JP2015188273A - defect diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect diagnosis device that can efficiently detect defect of an electronic device having a semiconductor element such as a solar battery or the like.SOLUTION: A defect diagnosis device has an acquiring part for acquiring a duty ratio for controlling an output voltage of an electronic device having a semiconductor element to a target voltage, a first calculator for calculating an integrated duty ratio obtained by the output voltage is varied and integrated with plural sine waves having different frequencies with the duty ratio as a reference, a second calculator for calculating an impedance of each frequency to the target voltage on the basis of the output voltage and output current of the electronic device when the integrated duty ratio is controlled by turn on/off of plural switches, and a determining part for generating characteristic information representing the frequency characteristic of the electronic device on the basis of the impedance of each frequency, collating the generated characteristic information and pre-generated characteristic information and determining the presence or absence of a defect of the semiconductor element or the electronic device.

Description

  The present invention relates to a defect diagnosis apparatus that detects defects in an electronic device that includes a semiconductor element such as a solar cell, and more particularly to a defect diagnosis apparatus that is suitable for efficiently detecting defects in an electronic device.

  As an electronic device provided with a semiconductor, for example, there is a solar battery module provided with a solar battery cell as a semiconductor element (hereinafter, a solar battery cell, a solar battery module, and a solar battery array are also simply referred to as a solar battery). . In general, pn junction diodes (photodiodes) as pn junction semiconductors are used in silicon-based and compound-based solar cells.

  In a solar cell, light is applied to a pn junction diode, and the energy of light is absorbed by an electron (light excitation) through a process opposite to that of an LED (Light Emitting Diode). The electron with the is taken out directly as power. A dye-sensitized solar cell using an oxide semiconductor such as titanium oxide is also known.

  In recent years, the life of solar cells has been extended, and performance degradation due to generation of defects during the period of use has become a problem. The assumed defects are various, and there are cases where the defects already exist due to the manufacturing process, or deterioration is caused by long-term use.

  Currently, as a technology for detecting defects in solar cells, in the manufacturing stage, visual inspection, inspection using an optical microscope, inspection using transmitted X-rays, cross-sectional inspection, inspection using an OM microscope, IV characteristics Inspection, IV characteristic inspection by solar simulator, etc.

  Usually, in the inspection at the time of manufacture, first, the power generation amount is inspected by the IV characteristic, and if the specification is not satisfied, a more detailed inspection is performed.

  Further, for example, in Patent Document 1, high performance is achieved by correlating and optimizing the electrochemical characteristics of the electrolyte layer and the distance between the electrodes in a wet solar cell (a structure in which an electrolyte is stored between two electrodes). And a technology that makes it possible to provide a highly durable photoelectric conversion element by a simple manufacturing method by providing a simple photoelectric conversion element and applying the association to a solid electrolyte.

  Further, in Patent Document 2, in order to calculate a depletion layer capacitance (C) in a semiconductor of a solar cell, a series component in which a resistance component R2 is added in parallel to an inductance component L, a resistance component R1, and a depletion layer capacitance C. In order to solve the technology using an equivalent circuit and the problems of this technology, frequency characteristics of the complex impedance of the device under test are measured in an electronic device such as a solar cell, and evaluated by the Monte Carlo method from the measured value. Calculate the element constant that minimizes the function, calculate the element constant that minimizes the evaluation function using the calculated element constant as the start value of the local search method, and set the number of repetitions of these calculation processes in advance. A technique is described in which a combination of element constants having the smallest value among the minimum values is extracted by repeating the arithmetic processing a predetermined number of times.

  Further, in Patent Document 3, an equivalent circuit in which a secondary battery such as a lithium ion battery or a lead storage battery is connected in series to a circuit in which a resistor (21) and a capacitor (22) are connected in parallel and a resistor (23) is connected. A technique for calculating and analyzing each parameter of the equivalent circuit is described.

JP 2005-044697 A JP 2010-249749 A JP 2013-250223 A

  With the widespread use of solar cells, it is required to improve operational reliability. In order to improve reliability and quality, it is necessary to increase the efficiency of detecting defective products during manufacturing and operation. However, along with this, if the cost required for inspection rises, the spread will be delayed.

  That is, reducing the yield at the time of manufacturing, reducing the inspection cost, and reducing the cost of maintenance inspection and part replacement maintenance during operation are important points for the spread of solar cells.

  A conventional technique for detecting defects in solar cells uses a general semiconductor-related inspection technique, and although it has a sufficient defect inspection capability, the inspection cost is high and it is difficult to identify a defect location. For example, even when a defect is detected, whether it is a defect at the junction interface of a pn junction semiconductor, a defect inside the semiconductor, a defect at the interface between the semiconductor and the metal, or a defect such as a cable. It cannot be specified. Therefore, when a defect is detected, it is necessary to replace the solar cell in units.

