Active clamping LED driving power supply without electrolytic capacitor

Abstract

The invention discloses an active clamping LED driving power supply without an electrolytic capacitor. The active clamping LED driving power supply comprises an AC input power supply, an input filtering part, a rectification part, a clamping circuit, a flyback converter, an output filtering capacitor Co, a parallel absorption loop and an LED load. The input filtering part is composed of an input filtering inductor and an input filtering capacitor. The rectification part is composed of four switch tubes. The clamping circuit is composed of a switching tube S2 and a clamping capacitor Caux; theflyback converter is composed of a flyback transformer, a switching tube S1 and a diode Ds. The flyback transformer comprises a primary side winding and a secondary side winding, the primary side winding comprises a main inductor Lm and a leakage inductor Lr, the primary side winding is connected with the input, and the secondary side winding is connected with the output; the parallel absorption circuit comprises a boost inductor Lb, a switching tube S3, a switching tube S4 and an energy storage capacitor Cds. According to the invention, the active clamping circuit is introduced, so that the switching stress of the switching tube S1 is reduced; both the switching tube S1 and the switching tube S2 realize soft switching, so that the switching loss is reduced; meanwhile, leakage inductance energy can be fed back.

Description

technical field [0001] The invention belongs to the field of LED lighting driving power supply, in particular to an LED driving power supply which applies active clamp technology to a flyback type parallel absorption circuit without electrolytic capacitor. Background technique [0002] As a new type of light source, LEDs have shown incomparable advantages over traditional light sources in terms of life, power consumption, and brightness. They are widely used in daily lighting, large-screen displays, and automobile transportation. Electrolytic capacitors are used in traditional LED drive power supplies to stabilize the output voltage, but the life of electrolytic capacitors is only 1 / 10 of that of LED light sources, and electrolytic capacitors become a short board for the life of LED drive power supplies. In order to improve the life of the LED driving power supply, it is necessary to remove the electrolytic capacitor in the LED driving power supply. At present, flyback conv...

AI Technical Summary

Problems solved by technology

However, due to the existence of the leakage inductance in the flyback converter, there will be resonance between the leakage inductance and the parasitic capacitance of the switch tube, and a voltage spike will appear at both ends of the switch tube, and the switching stress is relatively large, which is unfavorable for device selection

And because the switching tube is a hard switch, there is switching loss, which limits the efficiency of the overall LED drive power supply

[0003] The document with application number 201810788145.0 discloses a bidirectional Cuk circuit-based non-electrolytic capacitor LED drive power supply and its switching method. It uses a bidirectional Cuk structure as a parallel absorption circuit. The Cuk circuit requires two capacitors and inductors. Large, high cost; and the output voltage is reversed, the switching stress of the switch tube of the flyback converter is large, and a high voltage peak will appear at both ends of the switch tube when the switch tube is turned off; and the leakage inductance energy is consumed in the RCD absorption circuit resistors, the leakage inductance energy cannot be utilized

And the working mode of the switching tube is hard switching, so there is switching loss

Images