TWI385905B - Photovoltaic simulation apparatus - Google Patents

Description

Solar cell simulation device

This invention relates to a solar power plant, and more particularly to a simulator for a solar cell.

With the increasing demand for energy, the use of so-called renewable energy has become a very important issue in today's energy development. These renewable energy sources are theoretically inexhaustible natural energy sources such as solar energy, wind energy, tax revenue, tidal energy or biomass energy. Among them, the use of solar energy is a very important and popular part of research on energy development in recent years.

Since the voltage-current (VI) characteristic curve of a solar cell is not the same as a common commercial power supply. Please refer to FIG. 1 below. FIG. 1 shows an equivalent circuit diagram of a solar cell. The characteristic equation of the equivalent circuit of this solar cell is as shown in the following formula (1):

Where I ₀ represents the reverse saturation current of diode D, I _SC is the amount of light-converting current, R _S represents the effect of contact resistance and lead, and R _P represents the effect of leakage current, the above variables are dependent on the materials used. And production technology. And q is the unit charge = 1.6 * 10 ^-19 Coulomb (c), k is the Boltzmann constant = 1.38 * 10 ^-23 Joules (J) / ° K, T is the ambient temperature (at absolute temperature °K Unit)), R _L is the load impedance, and V and I are the output voltage and output current of the solar cell.

In addition, according to Ohm's law, V=R _L *I, and referring to equation (1), it is clear that when the load impedance R _L changes, the output voltage V and the output current I also change at the same time, and the output thereof The relationship between the voltage V and the output current I is as shown in FIG. 2, and the nonlinear relationship between the output voltage V of the solar cell and the output current I is shown.

Therefore, when conducting research on solar cells, it is impossible to assist research with a general power supply. However, if you directly use a variety of solar cells of different specifications for research, it will make the required experimental equipment more complicated and increase the cost of research.

Accordingly, the present invention provides a solar cell simulation device that provides a development platform for a solar cell device by simulating the characteristics of the solar cell.

The invention provides a solar cell simulation device, which comprises a calculator, a power converter and a signal feedback device. The calculator receives the illuminance parameter and the temperature parameter, and establishes a solar cell model according to the illuminance parameter and the temperature parameter received. In addition, the calculator also receives the feedback voltage and the feedback current, and calculates the operating point of the solar cell simulation device according to the received feedback voltage and the feedback current corresponding to the built solar battery model. And thereby generating a switching control signal.

In addition, the power converter is coupled to the calculator and receives a reference voltage, converts the reference voltage according to the conversion control signal to generate an output voltage, and provides the output voltage to the load. One end of the signal feedback device is coupled to the power converter and the load, and the other end is coupled to the calculator. The signal feedback device receives the output current and the output voltage flowing to the load, and respectively generates The above feedback voltage and feedback current.

The present invention uses a calculator to calculate a solar cell model to be simulated by a solar cell simulation device. Therefore, it is possible to develop a device for relative application without using a plurality of different sets of solar cells, and other devices such as a light source and a heat sink, and to study different solar cells.

The above described features and advantages of the present invention will be more apparent from the following description.

In the following, a plurality of embodiments will be described with reference to the solar cell simulation device of the present invention, and are illustrated by the following, in order to be understood by those skilled in the art and implemented.

Please refer to FIG. 3 first. FIG. 3 is a schematic diagram of an embodiment of a solar cell simulation device of the present invention. The solar cell simulation device 300 includes a calculator 310, a power converter 320, and a signal backhaul 330. The power converter 320 is coupled to the calculator 310 and coupled to the signal feedback device 330. Solar cell simulation device 300 is coupled to load 340 and is used to provide load 340 power.

