first operational amplifier U1A, resistors R1 and R2. When the output voltage of the solar panel, i.e., the input voltage of the input voltage detection sub-circuit 100, is greater than the first threshold, the first operational amplifier U1A outputs a high level. In this circuit, the first operational amplifier U1A can be an LM358D, the reference voltage Vref provided by the reference voltage sub-circuit 400 can be 5V, the resistors of the input voltage detection sub-circuit 100 are resistors with an accuracy of 1%, and the values ​​of resistors R1, R2, R3, and R4 can be 100KΩ, 24KΩ, 33KΩ, and 47KΩ, respectively. Based on the above resistor values ​​and the reference voltage Vref, the first threshold can be calculated to be 15.17V, that is, when the input voltage of the input voltage detection sub-circuit 100 is greater than 15.17V, the first operational amplifier U1A outputs a high level.

[0029] refer to Figure 4 In some embodiments, the input voltage detection sub-circuit 100 further includes a resistor R5, one end of which is connected to the output terminal of the first operational amplifier U1A, and the other end of which is connected to the negative input terminal of the first operational amplifier U1A for circuit debugging.

[0030] refer to Figure 5The battery voltage management sub-circuit 200 includes a second operational amplifier U1B, a first dual transistor U2, resistors R6, R7, R8, R9, and R10. The first dual transistor U2 has 6 pins. The second pin of the first dual transistor U2 serves as the input terminal of the battery voltage management sub-circuit 200 and is connected to the output terminal of the first operational amplifier U1A. The output terminal of the second operational amplifier U1B serves as the output terminal of the battery voltage management sub-circuit 200. The first pin of the first dual transistor U2 is grounded; the fifth and sixth pins of the first dual transistor U2 are connected; the fourth pin of the first dual transistor U2 is connected to the battery pack; the third pin of the first dual transistor U2 is connected to one end of resistor R6; the other end of resistor R6 is connected to the negative input terminal of the second operational amplifier U1B; one end of resistor R7 is connected to the negative input terminal of the second operational amplifier U1B, and the other end of resistor R7 is grounded; one end of resistor R8 is connected to the positive input terminal of the second operational amplifier U1B, and the other end of resistor R8 is grounded; one end of resistor R9 is connected to the positive input terminal of the second operational amplifier U1B, and the other end of resistor R9 is connected to the output terminal of the reference voltage sub-circuit 400; one end of resistor R10 is connected to the positive input terminal of the second operational amplifier U1B, and the other end of resistor R10 is connected to the output terminal of the second operational amplifier U1B; the positive power supply terminal of the second operational amplifier U1B is connected to the output terminal of the reference voltage sub-circuit 400, and the negative power supply terminal of the second operational amplifier U1B is grounded. When the battery voltage is lower than the full charge voltage, the op-amp outputs a high level, and the battery charges. When the battery voltage is higher than the full charge voltage, the op-amp outputs a low level, and the battery stops charging. After the battery is fully charged, when the battery voltage is lower than the recharge voltage, the op-amp outputs a high level, and the battery charges. One end of resistor R10 is connected to the positive input terminal of the second operational amplifier U1B, and the other end of resistor R10 is connected to the output terminal of the second operational amplifier U1B. When the second operational amplifier U1B outputs a low level, resistors R10 and R8 are connected in parallel and then in series with resistor R9, resulting in a voltage value at the positive input terminal of the second operational amplifier U1B, denoted as V3. When the second operational amplifier U1B outputs a high level, resistors R10 and R9 are connected in parallel and then in series with resistor R8, resulting in a voltage value at the positive input terminal of the second operational amplifier U1B, denoted as V4. The second threshold is calculated based on voltage value V3, resistors R6 and R7. When the current voltage value Vbat of the battery pack is less than the second threshold, the second operational amplifier U1B outputs a high level. The third threshold is calculated based on voltage value V4, resistors R6 and R7. When the current voltage value Vbat of the battery pack is greater than the third threshold, the second operational amplifier U1B outputs a low level. The second threshold is the recharge voltage value, and the third threshold is the full charge voltage value.In this embodiment, the first dual transistor U2 can be an LMUN5311DW. Pin 1 of the first dual transistor U2 is grounded, pin 2 is connected to the output terminal of the first operational amplifier U1A, pin 3 is connected to one end of resistor R6, pin 4 is connected to the battery pack, and pins 5 and 6 are connected. Pin 1 of the first dual transistor U2 is equivalent to the first pin of the first dual transistor U2 in this embodiment, pin 2 of the first dual transistor U2 is equivalent to the second pin of the first dual transistor U2 in this embodiment, pin 3 of the first dual transistor U2 is equivalent to the third pin of the first dual transistor U2 in this embodiment, pin 4 of the first dual transistor U2 is equivalent to the fourth pin of the first dual transistor U2 in this embodiment, pin 5 of the first dual transistor U2 is equivalent to the fifth pin of the first dual transistor U2 in this embodiment, and pin 6 of the first dual transistor U2 is equivalent to the sixth pin of the first dual transistor U2 in this embodiment. In this circuit, the second operational amplifier U1B can be an LM358D, the reference voltage Vref provided by the reference voltage sub-circuit 400 can be 5V, the resistors in the battery voltage management sub-circuit 200 are resistors with an accuracy of 1%, and the values ​​of resistors R6, R7, R8, R9, and R10 can be 100KΩ, 20KΩ, 22.6KΩ, 20KΩ, and 330KΩ, respectively. Based on the above resistor values ​​and the reference voltage Vref, the second threshold can be calculated to be 15.4V and the third threshold to be 16.4V. That is, when the current voltage value Vbat of the battery pack is less than 15.4V, the second operational amplifier U1B outputs a high level, and the battery pack is charging; when the current voltage value Vbat of the battery pack is greater than 16.4V, the second operational amplifier U1B outputs a low level, and the battery pack stops charging.

