CN202495780U - Wide-voltage-input intelligent photovoltaic charging control system with MPPT function - Google Patents

Abstract

The utility model discloses a wide-voltage input intelligent photovoltaic charging control system with MPPT function, which includes a solar cell array and a storage battery, the solar cell array is connected with a voltage-boosting circuit, the voltage-boosting circuit is connected with a charging circuit, and the charging circuit is connected with a storage battery; Including the single-chip controller, the single-chip controller is connected to the charging circuit, the output terminal of the charging circuit is fed back to the single-chip controller through the current and voltage detection circuit, the single-chip controller is also connected to the buck-boost circuit through the switch PWM control circuit, and the battery is also connected to the real-time A temperature sensor for monitoring the surface temperature of the accumulator, the temperature sensor is connected with a single-chip microcomputer control circuit; the single-chip microcomputer control circuit is also connected with a liquid crystal module for display and alarm. The utility model can charge a 12V storage battery in a preset mode within the range of 5V-26V, and the system works stably and reliably.

Description

Wide voltage input intelligent photovoltaic charging control system with MPPT function

technical field

The utility model relates to a photovoltaic charging system, in particular to a wide voltage input intelligent photovoltaic charging control system with MPPT function.

Background technique

Solar energy is a clean and renewable energy that is inexhaustible and inexhaustible. Relevant experts predict that global photovoltaic power generation will account for about 26% of the world's total power generation in 2040, and solar energy will become the pillar of world energy after 2050. However, at present, the photoelectric conversion efficiency of solar cells is low, and with the loss of system circuits, the overall efficiency is only about 11%. Therefore, how to improve the efficiency of photovoltaic systems is one of the key issues in the utilization of solar energy. As an energy storage element in a photovoltaic charging and discharging system, when the battery is charged at constant voltage or constant current, it is easy to form lead sulfate crystals on the plate that are difficult to convert into active substances, resulting in poor conductivity, high resistance, low solubility and dissolution rate of the battery , seriously affecting its service life.

A solar panel is a semiconductor device that can absorb sunlight and convert it into electrical energy. The equivalent circuit obtained according to its internal structure and output volt-ampere characteristics is shown in Figure 1. It consists of a solar panel that is affected by light intensity and temperature The current source consists of a diode in parallel and a resistor in series.

The maximum power point of the solar panel is affected by the light intensity at that time and the working temperature of the battery panel. The maximum power point is different under different light intensities, as shown in Figure 2. In Figure 2, S represents the light intensity, W, V and I represent the output power, output voltage and current of the solar panel, respectively. It can be seen from Figure 2 that when the solar panel always works at the maximum power point, its output energy reaches the maximum. Therefore, a corresponding control algorithm is required to effectively track the maximum power point under rapidly changing weather conditions, so that the battery panel can work at the maximum power point as much as possible, which is the MPPT algorithm.

和一个电源电阻r的串联，如图3所示，当然该直流电压源的电压和串联的电阻是变化的。 According to Thevenin's theorem, the solar cell is simply equivalent to an ideal DC voltage source

A series connection with a power supply resistance r, as shown in Figure 3, of course, the voltage of the DC voltage source and the series resistance change.

所获得的功率： Load resistance at a certain moment

Power gained:

                                     （1）

(1)

求导可得： Formula (1) on both sides

Derivation can be obtained:

        （2）

(2)

时输出功率P达到最大值。 It can be seen from formula (2): when

hour The output power P reaches the maximum value.

Since the solar panel is affected by light intensity, temperature, and sunlight incident angle, its output voltage, output current, and internal resistance are constantly changing. Therefore, only by dynamically changing the load equivalent resistance can the output power of the solar panel be maximized.

Utility model content

In order to overcome the low conversion efficiency of photovoltaic chargers, poor battery conductivity, large resistance, low solubility and dissolution speed, and other shortcomings of ordinary photovoltaic charge controllers in the prior art, the utility model uses the MPPT algorithm to improve the overall photoelectric conversion efficiency of the system , The pulse charging mode can slow down the sulfation crystallization process, repair damaged batteries, and effectively prolong their service life. In addition, the real-time monitoring of the surface temperature of the battery and the function of automatically stopping charging due to over-temperature make the charging process always in a safe state.

In order to achieve the above-mentioned technical purpose and achieve the above-mentioned technical effect, the utility model adopts the following technical solutions:

A wide-voltage input intelligent photovoltaic charging control system with MPPT function, including a solar cell array and a storage battery, the solar cell array is connected with a buck-boost circuit, and the buck-boost circuit is connected with a charging circuit with a pulse charging function, so The charging circuit is connected to the storage battery; it also includes a single-chip controller, the single-chip controller is connected to the charging circuit, and is used to control the charging circuit to charge in charging modes with different functions, including fast charging, pulse charging, float charging and Automatically stop charging, the output terminal of the charging circuit is fed back to the single-chip controller through the current and voltage detection circuit, and the single-chip controller is also connected to the buck-boost circuit through the switch PWM control circuit, and the switch PWM control circuit The equivalent resistance of the load part is changed by adjusting the pulse duty cycle of the switch tube.

