Efficient solar charging design based on MPPT technology

Probe domestic high frequency needle JKT-50L high frequency needle with 3 probes

MOSFET imported original FET

Overview:
Solar energy is recognized as the world's most technologically advanced and most promising new energy source. As a new type of energy system, solar power system (photovoltaic system) has attracted the attention and research of many countries and will occupy an important position in the future energy structure, which is of great significance to energy consumption and the environment.
Since the current main problem of photovoltaic system is low conversion efficiency and high price of the battery, how to further improve the conversion efficiency of the solar cell, how to make full use of the energy converted by the photovoltaic array has been an important direction of photovoltaic system research. The PV array output characteristics have non-linear characteristics that are affected by light intensity and ambient temperature. As the light intensity and ambient temperature are different, the voltage of the photovoltaic cell will change, and the output power will also change greatly. The photovoltaic cell itself is a very unstable power source. Therefore, how to improve the power output of the power supply and improve the system efficiency under different illumination and ambient temperature becomes a key challenge, which leads to the problem of maximum power tracking (MPPT) of photovoltaic cells in theory and practice.

Increasing the output of photovoltaic cells The output of photovoltaic cells is affected by factors such as solar intensity and battery junction temperature. Figure 1 and Figure 2 show the PV and PV characteristics of photovoltaic cells under the nonlinear function of different photovoltaics, the same junction temperature, the same illumination and different junction temperatures.
The following is a detailed analysis of the characteristics of photovoltaic cells in different situations.



Fig.1 IV and PV characteristic curves under different light intensity

Case 1: The junction temperature of the battery is constant, and the illumination changes can be drawn from Figure 1 as follows:
1 The short-circuit current of the photovoltaic cell becomes larger as the illumination intensity increases, and the two are approximately proportional; the open circuit voltage of the photovoltaic cell does not change much under various illumination conditions;
2 The maximum output power of a photovoltaic cell becomes larger as the illumination intensity increases, and has a unique maximum output power point in the same illumination environment. On the left side of the maximum power point, the output power increases linearly with the rise of the battery terminal voltage; after reaching the maximum power point, the output power begins to decrease rapidly, and the falling speed is much greater than the rising speed;
3 as shown in Figure 1 (a): On the left side of the dotted line A, the characteristics of the photovoltaic cell are approximated as the current source, and the right side is approximately the voltage source. The dotted line A corresponds to the operating current of the photovoltaic cell at the maximum power point, which is about 90% of the short-circuit current of the battery;
4 As shown in Fig. 1(b): When the junction temperature is constant, the output voltage value corresponding to the maximum power point of the photovoltaic cell is basically unchanged. This value is approximately 76% of the open circuit voltage.

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