CN102904302A - High-efficiency solar charging device and charging method thereof - Google Patents

Abstract

The invention discloses a high-efficiency solar charging device and a charging method thereof. The charging device comprises a controller, a starting circuit, a direct current to direct current (DC-DC) conversion circuit, a charging terminal battery and a photoelectric conversion input module; the controller is respectively connected with the starting circuit and the DC-DC conversion circuit; the photoelectric conversion input module is respectively connected with the starting circuit and the DC-DC conversion circuit; and the controller acquires voltage values of the photoelectric conversion input module, and controls the DC-DC conversion circuit to charge the charging terminal battery by using a step-down topology unit and a step-up topology unit according to the difference of the voltage values of the photoelectric conversion input module. By the high-efficiency solar charging device and the charging method of the high-efficiency solar charging device provided by the invention, the problem about the voltage value change of the photoelectric conversion input module is unnecessary to be worried about; and the overall device can be adjusted automatically, so that the charging efficiency is maximized. The charging device provided by the invention has the characteristics of high charging efficiency, high stability and the like; and the electric energy output by a photoelectric conversion device can be collected and utilized efficiently.

Description

High-efficiency solar charging device and charging method thereof

technical field

The invention belongs to the technical field of solar charging, and relates to a charging device, in particular to a high-efficiency solar charging device; meanwhile, the invention also relates to a charging method of a high-efficiency solar charging device.

Background technique

With the rapid development of the global economy, the problem of energy shortage has become increasingly serious, and how to improve the utilization rate of energy has gradually become the direction of research and development in various fields. Efficient energy utilization equipment has played a major role in saving energy and alleviating energy shortages.

The structure of the existing electric energy harvesting charging device is fixed, and it can only produce the most specific voltage output for a specific input voltage, and its own charging efficiency is not high, so it cannot be applied to occasions where the input voltage is not fixed. The output voltage of the photoelectric conversion device itself fluctuates greatly with the change of light intensity, so it cannot be directly used for charging.

In view of this, in order to adapt to charging and improve charging efficiency, it is necessary to use smart chip technologies such as single-chip microcomputers to transform the charging device.

Contents of the invention

The technical problem to be solved by the present invention is to provide a high-efficiency solar charging device, which can automatically adjust the DC-DC conversion circuit according to the charging voltage to achieve the highest charging efficiency, and can be better suitable for photoelectric conversion modules caused by unstable lighting High-efficiency electric energy harvesting and charging under large input voltage fluctuations.

In addition, the present invention also provides a charging method for a high-efficiency solar charging device, which can automatically adjust the DC-DC conversion circuit according to the charging voltage to achieve the highest charging efficiency, and is better suitable for the input of photoelectric conversion modules caused by unstable light. High-efficiency electric energy harvesting and charging under large voltage fluctuations.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A high-efficiency solar charging device, the charging device includes: a controller, a starting circuit, a DC-DC conversion circuit, a charging terminal battery, and a photoelectric conversion input module;

The controller is respectively connected to the starting circuit and the DC-DC conversion circuit, and the photoelectric conversion input is respectively connected to the starting circuit and the DC-DC conversion circuit;

The DC-DC conversion circuit includes a step-down topology unit and a step-up topology unit; the controller obtains the voltage value of the photoelectric conversion input module, and controls the DC-DC conversion circuit to use the step-down voltage value according to the voltage value of the photoelectric conversion input module. The topology unit or the boost topology unit charges the charging terminal battery;

The PWM function pin of the controller outputs PWM waves with different duty ratios to control the conduction time and pinch-off time of the field effect transistor of the DC-DC conversion circuit, thereby controlling the energy storage of the inductance in the DC-DC conversion circuit. size, and finally change the output voltage value of the DC-DC conversion circuit.

As a preferred solution of the present invention, the charging device also includes a voltage amplification acquisition module, and the charging terminal battery is respectively connected to a DC-DC conversion circuit and a voltage amplification acquisition module; the ADC pin of the controller is connected to the voltage acquisition amplification module. The charging voltage is sampled, and the controller controls the step-up or step-down range of the DC-DC conversion circuit to adjust the charging efficiency.

