A solar lamp battery high-efficiency charging circuit

Abstract

The utility model discloses a kind of battery efficient charging circuit of solar lamp, including photovoltaic panel, battery, photovoltaic panel is connected with photovoltaic detection circuit, anti-inversion circuit, anti-inversion circuit is connected with half-bridge synchronous step-down circuit, half-bridge synchronous step-down circuit is connected with battery;Photovoltaic detection circuit is connected with single-chip microcomputer, single-chip microcomputer is connected with anti-inversion circuit, half-bridge synchronous step-down circuit, current detection electrical appliance, battery voltage detection circuit;When the product works, single-chip microcomputer can automatically calculate the optimum power point of photovoltaic panel according to current photovoltaic panel voltage and battery voltage, single-chip microcomputer exports the waveform of corresponding duty cycle to half-bridge synchronous step-down circuit, then battery is charged by half-bridge synchronous step-down circuit, so that photovoltaic panel energy is transmitted to battery with optimal efficiency, compared with only diode charging mode, 50% can be improved 60% charging current, let battery have higher efficiency voltage charging, to improve charging efficiency;Meanwhile, after being fully charged, current can be prevented to photovoltaic panel.

Description

Technical Field

[0001] This utility model relates to solar lamp components, and more particularly to a high-efficiency battery charging circuit for a solar lamp. Background Technology

[0002] 1. Chinese Patent Publication No. CN204334026U discloses a charging circuit for a solar street light controller, comprising: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a first resistor, a second resistor, a third resistor, a fourth resistor, a first transistor, a second transistor, a first diode, and a second diode. One end of the first capacitor is connected to the positive terminal of a solar cell module, and the negative terminal of the solar cell module is connected to the other end of the first capacitor. One end of the first capacitor is also connected to the positive terminal of the first diode. The negative terminal of the first diode is connected to one end of the first resistor and the drain of the first transistor. The drain of the first transistor is connected to the other end of the first resistor. The source of the first transistor is connected to one end of the second capacitor, and the other end of the second capacitor is grounded. The other end of the first resistor is also connected to the collector of the second transistor. The base of the second transistor is connected to one end of the second resistor, and the other end of the second resistor is connected to the microcontroller's charging information management terminal. The emitter of the second transistor is connected to ground. The positive terminal of the first capacitor is connected to the entire solar module, and the negative terminal of the first capacitor is grounded. The positive terminal of the second capacitor is also connected to the positive terminal of the battery, and the negative terminal of the second capacitor is grounded. One end of the fourth resistor is connected to the positive terminal of the battery, and the other end of the fourth resistor is connected to the positive terminal of the third capacitor. The negative terminal of the third capacitor is grounded. The negative terminal of the third capacitor is connected to one end of the third resistor, and the other end of the third resistor is connected to the negative terminal of the battery. The positive terminal of the third capacitor is also connected to the positive terminal of the ninth Zener diode, and the negative terminal of the ninth Zener diode is grounded. The positive terminal of the ninth Zener diode is also connected to the input terminal of the voltage regulator circuit. The output terminal of the voltage regulator circuit is connected to one end of the fourth capacitor, and the other end of the fourth capacitor is grounded.

[0003] The charging circuit of the aforementioned solar street light controller is a single-function charging circuit that cannot switch between high and low levels for charging. This results in low charging efficiency and increases the charging load on the circuit.

[0004] 2. Chinese Patent Publication No. CN204304560U discloses a charging circuit for solar streetlights based on IRF3205, including a MOS switch Q1IRF3205. The drain (D) pin of the MOS switch Q1IRF3205 is connected to the anode of diode D1. The anode of diode D1 is connected to the anode of diode D3. The cathode (B) of diode D3 is connected to the positive terminal of battery BT. The gate (G) terminal of the MOS switch Q1IRF3205 is connected to the anode of resistor R1. The cathode (B) terminal of resistor R1 is connected to the emitter (e) terminals of transistors Q2 and Q4. The collector (C) terminal of transistor Q2... The base (b) and collector (c) terminals of transistor Q2 are connected to Vcc. A resistor R2 is connected in parallel between the base (b) and collector (c) terminals of transistor Q2. The collector (c) terminal of transistor Q2 is connected to the base (b) terminal of transistor Q4. The base (b) terminal of transistor Q2 is connected to the collector (c) terminal of transistor Q3. The emitter (e) terminal of transistor Q3 and the collector (c) terminal of transistor Q4 are both grounded. The base (b) terminal of transistor Q3 is connected to resistor R3, and the other end of resistor R3 is connected to the drive input terminal (in). A diode D2 is connected in parallel between the gate (G) and source (S) terminals of MOS switch Q1IRF3205, and the anode of diode D2 is grounded. The anode and cathode of diode D1 are connected to the signal input terminal (I) and the signal output terminal (O), respectively.

