CN201328012Y - Device for improving output efficiency of low power photovoltaic battery - Google Patents

Abstract

The utility model discloses a device for improving the output efficiency of a low-power photovoltaic cell, which belongs to the field of photoelectric technology. By configuring a supercapacitor and an optimal voltage controller between the photovoltaic cell and the energy storage, using the characteristics of the small internal resistance of the supercapacitor, the supercapacitor terminal voltage Vc directly affects the output voltage Vs of the photovoltaic cell; by controlling the charging and discharging of the supercapacitor The process controls the output voltage of the photovoltaic cell, so that the photovoltaic cell works in the maximum output power area, thereby effectively improving the output efficiency of the photovoltaic cell. The utility model has the advantages of simple circuit and low power consumption, and is suitable for use in low-power micro-photovoltaic systems.

Description

A device for improving the output efficiency of low-power photovoltaic cells

technical field

The utility model relates to a device for improving the output efficiency of a low-power photovoltaic cell, which belongs to the field of photoelectric technology.

Background technique

The manufacturing technology of photovoltaic cells and photovoltaic power generation technology are quite mature. However, the use of photovoltaic micro-energy to power the system in photovoltaic energy autonomous micro-systems has only been researched and applied in recent years. In photovoltaic energy autonomous microsystems, the area of photovoltaic cells is usually less than tens of square centimeters, the output voltage is low (generally several volts), and the power is less than 1 watt. Therefore, there is a need to improve the photovoltaic cell output efficiency of microsystems.

In the invention patent application "lithium-ion battery-supercapacitor hybrid energy storage photovoltaic system" (application number: 200710178894), the structure of photovoltaic energy storage using supercapacitors and lithium-ion batteries is introduced. In "Maximum Power Tracking Method and Device for Solar Power Generation System" (patent application number: CN200610098495.1), a method for maximum power point tracking using a DC-DC converter is introduced. In the document "Research on Supercapacitor-Battery Hybrid Energy Storage Independent Photovoltaic System" (Acta Solaris Sinica, Vol. 28, No. 2, pp178-183), a hybrid energy storage scheme of supercapacitor and lead-acid battery is proposed. These systems have good application prospects in high-power photovoltaic cell power generation systems, but are not suitable for low-power photovoltaic cell systems. The main reasons are: the complexity of the control system, the large power consumption of the control circuit itself, and the large conversion loss of the BUCK conversion circuit. When used in low-power photoelectric energy, it will increase the power consumption of the system and reduce the output power of the system.

Contents of the invention

The purpose of the utility model is to provide a device for improving the output efficiency of the low-power photovoltaic cell in order to improve the output efficiency of the photovoltaic cell in the low-power photovoltaic cell system.

In order to achieve the above object, the technical scheme adopted by the utility model is as follows:

A device for improving the output efficiency of a low-power photovoltaic cell, comprising:

Photovoltaic cell 1 , supercapacitor 2 , optimal voltage controller 3 , energy storage switch 4 , energy storage 5 and diode 6 .

The photovoltaic cell 1 converts solar energy into electrical energy;

The diode 6 acts as a reverse bias protection to prevent the photovoltaic cell 1 from being reversely input.

The supercapacitor 2 is used as an energy buffer to temporarily store the output energy of the photovoltaic cell 1 and to charge the energy storage 5 under the control of the optimal voltage controller 3 . This is because the supercapacitor 2 has the characteristics of long life, small internal resistance, and high output power density, which can avoid adverse effects caused by frequent charging and discharging of the energy storage 5 due to unstable output of the photovoltaic cell 1 .

The optimal voltage controller 4 detects the output voltage of the supercapacitor 2 and generates an optimal voltage control signal through calculation to control the on-off of the energy storage switch, thereby achieving the function of controlling the charging and discharging process. In order to make the photovoltaic cell 1 work in the optimal voltage variation region, the optimal voltage controller 2 is composed of a controller with hysteresis characteristics.

The energy storage 5 is used to store the output electric energy of the photovoltaic cell 1 .

Wherein, the photovoltaic cell 1 can be equivalent to a parallel connection of an ideal current source I _ph and a diode D, and Rs is its equivalent internal resistance. Its output voltage charges the supercapacitor 2 through the diode 6 (D1). Optimal voltage controller 3 consists of a step-up DC-DC converter, resistors R1, R2, R3, and an integrated operational amplifier.

The output end of the photovoltaic cell 1 is connected to the anode of the diode D1 , and the cathode of D1 is connected to the anode of the supercapacitor 2 . The input terminal of the DC-DC converter is connected to the positive pole of the supercapacitor 2, and the output terminal of the DC-DC converter is connected to the power supply terminal of the integrated operational amplifier. One end of the resistor R1 is connected to the reverse end of the integrated operational amplifier, and the other end is connected to the positive pole of the supercapacitor 2 . One end of the resistor R2 is connected to the output end of the DC-DC converter, and the other end is connected to the non-inverting end of the integrated operational amplifier. One end of the resistor R3 is connected to the output end of the integrated operational amplifier, and the other end is connected to the same direction end of the integrated operational amplifier. The output terminal of the integrated operational amplifier is connected to the control terminal of the energy storage switch 5 , the output terminal of the energy storage switch 5 is connected to the positive pole of the energy storage 4 , and the input terminal of the energy storage switch 5 is connected to the positive pole of the supercapacitor 2 . The negative pole of the photovoltaic cell 1 is connected with the negative poles of the supercapacitor 2 and the energy storage 5 at the same time.