[0031] refer to Figure 6The battery charging switch sub-circuit 300 includes a second dual transistor U3, resistors R11 and R12, and a field-effect transistor U4. The second dual transistor U3 has six pins. The second pin of the second dual transistor U3 serves as the input terminal of the battery charging switch sub-circuit 300 and is connected to the output terminal of the second operational amplifier U1B. The drain of the field-effect transistor U4 is connected to the voltage output terminal of the solar panel or the charger output terminal; that is, the drain of the field-effect transistor U4 is connected to the input voltage Vin, which is the input voltage of the solar panel or the charger. The source of the field-effect transistor U4 is connected to the battery pack. One end of resistor R11 is connected to the sixth pin of the second dual transistor U3, and the other end of resistor R11 is connected to the gate of the field-effect transistor U4. One end of resistor R12 is connected to the gate of the field-effect transistor U4, and the other end of resistor R12 is connected to the drain of the field-effect transistor U4. The battery charging switch subcircuit 300 also includes a Zener diode Z1 and a diode D1. The anode of Zener diode Z1 is connected to the source of MOSFET U4, and the cathode of Zener diode Z1 is connected to the drain of MOSFET U4. The anode of diode D1 is connected to the source of MOSFET U4, and the cathode of diode D1 is connected to the battery pack. The battery charging switch subcircuit 300 also includes capacitors C4 and C5. One end of capacitor C4 is connected to the output of reference voltage subcircuit 400, and the other end of capacitor C4 is grounded. One end of capacitor C5 is connected to the cathode of diode D1, and the other end of capacitor C5 is grounded. MOSFET U4 acts as a battery charging switch, controlled by battery voltage management subcircuit 200, and is turned on or off. In this embodiment, the second dual transistor U3 can be an LMUN5311DW. Pin 1 of the second dual transistor U3 is grounded, pin 2 is connected to the output of the second operational amplifier U1B, pin 6 is connected to one end of resistor R11, and pins 3, 4, and 5 are not connected to the circuit. Pin 1 of the second dual transistor U3 is equivalent to the first pin of the second dual transistor U3 in this embodiment, pin 2 of the second dual transistor U3 is equivalent to the second pin of the second dual transistor U3 in this embodiment, and pin 6 of the second dual transistor U3 is equivalent to the sixth pin of the second dual transistor U3 in this embodiment. In this embodiment, the field-effect transistor U4 can be an AM4599C, which includes 8 pins. Pins 1, 2, 7, and 8 are not connected to the circuit. Pin 4 is connected to the other end of resistor R11. Pin 3 is connected to the voltage output terminal of the solar panel or the output terminal of the charger, that is, pin 3 is connected to the input voltage Vin, which is the input of the solar panel or the input of the charger. Pins 5 and 6 are connected together and then connected to the battery pack. Pin 4 of the field-effect transistor U4 is equivalent to the gate in this embodiment, pin 3 of the field-effect transistor U4 is equivalent to the drain in this embodiment, and pin 5 or pin 6 of the field-effect transistor U4 is equivalent to the source in this embodiment.The resistors in the battery charging switch sub-circuit 300 are resistors with an accuracy of 1%. The values ​​of resistors R11 and R12 can be 2KΩ and 10KΩ, respectively. The values ​​of capacitors C4 and C5 can be 10μF / 10V and 0.1μF, respectively.

