MPPT control method suitable for photovoltaic cell

Abstract

The invention relates to an MPPT control method suitable for a photovoltaic cell. A double-straight-line approximation method and a small step perturbation and observation method are used for tracking the MPPT of the photovoltaic cell. Firstly two approximate straight lines between a maximal power point voltage and an ambient temperature and illumination intensity are established according to a photovoltaic cell equivalent model. Then a maximal power point voltage is determined according to the acquired ambient temperature, the illumination strength and two approximate straight lines. Then a PWM pulse signal of a driving switch device is generated through PI adjustment according to a difference between an actually output voltage of the photovoltaic cell and a maximal power point voltage. The photovoltaic cell is adjusted to next to the maximal power point, and finally a maximal power point is accurately tracked through the small step perturbation and observation method. The MPPT control method has advantages of high speed, high efficiency, high control accuracy, simple algorithm, low requirement for a controller, and convenient engineering implementation.

Description

technical field [0001] The invention relates to the technical field of solar photovoltaic power generation, in particular to an MPPT control method suitable for photovoltaic cells. Background technique [0002] Solar energy is clean, pollution-free, energy available everywhere, and it is inexhaustible and inexhaustible. Today, with the gradual shortage of fossil energy, solar energy has become one of the new energy sources that countries in the world are striving to develop. However, solar photovoltaic cells are extremely unstable power sources, and low photoelectric conversion efficiency is an important factor restricting their development. The proposal of maximum power point tracking (MaximPowerPointTracking, MPPT) technology has greatly improved the photoelectric conversion efficiency of solar photovoltaic cells. [0003] The principle of the conventional fixed voltage method is simple and easy to implement, but the control accuracy is relatively low; the disturbance an...

AI Technical Summary

Problems solved by technology

[0003] The principle of the conventional fixed voltage method is simple and easy to implement, but the control accuracy is relatively low; the disturbance and observation method has the disadvantages of large oscillation amplitude or slow tracking speed; the conductance incremental method has high requirements for hardware and requires high-speed A / D sampling; fuzzy adaptive Algorithms such as the neural network method and the neural network method are too complex, and it is difficult to implement in actual engineering; the simple straight line approximation method itself is too dependent on the equivalent model of the photovoltaic cell, and the partial straight line approximation method ignores the influence of temperature or sunlight intensity on the equivalent model, causing the algorithm low precision

Images