In terms of the overall operation of the solar cell simulation device 300. In order to increase the reaction speed of the solar cell simulation device 300 and reduce the computational complexity of the calculator 310, first, the equation (1) explained in the above prior art is simplified. The resistance R _P which causes the leakage current is regarded as infinite, and the equation (2) shown in the following formula (1) is rewritten:

In addition, assuming that the equivalent impedance of the load 340 is R _L , in accordance with Ohm's law V=R _L *I substituted into the equation (2), the equation (3) can be organized as follows:

The calculator 310 receives the illuminance parameter LUMIN and the temperature parameter TEMPIN. The temperature parameter TEMPIN corresponds to the ambient temperature T in the equation (3), and the illumination parameter LUMIN is used to correspond to the I _SC in the formula (3). In addition, the calculator 310 also receives the feedback signals returned by the signal backhaul 330, which are the feedback currents IFB returned by the current feedback circuit 332 in the signal backhaul 330, and are returned by the signals. The feedback voltage VFB returned by the voltage feedback circuit 331 in the transmitter 330. Wherein, R _L in the formula (3) is equivalent to the feedback voltage VFB divided by the feedback current IFB.

After the calculator 310 obtains the above related data (where k and q are constants), and the setting of the reverse saturation current I ₀ , the I in the equation (3), that is, the solar cell simulation can be calculated. The operating point of the solar cell to be simulated by the device 300 outputs the current I _OP . Specifically, the reverse saturation current I ₀ is set according to the solar cell to be simulated, that is, different solar cells have different reverse saturation currents I ₀ .

The calculator 310 determines the operating point output current I _OP , that is, the output current IO that is desired to be generated by the solar cell simulation device 300 is equal to the operating point output current I _OP . The equivalent impedance corresponding to the load 340 is R _L , and the desired output voltage VO of the solar cell simulation device 300 should be I _OP *R _L . In other words, the output voltage VO that the power converter 320 should produce is equal to I _OP *R _L .

In order for the power converter 320 to generate the output voltage VO described above, the calculator 310 generates a corresponding switching control signal CCS to control the power converter 320. The power converter 320 can be a DC-to-DC power converter or an AC-to-DC power converter. Therefore, the switching control signal CCS that controls the power converter 320 is a periodic pulse width modulation (PWM). ) Signal. The power converter 320 converts and generates the required output voltage VO according to the conversion control signal CCS and the reference voltage VDC received by it.

In the following, the voltage feedback circuit 331 and the current feedback circuit 332 and the calculator 310 in the power converter 320 and the signal feedback device 330 are separately described in the embodiments, so that those skilled in the art can better understand the solar battery. An embodiment of the simulation device 300.

Please refer to FIG. 3 and FIG. 4 at the same time. FIG. 4 illustrates an embodiment of the power converter 320 of FIG. In the present embodiment, the power converter 320 is a buck power converter of a DC to DC power converter. The power converter 320 is coupled by an inductor L1, a capacitor C1, a transistor T1, and a diode D1. The transistor T1 is controlled by the switching control signal CCS and the path of the disable/enable reference voltage VDC to the inductor L1. When the transistor T1 is enabled and turned on, the inductor L1 is connected to the reference voltage VDC and begins to store energy. The inductor L1 converts the stored electrical energy into the capacitor C1 when the transistor T1 is disabled.

Please pay special attention here, since the conversion control signal CCS is a periodic pulse width modulation signal, therefore, the positive pulse width is just It can be used to adjust the on-time of the transistor T1. Therefore, in the above embodiment, the calculator 310 can effectively achieve the function of causing the power converter 320 to generate the required output voltage VO by controlling the switching control signal CCS.

It is worth mentioning that the above embodiment of the power converter 320 is a step-down power converter that generates a voltage lower than the reference voltage VDC. If the solar cell simulation device 300 is to provide a voltage 340 higher than the reference voltage VDC, the power converter 320 must be replaced with a booster power converter.

However, either a step-up power converter or a step-down power converter is a power converter for generating a DC voltage. If the load 340 is an electronic device that requires an AC power source (such as a home appliance such as a television or an electric fan), a DC to AC power converter may be added after the power converter 320.

In addition, it is worth mentioning that the power converter 320 can be another AC-to-DC power converter in addition to a power converter that converts a DC voltage into a DC voltage.

Referring to FIG. 3 and FIG. 5 simultaneously, FIG. 5 illustrates an embodiment of the current feedback circuit 332 of FIG. The current feedback circuit 332 includes a Hall sensing unit 510 and an amplifier unit 520. The Hall sensing unit 510 detects the output current IO on the load 340. Such a method of detecting current using the Hall sensing unit 510 is a technique well known in the art with ordinary knowledge, and the principle thereof will not be described in detail herein.

