High step-up ratio converter for DC (Direct Current) module on basis of coupled inductors

Abstract

The invention discloses a high step-up ratio converter for a DC (Direct Current) module on the basis of coupled inductors, which comprises two main switching tubes, two clamping switching tubes, two freewheel diodes, two output diodes, two clamping capacitors, two voltage-multiplying capacitors, an output capacitor and tow coupled inductors each of which is respectively provided with two windings. According to the invention, a voltage gain of the converter is expanded and voltage stresses of the power switching tubes and the diodes are reduced by the coupled inductors; the leakage inductances of the coupled inductors are utilized to implement zero voltage switching of the switching tubes and inhibit reverse recovery currents of the diodes; a clamping circuit consisting of the clamping switching tubes and the clamping capacitors effectively adsorbs a voltage spike when the power switching tubes are switched on and switched off and implements lossless transfer of energy; a coupled inductor series circuit is utilized to further improve the gain of the converter and further reduce the voltage stresses of the power switching tubes and the output diodes; the high step-up ratio converter has a simple circuit structure, is convenient to control and is suitable for the high-gain and high-efficiency grid-connected photovoltaic power generation transformation place.

Description

technical field [0001] The invention relates to a DC-DC converter and its application, in particular to a converter with a high step-up ratio for a DC module based on coupled inductance. Background technique [0002] In the solar power generation system, since the output voltage of a single solar cell is low, and the voltage required for inverter grid-connected power generation is relatively high, a first-stage DC-DC converter is required to convert low-voltage DC power into a high voltage suitable for grid-connected power generation. Voltage DC. In the distributed solar power generation scheme, the power capacity of a single solar cell is small, but the requirement for efficiency is high. Therefore, how to realize a single-phase single-stage converter with high gain, high efficiency and simple structure is of great significance for promoting the development of the photovoltaic industry. [0003] The voltage gain of the conventional interleaved parallel boost DC-DC convert...

AI Technical Summary

Problems solved by technology

[0003] The voltage gain of the conventional interleaved parallel boost DC-DC converter is only determined by the duty cycle, the voltage gain is limited, and it is difficult to meet the conversion requirements of high gain

The voltage stress of the power switch tube is relatively large, and it is difficult to use a low-voltage high-performance switch tube to reduce the conduction loss

Moreover, the converter works in a hard switching state, and the switching loss is relatively large

In order to realize the soft switching action of the Boost converter, in recent years, some soft switching schemes by adding active power switches or passive devices have been studied successively. Although these circuits realize the soft switching action, they cannot reduce the voltage stress of the switching tube. It is also impossible to realize the high-gain conversion of the system

In order to increase the voltage gain of the converter, one solution is to use switched capacitors, but this solution requires a large number of switch tubes, which increases the system cost; another solution is to use a complex three-winding coupled inductor solution. The disadvantage of the scheme is that the structure of the coupled inductor is complex, which is not conducive to industrial processing, and it is difficult to ensure the consistency of the circuit

Images