8 views Yuda Electronic (HK) Technology Co.,Limited. 2020-07-28
The power consumption of a switching power supply includes fixed losses caused by parasitic resistances of semiconductor switches, magnetic elements, wiring, etc., and switching losses during switching operations. For fixed loss, since it mainly depends on the characteristics of the component itself, it needs to be suppressed through the improvement of component technology. In terms of magnetic components, there has been a long history of research on low-loss winding methods that take into account the skin effect and the adjacent wire effect. 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 introduces the following circuits and system methods to improve the efficiency of switching power supplies:
1, use resonant switching to reduce switching loss through ZVS (zero voltage switching), ZCS (zero current switching), etc.
This method is extremely effective for reducing switching losses, but the problem is that the fixed losses due to peak current and peak voltage will increase.
2. Use Edge ResONance represented by active clamp circuits to reduce switching loss
This method is an Active Snubber developed to solve this problem, and it is a very practical ZVS method. The efficiency drop caused by the reactive current under light load conditions is a major drawback.
Three, reduce the fixed loss by extending the on-time of the switching element to suppress the peak current
In this method, the tap inductor is more effective, which can cope with the surge phenomenon caused by the leakage inductance.
Fourth, in the occasion of low voltage and high current, reduce the fixed loss by improving the synchronous rectifier circuit
The two-stage structure is one of the ways to realize the high efficiency of the synchronous rectification circuit. It uses a fixed time ratio close to 0.5, and the output voltage is controlled by the converter in the previous stage. It is contrary to the traditional thinking mode of “two-stage structure will lead to a decrease in efficiency”, which is very effective in the occasion of low voltage and high current.
5. Use the parallel structure of converters to reduce fixed losses
In this last method, the entire converter circuit can be connected in parallel, or it can be partially connected in parallel like a Current Doubler.
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