In addition, in the present embodiment, the amplifier unit 520 includes a differential amplifier The amplifier 521, the proportional amplifier 522, and a Zener diode ZD1 function as a voltage limiting function. The differential amplifier 521 is mainly used to sense the output current IO from the Hall sensing unit 510 and convert it into a voltage form. The proportional amplifier 522 is used to adjust the amplitude level of this voltage signal. The Zener diode ZD1 is used to limit the maximum voltage value of the feedback current IFB outputted by the current feedback circuit 332. In general, the proportional amplifier 522 adjusts the average value of the output voltage of the differential amplifier 521 described above to be half of the maximum voltage value limited by the Zener diode ZD1.

As a matter of value, the current feedback circuit 332 may further include an analog to digital converter (ADC) unit 530 to convert the output feedback current IFB into a digital form. In this way, the current feedback circuit 332 can directly provide a digital signal to the calculator 310 constructed by using the digital circuit to perform operations.

Referring to FIG. 3 and FIG. 6 simultaneously, FIG. 6 illustrates an embodiment of the voltage feedback circuit 331 of FIG. The voltage feedback circuit 331 of the present embodiment includes a voltage follower unit 610 and a proportional amplifier 620. Further, the voltage feedback circuit 331 further includes a sigma diode ZD2 as a voltage limiting function. The voltage-synchronization unit 610 is used as an analog voltage buffer to enhance the driving capability of the output voltage VO, and the proportional amplifier 620 is coupled to the voltage-synchronization unit 610 for adjusting the generated voltage. The feedback voltage VFB voltage value. The JD diode ZD2 limits the maximum voltage of the feedback voltage VFB.

In general, the proportional amplifier 620 adjusts the average value of the voltage of the feedback voltage VFB to the maximum voltage value limited by the Zener diode ZD2. Half of it.

Like the embodiment of the current feedback circuit 332, the voltage feedback circuit 331 may further include an analog digital conversion unit 630 for converting the output voltage VFB into an output voltage in the form of a digital bit. In this way, the voltage feedback circuit 331 can directly provide a digital signal to the calculator 310 constructed by the digital circuit to perform the operation.

In addition, the calculator 310 is a computing power processor, such as a common personal computer (PC), a micro co-processor unit (MCU), or a digital signal processing unit (DSP). Both can be implemented as an implementation calculator 310. In the implementation of the solar cell simulation device 300, the digital signal processing unit is used, and the function of the calculator 310 is executed in conjunction with the software program.

Hereinafter, the flow of the software program in the calculator 310 used in the solar battery simulation device 300 will be described in a flowchart. The implementation of the calculator 310 will be explained more closely.

Please refer to FIG. 7. FIG. 7 is a flow chart showing the operation of the software program of the calculator 310. First, the illuminance parameter and the temperature parameter are set to the solar cell simulation device 300 (step S710), and then the feedback voltage and the feedback current are read (step S720). The equivalent resistance R _L =VFB/IFB of the load is calculated using the read feedback voltage VFB and the feedback current IFB (step S730). The operating point output current I _{OP is} calculated by the equation (3) in the above description of the embodiment (step S740), and the operating point output voltage V _OP is further calculated (step S750). Finally, the corresponding conversion control signal CCS is generated according to the output point output voltage V _OP to be output, and output to the power converter (step S760).

In summary, the present invention uses a calculator to calculate the voltage and current characteristics of the solar cell to be simulated, and generates a corresponding operating point output voltage and an operating point output current for the driven load. To provide a work platform for conducting related research on solar devices. In turn, solar device research can be more convenient, more accurate, and more cost effective.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

