Charging circuit and power supply equipment

Abstract

The utility model discloses a charging circuit and power supply equipment, the charging circuit comprises a power supply input end, a charging chip, an overvoltage protection circuit, a voltage conversion circuit and a master control circuit, the power supply input end is used for accessing a photovoltaic panel, and the overvoltage protection circuit is connected in series between the power supply input end and the charging chip. The input end of the voltage conversion circuit is connected with the power input end, the output end of the voltage conversion circuit is electrically connected with the charging chip, the detection end of the main control circuit is electrically connected with the output end of the overvoltage protection circuit, and the control end of the main control circuit is connected with the voltage conversion circuit. The utility model aims to solve the problem that a conventional photovoltaic panel cannot normally charge a battery in a complex illumination environment.

Description

Technical Field

[0001] The utility model relates to the technical field of charging, in particular to a charging circuit and a power supply device. Background Art

[0002] In a photovoltaic system, photovoltaic panels are responsible for converting solar energy into electrical energy, while charging chips are responsible for effectively storing this electrical energy in batteries. The DC power generated by photovoltaic panels is first processed by the charging chip, which intelligently adjusts the charging current and voltage according to the current state and needs of the battery to ensure that the battery can be fully charged safely and quickly.

[0003] The voltage of the photovoltaic panel changes with the change of light intensity. When the sun rises in the morning, as the light intensity increases, the voltage value of the photovoltaic panel becomes higher, and the photovoltaic panel begins to charge the battery through the charging chip (constant current charging stage). When the battery is fully charged, the charging current of the photovoltaic panel becomes smaller and the charging voltage becomes higher (constant voltage charging stage). When the sun sets, the cycle repeats. Once the voltage value of the photovoltaic panel exceeds the withstand voltage value of the charging chip, the charging chip may be damaged. Therefore, the maximum voltage of the photovoltaic panel needs to match the withstand voltage value of the charging chip. However, due to cost considerations, R&D personnel need to choose the most cost-effective photovoltaic panel to match the charging chip, but the market The photovoltaic panel with the highest cost performance may not match the charging chip. The open-circuit voltage of one of the common specifications of photovoltaic panels on the market is 21.6V±10%, and the temperature coefficient of monocrystalline silicon is -2mV / K, that is, when the ambient temperature is +25℃, the maximum voltage of the photovoltaic panel is 23.8V; when the ambient temperature is -20℃, the maximum voltage of the photovoltaic panel is 27V; when the ambient temperature is -30℃, the maximum voltage of the photovoltaic panel is 27.8V, while the maximum withstand voltage of the most cost-effective charging chip JW3655E on the market is 24V, that is, the photovoltaic panel and charging chip with the highest cost performance will have the risk of overvoltage when used in a low temperature environment.

[0004] In this regard, most solutions on the market are to add an overvoltage protection circuit between the photovoltaic panel and the charging chip. When the voltage value of the photovoltaic panel exceeds the preset voltage value, the charging path between the photovoltaic panel and the charging chip is disconnected to prevent excessive voltage from damaging the charging chip. However, this solution has reliability issues in complex lighting environments. For example, when the weather suddenly changes from cloudy to sunny, the ambient light suddenly becomes strong, causing the voltage of the photovoltaic panel to continue to rise and exceed the preset voltage value, causing the overvoltage protection circuit to disconnect the charging path between the photovoltaic panel and the charging chip. Although the overvoltage protection circuit protects the charging chip in the event of overvoltage, it also causes the battery to be unable to charge in this case. Therefore, the existing photovoltaic panels and charging chips cannot stably charge the battery in complex lighting environments, resulting in low overall charging efficiency. Utility Model Content

[0005] The main purpose of the utility model is to provide a charging circuit and a power supply device, aiming to solve the problem that the existing photovoltaic panels cannot charge the battery normally under complex lighting environments.

[0006] In order to achieve the above object, the utility model provides a charging circuit, comprising:

[0007] Power input terminal, used to connect to photovoltaic panels;

[0008] Charging chip;

[0009] an overvoltage protection circuit, which is arranged in series between the power input terminal and the charging chip; the overvoltage protection circuit is used to detect the output voltage of the photovoltaic panel connected to the power input terminal, and control the connection / disconnection between the power input terminal and the charging chip according to the detected output voltage of the photovoltaic panel, and output a corresponding voltage detection signal;

[0010] A voltage conversion circuit, wherein the input end of the voltage conversion circuit is connected to the power input end, the output end of the voltage conversion circuit is electrically connected to the charging chip, and the voltage conversion circuit is used to convert the output voltage of the photovoltaic panel connected to the power input end and output it to the charging chip;

[0011] A main control circuit, wherein the detection end of the main control circuit is electrically connected to the output end of the overvoltage protection circuit, the control end of the main control circuit is connected to the voltage conversion circuit, and the main control circuit is used to control the voltage conversion circuit to work / stop working according to the received voltage detection signal.