As a preferred solution of the present invention, the charging device requires low-voltage start-up and high-voltage operation, and uses different DC-DC circuits as start-up circuits for low-voltage start-up and high-voltage operation, and the DC-DC circuit outputs direct current to the controller powered by.

As a preferred solution of the present invention, the boost topology unit is a Boost boost topology unit, and the buck topology unit is a Buck buck topology unit;

When the switch tube in the Boost boost topology unit is turned on, the power supply forms a loop through the inductor and the switch tube, and the current is converted into magnetic energy storage in the inductor; One positive, this voltage is superimposed on the positive terminal of the power supply, and forms a loop through the diode and the load to complete the boost function;

In the Buck step-down circuit, the power supply supplies power to the load through an inductance, and the inductance stores part of the energy at the same time, and then the power supply is disconnected, and only the inductance supplies power to the load; such periodic work, by adjusting the relative time when the power supply is turned on, to To achieve the regulation of the output voltage.

A charging method of the above-mentioned high-efficiency solar charging device, said method comprising the steps of:

Step S1, the controller obtains the voltage value of the photoelectric conversion input module;

Step S2, according to the difference in the voltage value of the photoelectric conversion input module, control the DC-DC conversion circuit to use the step-down topology unit or the boost topology unit to charge the battery of the charging terminal; the control method is: the output of the PWM function pin of the controller is different. The PWM wave of the empty ratio is used to control the conduction time and pinch-off time of the field effect tube of the DC-DC conversion circuit, thereby controlling the size of the inductive energy storage in the DC-DC conversion circuit, and finally changing the output voltage of the DC-DC conversion circuit value.

As a preferred solution of the present invention, in the step S1, the ADC pin of the controller samples the charging voltage through the voltage acquisition and amplification module, and the controller controls the step-up or step-down range of the DC-DC conversion circuit.

As a preferred solution of the present invention, the charging device requires low-voltage start-up and high-voltage operation, and uses different DC-DC circuits as start-up circuits for low-voltage start-up and high-voltage operation, and the DC-DC circuit outputs direct current to the controller powered by.

As a preferred solution of the present invention, the step S2 includes: when the switch tube in the Boost boost topology unit is turned on, the power supply forms a loop through the inductor and the switch tube, and the current is converted into magnetic energy storage in the inductor; the switch tube is turned off When it is off, the magnetic energy in the inductor is converted into electric energy at the inductor end, one negative and one positive, and this voltage is superimposed on the positive end of the power supply, forming a loop through the diode and the load to complete the boost function. In the Buck step-down circuit, the power supply supplies power to the load through an inductance, and the inductance stores part of the energy at the same time, and then the power supply is disconnected, and only the inductance supplies power to the load; such periodic work, by adjusting the relative time when the power supply is turned on, to To achieve the regulation of the output voltage.

As a preferred solution of the present invention, the method also includes step S3, the controller performs real-time sampling on a sampling resistor of the battery part of the charging terminal, obtains real-time charging efficiency to feed back to the controller, and adjusts the control through algorithm control and calculation The duty cycle of the PWM wave output by the device determines the step-up or step-down range, thereby adjusting the DC-DC change circuit, and then adjusting the charging efficiency in real time.

The beneficial effect of the present invention is that: the high-efficiency solar charging device and its charging method proposed by the present invention do not need to worry about the change of the voltage value of the photoelectric conversion input, and the whole set of devices can be automatically adjusted to maximize the charging efficiency. The charging device of the invention has the characteristics of high charging efficiency and good stability, and can efficiently collect and utilize the electric energy output by the photoelectric conversion device.

Description of drawings

Fig. 1 is a schematic diagram of the composition of the charging device of the present invention.

Fig. 2 is a circuit diagram of the starting circuit in the charging device of the present invention.