300‧‧‧Solar battery simulator

310‧‧‧Calculator

320‧‧‧Power Converter

330‧‧‧Signal Retriever

331‧‧‧Voltage feedback circuit

332‧‧‧current feedback circuit

340‧‧‧load

510‧‧‧ Hall Sensing Unit

520‧‧Amplifier unit

521‧‧‧Differential Amplifier

522‧‧‧Proportional amplifier

530, 630‧‧‧ analog digital conversion unit

610‧‧‧Voltage Dependent Unit

620‧‧‧Proportional amplifier

S710~S760‧‧‧Steps

R _P , R _S ‧‧‧ resistance

R _L ‧‧‧load impedance

L1‧‧‧Inductance

D1, ZD1, ZD2‧‧‧ diodes

T1‧‧‧O crystal

C1‧‧‧ capacitor

CCS‧‧‧ conversion control signal

VDC‧‧‧ reference voltage

VO, V, V _OP ‧‧‧ output voltage

I, IO, I _OP ‧‧‧ output current

TEMPIN‧‧‧ temperature parameters

LUMIN‧‧‧ illuminance parameters

IFB‧‧‧Responding current

VFB‧‧‧ feedback voltage

FIG. 1 is an equivalent circuit diagram of a solar cell.

FIG. 2 is a diagram showing the relationship between the output voltage V of the solar cell and the output current I.

3 is a schematic view showing an embodiment of a solar cell simulation device of the present invention.

FIG. 4 illustrates an embodiment of the power converter 320 of FIG.

FIG. 5 illustrates an embodiment of the current feedback circuit 332 of FIG.

FIG. 6 illustrates an embodiment of the voltage feedback circuit 331 of FIG.

FIG. 7 is a flow chart showing the operation of the software program of the calculator 310.

300‧‧‧Solar battery simulator

310‧‧‧Calculator

320‧‧‧Power Converter

330‧‧‧Signal Retriever

331‧‧‧Voltage feedback circuit

332‧‧‧current feedback circuit

340‧‧‧load

CCS‧‧‧ conversion control signal

VDC‧‧‧ reference voltage

VO‧‧‧ output voltage

IO‧‧‧ output current

TEMPIN‧‧‧ temperature parameters

LUMIN‧‧‧ illuminance parameters

IFB‧‧‧Responding current

VFB‧‧‧ feedback voltage

Claims (10)

A solar battery simulation device for providing a load power source includes: a calculator receiving an illumination parameter and a temperature parameter, establishing a solar battery model according to the illumination parameter and the temperature parameter, and further receiving the calculator Transmitting a voltage and a feedback current, and calculating a working point of the solar cell simulation device according to the feedback voltage and the feedback current corresponding to the solar cell model, and thereby generating a conversion control signal; a power converter, coupled Connected to the calculator, and receive a reference voltage, convert the reference voltage according to the conversion control signal to generate an output voltage to the load; and a signal feedback device, one end of which is coupled with the power converter and the load The other end is coupled to the calculator, and the signal feedback device receives an output current flowing to the load and the output voltage to respectively generate the feedback voltage and the feedback current. The solar cell simulation device of claim 1, wherein the power converter comprises a DC power converter or an AC to DC power converter. The solar cell simulation device of claim 2, wherein when the power converter is the DC to DC power converter, the power converter comprises a step-down power converter or a step-up power converter. The solar cell simulation device of claim 1, wherein the conversion control signal is a periodic pulse width modulation signal. The solar cell simulation device of claim 1, wherein the signal feedback device comprises: a current feedback circuit for receiving the output current to generate the feedback current; and a voltage feedback circuit for The output voltage is received and the output voltage is adjusted to generate the feedback voltage. The solar cell simulation device of claim 5, wherein the current feedback circuit comprises: a Hall sensing unit coupled to the load for detecting the output current; and an amplifier unit coupled Connected to the Hall sensing unit for converting the output current to a corresponding voltage signal, and adjusting the corresponding voltage to generate the feedback current. The solar cell simulation device of claim 6, wherein the current feedback circuit further comprises: a first analog digital conversion unit for converting the feedback current into a digital signal. The solar cell simulation device of claim 5, wherein the voltage feedback circuit comprises: a voltage follower unit coupled to the load for enhancing the driving capability of the output voltage; and a proportional amplifier unit And coupled to the voltage follower unit for adjusting a voltage value of the output voltage to generate the feedback voltage. Solar cell simulation package as described in claim 8 The voltage feedback circuit further includes: a second analog digital conversion unit for converting the feedback voltage into a digital signal. The solar cell simulation device of claim 1, wherein the calculator comprises a digital signal processing unit, a micro processing unit or a personal computer.