[0012] Optionally, the main control circuit includes a control circuit and a timer, and the timer starts timing when the voltage conversion circuit is working, and outputs a corresponding timing signal when the timing time reaches a preset time;

[0013] The control circuit controls the voltage conversion circuit to stop working when receiving the timing signal.

[0014] Optionally, the control circuit and the timer are integrated into the same integrated chip.

[0015] Optionally, the overvoltage protection circuit includes:

[0016] A voltage detection circuit, wherein a detection end of the voltage detection circuit is electrically connected to the power input end, an output end of the voltage detection circuit is electrically connected to a detection end of the main control circuit, and the voltage detection circuit is used to detect an output voltage of the photovoltaic panel connected to the power input end and output a corresponding voltage detection signal;

[0017] A first switch circuit, wherein the input end of the first switch circuit is electrically connected to the power input end, the output end of the first switch circuit is electrically connected to the charging chip, the controlled end of the first switch circuit is electrically connected to the output end of the voltage detection circuit, and the first switch circuit is turned on / off according to the voltage detection signal.

[0018] Optionally, the voltage detection circuit includes:

[0019] A second switch circuit and a voltage divider circuit, wherein the input end and the controlled end of the second switch circuit are both electrically connected to the power input end, the output end of the second switch circuit is electrically connected to the first end of the voltage divider circuit, the second end of the voltage divider circuit is electrically connected to the controlled end of the first switch circuit, and the third end of the voltage divider circuit is electrically connected to the detection end of the main control circuit.

[0020] Optionally, the second switch circuit includes:

[0021] A first switch tube, a first resistor, a second resistor and a Zener diode, wherein the first end of the first resistor is electrically connected to the power input end, the second end of the first resistor is electrically connected to the first end of the second resistor and the cathode of the Zener diode respectively, the anode of the Zener diode is grounded, the second end of the second resistor is electrically connected to the controlled end of the first switch tube, the input end of the first switch tube is electrically connected to the power input end, and the output end of the first switch tube is electrically connected to the first end of the voltage divider circuit.

[0022] Optionally, the voltage divider circuit includes:

[0023] A third resistor and a fourth resistor, wherein the first end of the third resistor is electrically connected to the controlled end of the first switch circuit, the second end of the third resistor is electrically connected to the output end of the second switch circuit, the detection end of the main control circuit and the first end of the fourth resistor respectively, and the second end of the fourth resistor is grounded.

[0024] Optionally, the first switch circuit includes:

[0025] A second switch tube, wherein the input end of the second switch tube is electrically connected to the power input end, the output end of the second switch tube is electrically connected to the charging chip, and the controlled end of the second switch tube is electrically connected to the output end of the voltage detection circuit.

[0026] Optionally, the voltage conversion circuit includes:

[0027] A step-down circuit, wherein the input end of the step-down circuit is electrically connected to the power input end, the output end of the step-down circuit is electrically connected to the charging chip, the step-down circuit is electrically connected to the control end of the main control circuit, and the step-down circuit is used to step down the output voltage of the photovoltaic panel connected to the power input end and output it to the charging chip.

[0028] The utility model also provides a power supply device, comprising the charging circuit and photovoltaic panel described in any one of the above items; wherein the input end of the charging circuit is electrically connected to the photovoltaic panel.