[0005] The aforementioned charging circuit based on IRF3205 for solar streetlights is only a single-function charging circuit and cannot switch between high and low levels for charging. Its charging efficiency is low, which increases the charging load on the circuit. Utility Model Content

[0006] To solve the above-mentioned technical problems, this utility model provides a high-efficiency charging circuit for solar lamp batteries that has a reasonable structural design, high photovoltaic power conversion efficiency, and high charging efficiency.

[0007] The solution to the above technical problem is as follows:

[0008] A high-efficiency charging circuit for a solar lamp battery includes a photovoltaic panel and a battery BAT. The photovoltaic panel is connected to a photovoltaic detection circuit and an anti-backflow circuit. The anti-backflow circuit is connected to a half-bridge synchronous buck circuit, and the half-bridge synchronous buck circuit is connected to the battery BAT. The photovoltaic detection circuit is connected to a microcontroller U1, and the microcontroller U1 is connected to the anti-backflow circuit, the half-bridge synchronous buck circuit, a current detection device, and a battery voltage detection circuit.

[0009] The beneficial effects of this utility model's high-efficiency battery charging circuit for a solar lamp are as follows: 1. When the microcontroller U1 detects that the photovoltaic panel is exposed to sunlight and the voltage reaches 6V or higher, the microcontroller U1 outputs a high level, the anti-backflow circuit is activated, and the half-bridge synchronous buck circuit is started. The microcontroller U1 automatically calculates the optimal power point of the photovoltaic panel based on the current photovoltaic panel voltage and battery voltage. The microcontroller U1 outputs a waveform with the corresponding duty cycle to the half-bridge synchronous buck circuit, which then charges the battery. In this way, the photovoltaic panel energy is transferred to the battery with optimal efficiency. Compared with the charging method using only diodes, it can increase the charging current by 50%-60%, allowing the battery to be charged with a higher voltage, thereby improving charging efficiency; 2. When the microcontroller U1 detects that the battery voltage exceeds 3.5V, the microcontroller U1 outputs a low level to shut down the half-bridge synchronous buck circuit, preventing the battery voltage from flowing back to the photovoltaic panel. At this time, charging ends. Attached Figure Description

[0010] Figure 1 This is a circuit block diagram of the product of this utility model;

[0011] Figure 2 This is the circuit schematic diagram of the product of this utility model. Detailed Implementation

[0012] like Figures 1-2 The diagram shows a high-efficiency charging circuit for a solar lamp battery, including a photovoltaic panel and a battery BAT. The photovoltaic panel is connected to a photovoltaic detection circuit and an anti-backflow circuit. The anti-backflow circuit is connected to a half-bridge synchronous buck circuit, which is also connected to the battery BAT. The photovoltaic detection circuit is connected to a microcontroller U1, which is connected to the anti-backflow circuit, the half-bridge synchronous buck circuit, a current detection device, and a battery voltage detection circuit. The microcontroller is an MCU (Microcontroller Unit).

[0013] When the microcontroller U1 detects that the photovoltaic panel is exposed to sunlight and the voltage reaches 6V or higher, it outputs a high level, activating the backflow prevention circuit and simultaneously starting the half-bridge synchronous buck circuit. The microcontroller U1 automatically calculates the optimal power point for the photovoltaic panel based on the current photovoltaic panel and battery voltages. It then outputs a waveform with the corresponding duty cycle to the half-bridge synchronous buck circuit, which in turn charges the battery. This ensures optimal energy transfer from the photovoltaic panel to the battery, increasing the charging current by 50%-60% compared to diode-only charging methods. The high photovoltaic energy conversion efficiency, achieved through the microcontroller U1 and the half-bridge synchronous buck circuit, allows for efficient battery charging. When the microcontroller U1 detects that the battery voltage exceeds 3.5V, it outputs a low level to shut down the half-bridge synchronous buck circuit, preventing backflow of battery voltage to the photovoltaic panel, thus ending the charging process. The overall workload of this product's charging circuit is low.

[0014] Duty cycle refers to the proportion of the on-time relative to the total time in a pulse cycle, the proportion of the effective state time in a periodic signal, and is usually used for pulse signals or switching circuits.

[0015] Mathematical expression: For example, with a pulse width of 1μs and a period of 4μs, the duty cycle is 25%.

