Research On The Dule-mode Test System For PV Cell/Array Based On FPGA

With the rapid development of world economy, energy demand continues to increase. Inthe case of traditional energy limited, people began to devote more attention to new energyresource, in which the solar industry takes a significant proportion with its outstandingadvantages. Correspondingly, the solar cell industry is expanding quickly and the testingtechnology of solar cell is also improved. Traditional testing systems usually measurephotovoltaic solar cell for voltammetry curve and some characteristic parameters; theygenerally relatively expensive, high in power consumption and takes up large space. Toaddress these issues, a dual-mode PV test system was proposed in this paper.The test system is designed based on FPGA. It used a capacitor as sample load insteadof a variable resistor, compared with the traditional system, can improve the accuracy ofmeasurement of the open-circuit voltage and make the measurement of the voltammetrycurve more close to the real value. By increasing two sampling channel, the system can alsodetect the real-time output of photovoltaic cells. In order to correct the measurement resultsto standard reporting conditions, a temperature sensor and a photoelectric diode are used tomeasure temperature and illumination intensity. Cascade to be16using PGA202/203controllable gain, expanding the range to meet the diverse needs of the test. The entiresystem using only two AD chips for data conversion, FPGA sends strobe signal to select theappropriate channel to complete the different data samples. This method can reduce powerconsumption and saving costs. There are two approaches to deal with the sampling results. AFLASH chip used to store all of the sampled data, while the simplifying signal will beprocessed directly by the LCM.In the simulation test, the system used a simplified two-exponential model project tobuild mathematical models of photovoltaic cells TDB100model. In the VA sample mode,using the mathematical model as input excitation, the simulation curves fit well with themodel curve. In the Real-time detection mode, making the input signal to fluctuate withinsome different ranges, the system can send out a stable value. The results of the samplingvariance is small, and the maximum error rate is very low, indicating that the system’s highaccuracy and good repeatability.