[0029] The technical solution of the utility model includes an overvoltage protection circuit, a voltage conversion circuit and a main control circuit. The overvoltage protection circuit is used to detect the output voltage of the photovoltaic panel connected to the power input terminal, and output a corresponding voltage detection signal to the main control circuit. When the output voltage of the photovoltaic panel exceeds a preset voltage value (the withstand voltage value of the charging chip), the overvoltage protection circuit disconnects the path between the power input terminal and the charging chip, thereby preventing the photovoltaic panel from outputting excessive voltage to the charging chip and causing damage to the charging chip. At this time, when the main control circuit receives the voltage detection signal, it controls the voltage conversion circuit to work, so that the voltage conversion circuit converts the excessive voltage output by the photovoltaic panel and outputs a suitable power supply voltage to the charging chip, so that the photovoltaic panel can still charge the charging chip when its output voltage is too large; when the output voltage of the photovoltaic panel does not exceed the preset voltage value, the overvoltage protection circuit conducts the path between the power input terminal and the charging chip, and the main control circuit controls the voltage conversion circuit to stop working according to the voltage detection signal. With such arrangement, in actual application, when the illumination environment suddenly changes from weak to strong, the output voltage of the photovoltaic panel increases continuously and exceeds the preset voltage value, and the charging circuit of the utility model can timely disconnect the normal path (overvoltage protection circuit) between the photovoltaic panel and the charging chip to prevent the photovoltaic panel from outputting excessive voltage to the charging chip and causing damage to the charging chip, and after voltage conversion of the excessive output voltage of the photovoltaic panel, output a suitable supply voltage to the charging chip through another path (voltage conversion circuit), so that the voltage output by the photovoltaic panel in a complex illumination environment where the illumination suddenly becomes strong can still match the withstand voltage value of the charging chip, thereby charging the battery; however, the voltage conversion circuit will reduce the efficiency of the photovoltaic panel charging the battery through the charging chip, so when the illumination changes from strong to weak, the overvoltage protection circuit conducts the normal path between the photovoltaic panel and the charging chip according to the voltage detection signal, and the main control circuit controls the voltage conversion circuit to stop working according to the voltage detection signal, so that the photovoltaic panel can charge the battery normally through the overvoltage protection circuit and the charging chip, and will not be reduced due to passing through the voltage conversion circuit. Therefore, the charging circuit of the utility model can solve the problem that the existing photovoltaic panel cannot charge the battery normally under a complex illumination environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 This is a schematic diagram of a module of an embodiment of the utility model;

[0032] Figure 2 This is a schematic diagram of a module of another embodiment of the utility model;

[0033] Figure 3 This is a module schematic diagram of another embodiment of the utility model;

[0034] Figure 4 This is a schematic diagram of the circuit structure of another embodiment of the utility model;

[0035] Figure 5 This is a schematic diagram of the circuit structure of another embodiment of the utility model.

[0036] Description of Figure Numbers:

[0037] Label name Label name 10 Photovoltaic panels 311 Second switch circuit 20 Charging chip 312 Voltage divider circuit 30 Overvoltage protection circuit 32 First switch circuit 31 Voltage detection circuit 40 Voltage conversion circuit 50 Main control circuit

[0038] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0042] In a photovoltaic system, photovoltaic panels are responsible for converting solar energy into electrical energy, while charging chips are responsible for effectively storing this electrical energy in batteries. The DC power generated by photovoltaic panels is first processed by the charging chip, which intelligently adjusts the charging current and voltage according to the current state and needs of the battery to ensure that the battery can be fully charged safely and quickly.

[0043] The voltage of the photovoltaic panel changes with the change of light intensity. When the sun rises in the morning, as the light intensity increases, the voltage value of the photovoltaic panel becomes higher, and the photovoltaic panel begins to charge the battery through the charging chip (constant current charging stage). When the battery is fully charged, the charging current of the photovoltaic panel becomes smaller and the charging voltage becomes higher (constant voltage charging stage). When the sun sets, the cycle repeats. Once the voltage value of the photovoltaic panel exceeds the withstand voltage value of the charging chip, the charging chip may be damaged. Therefore, the maximum voltage of the photovoltaic panel needs to match the withstand voltage value of the charging chip. However, due to cost considerations, R&D personnel need to choose the most cost-effective photovoltaic panel to match the charging chip, but the market The photovoltaic panel with the highest cost performance may not match the charging chip. The open-circuit voltage of one of the common specifications of photovoltaic panels on the market is 21.6V±10%, and the temperature coefficient of monocrystalline silicon is -2mV / K, that is, when the ambient temperature is +25℃, the maximum voltage of the photovoltaic panel is 23.8V; when the ambient temperature is -20℃, the maximum voltage of the photovoltaic panel is 27V; when the ambient temperature is -30℃, the maximum voltage of the photovoltaic panel is 27.8V, while the maximum withstand voltage of the most cost-effective charging chip JW3655E on the market is 24V, that is, the photovoltaic panel and charging chip with the highest cost performance will have the risk of overvoltage when used in a low temperature environment.

