Switching power converter

Abstract

A power converter of switching over type consists of a transformer with the first primary winding and the second primary winding being separately connected to positive and negative electric rails, a switch connected between two said windings, a control circuit coupled to switch and the second primary winding, a supply capacity for providing power to control circuit, a dipolar body coupled to negative rail and supply capacity, a leakage inductance for storing energy when switch is on and for releasing energy to supply capacity through dipolar body when switch is off.

Description

Technical field: [0001] The present invention relates to a power converter, in particular to a switching power converter. Background technique: [0002] By the way, power converters have been widely used to provide adjustable voltage and current. At present, the focus of research on power converters is how to make power converters more efficient and save power. Switching mode power converters usually include a control unit, a switch and a transformer, wherein the control unit is used to sense the output voltage and / or output current of the switching mode power converter, and generate a control signal to control switching and adjustment of the switch The output voltage and / or output current of the switching mode power converter. [0003] see figure 1 , which is a circuit diagram of a conventional switching power converter. As shown in the figure, the conventional switching power converter includes a transformer 10, which includes a primary side winding N P , primary and s...

AI Technical Summary

Problems solved by technology

The first disadvantage is that the leakage inductance of the transformer 10 leads to high power consumption. In addition, because the leakage inductance will store energy and form a high voltage surge, it is easy to damage the switch 11. Therefore, in order to protect the switch 11, the conventional switching power converter is equipped with a A snubber circuit, which includes a snubber diode 19, a snubber capacitor 20 and a snubber resistor 21, is used to consume the energy stored in the leakage inductance of the transformer 10, avoiding the formation of high voltage surges to protect the switch 11

[0013] The second disadvantage is the lack of regulation of switching power converters under light load and no load conditions

If the output load of the switching power converter is lower than the auxiliary winding N A When the load is high, the energy stored in the transformer 10 will only be able to pass through the diode 18 and the auxiliary winding N A Released to the supply capacitor 17, so when the switch 11 is turned off, the rectifier 13 will remain in the off state, so the output voltage V of the switching power converter O not available from the auxiliary winding N A Feedback to the control unit 25, so in the light load and no load state, the detection voltage V generated by the voltage detection terminal VS DET1 It is only related to the voltage of the supply terminal VDD, so the conventional switching power converter lacks adjustability

[0014] Another known technology is the US Patent No. 6,853,563 "Primary-side controlled flyback power converter (Primary-side controlled flyback power converter)" proposed by Mr. Yang et al. One of the main shortcomings of this known technology It is Electromagnetic Interference (Electric and Magnetic Interference, EMI), which is caused by the fact that the drain of the switch is directly connected to the positive supply rail, so a parasitic capacitance of the switch is coupled with a parasitic inductance, thus forming a high-frequency resonance tank, so Will generate high electromagnetic interference

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