Fig. 3 is a circuit diagram of the Boost voltage boosting circuit in the charging device of the present invention.

Fig. 4 is a circuit diagram of the Buck step-down circuit in the charging device of the present invention.

Fig. 5 is a circuit diagram of a voltage amplification acquisition module in the charging device of the present invention.

Fig. 6 is a flow chart of the program in the charging device of the present invention.

Detailed ways

Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Embodiment one

Please refer to FIG. 1 , the present invention discloses a high-efficiency solar charging device, including a single-chip microcomputer 1 , a photoelectric conversion input module 2 , a starting circuit 3 , a DC-DC conversion circuit 4 , a battery 5 , and a voltage acquisition and amplification module 6 . The DC-DC conversion circuit 4 includes a Buck step-down circuit and a Boost step-up circuit. The DC voltage from the photoelectric conversion input module 2 supplies power to the entire charging device.

The single-chip microcomputer 1 obtains the voltage value of the photoelectric conversion input module 2. After analyzing the voltage, the single-chip microcomputer 1 controls the DC-DC conversion circuit 4 to use the Buck step-down circuit and the Boost boost circuit to adjust the input voltage according to the difference in the voltage value of the photoelectric conversion input module 2. Perform DC-DC conversion. Specifically, the ADC pin of the single-chip microcomputer 1 samples the charging voltage through the voltage acquisition and amplification module, and the controller controls the step-up or step-down range of the DC-DC conversion circuit to adjust the charging efficiency.

At the same time, MCU 1 uses AD to sample a sampling resistor of battery 5 in real time to obtain real-time charging efficiency and feed it back to MCU 1. Through algorithm control and calculation, the duty ratio of the PWM wave output by MCU is adjusted to determine whether to boost or lower the voltage. The amplitude of the voltage can be adjusted to adjust the DC-DC change circuit, and then the charging efficiency can be adjusted in real time. The PWM function pin of the single-chip microcomputer 1 outputs PWM waves with different duty ratios to control the conduction time and pinch-off time of the field effect transistor of the DC-DC conversion circuit, thereby controlling the size of the inductive energy storage in the DC-DC conversion circuit. Finally, the output voltage value of the DC-DC conversion circuit is changed.

Please refer to FIG. 2, which is a circuit diagram of the startup circuit of the present invention. The voltage range of the photoelectric conversion input module 2 is 0~20V, and the control circuit part is 5V, so it is necessary to step down or boost the input voltage. The working voltage of 2108AG is relatively low, and it can work at 0.7V, so it is suitable as a low voltage the start-up circuit. The voltage of the photoelectric conversion input module can reach 20V, so when the voltage is high, use LM2596 to provide the working voltage for the system. Since it is difficult to automatically control the input voltage range through the control circuit, the input voltage is detected to remind whether to switch and start the circuit. The two switches in the picture are relays, which are connected to the 2108AG circuit below by default. The system can start to work when the input voltage is about 0.7V, and then the main chip detects the input voltage. When the input voltage is greater than the battery charging voltage, the main chip controls the relay action. , switch to the circuit of the upper LM2596 chip to supply power for the whole system.

Please refer to FIG. 3 and FIG. 4, FIG. 3 is a circuit diagram of the Boost voltage boosting circuit of the present invention, and FIG. 4 is a circuit diagram of the Buck voltage reduction circuit. When the switch tube in the Boost boost circuit is turned on, the power supply forms a loop through the inductor-switch tube, and the current is converted into magnetic energy storage in the inductor; This voltage is superimposed on the positive terminal of the power supply and forms a loop through the diode-load to complete the boost function. In the Buck step-down circuit, the power supply supplies power to the load through an inductor, and at the same time the inductor stores a part of energy, and then the power supply is disconnected, and only the inductor supplies power to the load. With such periodic work, the adjustment of the output voltage is realized by adjusting the relative time when the power is turned on.