Further, the battery is also connected with a temperature sensor for monitoring the surface temperature of the battery in real time, and the temperature sensor is connected to the single-chip microcomputer control circuit; the temperature sensor monitors the surface temperature of the battery in real time, so that the charging process is always in a safe state , When its surface temperature exceeds 45 ℃, it will automatically stop charging.

Further, the single-chip microcomputer control circuit is also connected with a liquid crystal module for display and alarm.

Compared with the prior art, the utility model has the following advantages:

(1) The utility model adopts the MPPT algorithm, and the photoelectric conversion efficiency of the system is high;

(2) Through the buck-boost circuit, a wide voltage input can be realized, and the charging function can be realized within the input voltage range of 5V-26V;

(3) When charging, it has the functions of fast charging, pulse charging and floating charging, which can effectively delay the service life of the battery;

(4) When the battery temperature reaches the set value, the charging is automatically turned off, charging safely and protecting the battery;

(5) After repeated tests, the wide voltage input intelligent photovoltaic charging control system of the utility model works stably and reliably.

The above description is only an overview of the technical solution of the utility model. In order to understand the technical means of the utility model more clearly and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiment of the utility model with accompanying drawings. back.

Description of drawings

The drawings described here are used to provide a further understanding of the utility model and constitute a part of the application. The schematic embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute improper limitations to the utility model. In the attached picture:

Figure 1 is an equivalent circuit diagram of a solar panel.

FIG. 2 is a graph showing the relationship between the output power of the solar panel and the output voltage and current.

Figure 3 is a circuit diagram of the linear system.

Fig. 4 is a general schematic diagram of the wide voltage input intelligent photovoltaic charging system with MPPT function of the present invention.

Fig. 5 is a schematic diagram of a buck-boost circuit of a wide voltage input intelligent photovoltaic charging system with MPPT function of the present invention.

Fig. 6 is a schematic diagram of the charging circuit of the wide voltage input intelligent photovoltaic charging system with MPPT function of the present invention.

Fig. 7 is a schematic diagram of the voltage and current detection circuit of the wide voltage input intelligent photovoltaic charging system with MPPT function of the present invention; among them, Fig. 7 (a) is a schematic diagram of a voltage detection circuit; Fig. 7 (b) is a schematic diagram of a circuit detection circuit picture.

Detailed ways

The utility model will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

Referring to Fig. 4, a wide voltage input intelligent photovoltaic charging control system with MPPT function includes a solar cell array 8 and a storage battery 9, the solar cell array 8 is connected with a buck-boost circuit 1, and the buck-boost circuit 1 is connected to the charging circuit 2 with pulse charging function, and the charging circuit 2 is connected to the battery 9; it also includes a single-chip controller 6, and the single-chip controller 6 is connected to the charging circuit 2 for controlling the charging circuit to perform different functions Charge in the charging mode, including fast charging, pulse charging, floating charging and automatic stop charging. The output terminal of the charging circuit 2 is fed back to the single-chip controller 6 through the current and voltage detection circuit 3, and the single-chip controller 6 It is also connected to the buck-boost circuit 1 through a switch PWM control circuit 4, and the switch PWM control circuit 4 changes the equivalent resistance of the load part by adjusting the pulse duty cycle of the switch tube.

Further, the storage battery 9 is also connected with a temperature sensor 7 for real-time monitoring of the surface temperature of the storage battery, and the temperature sensor 7 is connected to the single-chip microcomputer control circuit 6; the temperature sensor 6 monitors the surface temperature of the storage battery 9 in real time, so that The charging process is always in a safe state, and it will automatically stop charging when its surface temperature exceeds 45°C.

Further, the single-chip microcomputer control circuit 6 is also connected to a liquid crystal module 5 for display and alarm, and the liquid crystal module 5 is connected to the temperature sensor 7 .

Referring to FIG. 5 , the buck-boost circuit 1 includes a boost regulator circuit 101 mainly composed of a boost regulator U1 and a switching voltage regulator circuit 102 mainly composed of a switching voltage regulator U2. The output end of the voltage regulator circuit 101 is connected to the input end of the switching voltage regulator circuit 102; the input end of the boost voltage regulator circuit 101 is connected with the first regulator tube D1, and the output end is connected with the light-emitting diode D2 A light-emitting branch formed in series with a resistor; the feedback end of the switching voltage regulating circuit 102 is an adjustable resistor R_adj, one end of the adjustable resistor R_adj is grounded through a resistor, and the other end is grounded through a capacitor.

Referring to FIG. 6, the charging circuit 2 is mainly composed of a current source U3 of an adjustable output switching mode synchronous rectifier, and the current detection negative comparator input terminal CS- of the current detection negative comparator input terminal CS- of the current source U3 of the adjustable output switching mode synchronous rectifier A first resistor R1 is connected between the input terminals CS+ of the positive current detection comparator through the second switch J2 and the third switch J3, and a second resistor R2 is connected through the fourth switch J4 and the fifth switch J5. The first resistor A first switch J1 is connected across R1, and a sixth switch J6 is connected across the second resistor R2.

