Method and system for realizing optimal value of battery charging current in off-grid charging system

Abstract

The invention discloses a method and a system for realizing an optimal value of charging current of a storage battery in an off-network charging system. The method comprises the following steps: A, selecting an initial output current reference value, outputting operation results by a digital regulator, feeding the operation results into a pulse width regulator to generate a control signal, and obtaining an actual output current value by current feedback; B, calculating the change direction of the current according to the actual output current value and the initial output circuit reference value, calculating and updating the current disturbance direction results of next MPPT (maximum power point tracking) by combining the current disturbance direction of this MPPT; C, updating the output current reference value at fixed step length according to the calculated current disturbance direction results of next MPPT, and obtaining maximal charging current by repeatedly updating. According to the method and the system for realizing the optimal value of the charging current of the storage battery in the off-network charging system, measurement for voltage and current signals is cancelled, so that the maximum power tracking of a PV (photovoltaic) component can be realized by only needing to measure the charging current of the storage battery, and therefore, the hardware cost is lowered, and the requirements of processor performances are lowered.

Description

technical field [0001] The invention relates to the technical field of photovoltaic off-grid power generation, in particular to a method and system for realizing the optimal value of battery charging current in an off-grid charging system. Background technique [0002] Photovoltaic cells are devices that convert light energy into electrical energy using the photovoltaic effect. Since the output power of photovoltaic cells is a nonlinear function of light intensity, temperature and load, in order to make full use of the energy of the photovoltaic array, the photovoltaic power generation system is equipped with a Maximum Power Point Tracking (MPPT) control algorithm. [0003] Traditional photovoltaic maximum power point tracking focuses on tracking the maximum output power of photovoltaic modules. Commonly used tracking methods include: hill climbing method / perturbation and observation method (P&Q), conductance incremental rate method (INC), improved variable step size algorit...

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Problems solved by technology

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a method and system for realizing the optimal value of the battery charging current in an off-grid charging system, aiming at solving the problem of the high cost of the existing control method for the optimal value of the battery charging current and the burden on the processor. high performance issues

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