[0032] The first operational amplifier U1A operates when the input voltage Vin > 15.17V, outputting a high level. The two transistors in the first dual transistor U2 then activate the battery voltage management sub-circuit 200. If the input voltage is lower than the battery voltage (15.17V), charging stops. When the solar panel voltage or the input charging circuit voltage is higher than the battery voltage (15.17V), charging begins. At this time, part of the second operational amplifier U1B detects whether the battery voltage has reached the set full charge voltage (16.4V). When the battery voltage is higher than 16.4V, the field-effect transistor U4 is turned off, stopping charging. When the battery discharges, the battery voltage drops until it falls below the set recharge voltage (15.4V), at which point charging resumes. This circuit uses simple components to implement battery charging management. It prevents repeated voltage fluctuations from causing the battery to enter a charging state when connected to a solar panel, thus extending battery life. The battery pack here can be a 4-in-1-in-parallel lithium battery configuration.

[0033] The solar charging circuit of this embodiment includes an input voltage detection subcircuit 100, a battery voltage management subcircuit 200, and a battery charging switch subcircuit 300. Through the cooperation of these three subcircuits, the battery voltage management subcircuit 200 outputs a high level only when the current voltage of the battery pack is less than a second threshold after the battery is fully charged. This prevents the battery pack from entering a charging state as soon as its charge level drops slightly, thus extending the battery pack's lifespan. This solves the problem in existing technologies where voltage fluctuations in the battery pack easily lead to frequent charge-discharge cycles when a solar panel is connected, accelerating battery aging and shortening its lifespan. This embodiment achieves solar panel charging of lithium batteries with fewer components and features charging hysteresis to avoid repeated charging of the battery pack when the charge level is high, thus protecting the battery pack. This circuit also supports external adapters. Meanwhile, the solar charging circuit of this embodiment uses simple components to achieve battery charging management, which is a low-cost control scheme and is conducive to the promotion and application of electric curtain products using the solar charging circuit of this embodiment.

[0034] refer to Figure 7The reference voltage subcircuit 400 includes connector J1, a voltage regulator, capacitors C1, C2, and C3. The first pin of connector J1 is connected to the input terminal of the voltage regulator, and the second pin of connector J1 is grounded. One end of capacitor C1 is connected to the input terminal of the voltage regulator, and the other end of capacitor C1 is grounded. One end of capacitor C2 is connected to the output terminal of the voltage regulator, and the other end of capacitor C2 is grounded. One end of capacitor C3 is connected to the output terminal of the voltage regulator, and the other end of capacitor C3 is grounded. The output terminal of the voltage regulator is the output terminal of the reference voltage subcircuit 400. The reference voltage subcircuit 400 generates a 5V reference voltage when the input voltage is [value missing]. Connector J1 includes pin 1 and pin 2. Pin 1 is connected to the voltage output terminal of the solar panel or the charger output terminal, i.e., pin 1 is connected to the input voltage Vin, which is the input voltage of the solar panel or the charger. Pin 2 is grounded. Pin 1 of connector J1 corresponds to the first pin of connector J1 in this embodiment, and pin 2 of connector J1 corresponds to the second pin of connector J1 in this embodiment. The voltage regulator can be a linear regulator, such as IC1 7550. The values ​​of capacitors C1, C2, and C3 can be 0.1μF, 0.1μF, and 10μF / 10V, respectively.

[0035] The technical features of the above-described embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model. Any appropriate changes and variations made to the above embodiments within the scope of the essential spirit of the present utility model shall fall within the scope of protection claimed by the present utility model.

Claims

1. A solar charging circuit, characterized in that, This includes an input voltage detection subcircuit, a battery voltage management subcircuit, and a battery charging switch subcircuit; The input voltage detection sub-circuit is connected to the voltage output terminal of the solar panel and the input terminal of the battery voltage management sub-circuit, respectively, and is used to output a high level when the output voltage of the solar panel is greater than the first threshold. The battery voltage management sub-circuit is connected to the output terminal of the input voltage detection sub-circuit, the input terminal of the battery charging switch sub-circuit, and the battery pack, respectively. It is used to output a high level when the current voltage value of the battery pack is less than the second threshold, and to output a low level when the current voltage value of the battery pack is greater than the third threshold. The battery charging switch sub-circuit is connected to the output terminal of the battery voltage management sub-circuit, the battery pack, and the voltage output terminal of the solar panel, respectively, and is used to charge the battery pack using the solar panel when the battery voltage management sub-circuit outputs a high level.

