Isn't it all zero voltage? Then where does the loss of ZVS come from?

okhxyyo

Isn't it all zero voltage? Then where does the loss of ZVS come from? [Copy link]

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Engineers should basically know a simple formula for calculating power consumption, P=UI. According to this formula, if U=0, should the power consumption also be 0?

For example, ZVS soft switching, I saw that it is zero loss in theory, but in reality it is not zero loss?

Where does the loss of ZVS come from?

Can anyone who knows tell me about it?

Guan Guan also sorted out articles and materials that explain the ZVS circuit. If you want to know more, you can take a look:

In zero voltage switching applications, the selection and design of power devices need to take into account several key performance indicators

Principle and main circuit parameter calculation of phase-shifted full-bridge ZVS converter

Research on ZVS Control Strategy of Four-Switch Buck-Boost Converter

Research on 5kW Phase-Shifted Full-Bridge ZVS-DCDC Converter

木犯001号

Let me answer it~

ZVS losses mainly come from the following aspects:

1. Turn-on loss

• Overlap of voltage and current : In ZVS applications, although the switch is turned on when the voltage is zero or close to zero, in actual operation, the overlap of voltage and current is still difficult to completely avoid. This overlap causes energy to be consumed during the switching process, resulting in turn-on loss.
• Miller effect : When switching devices such as power MOSFET are turned on, the existence of Miller capacitance will produce Miller platform time. The overlap of voltage and current during this period will also cause turn-on loss.

2. Turn-off loss

• Hard switch shutdown : Although ZVS technology focuses on zero voltage turn-on, hard switching is still used in many cases during the shutdown process. This means that at the moment of shutdown, the voltage and current will change rapidly, resulting in large turn-off losses.
• Overlap of VDS and ID current : During the shutdown process, the VDS voltage starts to rise from 0, while the ID current starts to decrease from the maximum value. The overlapping area between the two will produce shutdown loss. In order to reduce this loss, some measures are usually taken, such as increasing the VDS rise time, reducing the VDS rise slope, etc.

3. Dead time loss

• Conduction loss during dead time : In ZVS applications, a certain dead time is usually set to prevent the switching devices of the upper and lower bridge arms from being turned on at the same time and causing a short circuit. During this period, although the switching device is in the off state, due to the presence of components such as inductance in the circuit, current still flows, resulting in conduction loss.

4. Other losses

• Loss of the switching device itself : During the on and off process of the switching device, certain losses will be generated due to the existence of parameters such as resistance and capacitance. In addition, factors such as the switching frequency and operating temperature of the switching device will also affect its loss.

okhxyyo

Posted by Mufan 001 on 2024-9-4 10:49 Let me answer it~ ZVS loss mainly comes from the following aspects: 1. Turn-on loss Overlap of voltage and current: In ZVS application...

This is very detailed.