Beneficial effect

The device for improving the output efficiency of low-power photovoltaic cells proposed by the utility model is based on the optimal voltage control method, and the output voltage of the photovoltaic cells is at the optimum by disposing a super capacitor and an optimal voltage controller between the photovoltaic cell and the energy storage. The voltage change area effectively improves the output efficiency of the photovoltaic cell. The utility model has the advantages of simple circuit and low power consumption, and is suitable for use in low-power micro-photovoltaic systems.

Description of drawings

Fig. 1 is a circuit schematic diagram of improving the output efficiency of photovoltaic cells by adopting the optimal voltage control method;

Among them, 1-photovoltaic cell, 2-supercapacitor, 3-optimal voltage controller, 4-energy storage switch, 5-energy storage, 6-diode.

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the utility model is described in detail.

As shown in Figure 1, the device for improving the output efficiency of low-power photovoltaic cells of the present invention includes:

Photovoltaic cell 1 , supercapacitor 2 , optimal voltage controller 3 , energy storage switch 4 , energy storage 5 and diode 6 .

Wherein, the photovoltaic cell 1 can be equivalent to a parallel connection of an ideal current source I _ph and a diode D, and Rs is its equivalent internal resistance. Its output voltage charges the supercapacitor 2 through the diode 6 (D1). Optimal voltage controller 3 consists of a step-up DC-DC converter, resistors R1, R2, R3, and an integrated operational amplifier.

The output end of the photovoltaic cell 1 is connected to the anode of the diode D1 , and the cathode of D1 is connected to the anode of the supercapacitor 2 . The input terminal of the DC-DC converter is connected to the positive pole of the supercapacitor 2, and the output terminal of the DC-DC converter is connected to the power supply terminal of the integrated operational amplifier. One end of the resistor R1 is connected to the reverse end of the integrated operational amplifier, and the other end is connected to the positive pole of the supercapacitor 2 . One end of the resistor R2 is connected to the output end of the DC-DC converter, and the other end is connected to the non-inverting end of the integrated operational amplifier. One end of the resistor R3 is connected to the output end of the integrated operational amplifier, and the other end is connected to the same direction end of the integrated operational amplifier. The output terminal of the integrated operational amplifier is connected to the control terminal of the energy storage switch 5 , the output terminal of the energy storage switch 5 is connected to the positive pole of the energy storage 4 , and the input terminal of the energy storage switch 5 is connected to the positive pole of the supercapacitor 2 . The negative pole of the photovoltaic cell 1 is connected with the negative poles of the supercapacitor 2 and the energy storage 5 at the same time.

Example

Assuming a photovoltaic cell with an area of 150mm×67mm is under the condition of average solar irradiance E=93mW/ ^cm2 , in an optimal voltage control cycle, the output energy of the photovoltaic cell is stored in two 120F supercapacitors in series.

When the voltage of the supercapacitor rises from 4.3V to 5.3V, the output power _W1 of the photovoltaic cell is as follows:

${\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; (</span>{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 30</span>}<span\; class="notranslate">\; \&times;</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; 5.3</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; 4.3</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

=288(J)

The average output conversion efficiency of the photovoltaic cell is η ₀ =9.1%.

As a comparison, if the optimal voltage control is not used, that is, the voltage is not controlled in the optimal voltage range, as shown in b in Figure 5, but the output of the photovoltaic cell is directly stored in a 70F supercapacitor, the When the voltage is from 0.46V to 1.162V, the output energy W ₂ of the photovoltaic cell 1 is 79.38 (J). After calculation by the above formula, the output conversion efficiency of the photovoltaic cell is η ₀ =2.5%.

It can be seen that after adopting the optimal voltage control, the output conversion rate of the photovoltaic cell is increased by nearly 3 times.

Claims (1)

1. A device for improving the output efficiency of a low-power photovoltaic cell, comprising a photovoltaic cell (1), an energy store (3), a supercapacitor (2), and a diode (6), characterized in that it also includes an optimal voltage controller ( 3) and energy storage switch (5); Among them, the photovoltaic cell (1) can be equivalent to a parallel connection of an ideal current source I _ph and a diode D, Rs is its equivalent internal resistance, and its output voltage charges the supercapacitor (2) through the diode (6); the optimum voltage The controller (3) is composed of a step-up DC-DC converter, resistors R1, R2, R3, and an integrated operational amplifier; The output end of the photovoltaic cell (1) is connected to the anode of the diode (6), the cathode of the diode (6) is connected to the anode of the supercapacitor (2), and the input end of the DC-DC converter is connected to the anode of the supercapacitor (2). The positive poles are connected, the output end of the DC-DC converter is connected with the power supply end of the integrated operational amplifier; one end of the resistor R1 is connected with the reverse end of the integrated operational amplifier, and the other end is connected with the positive pole of the supercapacitor (2); One end of the resistor R2 is connected to the output end of the DC-DC converter, and the other end is connected to the same direction end of the integrated operational amplifier; one end of the resistor R3 is connected to the output end of the integrated operational amplifier, and the other end is connected to the integrated operational amplifier. The same direction terminal is connected; the output terminal of the integrated operational amplifier is connected with the control terminal of the energy storage switch (5), the output terminal of the energy storage switch (5) is connected with the positive pole of the energy storage device (4), and the energy storage switch (5) ) is connected to the positive pole of the supercapacitor (2); the negative pole of the photovoltaic cell (1) is connected to the negative pole of the supercapacitor (2) and the energy storage (5) at the same time.