[0016] The photovoltaic detection circuit includes resistors R8 and R7. Resistors R8 and R7 are connected in series between the positive and negative terminals of the photovoltaic panel. Pin 11 of the microcontroller U1 is connected between resistors R8 and R7. The microcontroller U1 collects the voltage signal of the photovoltaic panel through resistors R8 and R7 for subsequent processing.

[0017] The backflow prevention circuit includes a PMOS transistor M3, an NMOS transistor U5, and a resistor R16. The positive terminal of the photovoltaic panel is connected to the drain (D) of the PMOS transistor M3, the gate (G) of the PMOS transistor M3 is connected to the source (S) of the NMOS transistor U5, the source (S) of the PMOS transistor M3 is connected to one end of the resistor R16, and the other end of the resistor R16 is connected to the source (S) of the NMOS transistor U5 and the gate (G) of the PMOS transistor M3. The drain (D) of the NMOS transistor U5 is connected to the ground wire, and the gate (G) of the NMOS transistor U5 is connected to pin 9 of the microcontroller U1.

[0018] A high-efficiency battery charging circuit for a solar lamp also includes an electrolytic capacitor EC2; the source terminal of the PMOS transistor M3 is connected to one end of the resistor R16 and the positive terminal of the electrolytic capacitor EC2, and the negative terminal of the electrolytic capacitor EC2 is connected to the ground wire.

[0019] The half-bridge synchronous buck circuit includes a half-bridge driver chip U3, diode D2, NMOS transistors M1 and M2, inductor L1, and electrolytic capacitor EC1. Pin 3 of the half-bridge driver chip U3 is connected to the gate (G) of NMOS transistor U5 and pin 9 of microcontroller U1. Pin 1 of the half-bridge driver chip U3 is connected to the anode of diode D2, the cathode of diode D2 is connected to pin 8 of the half-bridge driver chip U3, pin 6 of the half-bridge driver chip U3 is connected to pin 1 of inductor L1, the source (S) of NMOS transistor M2, and the drain (D) of NMOS transistor M1, the gate (G) of NMOS transistor M2 is connected to pin 7 of the half-bridge driver chip U3, the gate (G) of NMOS transistor M1 is connected to pin 5 of the half-bridge driver chip U3, pin 2 of inductor L1 is connected to the anode of electrolytic capacitor EC1 and the anode of battery BAT, and pin 2 of the half-bridge driver chip U3 is connected to pin 10 of microcontroller U1.

[0020] The current sensing device includes a current sampling resistor RCS, a capacitor C6, and a resistor R6. One end of the current sampling resistor RCS is connected to the negative terminal of the photovoltaic panel, the source terminal of the NMOS transistor M1, and the positive terminal of the capacitor C6. The other end of the current sampling resistor RCS is connected to the negative terminal of the battery BAT, the negative terminal of the electrolytic capacitor EC1, and one end of the resistor R6. The other end of the resistor R6 is connected to the negative terminal of the capacitor C6 and pin 8 of the microcontroller U1. The voltage on the current sampling resistor RCS is filtered by the resistor R6 and the capacitor C6 and converted into a current signal for the microcontroller U1 to read, so as to prevent the charging current from being too high and damaging the battery or hardware, and to ensure the stability of the system.

[0021] The battery voltage detection circuit includes resistors R4 and R5. One end of resistor R4 is connected to the positive terminal of battery BAT and pin 2 of inductor L1. The other end of resistor R4 is connected to one end of resistor R5 and pin 7 of microcontroller U1. The other end of resistor R5 is connected to ground.

[0022] Electrolytic capacitors EC1 and EC2 utilize their charging and discharging characteristics to transform the pulsating DC voltage during the charging process into a relatively stable DC voltage, thereby filtering out high-frequency and pulse interference.

[0023] The NMOS transistors M1 and M2 are controlled to turn on and off by outputting high or low levels at pins 7 (HI) and 5 (LO) of the half-bridge driver chip U3. This allows NMOS transistors M1 and M2 to alternately conduct, forming a Buck circuit that synchronously steps down the voltage to charge the battery BAT. In the Buck circuit, diode D2 is used to release the energy stored in the inductor when either NMOS transistor M1 or M2 is switched off, forming a freewheeling circuit. This effectively reduces reverse recovery losses and improves energy conversion efficiency.

[0024] When pin 11 PA6 of MCU microcontroller U1 detects that the photovoltaic panel voltage is lower than 6V, the voltage is too low. Pin 9 PB0 of microcontroller U1 outputs a low level, the half-bridge driver chip U3 does not work, the NMOS transistor U5 does not conduct, and charging does not start.