2. The solar charging circuit according to claim 1, characterized in that, The solar charging circuit also includes a reference voltage sub-circuit; The reference voltage sub-circuit is connected to the voltage detection sub-circuit, the battery voltage management sub-circuit, the battery charging switch sub-circuit, and the voltage output terminal of the solar panel, respectively, to provide a reference voltage.

3. The solar charging circuit according to claim 2, characterized in that, The input voltage detection sub-circuit includes a first operational amplifier, resistors R1, R2, R3, and R4, with the output terminal of the first operational amplifier serving as the output terminal of the input voltage detection sub-circuit.

4. The solar charging circuit according to claim 3, characterized in that, One end of resistor R1 is connected to the voltage output terminal of the solar panel, and the other end of resistor R1 is connected to the positive input terminal of the first operational amplifier; one end of resistor R2 is connected to the positive input terminal of the first operational amplifier, and the other end of resistor R2 is grounded; one end of resistor R3 is connected to the output terminal of the reference voltage sub-circuit, and the other end of resistor R3 is connected to the negative input terminal of the first operational amplifier; one end of resistor R4 is grounded, and the other end of resistor R4 is connected to the negative input terminal of the first operational amplifier; the positive power supply terminal of the first operational amplifier is connected to the output terminal of the reference voltage sub-circuit, and the negative power supply terminal of the first operational amplifier is grounded.

5. The solar charging circuit according to claim 3, characterized in that, The battery voltage management sub-circuit includes a second operational amplifier, a first dual transistor, resistors R6, R7, R8, R9, and R10. The first dual transistor has 6 pins. The second pin of the first dual transistor serves as the input terminal of the battery voltage management sub-circuit and is connected to the output terminal of the first operational amplifier. The output terminal of the second operational amplifier serves as the output terminal of the battery voltage management sub-circuit.

6. The solar charging circuit according to claim 5, characterized in that, The first pin of the first dual transistor is grounded; the fifth and sixth pins of the first dual transistor are connected; the fourth pin of the first dual transistor is connected to the battery pack; the third pin of the first dual transistor is connected to one end of resistor R6; the other end of resistor R6 is connected to the negative input terminal of the second operational amplifier; one end of resistor R7 is connected to the negative input terminal of the second operational amplifier, and the other end of resistor R7 is grounded; one end of resistor R8 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R8 is grounded; one end of resistor R9 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R9 is connected to the output terminal of the reference voltage sub-circuit; one end of resistor R10 is connected to the positive input terminal of the second operational amplifier, and the other end of resistor R10 is connected to the output terminal of the second operational amplifier; the positive power supply terminal of the second operational amplifier is connected to the output terminal of the reference voltage sub-circuit, and the negative power supply terminal of the second operational amplifier is grounded.

7. The solar charging circuit according to claim 5, characterized in that, The battery charging switch sub-circuit includes a second dual transistor, resistors R11 and R12, and a field-effect transistor. The second dual transistor has 6 pins. The second pin of the second dual transistor serves as the input terminal of the battery charging switch sub-circuit and is connected to the output terminal of the second operational amplifier. The drain of the field-effect transistor is connected to the voltage output terminal of the solar panel, and the source of the field-effect transistor is connected to the battery pack.

8. The solar charging circuit according to claim 7, characterized in that, One end of resistor R11 is connected to the sixth pin of the second dual transistor, and the other end of resistor R11 is connected to the gate of the field-effect transistor. One end of resistor R12 is connected to the gate of the field-effect transistor, and the other end of resistor R12 is connected to the drain of the field-effect transistor.

9. The solar charging circuit according to claim 7, characterized in that, The battery charging switch sub-circuit also includes a Zener diode Z1 and a diode D1. The positive terminal of the Zener diode Z1 is connected to the source of the field-effect transistor, and the negative terminal of the Zener diode Z1 is connected to the drain of the field-effect transistor. The positive terminal of the diode D1 is connected to the source of the field-effect transistor, and the negative terminal of the diode D1 is connected to the battery pack.

10. The solar charging circuit according to claim 2, characterized in that, The reference voltage sub-circuit includes a connector, a voltage regulator, capacitors C1, C2, and C3. The first pin of the connector is connected to the input terminal of the voltage regulator, and the second pin of the connector is grounded. One end of capacitor C1 is connected to the input terminal of the voltage regulator, and the other end of capacitor C1 is grounded. One end of capacitor C2 is connected to the output terminal of the voltage regulator, and the other end of capacitor C2 is grounded. One end of capacitor C3 is connected to the output terminal of the voltage regulator, and the other end of capacitor C3 is grounded. The output terminal of the voltage regulator is the output terminal of the reference voltage sub-circuit.

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