Control method for switch tube of photovoltaic grid-connected staggered shunt-wound flyback inverter

Abstract

The invention provides a control method for a switch tube of a photovoltaic grid-connected staggered shunt-wound flyback inverter. The control method comprises the steps as follows: dividing a reference current curve in a half power frequency cycle into a first interval, a second interval and a third interval; in the first interval, raising the reference current curve, and calculating a switch cycle of the switch tube by a software; in the second interval, calculating the turn-off time of the switch tube by the software; and in the third interval, realizing next turn-on just in the positions of valleys of source and drain voltages of the switch tube by quasi-resonant circuit hardware detection in combination with a soft compensation method so as to determine the time length of the turn-off time in one switch cycle. According to the control method, the quality of output current waveforms can be guaranteed, the computing resources are saved, and the precision of the switch cycle is improved; and meanwhile, a quasi-resonant control mode is adopted as far as possible, and the conversion efficiency of the inverter is enhanced.

Description

technical field [0001] The invention relates to the technical field of high-frequency frequency control of a flyback circuit. Specifically, the invention relates to a control method for a switching tube of a photovoltaic grid-connected interleaved parallel flyback inverter. Background technique [0002] The flyback circuit is a common topology for DC-DC converters. Quasi-resonant technology is a widely used method to improve efficiency, improve reliability, and reduce cost. It enables the main switch tube to be turned on at the valley of the voltage at both ends, and sometimes the voltage at both ends may drop to 0 to realize zero-voltage turn-on, thereby reducing the energy loss of the switch tube. Quasi-resonant technology reduces MOSFET switching losses, thereby increasing reliability. In addition, the softer turn-on improves the EMI characteristics of the power supply, allowing designers to reduce the number of filters used, thereby reducing costs. There are several a...

AI Technical Summary

Problems solved by technology

[0003] However, one of the disadvantages of ZVS (quasi-resonant switching) zero-voltage turn-on work is that the output voltage is higher than the reflected voltage Vout>Vin / N of the input voltage at the output terminal. In the low phase of the grid voltage, when this condition is not met, it cannot be completed. Quasi-resonant switching on

In addition, in the low phase, the quasi-resonant control causes the switching frequency to be too high, resulting in increased switching loss and reduced conversion efficiency, so it is generally not suitable to use the quasi-resonant control method in the low phase part

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