Switch converter and control method thereof

Abstract

The invention discloses a switch converter and a control method thereof. The switch converter comprises a positive input power source, a positive output voltage source, a power source common ground, switch tubes Q1 to Q4, an inductor L1 and a capacitor C1, the drain of the switch tube Q1 and the drain of the switch tube Q3 are connected to the positive input power source, the source of the switchtube Q1 and the drain of the switch tube Q2 are connected to one end of the inductor L1, the source of the switch tube Q3 and the drain of the switch tube Q4 are connected to the other end of the inductor L1, the source of the switch tube Q4 is connected to one end of the capacitor C1, and the source of the switch tube Q2 and the other end of the capacitor C1 are connected to the power source common ground. The inductor L1 can be rapidly demagnetized under a relatively high ratio of input voltage to output voltage, current waveform of the inductor L1 is converted from triangular into quadrangular, and high-efficiency high-frequency work of the switch converter is realized.

Description

technical field [0001] The invention relates to a switching power supply, in particular to a switching converter circuit and a control method thereof. Background technique [0002] figure 1 It is a traditional step-down circuit, the effective value of the current is relatively large when the circuit works in discontinuous mode, the MOS transistor Q1 is a hard switch, and the conduction loss of the diode D1 is large. [0003] figure 2 It is a step-down circuit with synchronous rectification function. Compared with the traditional step-down circuit, it reduces the conduction loss in the freewheeling stage. In FCCM mode, it can also realize the ZVS turn-on of the MOS transistor Q1, because the ZVS turn-on of the MOS transistor Q1 and The range of high-efficiency work is relatively narrow, so there is a problem of low overall efficiency in the wide voltage input range and full load range. [0004] image 3 It is the drawing of the abstract of the US patent with the applicat...

AI Technical Summary

Problems solved by technology

[0005] In view of the technical defects of the existing step-down circuit and its improved patented circuit and control method, the present invention proposes a switching converter and its control method to solve the problem that the current effective value of the step-down circuit is large when the step-down circuit works in discontinuous mode, and the conduction The problem of excessive loss

It also solves the problem of compromise between high-current output and high-efficiency operation when the ratio of input-output voltage is greater than 3, the ton time of MOS transistor Q1 is too small and the freewheeling time of MOS transistor Q2 is too long to achieve high frequency.

Images