  In addition, in any of the techniques of Patent Documents 1 to 3, it is not possible to detect a deteriorated portion in the solar cell. For example, the techniques of Patent Documents 1 and 3 relate to wet solar cells and secondary batteries, and cannot measure solar cells including semiconductor elements. Moreover, the technique of the said patent document 2 only calculates the depletion layer capacity | capacitance in the semiconductor of a solar cell. As described above, none of the above Patent Documents 1 to 3 can efficiently detect the defective portion of the solar cell.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a defect diagnosis apparatus that can efficiently detect defects in an electronic device including a semiconductor such as a solar cell. .

  In order to achieve the above object, a defect diagnosis apparatus according to the present invention includes an acquisition unit that acquires a duty ratio for controlling an output voltage of an electronic device including a semiconductor element to a target voltage, and a plurality of reference values based on the duty ratio. A first calculation unit that calculates an integrated duty ratio by changing the output voltage with sine waves having different frequencies, and an output voltage of the electronic device when the integrated duty ratio is controlled by turning on and off a plurality of switches, and A second computing unit for computing an impedance for each frequency with respect to the target voltage based on an output current; and generating characteristic information indicating a frequency characteristic of the electronic device based on the impedance for each frequency; And a determination unit that determines whether or not there is a defect in the semiconductor element or the electronic device by collating with characteristic information generated in advance. The features.

  The defect diagnosis apparatus may use the target voltage as a plurality of target voltages, and the acquisition unit may acquire a plurality of duty ratios for controlling output voltages of the electronic device to a plurality of target voltages, respectively. 1 calculation unit calculates, for each target voltage of each of the plurality of target voltages, an integrated duty ratio that is integrated by changing the output voltage with a plurality of sine waves having different frequencies with respect to each of the plurality of duty ratios. The second calculation unit is configured to determine the plurality of target voltages based on each of the output voltage and output current of the electronic device when each of the plurality of integrated duty ratios is controlled by turning on and off the plurality of switches. An impedance for each frequency with respect to each target voltage is calculated, and the determination unit performs an impedance for each frequency of the electronic device with respect to each target voltage of the plurality of target voltages. Based on the dance, characteristic information indicating the frequency characteristic of the electronic device is generated, and the generated characteristic information is compared with the previously generated characteristic information to determine the presence or absence of a defect in the semiconductor element or the electronic device. It is characterized by that.

  In the defect diagnosis apparatus, the plurality of sine waves are sine waves having different frequencies and phases.

  In the defect diagnosis apparatus, the determination unit generates a Nyquist diagram or a Bode diagram based on the impedance and the respective frequencies, and generates the generated Nyquist diagram and a pre-generated Nyquist diagram. The presence or absence of a defect in the semiconductor element or the electronic device is determined by comparing the figure or the generated Bode diagram with a previously generated Bode diagram.

  In the defect diagnosis apparatus, the electronic device is a solar cell module including solar cells as semiconductor elements.

  In the defect diagnosis apparatus, the electronic device is a solar cell module including a solar cell as a semiconductor element, and the solar cell to be subjected to impedance calculation by the second arithmetic unit from the plurality of solar cells. A switching unit that sequentially switches cells is included.

  In the defect diagnosis apparatus, the electronic device is a light control device including an LED as a semiconductor element.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to detect efficiently the defect of the electronic apparatus provided with semiconductors, such as a solar cell.

It is a block diagram which shows schematic structure of the solar energy power generation system provided with the defect diagnostic apparatus which concerns on embodiment. It is a block diagram which shows the detailed structure of the solar energy power generation system provided with the defect diagnostic apparatus which concerns on embodiment. It is a block diagram which shows the structural example of the microcontroller with which the defect diagnostic apparatus which concerns on embodiment was equipped. It is a flowchart which shows the processing operation example of the defect diagnostic apparatus which concerns on embodiment. It is explanatory drawing which shows the example of an alternating current input signal produced | generated with the defect diagnostic apparatus which concerns on embodiment. It is explanatory drawing which shows each signal example produced | generated and calculated by the defect diagnostic apparatus which concerns on embodiment. It is explanatory drawing which shows the example of the energy band of the solar cell which concerns on embodiment, an equivalent circuit, and a Nyquist diagram. It is explanatory drawing which shows the analysis result at the time of degrading the semiconductor part of the solar cell which concerns on embodiment. It is explanatory drawing which shows the analysis result when a defect is formed between the semiconductor part and metal part (electrode) of the solar cell which concerns on embodiment. It is explanatory drawing which shows the analysis result at the time of deteriorating the metal part of the solar cell which concerns on embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a solar cell including a semiconductor element (hereinafter also simply referred to as a semiconductor) is described as an example of an electronic device.

  FIG. 1 shows a schematic configuration of a photovoltaic power generation system provided with a defect diagnosis apparatus according to the present invention.

