Magnetic bias suppression system and method of phase-shifted full bridge converter for photovoltaic power generation

Abstract

The invention provides a magnetic bias suppression system and method of a phase-shifted full bridge converter for photovoltaic power generation, and belongs to the technical field of power electronics. The input end of a primary side current detection circuit is electrically connected with a primary side of a high-frequency transformer, and the output end of the primary side current detection circuit is connected to an analog input interface of a CPU (central processing unit); the input end of each isolation drive circuit is respectively connected with corresponding output ends of the CPU; the CPU receives analog signals transmitted by a current conditioning circuit and converts the analog signals into digital signals through an A / D (analog-to-digital) converter; a computing unit of the CPU computes a duty ratio offset controlling a primary side current direct-current component through PI (proportion integral) regulation so that the primary side current direct-current component is zero; 0.5 is added as a duty ratio offset of the primary side direct-current component by a PWM (pulse width modulation) controller in the CPU to output a logic drive signal to the isolation drive circuits; and the isolation drive circuits control on and off of corresponding MOS (metal oxide semiconductor) pipes. According to the magnetic bias suppression system and method of the phase-shifted full bridge converter for the photovoltaic power generation, disclosed by the invention, positive wave and negative wave of the primary side output current are symmetric and the magnetic bias of the high-frequency transformer is effectively restrained.

Description

technical field [0001] The invention relates to a converter, in particular to a bias suppression system for a phase-shifting full-bridge converter for photovoltaic power generation, and belongs to the technical field of power electronics. The invention also relates to a bias suppression method for a phase-shifting full-bridge converter for photovoltaic power generation. Background technique [0002] The phase-shifting full-bridge converter for photovoltaic power generation includes a main circuit and a control circuit. The main circuit includes an inverter circuit, a high-frequency transformer, a rectifier circuit and a filter circuit. The primary side of the high-frequency transformer is electrically connected to the output terminal of the inverter circuit. The secondary side of the high-frequency transformer is electrically connected to the input terminal of the rectifier circuit; the inverter circuit is composed of a full-bridge inverter module and parallel capacitors, th...

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Problems solved by technology

[0003] Its shortcoming is that in actual operation, many factors make the positive and negative waveforms of the transformer primary current asymmetrical, causing the magnetization curve of the transformer core to no longer be symmetrical about the origin when the transformer core is working. Since the magnetization curve is nonlinear, when the bias is severe , the iron core will enter deep saturation in one direction, which will cause a sharp increase in the one-way magnetization current, increase the loss, and even cause damage to the switch tube in severe cases.

In order to suppress the magnetic bias and make the positive and negative waveforms of the primary current symmetrical, there are many digital implementation methods for phase-shift PWM control. However, since the DSP chips currently used do not have the function of directly generating phase-shift signals, analog chips, FPGA and DSP plus external Realized by expanding digital circuit

In addition, this method has the disadvantages of complex implementation, control accuracy is directly limited by memory capacity and inconvenient for remote communication

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