[0025] When pin 11 PA6 of microcontroller U1 detects that the photovoltaic panel is exposed to sunlight and the voltage reaches 6V or higher, pin 9 PB0 of microcontroller U1 outputs a high level, NMOS transistor U5 and PMOS transistor M3 are turned on, and the half-bridge driver chip U3 is started. Microcontroller U1 starts to automatically calculate the optimal duty cycle based on the current photovoltaic panel voltage and battery BAT voltage, and starts to automatically calculate the optimal power point of the photovoltaic panel based on the current photovoltaic panel voltage and battery voltage. Microcontroller U1 outputs the waveform corresponding to the duty cycle from pin 10 PA7 to pin 2 IN of half-bridge driver chip U3.

[0026] When the IN input of pin 2 of the half-bridge driver chip U3 is low, the HI input of pin 7 of the half-bridge driver chip U3 is low and the LO input of pin 5 of the half-bridge driver chip U3 is high. The NMOS transistor M1 is high and turns on, while the NMOS transistor M2 is off. The battery BAT is charged through the half-bridge driver chip U3 and the inductor L1.

[0027] When the IN pin of the half-bridge driver chip U3 is high, the HI pin of the half-bridge driver chip U3 is high and the LO pin of the half-bridge driver chip U3 is low. The NMOS transistor M2 is high and turns on, while the NMOS transistor M1 is off. The battery BAT is charged through the half-bridge driver chip U3 and the inductor L1.

[0028] Inductor L1 serves as an energy storage element in the charging circuit. During the charging process, the inductor stores electrical energy. For example, when NMOS transistors M1 and M2 alternately switch on and off, current flows through inductor L1 to store electrical energy. When switching, the stored electrical energy is released through inductor L1, providing a continuous power supply to the circuit and ensuring a stable and continuous supply of charging voltage and current. Inductor L1 can also suppress current changes, enabling the inductor to effectively suppress drastic changes in current and ensure a smooth transition of charging current.

[0029] Electrolytic capacitor EC1 utilizes its charging and discharging characteristics to transform the pulsating DC voltage during the charging process into a relatively stable DC voltage as NMOS transistors M1 and M2 alternately switch, thereby filtering out high-frequency and pulse interference.

[0030] A Buck circuit, also known as a step-down converter circuit, is a type of step-down DC-DC converter used to convert an input DC voltage into a lower, stable output voltage.

[0031] During the charging process, pin 8 PB2 of MCU microcontroller U1 continuously monitors the current on the current sampling resistor RCS to prevent the charging current from exceeding the set value. Based on the voltage of the photovoltaic panel, it calculates the optimal duty cycle and changes the current of the BUCK circuit synchronous buck circuit through pin 10 PA7 of MCU microcontroller U1.

[0032] During the charging process, pin 7 PB3 of the MCU microcontroller U1 continuously detects the voltage of the battery BAT through resistors R4 and R5.

[0033] When pin 7 PB3 of the MCU microcontroller U1 detects that the voltage of the battery BAT is lower than 3.5V, it is considered that the battery is not fully charged and needs to be charged.

[0034] When pin 7 (PB3) of the MCU U1 detects that the voltage of battery BAT is higher than 3.5V, it means that the battery is fully charged. Pin 9 (PB0) of the MCU U1 outputs a low level to turn off the half-bridge driver chip U3, and turns off NMOS transistor U5 and PMOS transistor M3 to prevent the voltage of battery BAT from flowing back to the photovoltaic panel. At this time, charging ends.

[0035] The charging efficiency of the above circuit can be significantly improved. At the same time, since the MCU microcontroller U1 controls the half-bridge driver chip U3, the complex peripheral circuits are eliminated, and the cost can be reduced to a very low level.

[0036] The microcontroller U1 mentioned is a microcontroller U1 with AD function; a microcontroller with AD function refers to a microcontroller with built-in analog-to-digital converter (ADC), which can convert analog signals into digital signals for digital processing and storage. This microcontroller can be applied to application scenarios that require analog signal acquisition, such as temperature measurement, light intensity detection, voltage monitoring, etc.

[0037] The battery BAT mentioned is a lithium iron phosphate battery.

[0038] The high-efficiency battery charging circuit of the solar lamp is the battery charging circuit of a solar street lamp or a battery charging circuit of a solar floodlight.