[0044] In this regard, most solutions on the market are to add an overvoltage protection circuit between the photovoltaic panel and the charging chip. When the voltage value of the photovoltaic panel exceeds the preset voltage value, the charging path between the photovoltaic panel and the charging chip is disconnected to prevent excessive voltage from damaging the charging chip. However, this solution has reliability issues in complex lighting environments. For example, when the weather suddenly changes from cloudy to sunny, the ambient light suddenly becomes strong, causing the voltage of the photovoltaic panel to continue to rise and exceed the preset voltage value, causing the overvoltage protection circuit to disconnect the charging path between the photovoltaic panel and the charging chip. Although the overvoltage protection circuit protects the charging chip in the event of overvoltage, it also causes the battery to be unable to charge in this case. Therefore, the existing photovoltaic panels and charging chips cannot stably charge the battery in complex lighting environments, resulting in low overall charging efficiency.

[0045] To this end, the utility model proposes a charging circuit and a power supply device, aiming to solve the problem that the existing photovoltaic panels cannot charge the battery normally under complex lighting environments.

[0046] refer to Figure 1 In one embodiment of the present utility model, the charging circuit includes:

[0047] A power input terminal, used to connect to the photovoltaic panel 10;

[0048] Charging chip 20;

[0049] An overvoltage protection circuit 30 is arranged in series between the power input terminal and the charging chip 20; the overvoltage protection circuit 30 is used to detect the output voltage of the photovoltaic panel 10 connected to the power input terminal, and control the connection / disconnection between the power input terminal and the charging chip 20 according to the detected output voltage of the photovoltaic panel 10, and output a corresponding voltage detection signal;

[0050] A voltage conversion circuit 40, wherein the input end of the voltage conversion circuit 40 is connected to the power input end, and the output end of the voltage conversion circuit 40 is electrically connected to the charging chip 20, and the voltage conversion circuit 40 is used to convert the output voltage of the photovoltaic panel 10 connected to the power input end and output it to the charging chip 20;

[0051] A main control circuit 50, wherein the detection end of the main control circuit 50 is electrically connected to the output end of the overvoltage protection circuit 30, and the control end of the main control circuit 50 is connected to the voltage conversion circuit 40, and the main control circuit 50 is used to control the voltage conversion circuit 40 to work / stop working according to the received voltage detection signal.

[0052] In this embodiment, the main control circuit 50 can be implemented by a main controller, such as an MCU (Microcontroller Unit), a DSP (Digital Signal Process), an FPGA (Field Programmable Gate Array), a SOC (System On Chip), etc.

[0053] In this embodiment, the voltage conversion circuit 40 can adopt a step-down circuit such as a BOOST-BUCK conversion circuit or a BUCK conversion circuit. The step-down circuit is electrically connected to the power input end, the output end of the step-down circuit is electrically connected to the charging chip 20, and the step-down circuit is electrically connected to the control end of the main control circuit 50. The step-down circuit is used to step down the output voltage of the photovoltaic panel 10 connected to the power input end and output it to the charging chip 20.

[0054] In the present embodiment, specifically, the overvoltage protection circuit 30 is used to detect the output voltage of the photovoltaic panel 10 connected to the power input terminal, and output a corresponding voltage detection signal to the main control circuit 50. When the output voltage of the photovoltaic panel 10 exceeds a preset voltage value (generally, the withstand voltage value of the charging chip 20 is 24V), the overvoltage protection circuit 30 disconnects the path between the power input terminal and the charging chip 20, thereby preventing the photovoltaic panel from outputting an excessive voltage to the charging chip 20, causing damage to the charging chip 20. At this time, when the main control circuit 50 receives the voltage detection signal, it controls the voltage conversion circuit 40 to work, so that the voltage conversion circuit 40 converts the excessive voltage output by the photovoltaic panel 10 and outputs a suitable power supply voltage to the charging chip 20, so that the photovoltaic panel 10 can still charge the charging chip 20 when its output voltage is too large; when the output voltage of the photovoltaic panel 10 does not exceed the preset voltage value, the overvoltage protection circuit 30 connects the path between the power input terminal and the charging chip 20, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working according to the voltage detection signal. With such a configuration, in actual applications, when the light environment suddenly changes from weak to strong, the output voltage of the photovoltaic panel 10 continues to increase and exceeds the preset voltage value. The charging circuit of the utility model can promptly disconnect the normal path (overvoltage protection circuit 30) between the photovoltaic panel 10 and the charging chip 20 to prevent the photovoltaic panel from outputting excessive electricity to the charging chip 20, thereby damaging the charging chip 20. The excessive output voltage of the photovoltaic panel 10 is converted into a voltage and then outputted to the charging chip 20 through another path (voltage conversion circuit 40) to provide a suitable supply voltage, so that the voltage output by the photovoltaic panel 10 in a complex light environment where the light suddenly changes into strong can still match the withstand voltage value of the charging chip 20. However, the voltage conversion circuit 40 will reduce the efficiency of the photovoltaic panel 10 charging the battery through the charging chip 20. Therefore, when the light changes from strong to weak, the overvoltage protection circuit 30 conducts the path between the photovoltaic panel 10 and the charging chip 20 according to the voltage detection signal, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working according to the voltage detection signal, so that the overvoltage protection circuit of the photovoltaic panel 10 and the charging chip 20 can charge the battery normally, and will not be reduced due to passing through the voltage conversion circuit 40. Therefore, the charging circuit of the utility model can solve the problem that the existing photovoltaic panel cannot charge the battery normally under complex lighting environments.