  A solar power generation system 10 shown in FIG. 1 includes a solar cell panel 1 and a power conditioner 2, the solar cell panel 1 includes a plurality of solar cells 1a, and the power conditioner 2 includes a defect diagnosis device 2a according to the present invention. I have.

  The solar cell panel 1 converts sunlight into electric power. For example, a plurality of solar cell modules in which solar cells 1a such as a plurality of crystal solar cells or amorphous silicon solar cells are connected in series and parallel are serially parallel. Connected to and configured.

  The solar cell 1a is a basic unit of a solar cell and is a solar cell element itself called a cell. The solar cell module is a package in which the required number of cells are arranged and protected with resin, tempered glass, or the like. And the solar cell panel 1 connects a plurality of solar cell modules in series and parallel, and is also called a solar cell array.

  The power conditioner 2 is connected to the solar cell panel 1 and includes a DC-AC inverter or the like for converting a direct current output from the solar cell panel 1 into an alternating current and outputting the alternating current to the power system.

  In addition, the power conditioner 2 has a function of adjusting to a stable voltage in order to prevent the voltage generated by the solar cell panel 1 that changes irregularly according to the amount of solar radiation from adversely affecting the home appliance of the supply destination. Is provided. In this way, the power whose voltage is adjusted by the power conditioner 2 is supplied to the home via the power system or the indoor distribution board.

  As shown in FIG. 1A, during power generation by the solar power generation system 10, the solar cell panel 1 generates and outputs DC power based on incident sunlight. The power conditioner 2 converts the DC power output from the solar cell panel 1 into AC power of 50 Hz or 60 Hz and outputs the AC power.

  On the other hand, when diagnosing a defect of the solar cell 1a of the solar cell panel 1, the power conditioner 2 activates the defect diagnosis device 2a. The activation of the defect diagnosis apparatus 2a may be automatically performed at a predetermined time using a timer or may be performed at an arbitrary time by an operator.

  As shown in FIG. 1 (b), the activated defect diagnosis apparatus 2a generates a plurality of alternating current signals each having a different frequency, inputs them to the solar cell 1a to be inspected of the solar cell panel 1, and from the solar cell 1a. The impedance signal of the solar cell 1a is calculated.

  Here, based on the calculated impedance and the input frequency, characteristic information indicating the performance state of the solar cell 1a, for example, a Nyquist diagram, is generated, and the generated characteristic information is generated in advance in the storage device. The presence / absence of a defect in the solar cell 1a to be inspected is determined by collating the stored characteristic information for determination indicating the defect state of the solar cell or indicating a normal state.

  Thus, in the present embodiment, both the cross flow conversion and the solar cell defect diagnosis can be performed with one power conditioner 2.

  FIG. 2 shows an internal configuration of the power conditioner 2.

  The power conditioner 2 includes a DC / DC converter (described as “DC / DC converter” in the figure) 2b for adjusting the power output from the solar panel 1, and an inverter circuit for performing general DC / AC conversion. 2c and a defect diagnosis apparatus 2a according to the present invention.

  During the power generation operation, the power conditioner 2 converts a DC signal from the solar cell panel 1 (described as “PV” in the figure) into an AC signal by the DC / DC converter 2b and the inverter circuit 2c. Electric power is supplied to a power system (Grid) such as a power board, and at the time of defect diagnosis, the presence or absence of a defect in the solar cell 1a constituting the solar cell panel 1 is determined by the defect diagnosis device 2a.

  The defect diagnosis apparatus 2a includes a duty ratio acquisition unit 2d as an acquisition unit according to the present invention, an integrated duty ratio calculation unit 2e as a first calculation unit according to the present invention, and an impedance calculation unit as a second calculation unit according to the present invention. 2f, a storage unit 2g, and a determination unit 2h according to the present invention, and efficiently detects the presence or absence of defects in the solar cell 1a.

  The DC / DC converter 2b is an adjustment circuit that performs normal power adjustment. The choppers A and B (described as “Chopper A and B” in the figure), the inductor L, the capacitor C, and the switching as the voltage transformer according to the present invention. An element Q, a microcontroller MC, and a battery (described as “Battery” in the figure) are provided.

  The microcontroller MC includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like, and executes computer processing based on a program, as well as a PI control operation unit, an analog / digital converter A / D, And a fast Fourier transform FFT. The PI control calculation unit may perform control other than PI control as long as it performs feedback control such as PID (Proportional Integral Derivative) control.

  The choppers A and B are step-up choppers as long as they can perform voltage conversion. The inductor L and the capacitor C are smoothing inductors and capacitors. The switching element Q is made of, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor).

  A microcontroller capable of high-speed computation such as a DSP (Digital Signal Processor) is used. The analog / digital converter A / D converts the voltage value into a digital signal.