Preferably, the current source U3 of the adjustable output switching mode synchronous rectifier is a MAX1640 integrated chip or a MAX1641 integrated chip.

When the current source U3 of the adjustable output switching mode synchronous rectifier is a MAX1640 integrated chip, the first switch J1, the fourth switch J4, and the fifth J5 switch need to be disconnected, and the second switch J2, the third switch J3, and the The six switches J6 are closed; when the current source U3 of the adjustable output switching mode synchronous rectifier is a MAX1641 integrated chip, the first switch J1, the fourth switch J4, and the fifth J5 switch need to be closed, and the second switch J2, the third The switch J3 and the sixth switch J6 are turned off.

Referring to FIG. 7 , the current and voltage detection circuit 3 includes a current detection circuit, a voltage detection circuit and an A/D conversion circuit, and the A/D conversion circuit is used for collecting voltage and current. The current detection circuit mainly includes a first two-way differential input operational amplifier U4 , as shown in FIG. 7( a ). The voltage detection circuit mainly includes a second dual-channel differential input operational amplifier U5, as shown in FIG. 7(b).

The above descriptions are only preferred embodiments of the utility model, and are not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present utility model shall be included in the protection scope of the present utility model.

Claims (10)

1. A wide voltage input intelligent photovoltaic charging control system with MPPT function, including a solar cell array (8) and a storage battery (9), characterized in that: the solar cell array (8) is connected with a power supply for realizing the output voltage of the solar cell panel A buck-boost circuit (1) with stabilized voltage input, the buck-boost circuit (1) is connected to a charging circuit (2) with a pulse charging function, and the charging circuit (2) is connected to the battery (9); it also includes A single-chip controller (6), the single-chip controller (6) is connected to the charging circuit (2), and is used to control the charging circuit to perform charging in different charging modes, including fast charging, pulse charging, floating charging and automatic charging. stop charging, the output terminal of the charging circuit (2) is fed back to the single-chip controller (6) through the current and voltage detection circuit (3), and the single-chip controller (6) is also connected through the switch PWM control circuit (4) For the buck-boost circuit (1), the switch PWM control circuit (4) changes the equivalent resistance of the load part by adjusting the pulse duty cycle of the switch tube. 2. The wide voltage input intelligent photovoltaic charging control system with MPPT function according to claim 1, characterized in that: the battery (9) is also connected with a temperature sensor (7) for real-time monitoring of the surface temperature of the battery, the The temperature sensor (7) is connected to the single-chip microcomputer control circuit (6). 3. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 1, characterized in that: the single-chip microcomputer control circuit (6) is also connected to a liquid crystal module (5) for display and alarm. 4. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 2, characterized in that: the single-chip microcomputer control circuit (6) is also connected to a liquid crystal module (5) for display and alarm. 5. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 1, characterized in that: the step-up and step-down circuit (1) includes a step-up voltage booster mainly composed of a step-up regulator (U1) A voltage regulator circuit (101) and a switching voltage regulating circuit (102) mainly composed of a switching voltage regulator (U2), the output terminal of the boosting voltage regulator circuit (101) is connected to the switching voltage regulating circuit (102 ) input terminal; the input terminal of the step-up voltage regulator circuit (101) is connected with a first voltage regulator tube (D1), and the output terminal is connected with a light-emitting branch composed of a light-emitting diode (D2) and a resistor connected in series; the The feedback terminal of the switch voltage regulating circuit (102) is an adjustable resistor (R_adj), one end of the adjustable resistor (R_adj) is grounded through a resistor, and the other end is grounded through a capacitor. 6. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 1, characterized in that: the charging circuit (2) is mainly composed of a current source (U3) of a synchronous rectifier with an adjustable output switch mode, The adjustable output switching mode synchronous rectifier current source (U3) is connected between the current detection negative comparator input terminal (CS-) and the positive current detection comparator input terminal (CS+) through the second switch (J2) and the third The switch (J3) is connected with the first resistor (R1), and is connected with the second resistor (R2) through the fourth switch (J4) and the fifth switch (J5), and the first resistor (R1) is connected across the first resistor (R1). A switch (J1), a sixth switch (J6) connected across the second resistor (R2). 7. The wide voltage input intelligent photovoltaic charging control system with MPPT function according to claim 6, characterized in that: the current source (U3) of the adjustable output switch mode synchronous rectifier is a MAX1640 integrated chip or a MAX1641 integrated chip. 8. The wide voltage input intelligent photovoltaic charging control system with MPPT function according to any one of claims 1 to 7, characterized in that: the current and voltage detection circuit (3) includes a current detection circuit and a voltage detection circuit. 9. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 8, characterized in that: the current detection circuit mainly includes a first two-way differential input operational amplifier (U4). 10. The wide-voltage input intelligent photovoltaic charging control system with MPPT function according to claim 8, characterized in that: the voltage detection circuit mainly includes a second dual-way differential input operational amplifier (U5).

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