Please refer to FIG. 5 . FIG. 5 is a circuit diagram of the voltage amplification acquisition module of the present invention. The single-chip microcomputer collects the voltage value of the sampling resistor on the system loop, and obtains the charging current from Ohm's law, thereby calculating the charging power at this time. In order to reduce the impact of the sampling resistor on the overall system, the power obtained by the sampling resistor must be much smaller than the charging power. After calculation, the voltage divided by the sampling resistor is at the millivolt level. It needs to be amplified and then sampled by AD, and then sent to the microcontroller for control. .

The system is monitored and controlled by the MSP430 microcontroller through the AD sampling value and the modulation of the PWM duty cycle. The output voltage value of the DC-DC conversion circuit is controlled by the PWM of the single-chip microcomputer. According to the different duty ratios of the PWM, the conduction time and the pinch-off time of the field effect tube of the corresponding DC conversion circuit are different, thereby controlling the inductance storage in the converter circuit. The size of the energy, and finally change the output voltage value, thereby changing the size of the charging current, that is, the charging power, and the charging power satisfies the equation: P _E =P _Rs +P _t +P _c (P _E is the output power of the power supply, P _Rs is the power consumed by the internal resistance of the power supply, P _t is the power loss on the DC converter, and P _c is the charging power), it can be known that P _c has a maximum value, so the voltage on the sampling resistor must be collected in real time through the single-chip microcomputer. The resistance value is converted to the charging power, and then the duty cycle of the PWM is adjusted through the feedback of the single-chip microcomputer, so that the charging power is kept at the maximum value, that is, the utilization rate of the photoelectric conversion output power is maximized.

Referring to FIG. 6, FIG. 6 is a system program flow chart of the present invention. In order to improve the working efficiency of the system and reduce power consumption, it is necessary to charge with as much power as possible. Therefore, the method commonly used in photovoltaic power generation systems - maximum power point tracking (MPPT). Every time the MCU outputs a PWM signal, it samples the charging current and compares it with the previous one to determine whether the duty cycle of the PWM will increase or decrease, and finally find the maximum power point for the system to work. When the voltage of the photoelectric conversion input module changes very slightly for a period of time, it is unnecessary for the single-chip microcomputer to control the circuit in real time, and that will only increase the power consumption of the system. So when the system works at the maximum charging current, let the microcontroller enter the low power consumption mode. Wake up every 1S interrupt, judge whether the voltage of the system is safe, and whether it is working at the maximum charging current; if not, perform PWM adjustment.

The composition of the high-efficiency solar charging device of the present invention has been described above. While disclosing the above-mentioned charging device, the present invention also discloses a charging method for the above-mentioned high-efficiency solar charging device. The method includes the following steps:

[Step S1] The controller obtains the voltage value of the photoelectric conversion input module. The ADC pin of the controller samples the charging voltage through the voltage acquisition and amplification module, so as to control the step-up or step-down range of the DC-DC conversion circuit.

[Step S2] According to the difference in the voltage value of the photoelectric conversion input module, the DC-DC conversion circuit is controlled to charge the battery of the charging terminal by using a step-down topology unit or a boost topology unit.

The control method is: first sample the voltage input by the photoelectric conversion, if it is less than the battery charging voltage, directly switch to the boost circuit, if it is greater than the battery charging voltage, use the boost or step-down circuit according to the situation. The PWM function pin of the controller outputs PWM waves with different duty ratios to control the conduction time and pinch-off time of the field effect transistor of the DC-DC conversion circuit, thereby controlling the size of the inductive energy storage in the DC-DC conversion circuit. Finally, the output voltage value of the DC-DC conversion circuit is changed.

In addition, the charging device requires low-voltage start-up and high-voltage operation, and uses two different sets of DC-DC start-up circuits for low-voltage start-up and high-voltage operation, and the DC-DC start-up circuit outputs direct current to supply power to the controller.