  The DC / DC converter 2b having such a configuration performs a power adjustment operation as a normal DC / DC converter by the built-in microcontroller MC, and at the same time, the solar battery panel 1 is configured by the defect diagnosis device 2a. Diagnose the presence or absence of defects in the battery 1a.

  As shown in FIG. 3, the microcontroller MC stores a CPU 31 that performs various processes by executing a program, a RAM 32 that is used as a work area when the CPU 31 executes various programs, various control programs, various parameters, and the like. ROM (Read Only Memory) 33 as a recording medium, nonvolatile memory 34 such as EEPROM (Electrically Erasable Programmable Read-Only Memory), input / output interface unit for inputting / outputting data to / from outside) 35, and system A bus 36 and the like are provided.

  The CPU 31 develops the program stored in the ROM 33 and the like on the RAM 32 and executes the program so that the duty ratio acquisition unit 2d, the integrated duty ratio calculation unit 2e, the impedance calculation unit 2f, and the determination unit 2h of the defect diagnosis apparatus 2a The function is executed. The storage unit 2g corresponds to the nonvolatile memory 34.

  For example, the duty ratio acquisition unit 2d includes a switching unit, an A / D conversion unit, and a PI control calculation unit, and changes by ON / OFF control of a plurality of switching elements of the chopper A connected to the solar cell 1a. The duty ratio for controlling the output voltage to the target voltage is acquired.

  The integrated duty ratio calculation unit 2e calculates an integrated duty ratio that is integrated by making minute changes with a plurality of sine waves having different frequencies, based on the duty ratio acquired by the duty ratio acquisition unit 2d.

  The impedance calculation unit 2f is an impedance for each frequency with respect to the target voltage, based on the output voltage and output current of the solar cell 1a when the on / off control of the plurality of switching elements is performed with the integrated duty ratio integrated by the integrated duty ratio calculation unit 2e. Is calculated.

  The determination unit 2h generates characteristic information indicating the frequency characteristics of the solar cell 1a based on the impedance for each frequency calculated by the impedance calculation unit 2f, and collates the generated characteristic information with the previously generated characteristic information. Then, the presence or absence of defects in the solar cell 1a is determined.

  Hereinafter, the operation of the DC / DC converter 2b in FIG. 2 will be described in detail with reference to the flowcharts of FIG. 2 and FIG. Note that the defect diagnosis apparatus 2a uses a Nyquist diagram as characteristic information indicating the performance state of the solar cell.

  The following processes (a) to (i) correspond to (a) to (i) in FIG. 2, and also correspond to the steps (S401 to S409) in FIG.

  First, the power adjustment operation as a normal DC / DC converter will be described.

During operation as a normal DC / DC converter, the connection positions of the switches SW1 and SW2 are S1 and T1. Voltage of the solar cell panel 1 is compared with the target voltage V ^* _PV, that is fed back to the duty ratio D _A chopper A, equal to the target value. For example, the target voltage V ^* _PV is a voltage at which the maximum power of the solar battery panel 1 can be obtained.

  Next, the operation | movement at the time of the diagnosis of the defect of the solar cell which comprises the solar cell panel 1 is demonstrated. In addition, here, it is the operation | movement at the time of diagnosis regarding one solar cell 1a which comprises the solar cell panel 1. FIG.

  The processing operations (1) to (8) below correspond to the processing operations of the duty ratio acquisition unit 2d, the integrated duty ratio calculation unit 2e, and the impedance calculation unit 2f according to the present invention.

(1) First, the target voltage V ^* _PV of the voltage output from the solar cell 1a is set as the bias voltage V _bias for which the AC impedance is to be measured. The voltage of the solar cell 1a matches the value of the bias voltage. That is, by controlling the duty ratio D _A chopper A, the voltage of the solar cell 1a is constant (bias voltage to be measured AC impedance), and stores the duty ratio at this time (D ₀₎ (... a) (FIG. 4 step S401).

(2) Next, the positions of the switches SW1 and SW2 are switched to S2 and T2, and a minute change in the duty ratio of the chopper A is started around the duty ratio D ₀ stored in the operation of (1) (... B (Step S402 in FIG. 4). Thereby, the voltage of the solar cell 1a changes in proportion to the duty ratio D _A (V _PV = α D _A , α is a proportional coefficient).

As shown in FIG. 5, the minute change in the voltage of the solar cell 1 a becomes a waveform (SUM in the figure) obtained by adding a plurality of sine waves of frequencies. Thereby, the impedance corresponding to a plurality of frequencies can be measured at a time. At this time, the duty ratio is D _A = D ₀ + Σd sin (2πf _i + θ _i ). In this equation, d is the amplitude of the sine wave and f _i is the frequency of the impedance to be measured.

If the phases of the sine waves of all frequencies are made equal, it takes time to reinforce the values, so the phase is shifted by θ _i . At this time, the voltage of the solar cell is V _PV = α D _A = α {D ₀ + Σd sin (2πf _i + θ _i )} = V _bias + αΣd sin (2πf _i + θ _i )).

