Design principle of zero voltage switch

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Overview:
When ZVS is turned off, when the switch is turned on, the voltage across it is already zero. In this way, the switching loss of the switching tube can be minimized. However, there is a disadvantage in that the adjustment range is generally narrow. Here is a technical post, a technical engineer's own detailed anatomy of the zero-voltage switching circuit, and some of his own design ideas based on zero-voltage switching circuits. Give everyone a reference!

ZVS circuit principle and design

What is ZVS, and the mother is looking for "Zero Voltage Switch". That is, when the switch is turned off, when the switch is turned on, the voltage across it is already zero. In this way, the switching loss of the switching tube can be minimized. The induction cooker and LLC power supply that we usually use are all such resonant power supplies. The ordinary chargers and the like are hard-switched, which is larger than the loss of this resonant power supply. Therefore, ZVS can achieve high efficiency, but there is a disadvantage that the adjustment range is generally narrow. For example, the induction cooker, when we adjust the power to a relatively large, for continuous heating; when the power is small, it begins to intermittently heat, because at that time can not reach the resonance state. Power supplies like our normal chargers, which are hard-switched, are constantly oscillating, both empty and full.

When I first saw the ZVS circuit, I was shocked. Two MOS transistors plus several resistors and capacitors could form a resonant switch. I really admire the imagination of the people.


This circuit requires only a few components to achieve zero voltage switching. Some people have to do more than 2KW of power. If you have several hundred watts, you only need to add a small radiator.

So it took a few days to conduct an in-depth study of the ZVS circuit, so that everyone can understand its working principle.
(Please read the PDF for details)