Specifically, when the switch in the Boost topology unit is turned on, the power supply forms a loop through the inductor and the switch, and the current is converted into magnetic energy storage in the inductor; when the switch is turned off, the magnetic energy in the inductor is converted into electrical energy in the inductor One terminal is negative and the other is positive. This voltage is superimposed on the positive terminal of the power supply, and a loop is formed through the diode and the load to complete the boost function. In the Buck step-down circuit, the power supply supplies power to the load through an inductance, and the inductance stores part of the energy at the same time, and then the power supply is disconnected, and only the inductance supplies power to the load; such periodic work, by adjusting the relative time when the power supply is turned on, to To achieve the regulation of the output voltage.

[Step S3] The algorithmic logic of adjusting the DC change module is: the controller samples a sampling resistor in the battery part of the charging terminal in real time. If the voltage obtained at both ends of the resistor is the largest, that is, the current passing through it is the largest, the charging efficiency is considered Highest. When the photoelectric input voltage is lower than the charging voltage of the battery, the boost circuit in the DC-DC conversion circuit is started, and the duty cycle of the PWM wave is sequentially changed from 0% to 100% to control the boost amplitude successively, and the sampling resistance of each conversion point is compared. Voltage, look for the PWM duty cycle point that maximizes the voltage of the sampling resistor, which is the maximum power point. When the photoelectric input voltage is greater than twice the battery charging voltage, the step-down circuit in the DC-DC conversion circuit is started, and the duty cycle of the PWM wave is sequentially changed from 50% to 100% to control the step-down range successively, and compare the sampling of each conversion point Find the duty cycle point of the PWM that maximizes the voltage of the sampling resistor, which is the maximum power point. When the photoelectric input voltage is greater than the battery charging voltage and less than twice the battery charging voltage, first start the step-down circuit in the DC-DC conversion circuit, and the duty cycle of the PWM wave is changed from 50% to 100% to control the step-down range successively. Start the step-up circuit in the DC-DC conversion circuit, and the duty cycle of the PWM wave changes from 0% to 50% successively to control the step-down range and compare the voltage of the sampling resistor at each conversion point to find the maximum voltage boost of the sampling resistor. The duty cycle point of the buck or step-down PWM is the maximum power point. The real-time charging efficiency is fed back to the controller. Through the above algorithm control and calculation, the duty cycle of the PWM wave output by the controller is adjusted to determine the step-up or step-down range, thereby adjusting the DC-DC change circuit, and then adjusting the charging in real time. efficiency.

To sum up, the high-efficiency solar charging device and its charging method proposed by the present invention do not need to worry about the change of the voltage value of the photoelectric conversion input, and the whole device will automatically adjust to maximize the charging efficiency. The charging device of the invention has the characteristics of high charging efficiency and good stability, and can efficiently collect and utilize the electric energy output by the photoelectric conversion device.

The description and application of the invention herein is illustrative and is not intended to limit the scope of the invention to the above-described embodiments. Variations and changes to the embodiments disclosed herein are possible, and substitutions and equivalents for various components of the embodiments are known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be realized in other forms, structures, arrangements, proportions, and with other components, materials and components without departing from the spirit or essential characteristics of the present invention. Other modifications and changes may be made to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims (9)