  The above is the processing operation related to the duty ratio acquisition unit 2d and the integrated duty ratio calculation unit 2e, and the following is the processing operation related to the impedance calculation unit 2f.

(3) While performing the operation of (2) above, the voltage and current at that time are sampled and A / D converted (... C) and stored in a memory (not shown) (V [t] and i [ t] (... d) (step S403 in FIG. 4) Here, for example, if the sampling frequency f _s and the number of samples N are stored, in principle, in the impedance measurement in (6) described later, f _s The impedance of the frequency band in the range of / 2 to f _s / N can be calculated.

  (4) The positions of the switches SW1 and SW2 are returned to S1 and T1 (step S404), the chopper A is returned to the normal power adjustment operation (step S405), and the processing operation by the impedance calculator 2f is performed. It should be noted that the processing operation of the impedance calculation unit 2f after the next (5) is only calculation and can be processed in the background.

  (5) The voltage and current values stored in the memory are decomposed for each frequency component using FFT (Fast Fourier Transform), respectively (... E) (step S406 in FIG. 4). The frequency components calculated in this way are expressed in complex numbers as V [f] and I [f] (... F).

  (6) Take the quotient for each frequency component of the decomposed complex voltage and complex current (... G), calculate the impedance (Z [f] = V [f] / I [f]), and store it in the memory ( ... H) (step S407 in FIG. 4).

(7) The processes from (1) to (6) are repeated for each different bias voltage V _bias (for each target voltage) and for each amplitude d of the sine wave (step S408 in FIG. 4).

  (8) The impedance calculated in (6) above is read from the memory and input to the determination unit 2h (... i), and the determination unit 2h compares with the abnormal impedance stored in advance in the storage unit 2g, It is determined whether or not the solar cell 1a has a defect (step S409 in FIG. 4). If it is determined that there is a defect, a warning is given or data is transmitted to the display.

  In addition, the normal value of the impedance is stored in the storage unit 2g in advance, and is stored in the storage unit 2g in advance by the determination unit 2h using the impedance of the solar cell 1a calculated by the processing of the impedance calculation unit 2f. It may be determined that the solar cell 1a has a defect if a significant difference is recognized by comparing the impedance with a normal value.

  Moreover, it is good also as a structure which provided the switching part which switches the solar cell used as the object of a diagnosis sequentially from several solar cell 1a or a module. Defect evaluation is performed in units of an array or a plurality of modules, and when switching and diagnosing in this way, measurement is performed for each module. Further, when a defect is detected, repair is performed in units of cells or modules.

  Further, when the electromotive force of the solar cell is insufficient, such as at night, the voltage or current necessary for diagnosis is compensated by causing the grid power to flow backward through the inverter. For example, as shown by a portion surrounded by a dotted line in FIG. 2, it is possible to diagnose without reverse power flow by mounting a battery, chopper B, and the like.

  FIG. 6 shows waveforms during the processing operations (1) to (8). FIG. 6A shows a state where the duty ratio is obtained when the bias voltage is applied, and FIG. 6B shows a state where the duty ratio is slightly changed to change the voltage and current of the solar cell. FIG. 6C shows a state where frequency components of voltage and current are obtained by FFT, and FIG. 6D shows a situation where the impedance Z is obtained.

  In FIG. 2, a chopper that performs DC / DC voltage conversion is a widely used technique, and can be applied to the present embodiment with almost no change in the existing circuit configuration.

  In recent years, since the control unit of the circuit is being replaced with a microcomputer (microcontroller) capable of high-speed calculation, the microcomputer program includes the integrated duty ratio calculation unit 2e and the determination unit 2h according to the present embodiment. The processing operation according to the present embodiment can be realized only by adding a program for processing.

  Further, by using a waveform obtained by adding sine waves of a plurality of frequencies, impedances of a plurality of frequencies can be measured at the same time, so that the measurement time can be shortened.

  The time required for impedance measurement is the time during which current and voltage are sampled (= the time of one cycle of the minimum frequency of the impedance to be measured) and the time required for the FFT calculation (negligible). Inspection of battery defects can be completed in a very short time.

  Moreover, since the inspection of the defects of the solar cell 1a can be completed in a very short time, it is possible to frequently measure the impedance and examine the change with time.

  In addition, since the battery is used, power supply to the load can be continued. For example, in a configuration that does not use a battery, it is necessary to supply power used for impedance measurement from the load side.

  As described above, in the defect diagnosis apparatus 2a, the integrated duty ratio calculation unit 2e synthesizes sine waves having different predetermined frequencies and inputs the combined sine waves to the solar cell 1a constituting the solar cell panel 1.

