A buck circuit and a method for maximum power point tracking based on the buck circuit

Abstract

The invention discloses a BUCK circuit and a maximum power point tracking method based on the BUCK circuit. The BUCK circuit comprises a solar panel and a storage battery and further comprises, between the solar panel and the storage battery, an input filter unit, a master control unit, a synchronous rectifier unit, a drive circuit unit, an output filter unit, a current sampling unit, a counter-current protection unit and an overcurrent protection unit. The maximum power point tracking method based on the BUCK circuit comprises the steps that S01, maximum power point tracking is started; S02, maximum power point tracking is performed; S03, maximum power point tracking is ended. According to an algorithm of the maximum power point tracking method based on the BUCK circuit, the maximum power point of the solar panel can be found accurately and quickly, and the method is not limited by illumination, temperature, shadow shading and other environments; besides, the method has the advantages of being high in tracking speed, high in efficiency, small in ripple and the like.

Description

technical field [0001] The invention relates to the field of solar energy conversion, in particular to a BUCK circuit and a method for tracking a maximum power point based on the BUCK circuit. Background technique [0002] The earth's surface receives 5.4×10 solar radiation every year 24 J, item equivalent to 1.8×10 14 t standard coal. If 0.1% of it is converted into electrical energy at a conversion rate of 5%, the annual power generation can reach 5600TW·h, which is equivalent to 40 times the current world energy consumption. Therefore, solar power generation is of great significance to future energy development. At present, solar power mainly refers to photovoltaic power generation. [0003] Due to the special power output curve of photovoltaic panels, currently commonly used algorithms are: [0004] 1. The constant voltage method is the earliest MPPT (maximum power point tracking) control method. Under different light intensities, the voltage approximation of the M...

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Problems solved by technology

This method cannot achieve MPPT control more accurately

[0005] 2. The perturbation and observation method, that is, the hill climbing method, is a more practical MPPT control algorithm. This algorithm increases the burden on the CPU to a certain extent, and due to periodic optimization, it will cause periodic fluctuations in the output voltage of the system. fluctuation

[0006] 3. The conductance incremental method is one of the fast and accurate algorithms for tracking MPP at present, but its disadvantages are: the requirements for hardware are very high, especially the digital conversion of analog signals is required to be accurate and fast, and the signals must be high-quality filtering processing, otherwise the function of finding the MPP cannot be realized

In addition, it has the same disadvantage of taking up too much CPU time like the perturbation and observation method.

[0007] These technologies are generally adjusted with voltage as a reference value. When the above algorithm is shaded or blocked by the solar panel, there is no way to overcome the double or multiple peaks at all, so there are many shortcomings in application.

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