[0055] In one embodiment of the present utility model, the main control circuit 50 includes a control circuit and a timer. When the voltage conversion circuit 40 is working, the timer starts timing, and when the timing time reaches a preset time, the timer outputs a corresponding timing signal;

[0056] The control circuit controls the voltage conversion circuit 40 to stop working when receiving the timing signal.

[0057] In this embodiment, when the voltage conversion circuit 40 starts to work, the timer starts timing. When the timing time reaches the preset time (10 minutes), the control circuit controls the voltage conversion circuit 40 to stop working according to the timing signal output by the timer. With such a configuration, in actual applications, when the ambient light changes continuously in a short period of time, for example, the light changes from weak to strong and then from weak to strong repeatedly, the voltage conversion circuit 40 starts working when the light changes from weak to strong for the first time, and stops working after working continuously for 10 minutes, thereby avoiding the problem that the voltage conversion circuit 40 repeatedly works / stops working in a short period of time under a complex lighting environment, resulting in the photovoltaic panel 10 being unable to stably charge the battery through the charging chip 20, thereby shortening the service life of the charging chip 20 and the battery.

[0058] In this embodiment, the control circuit and the timer are integrated into the same integrated chip, which can further optimize the coordinated operation of the control circuit and the timer to achieve higher efficiency and accuracy, and can significantly reduce the required external components and connection lines, thereby simplifying the structure of the entire circuit system.

[0059] refer to Figure 2 In one embodiment of the present utility model, the overvoltage protection circuit 30 includes:

[0060] A voltage detection circuit 31, wherein the detection end of the voltage detection circuit 31 is electrically connected to the power input end, and the output end of the voltage detection circuit 31 is electrically connected to the detection end of the main control circuit 50, and the voltage detection circuit 31 is used to detect the output voltage of the photovoltaic panel 10 connected to the power input end, and output a corresponding voltage detection signal;

[0061] The first switch circuit 32, the input end of the first switch circuit 32 is electrically connected to the power input end, the output end of the first switch circuit 32 is electrically connected to the charging chip 20, the controlled end of the first switch circuit 32 is electrically connected to the output end of the voltage detection circuit 31, and the first switch circuit 32 is turned on / off according to the voltage detection signal.

[0062] In this embodiment, the voltage detection circuit 31 may be a resistor divider, a voltage transformer or a Hall voltage sensor.

[0063] In this embodiment, the first switch circuit 32 can be implemented by at least one switch tube, such as a MOS tube, an IGBT tube, a thyristor, a triode, a power tube, etc., and / or by at least one switch device, such as a contactor, a circuit breaker and a relay.

[0064] In the present embodiment, the voltage detection circuit 31 is used to detect the output voltage of the photovoltaic panel 10 connected to the power input terminal, and output a corresponding voltage detection signal. When the ambient light changes from weak to strong, the voltage value of the voltage detection signal exceeds the preset voltage value (i.e., a high level), and the first switch circuit 32 is disconnected after receiving the high level, so that the path between the photovoltaic panel 10 and the charging chip 20 is disconnected, and the main control circuit 50 controls the voltage conversion circuit 40 to work, so as to prevent the excessive output voltage of the photovoltaic panel 10 from being transmitted to the charging chip 20, causing damage to the charging chip 20. At this time, the photovoltaic panel 10 charges the battery through the voltage conversion circuit 40 and the charging chip 20; when the ambient light changes from strong to weak or normal, the voltage value of the voltage detection signal is less than the preset voltage value (i.e., a low level), and the first switch circuit 32 is turned on after receiving the low level, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working after receiving the low level, so that the photovoltaic panel 10 charges the battery through the first switch circuit 32 and the charging chip 20 without loss, and the charging efficiency of the photovoltaic panel 10 will not be reduced due to passing through the voltage conversion circuit 40.