  The impedance calculation unit 2f calculates the impedance of the solar cell 1a for each of a plurality of frequencies based on the output of the solar cell 1a to which a plurality of sine waves (AC signals) are input.

  The memory | storage part 2g memorize | stores the Nyquist diagram as characteristic information which shows the frequency characteristic of the solar cell 1a produced | generated beforehand. The characteristic information includes, for example, a plurality of determination Nyquist diagrams generated by inputting AC signals of a plurality of frequencies into a plurality of solar cells 1a each having a different defect, or a normal solar cell 1a. For example, a Nyquist diagram for determination generated by inputting AC signals having a plurality of frequencies can be used.

  The determination unit 2h generates frequency characteristic information such as a Nyquist diagram indicating the circuit characteristics of the solar cell 1a based on the impedance for each of the plurality of frequencies calculated by the impedance calculation unit 2f and the plurality of frequencies, and the generated characteristics The information is compared with the characteristic information stored in the storage unit 2g to determine whether there is a defect in the solar cell 1a to be inspected.

  Next, the processing operation by the determination unit 2h in the defect diagnosis apparatus 2a will be described with reference to FIGS.

  Hereinafter, the determination unit 2h is based on the Nyquist diagram generated using the impedance (Z [f] = V [f] / I [f]) of the solar cell 1a calculated by the processing of the impedance calculation unit 2f. A technique for determining whether or not the solar cell 1a has a defect will be described.

  Fig.7 (a) has shown the example of the energy band figure of the solar cell 1a, FIG.7 (b) has shown the example of the equivalent circuit of the solar cell 1a, FIG.7 (c) shows the solar cell. The example of the Nyquist diagram showing the measurement result of the impedance of 1a is shown.

In the example of FIG. 7A, a solar cell 1a includes a transparent conductive layer (surface electrode) made of low resistance ZnO, an n-type high forbidden band width semiconductor made of high resistance ZnO, an n-type high resistance semiconductor made of CdS, and CIGS. It has a p-type semiconductor energy band configuration made of (Cu (In, Ga) Se ₂ ) and is provided with a back electrode made of Mo.

In the example of FIG. 7B, in the solar cell 1a, the front electrode ZnO, a part of the p-type semiconductor, and the back electrode Mo in FIG. 7A are represented by a resistance R _bulk . Note that a part of the p-type semiconductor is a region where no depletion layer is generated in CIGS.

Further, R _n and C _n represent the vicinity of the interface between the n-type high-resistance semiconductor and the transparent conductive film or the vicinity of the interfaces of the plurality of semiconductors forming the n-type high-resistance layer, which are present in the depletion layer region. When an electric field is generated in the semiconductor, a depletion layer is formed, and the surroundings behave like a capacitor, which can be expressed by C (capacitance) and R (resistance). Defects generally occur near the interface and represent the vicinity of the semiconductor interface.

Further, the vicinity of the interface between the n-type high resistance semiconductor and the p-type semiconductor existing in the depletion layer region is represented by R _j and Z _CPEj .

Further, when there is a defect between the semiconductor and the metal, the vicinity of the interface between the semiconductor and the metal existing in the depletion layer region formed by applying a bias or the like is represented by R _m and C _m .

  In FIG. 7 (c), the raw data obtained by measurement (black diamond points in the figure) and the data when the data separation is performed based on the equivalent circuit shown in FIG. 7 (b). Two semicircles (dotted lines in the figure) representing each component are shown.

  FIGS. 8-10 has shown the Nyquist diagram and the Bode diagram showing the analysis result in case the solar cell 1a has a defect.

  FIG. 8 shows an analysis result when a defect is intentionally formed in a semiconductor portion including a pn junction in the solar cell 1a, and the semicircle in the Nyquist diagram is compared with the semicircle in a normal state (no abnormality). Based on the analysis result, it is possible to determine the degradation location and degree of degradation of the semiconductor in the solar cell 1a.

  FIG. 9 shows an analysis result in the case where a defect is intentionally formed between the semiconductor portion and the metal portion (electrode) of the solar cell 1a. A new semicircle appears on the right side of the figure. Based on the analysis result, it is possible to determine a failure or deterioration between the semiconductor and the metal portion (electrode) in the solar cell 1a.

  FIG. 10 shows the analysis result when the metal parts such as the electrodes and lead wires of the solar cell 1a are intentionally deteriorated, and the semicircle is shifted to the left and right as compared with the normal case (no abnormality). Based on the analysis result, failure or deterioration of the metal portion in the solar cell 1a can be determined.

  In this way, the determination unit 2h collates the Nyquist diagram calculated from the measured impedance of the solar cell 1a to be inspected with the Nyquist diagram of a normal solar cell generated in advance, and the solar cell 1a to be inspected The presence or absence of defects is determined.