Claims

1. A high-efficiency battery charging circuit for a solar lamp, comprising a photovoltaic panel and a battery BAT, characterized in that: The photovoltaic panel is connected to a photovoltaic detection circuit and an anti-backflow circuit. The anti-backflow circuit is connected to a half-bridge synchronous buck circuit, which is connected to the battery BAT. The photovoltaic detection circuit is connected to a microcontroller U1, which is connected to the anti-backflow circuit, the half-bridge synchronous buck circuit, a current detection device, and a battery voltage detection circuit.

2. The high-efficiency battery charging circuit for a solar lamp according to claim 1, characterized in that: The photovoltaic detection circuit includes resistors R8 and R7. Resistors R8 and R7 are connected in series between the positive and negative terminals of the photovoltaic panel. Pin 11 of the microcontroller U1 is connected between resistors R8 and R7.

3. The high-efficiency battery charging circuit for a solar lamp according to claim 1, characterized in that: The backflow prevention circuit includes a PMOS transistor M3, an NMOS transistor U5, and a resistor R16. The positive terminal of the photovoltaic panel is connected to the drain (D) of the PMOS transistor M3, the gate (G) of the PMOS transistor M3 is connected to the source (S) of the NMOS transistor U5, the source (S) of the PMOS transistor M3 is connected to one end of the resistor R16, and the other end of the resistor R16 is connected to the source (S) of the NMOS transistor U5 and the gate (G) of the PMOS transistor M3. The drain (D) of the NMOS transistor U5 is connected to ground, and the gate (G) of the NMOS transistor U5 is connected to pin 9 of the microcontroller U1.

4. The high-efficiency battery charging circuit for a solar lamp according to claim 3, characterized in that: It also includes an electrolytic capacitor EC2; the source terminal of the PMOS transistor M3 is connected to one end of the resistor R16 and the positive terminal of the electrolytic capacitor EC2, and the negative terminal of the electrolytic capacitor EC2 is connected to the ground wire.

5. The high-efficiency battery charging circuit for a solar lamp according to claim 3, characterized in that: The half-bridge synchronous buck circuit includes a half-bridge driver chip U3, a diode D2, an NMOS transistor M1, an NMOS transistor M2, an inductor L1, and an electrolytic capacitor EC1. Pin 3 of the half-bridge driver chip U3 is connected to the gate of NMOS transistor U5 and pin 9 of microcontroller U1; Pin 1 of the half-bridge driver chip U3 is connected to the positive terminal of diode D2, the negative terminal of diode D2 is connected to pin 8 of the half-bridge driver chip U3, pin 6 of the half-bridge driver chip U3 is connected to pin 1 of inductor L1, the source terminal of NMOS transistor M2, the drain terminal of NMOS transistor M1, the gate terminal of NMOS transistor M2 is connected to pin 7 of the half-bridge driver chip U3, the gate terminal of NMOS transistor M1 is connected to pin 5 of the half-bridge driver chip U3, and pin 2 of inductor L1 is connected to the positive terminal of electrolytic capacitor EC1 and the positive terminal of battery BAT. Pin 2 of the half-bridge driver chip U3 is connected to pin 10 of the microcontroller U1.

6. The high-efficiency battery charging circuit for a solar lamp according to claim 5, characterized in that: The current sensing device includes a current sampling resistor RCS, a capacitor C6, and a resistor R6. One end of the current sampling resistor RCS is connected to the source (S) terminal of the NMOS transistor M1, the positive terminal of the capacitor C6, and the negative terminal of the photovoltaic panel. The other end of the current sampling resistor RCS is connected to the negative terminal of the battery BAT, the negative terminal of the electrolytic capacitor EC1, and one end of the resistor R6. The other end of the resistor R6 is connected to the negative terminal of the capacitor C6 and pin 8 of the microcontroller U1.

7. The high-efficiency battery charging circuit for a solar lamp according to claim 5, characterized in that: The battery voltage detection circuit includes resistors R4 and R5. One end of resistor R4 is connected to the positive terminal of battery BAT, the positive terminal of capacitor C6, and pin 2 of inductor L1. The other end of resistor R4 is connected to one end of resistor R5 and pin 7 of microcontroller U1. The other end of resistor R5 is connected to ground.

8. A high-efficiency battery charging circuit for a solar lamp according to any one of claims 1 to 7, characterized in that: The microcontroller U1 is a microcontroller U1 with AD function.

9. A high-efficiency battery charging circuit for a solar lamp according to any one of claims 1 to 7, characterized in that: The battery BAT mentioned is a lithium iron phosphate battery.

10. A high-efficiency battery charging circuit for a solar lamp according to any one of claims 1 to 7, characterized in that: The high-efficiency battery charging circuit of the solar lamp is the battery charging circuit of a solar street lamp or a battery charging circuit of a solar floodlight.

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