[0065] refer to Figure 3 In one embodiment of the present utility model, the voltage detection circuit 31 includes:

[0066] A second switch circuit 311 and a voltage divider circuit 312, wherein the input end and the controlled end of the second switch circuit 311 are both electrically connected to the power input end, the output end of the second switch circuit 311 is electrically connected to the first end of the voltage divider circuit 312, the second end of the voltage divider circuit 312 is electrically connected to the controlled end of the first switch circuit 32, and the third end of the voltage divider circuit 312 is electrically connected to the detection end of the main control circuit 50.

[0067] In this embodiment, the second switch circuit 311 can be implemented by at least one switch tube, such as a MOS tube, an IGBT tube, a thyristor, a triode, a power tube, etc., and / or by at least one switch device, such as a contactor, a circuit breaker and a relay.

[0068] In this embodiment, the voltage divider circuit 312 may be composed of at least one resistor.

[0069] In this embodiment, when the output voltage of the photovoltaic panel 10 connected to the power input terminal exceeds the preset voltage value, the second switch circuit 311 is turned on, and part of the current output by the photovoltaic panel 10 is transmitted to the voltage divider circuit 312 through the second switch circuit 311. At this time, the voltage value of the voltage divider circuit 312 is relatively large (high level). Since the controlled end of the first switch circuit 32 is electrically connected to the voltage divider circuit 312, Figure 5, the first switch circuit 32 is a PMOS tube Q2, so the first switch circuit 32 is disconnected after receiving the high level of the voltage divider circuit 312, so that the path between the photovoltaic panel 10 and the charging chip 20 is disconnected, so as to avoid excessive voltage output to the charging chip 20 and damage to the charging chip 20, and the main control circuit 50 controls the voltage conversion circuit 40 to work according to the higher voltage of the voltage divider circuit 312, so that the voltage conversion circuit 40 converts the output voltage of the photovoltaic panel 10 and outputs a suitable power supply voltage to the charging chip 20; when the output voltage of the photovoltaic panel 10 connected to the power input end does not exceed the preset voltage value, the second switch circuit 311 is disconnected, the voltage value of the voltage divider circuit 312 is small (low level), the first switch circuit 32 is turned on after receiving the low level, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working according to the lower voltage value of the voltage divider circuit 312, so that the photovoltaic panel 10 charges the battery through the first switch circuit 32 and the charging chip 20 in turn.

[0070] refer to Figure 4 In one embodiment of the present utility model, the second switch circuit 311 includes:

[0071] A first switch tube Q1, a first resistor R1, a second resistor R2 and a Zener diode D1, wherein the first end of the first resistor R1 is electrically connected to the power input end, the second end of the first resistor R1 is electrically connected to the first end of the second resistor R2 and the cathode of the Zener diode D1 respectively, the anode of the Zener diode D1 is grounded, the second end of the second resistor R2 is electrically connected to the controlled end of the first switch tube Q1, the input end of the first switch tube Q1 is electrically connected to the power input end, and the output end of the first switch tube Q1 is electrically connected to the first end of the voltage divider circuit 312.

[0072] In this embodiment, the first switch tube Q1 is a PNP transistor. When the output voltage of the photovoltaic panel 10 connected to the power input terminal is greater than the preset voltage value, the voltage regulator diode D1 is turned on to reduce the voltage of the second resistor R2 to a low level. The first switch tube Q1 is turned on, and part of the current output by the photovoltaic panel 10 is transmitted to the voltage divider circuit 312 through the first switch tube Q1. At this time, the voltage of the voltage divider circuit 312 is relatively high. Since the controlled end of the first switch circuit 32 is electrically connected to the voltage divider circuit 312, the reference Figure 5, the first switch circuit 32 is a PMOS tube Q2, so the first switch circuit 32 is disconnected to disconnect the path between the photovoltaic panel 10 and the charging chip 20 through the first switch circuit 32, and the main control circuit 50 controls the voltage conversion circuit 40 to work; when the output voltage of the photovoltaic panel 10 connected to the power input end is less than the preset voltage value, the voltage regulator diode D1 is turned off, and the voltage of the second resistor R2 increases, so that the first switch tube Q1 is disconnected, and the current output by the photovoltaic panel 10 cannot be transmitted to the voltage divider circuit 312 through the first switch tube Q1. At this time, the voltage of the voltage divider circuit 312 is low, the first switch circuit 32 is turned on, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working, so that the photovoltaic panel 10 can charge the battery normally through the first switch circuit 32 and the charging chip 20 in turn.