1. A high-efficiency solar charging device, characterized in that the charging device includes: a controller, a starting circuit, a DC-DC conversion circuit, a charging terminal battery, and a photoelectric conversion input module; The controller is respectively connected to the starting circuit and the DC-DC conversion circuit, and the photoelectric conversion input is respectively connected to the starting circuit and the DC-DC conversion circuit; The DC-DC conversion circuit includes a step-down topology unit and a step-up topology unit; the controller obtains the voltage value of the photoelectric conversion input module, and controls the DC-DC conversion circuit to use the step-down voltage value according to the voltage value of the photoelectric conversion input module. The topology unit or the boost topology unit charges the charging terminal battery; The PWM function pin of the controller outputs PWM waves with different duty ratios to control the conduction time and pinch-off time of the field effect transistor of the DC-DC conversion circuit, thereby controlling the inductive energy storage in the DC-DC conversion circuit size, and finally change the output voltage value of the DC-DC conversion circuit. 2. The high-efficiency solar charging device according to claim 1, characterized in that: The charging device also includes a voltage amplification acquisition module, and the charging terminal battery is respectively connected to a DC-DC conversion circuit and a voltage amplification acquisition module; The ADC pin of the controller samples the charging voltage through the voltage acquisition and amplification module, and the controller controls the step-up or step-down range of the DC-DC conversion circuit to adjust the charging efficiency. 3. The high-efficiency solar charging device according to claim 2, characterized in that: The controller is also used for real-time sampling of a sampling resistor of the battery part of the charging terminal to obtain real-time charging efficiency to feed back to the controller, through algorithmic control and calculation to adjust the duty cycle of the PWM wave output by the controller to determine the voltage boost Or the magnitude of the step-down, so as to adjust the DC-DC conversion circuit, and then adjust the charging efficiency in real time. 4. The high-efficiency solar charging device according to claim 1, characterized in that: The charging device requires low-voltage start-up and high-voltage operation, and uses two different sets of DC-DC start-up circuits for low-voltage start-up and high-voltage operation, and the DC-DC start-up circuit outputs direct current to supply power to the controller. 5. The high-efficiency solar charging device according to claim 1, characterized in that: The step-up topology unit is a Boost step-up topology unit, and the step-down topology unit is a Buck step-down topology unit; When the switch tube in the Boost boost topology unit is turned on, the power supply forms a loop through the inductor and the switch tube, and the current is converted into magnetic energy storage in the inductor; One positive, this voltage is superimposed on the positive terminal of the power supply, and forms a loop through the diode and the load to complete the boost function; In the Buck step-down circuit, the power supply supplies power to the load through an inductance, and the inductance stores part of the energy at the same time, and then the power supply is disconnected, and only the inductance supplies power to the load; such periodic work, by adjusting the relative time when the power supply is turned on, to To achieve the regulation of the output voltage. 6. A method for charging the high-efficiency solar charging device according to claim 1, wherein the method comprises the steps of: Step S1, the controller obtains the voltage value of the photoelectric conversion input module; Step S2, according to the difference in the voltage value of the photoelectric conversion input module, control the DC-DC conversion circuit to use the step-down topology unit or the boost topology unit to charge the battery of the charging terminal; the control method is: the output of the PWM function pin of the controller is different. The PWM wave of the empty ratio is used to control the conduction time and pinch-off time of the field effect tube of the DC-DC conversion circuit, thereby controlling the size of the inductive energy storage in the DC-DC conversion circuit, and finally changing the output voltage of the DC-DC conversion circuit value. 7. The charging method according to claim 6, characterized in that: In the step S1, the ADC pin of the controller samples the charging voltage through the voltage acquisition and amplification module, and the controller controls the step-up or step-down range of the DC-DC conversion circuit. 8. The charging method according to claim 6, characterized in that: Described step S2 comprises: When the switch tube in the Boost boost topology unit is turned on, the power supply forms a loop through the inductor and the switch tube, and the current is converted into magnetic energy storage in the inductor; One positive, this voltage is superimposed on the positive terminal of the power supply, and forms a loop through the diode and the load to complete the boost function; In the Buck step-down circuit, the power supply supplies power to the load through an inductance, and the inductance stores part of the energy at the same time, and then the power supply is disconnected, and only the inductance supplies power to the load; such periodic work, by adjusting the relative time when the power supply is turned on, to To achieve the regulation of the output voltage. 9. The charging method according to claim 6, characterized in that: The method also includes step S3, the controller samples a sampling resistor of the battery part of the charging terminal in real time, obtains real-time charging efficiency to feed back to the controller, and simultaneously samples the input voltage of the photoelectric conversion and the charging voltage required by the battery for comparison , to determine whether to switch to a boost circuit or a step-down circuit, through algorithmic control, calculation and adjustment of the duty cycle of the PWM wave output by the controller, to determine the magnitude of the boost or step-down, thereby adjusting the DC-DC change circuit, and then adjusting the charging in real time efficiency.

Images