  In addition, the Nyquist diagram calculated from the measured impedance of the solar cell 1a to be inspected using the Nyquist diagram of the solar cell showing abnormality as the Nyquist diagram generated in advance is the Nyquist of the abnormal solar cell generated in advance. The presence or absence of a defect in the solar cell 1a to be inspected may be determined depending on whether or not it is similar to the diagram.

  Further, instead of using the Nyquist diagram, it is possible to compare the normal reference board diagram with the failure board diagram at the time of abnormality, or about the various data shown in FIGS. The presence / absence of a defect in the solar cell 1a to be inspected may be determined by comparison with reference data or data at the time of abnormality.

  Moreover, the defect which can be determined with the defect diagnostic apparatus of this Embodiment is not restricted to the above-mentioned defect.

  Various data shown in FIGS. 7 to 10 will be described below.

Z _CPEj is a complex element component in the vicinity of the pn junction interface having inhomogeneities and defects, and “Z _CPEj = 1 / (jω) ^p T”. Note that ω = 2πf (f = frequency of the applied AC voltage [Hz]), p represents a deviation from a perfect circle in the Nyquist diagram, and this p takes a value of 0 to 1 and p = 1 , Z _CPEj is considered to be normal C in the same shape as the capacitor impedance, and represents nonuniformity and defects near the pn interface (p = 1 is an ideal pn junction). T corresponds to the capacitance of the ideal capacitance impedance.

C _j is obtained by extracting only the capacitive component from the element Z _CPEj having a complex component. “C _j = T ^{1 / p} R ^{1−p / p} ”, where C _j is information on non-uniformity / defects at the pn junction interface and parameters affected by defects / failures in the semiconductor portion, that is, Represents a value whose value changes to reflect a defect or failure. A failure can be diagnosed based on the comparison between the parameter value and the normal value.

R _j represents the resistance component in the vicinity of pn junction interface, C _j × R _j in which _{t j (t j = C j} × R j) corresponds to the diffusion time constant of the carrier near the pn junction interface, a semiconductor Represents a parameter that is affected by a defect or failure of a part.

C _n is a uniform capacitance value near the junction (nn junction) interface between n-type semiconductors in the part _where the internal electric field occurs (in the depletion layer), and is a parameter affected by defects and failures near the surface of the semiconductor Represents. “C _n = 1 / 2πRf _max ”, and f _max is a frequency at which the imaginary term (vertical axis of the graph) of the corresponding Nyquist diagram is maximum.

R _n is a resistance value near the junction (nn junction) interface between n-type semiconductors in the part _where the internal electric field is generated (in the depletion layer), and represents a parameter affected by defects / failures near the surface of the semiconductor. ing.

C _m is a capacitance (contact capacitance) value near the interface between the semiconductor and the metal caused by defects or deterioration, and is “0” when there is no defect, and is a parameter affected by defects and failures between the semiconductor and the electrode. Represents.

R _m is the resistance (contact resistance) value near the interface between the semiconductor and the metal caused by defects and deterioration, and is “0” when there is no defect or deterioration, and is affected by defects and failures between the semiconductor and the electrode. Represents a parameter.

R _bulk is the resistance component of the semiconductor (where the CIGS layer and transparent conductive film layer are semiconductors, although it is a semiconductor) where there is no internal electric field (regardless of the depletion layer), and metal parts such as wiring cables It represents a parameter affected by a defect or failure of a metal.

  Regarding the abnormal Nyquist diagram used for the determination of defects (abnormalities, failures), first, based on a reference Nyquist diagram generated by inputting AC signals of a plurality of frequencies into a normal solar cell in advance, Calculate each value of each circuit constituting the equivalent circuit of the battery as a reference value, and then set each calculated value of each circuit of the equivalent circuit to a defect value different from each reference value. By calculating, a plurality of abnormal Nyquist diagrams for defect determination can be generated.

  Further, the equivalent circuit of the solar cell is not limited to that shown in FIG. For example, the equivalent circuit of a solar cell varies depending on the material constituting the solar cell, the laminated structure (deposition order), the thickness of each layer, the presence or absence of light irradiation, and the like. That is, the equivalent circuit changes when the energy band changes. For this reason, the number of resistors, capacitance components, and the like may change depending on the temporal change of the solar cell, the laminated structure, and the like.

  As described above with reference to the drawings, in the photovoltaic power generation system provided with the defect diagnosis apparatus according to the present embodiment, the defect diagnosis apparatus 2a generates and generates a plurality of AC signals each having a different frequency. A plurality of alternating current signals are collectively input to the solar cell 1a to be inspected of the solar cell panel 1, the impedance signal from the solar cell 1a is input, the impedance of the solar cell 1a is calculated, and the calculated impedance is input. Based on the frequency, a Nyquist diagram or the like indicating the performance state of the solar cell 1a is generated and used to determine the generated Nyquist diagram and the defect state of the solar cell that is generated in advance and stored in the storage device. The reference Nyquist diagram is collated to determine the presence or absence of defects in the solar cell 1a to be inspected, and it is possible to perform failure diagnosis in an extremely short time.