[0073] refer to Figure 4 In one embodiment of the present utility model, the voltage divider circuit 312 includes:

[0074] A third resistor R3 and a fourth resistor R4, wherein the first end of the third resistor R3 is electrically connected to the controlled end of the first switch circuit 32, the second end of the third resistor R3 is electrically connected to the output end of the second switch circuit 311, the detection end of the main control circuit 50 and the first end of the fourth resistor R4 respectively, and the second end of the fourth resistor R4 is grounded.

[0075] In this embodiment, when the output voltage of the photovoltaic panel 10 connected to the power input terminal is greater than the preset voltage value, the second switch circuit 311 is turned on, and part of the current of the photovoltaic panel 10 is transmitted to the fourth resistor R4 through the second switch circuit 311. At this time, the voltage of the fourth resistor R4 is relatively large, and the first switch circuit 32 is disconnected according to the larger voltage of the fourth resistor R4, so that the path between the photovoltaic panel 10 and the charging chip 20 is disconnected, and the main control circuit 50 controls the voltage conversion circuit 40 to work according to the larger voltage of the fourth resistor R4; when the output voltage of the photovoltaic panel 10 connected to the power input terminal is less than the preset voltage value, the second switch circuit 311 is disconnected, and part of the current of the photovoltaic panel 10 cannot be transmitted to the fourth resistor R4 through the second switch circuit 311. At this time, the voltage of the fourth resistor R4 is relatively low, and the first switch circuit 32 is turned on according to the lower voltage of the fourth resistor R4, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working according to the lower voltage of the fourth resistor R4.

[0076] refer to Figure 5 In one embodiment of the present utility model, the first switch circuit 32 includes:

[0077] The second switch tube Q2, the input end of the second switch tube Q2 is electrically connected to the power input end, the output end of the second switch tube Q2 is electrically connected to the charging chip 20, and the controlled end of the second switch tube Q2 is electrically connected to the output end of the voltage detection circuit 31.

[0078] In this embodiment, the second switch tube Q2 is a PMOS tube, and the voltage detection circuit 31 is used to detect the output voltage of the photovoltaic panel 10 connected to the power input terminal, and output a corresponding voltage detection signal. When the ambient light changes from weak to strong, the voltage value of the voltage detection signal exceeds the preset voltage value (i.e., a high level), and the second switch tube Q2 is disconnected to disconnect the path between the photovoltaic panel 10 and the charging chip 20. The main control circuit 50 controls the voltage conversion circuit 40 to work to prevent the photovoltaic panel 10 from outputting an excessive voltage to the charging chip 20, which may cause damage to the charging chip 20. At this time, the photovoltaic panel 10 is connected to the charging chip 20 through the voltage conversion circuit 40. 0 and the charging chip 20 charge the battery; when the ambient light changes from strong to weak or normal, the voltage value of the voltage detection signal is less than the preset voltage value (i.e., a low level), and the second switch tube Q2 is turned on after receiving the low level, and the main control circuit 50 controls the voltage conversion circuit 40 to stop working after receiving the low level, so that the photovoltaic panel 10 charges the battery through the second switch tube Q2 and the charging chip 20. Since the resistance of the second switch tube Q2 is extremely low, the efficiency of the photovoltaic panel 10 charging the battery through the charging chip 20 will basically not be lost, and its charging efficiency will not be reduced due to passing through the voltage conversion circuit 40.

[0079] The utility model further proposes a power supply device, comprising a photovoltaic panel 10 and the charging circuit as described above; wherein an input end of the charging circuit is electrically connected to the photovoltaic panel 10 .

