Common mode thunderstrike killer circuit of power supply

Abstract

A common mode thunderstrike killer circuit of a power supply comprises: a filter, the filter can be one or two difference mode inductors, or can be a common mode inductor of a conjugate iron core, so high frequency noises are filtered; a rectifier, and the rectifier can be full wave rectification or half wave rectification of any mode; an isolation transformer; a Y capacitance used for suppressing electromagnetic interference; and common mode strike killing member being impedance member, the common mode strike killing member can be constant value resistance, variable resistance, or thermistor, the common mode strike killing member is connected in series with the Y capacitance, and two ends of the common mode strike killing member connected in series with the Y capacitance are respectively connected with a primary side ground wire and a secondary side ground wire of the isolation transformer.

Description

technical field [0001] The invention relates to a circuit design for a power supply to suppress common-mode lightning strikes. Background technique [0002] In recent years, the rise of the concept of energy saving has led to a large number of power supplies (SPS) being used in various electronic products. Since power transmission often has to go through long distances, high and low altitudes, latitudes and other environments, it often leads to outdoor lightning strikes. High-voltage energy signals are induced on power transmission. In view of this, the relevant safety regulations of various countries have formulated relevant specifications and requirements for lightning strike (surge) testing, generally based on IEC61000-4-5 and IEC61000-4-12. Specifications prevail. [0003] Such as figure 1 As shown, the main components passed by the common-mode lightning strike circuit are the filter 11 , the rectifier 13 and the Y capacitor 17 . Currently common lightning strike coun...

AI Technical Summary

Problems solved by technology

However, the original purpose of the Y capacitor 17 is to balance the stray parameters of the transformer, so that the high-frequency noise has a low-impedance path loop, so as to reduce the leakage of the high-frequency noise signal of the EMI electromagnetic wave, so reducing the capacitance of the Y capacitor 17 will lead to the solution to the EMI countermeasures. rising costs

[0006] Place thermistors TR1 and TR2 on the power lines L (Line) and N (Neutral) (such as figure 1 As shown), increasing the line impedance thermistors TR1 and TR2 of the lightning strike circuit is often used in the power supply to reduce the inrush current at the moment of starting up. Here, it also has the function of slowing down the lightning strike current, but common mode lightning strikes have separate L pairs PE (Protect Earth), and N to PE, so it is necessary to place thermistors TR1 and TR2 on L and N at the same time, and L and N are still the energy transfer paths of the power supply, so the efficiency of the power supply and The temperature will have a non-negligible effect, so that the impedance can only be selected with a small impedance value, and the impedance will be further reduced after the heat engine

[0007] Based on the above lightning strike countermeasures, it is found that there will be efficiency loss caused by the path, and the impact of lightning strikes cannot be effectively suppressed due to the different impedance characteristics due to the frequency response. Furthermore, the cost of other safety requirements of the power supply will increase due to the lightning strike countermeasures, so there are It is necessary to develop a countermeasure that can effectively suppress lightning strikes without affecting the energy efficiency and EMI electromagnetic interference characteristics of the power supply system

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