DC-DC conversion decompression soft switch circuit

Abstract

The invention relates to a soft switch circuit for DC-DC conversion and voltage-reducing comprising an NMOS tube Q4, inductors L14 and L18, capacities C9 and C11 and diodes D11-D13. When the NMOS tube Q4 is turned on, the vin input terminal charges the C9 through a loop of C11, D13, L14, C9, Q4, wherein the diode D12 is in clamp after the follow current. When the Q4 is turned off, the voltage of the C9 is the input voltage of Vin, and the drain electrode and the source electrode voltages of the Q4 are zero. The benefit of the invention is to use less electronic components to realize the turn-off of zero voltage of the switch tube, thereby effectively reducing the electromagnetic interference and realizing the zero loss of the NMOS tube turn-off.

Description

A kind of DC-DC conversion step-down soft switch circuit 【Technical field】 The invention relates to an electronic ballast, in particular to a DC-DC conversion step-down soft switch circuit for a high-intensity gas discharge lamp. 【Background technique】 Please refer to Figure 1, Figure 2 and Figure 5, the current common DC-DC step-down conversion circuit basically uses a hard switching circuit, but in traditional power, the drain and source voltage of the MOSFET will be instantaneous when it is turned off. If it becomes very high, it will cause a lot of harm. One is to generate a large amount of electromagnetic interference, because the drain and source voltage change from zero to input voltage instantaneously, and the voltage change rate is very high, which makes it difficult for the product to pass the EMC, that is, electromagnetic compatibility. The second is that the switching loss is very large, because the shutdown will generate a lot of heat to reduce the efficiency...

AI Technical Summary

Problems solved by technology

Please refer to Figure 1, Figure 2 and Figure 5, the current common DC-DC step-down conversion circuit basically uses a hard switching circuit, but in traditional power, the drain and source voltage of the MOSFET will be instantaneous when it is turned off. become very high, causing a lot of harm

One is to generate a large amount of electromagnetic interference, because the drain and source voltages change from zero to input voltage instantaneously, and the voltage change rate is very high, which makes it difficult for the product to pass the EMC, that is, electromagnetic compatibility.

The second is that the switching loss is very large, because the shutdown will generate a lot of heat to reduce the efficiency of the power supply, thereby reducing the service life of the power supply

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