The power consumption of the switching power supply includes the fixed loss generated by the parasitic resistance of the semiconductor switch, magnetic components and wiring, and the switching loss during the switching operation. As for the fixed loss, since it mainly depends on the characteristics of the component itself, it needs to pass through the component It can be suppressed by the improvement of technology. In terms of magnetic components, it is low for taking into account the skin effect and the adjacent wire effect.
The research on the loss winding method has a long history. In order to reduce the switching loss caused by the switching surge caused by the leakage inductance of the transformer, new circuit technologies such as a snubber circuit with a surge energy regeneration function have been developed. The power adapter manufacturer will introduce to you The following circuit and system approaches to improve the efficiency of switching power supplies:
1. Use resonant switches to reduce switching losses through ZVS (zero voltage switching), ZCS (zero current switching), etc.
This method is very effective for reducing switching losses, but the problem is that the fixed losses due to peak current and peak voltage will increase.
2, use the edge resonance (Edge ResONance) represented by the active clamp circuit to reduce the switching loss
This method is an active snubber (Active Snubber) developed to solve this problem. It is a very practical ZVS method. The problem of efficiency drop caused by reactive current under light load conditions is a major defect. .
3, reduce the fixed loss by extending the conduction time of the switching element to suppress the peak current
In this method, it is more effective to use a tapped inductor (Tap Inductor), which can cope with the surge phenomenon caused by the leakage inductance.
4, in the case of low voltage and high current, the fixed loss can be reduced by improving the method of synchronous rectification circuit
The two-stage structure is one of the methods to realize the high-efficiency operation of the synchronous rectification circuit. It uses a fixed time ratio (Time Ratio) close to 0.5, and the output voltage is controlled by the converter in the front stage. It reverses the “two-stage structure. The traditional thinking mode of “leading to a decrease in efficiency” is very effective in low voltage and high current occasions.
5, use the parallel structure of the converter to reduce the fixed loss
In the last method, the entire converter circuit can be connected in parallel, or part of the parallel structure can be used like the current doubler (Current Doubler).