  Moreover, in the solar power generation system provided with the defect diagnosis apparatus according to the present embodiment, an AC signal is output to the solar cell side using the function of the power conditioner 2, and new equipment and wiring are used. The impedance of the solar cell can be measured without any problem.

  Further, as in the prior art, when the failure diagnosis of the solar battery panel is performed, the operation of stopping the power generation and removing the panel becomes unnecessary, and the maintenance cost can be reduced. Moreover, it is not necessary to monitor the voltage, current, and power during power generation, and failure diagnosis can be performed without being affected by changes in weather and temperature. In addition, it is not necessary to equip the photovoltaic power generation system with a large-scale failure diagnosis system, so that the equipment cost is not required and the present invention can be applied to a small-scale photovoltaic power generation system for home use.

  In the defect diagnosis apparatus according to the present embodiment, the solar cell panel may be composed of any number of solar cells, and can be applied regardless of the size, power generation amount, and scale of the solar cell panel. Diagnosis can be performed day and night.

  Furthermore, since the failure part can be specified, the repair work can be performed efficiently. Moreover, it can be used not only for failure diagnosis after installation but also for quality confirmation before factory shipment.

  The present invention is not limited to the embodiments described above, and various modifications and applications can be made without departing from the gist of the present invention. For example, in the present embodiment, a solar cell is described as an example of an electronic device including a semiconductor element. However, the defect diagnosis apparatus according to the present invention is a defect such as an illumination or image display device using a semiconductor element such as an LED. -It can also be used for failure diagnosis.

  In addition, although a DSP is used as the microcontroller MC in the present embodiment and is configured by a computer that can execute each function by a program, a hardware configuration including a logic element circuit may be used.

DESCRIPTION OF SYMBOLS 1 Solar cell panel 1a Solar cell 2 Power conditioner 2a Defect diagnosis apparatus 2b DC / DC converter 2c Inverter circuit 2d Duty ratio acquisition part 2e Integrated duty ratio calculation part 2f Impedance calculation part 2g Storage part 2h Determination part 10 Solar power generation system

Claims (7)

An acquisition unit for acquiring a duty ratio for controlling an output voltage of an electronic device including a semiconductor element to a target voltage;
A first calculation unit that calculates an integrated duty ratio by changing the output voltage with a plurality of sine waves of different frequencies based on the duty ratio; and
A second calculator that calculates an impedance for each frequency with respect to the target voltage, based on an output voltage and an output current of the electronic device when the integrated duty ratio is controlled by turning on and off a plurality of switches;
Based on the impedance for each frequency, the characteristic information indicating the frequency characteristic of the electronic device is generated, and the generated characteristic information is compared with the previously generated characteristic information to determine the defect of the semiconductor element or the electronic device. A determination unit for determining presence or absence;
Defect diagnosis device including The target voltage is a plurality of target voltages,
The acquisition unit acquires a plurality of duty ratios for controlling the output voltage of the electronic device to each of a plurality of target voltages,
The first calculation unit sets an integrated duty ratio that is integrated by changing the output voltage with a plurality of sine waves having different frequencies with respect to each of the plurality of duty ratios, for each target voltage of the plurality of target voltages. To
The second arithmetic unit is configured to control each of the plurality of target voltages based on an output voltage and an output current of the electronic device when each of the plurality of integrated duty ratios is controlled by turning on and off the plurality of switches. Calculate the impedance for each frequency with respect to the target voltage,
The determination unit generates characteristic information indicating a frequency characteristic of the electronic device based on an impedance for each frequency of the electronic device with respect to each target voltage of the plurality of target voltages. The presence or absence of defects in the semiconductor element or the electronic device by comparing with the characteristic information
The defect diagnosis apparatus according to claim 1.   The defect diagnosis apparatus according to claim 1, wherein the plurality of sine waves are sine waves having different frequencies and phases. The determination unit generates a Nyquist diagram or a Bode diagram based on the impedance and the respective frequencies, and generates the generated Nyquist diagram and a pre-generated Nyquist diagram, or a generated Bode diagram. And a board diagram generated in advance to determine the presence or absence of defects in the semiconductor element or the electronic device,
The defect diagnosis apparatus according to any one of claims 1 to 3.   The defect diagnosis apparatus according to any one of claims 1 to 4, wherein the electronic device is a solar cell module including solar cells as semiconductor elements. The electronic device is a solar cell module provided with solar cells as semiconductor elements,
From a plurality of the solar cells, including a switching unit for sequentially switching the solar cells to be subjected to impedance calculation by the second calculation unit,
The defect diagnosis apparatus according to any one of claims 1 to 4.   The defect diagnosis device according to claim 1, wherein the electronic device is a light control device including an LED as a semiconductor element.