[0080] It is worth noting that since the power supply device of the present invention is based on the above-mentioned charging circuit, the embodiments of the power supply device of the present invention include all technical solutions of all embodiments of the above-mentioned charging circuit, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0081] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A charging circuit, characterized in that: The charging circuit comprises: Power input terminal, used to connect to photovoltaic panels; Charging chip; an overvoltage protection circuit, which is arranged in series between the power input terminal and the charging chip; the overvoltage protection circuit is used to detect the output voltage of the photovoltaic panel connected to the power input terminal, and control the connection / disconnection between the power input terminal and the charging chip according to the detected output voltage of the photovoltaic panel, and output a corresponding voltage detection signal; A voltage conversion circuit, wherein the input end of the voltage conversion circuit is connected to the power input end, the output end of the voltage conversion circuit is electrically connected to the charging chip, and the voltage conversion circuit is used to convert the output voltage of the photovoltaic panel connected to the power input end and output it to the charging chip; A main control circuit, wherein the detection end of the main control circuit is electrically connected to the output end of the overvoltage protection circuit, the control end of the main control circuit is connected to the voltage conversion circuit, and the main control circuit is used to control the voltage conversion circuit to work / stop working according to the received voltage detection signal.

2. The charging circuit according to claim 1, characterized in that: The main control circuit includes a control circuit and a timer. When the voltage conversion circuit is working, the timer starts timing and outputs a corresponding timing signal when the timing time reaches a preset time. The control circuit controls the voltage conversion circuit to stop working when receiving the timing signal.

3. The charging circuit according to claim 2, characterized in that: The control circuit and the timer are integrated into the same integrated chip.

4. The charging circuit according to claim 1, characterized in that: The overvoltage protection circuit comprises: A voltage detection circuit, wherein a detection end of the voltage detection circuit is electrically connected to the power input end, an output end of the voltage detection circuit is electrically connected to a detection end of the main control circuit, and the voltage detection circuit is used to detect an output voltage of the photovoltaic panel connected to the power input end and output a corresponding voltage detection signal; A first switch circuit, wherein the input end of the first switch circuit is electrically connected to the power input end, the output end of the first switch circuit is electrically connected to the charging chip, the controlled end of the first switch circuit is electrically connected to the output end of the voltage detection circuit, and the first switch circuit is turned on / off according to the voltage detection signal.

5. The charging circuit according to claim 4, characterized in that: The voltage detection circuit comprises: A second switch circuit and a voltage divider circuit, wherein the input end and the controlled end of the second switch circuit are both electrically connected to the power input end, the output end of the second switch circuit is electrically connected to the first end of the voltage divider circuit, the second end of the voltage divider circuit is electrically connected to the controlled end of the first switch circuit, and the third end of the voltage divider circuit is electrically connected to the detection end of the main control circuit.

6. The charging circuit according to claim 5, characterized in that: The second switch circuit comprises: A first switch tube, a first resistor, a second resistor and a Zener diode, wherein the first end of the first resistor is electrically connected to the power input end, the second end of the first resistor is electrically connected to the first end of the second resistor and the cathode of the Zener diode respectively, the anode of the Zener diode is grounded, the second end of the second resistor is electrically connected to the controlled end of the first switch tube, the input end of the first switch tube is electrically connected to the power input end, and the output end of the first switch tube is electrically connected to the first end of the voltage divider circuit.

7. The charging circuit according to claim 5, characterized in that: The voltage divider circuit comprises: A third resistor and a fourth resistor, wherein the first end of the third resistor is electrically connected to the controlled end of the first switch circuit, the second end of the third resistor is electrically connected to the output end of the second switch circuit, the detection end of the main control circuit and the first end of the fourth resistor respectively, and the second end of the fourth resistor is grounded.

8. The charging circuit according to claim 4, characterized in that: The first switch circuit comprises: A second switch tube, wherein the input end of the second switch tube is electrically connected to the power input end, the output end of the second switch tube is electrically connected to the charging chip, and the controlled end of the second switch tube is electrically connected to the output end of the voltage detection circuit.

9. The charging circuit according to claim 1, characterized in that: The voltage conversion circuit comprises: A step-down circuit, wherein the input end of the step-down circuit is electrically connected to the power input end, the output end of the step-down circuit is electrically connected to the charging chip, the step-down circuit is electrically connected to the control end of the main control circuit, and the step-down circuit is used to step down the output voltage of the photovoltaic panel connected to the power input end and output it to the charging chip.

10. A power supply device, characterized in that: It comprises a charging circuit and a photovoltaic panel as described in any one of claims 1 to 9; wherein an input end of the charging circuit is electrically connected to the photovoltaic panel.

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