Here is the half-bridge LLC. The excitation current, resonant current, and current waveform of the MOS tube are all drawn. I have some questions.

西里古1992

Here is the half-bridge LLC. The excitation current, resonant current, and current waveform of the MOS tube are all drawn. I have some questions. [Copy link]

 

First, when the MOS tube is turned on, is the current waveform passing through the MOS tube exactly the same as the resonant current waveform? For example, when the tube current passes through zero, I see that the resonant inductor current also passes through zero. The excitation current also passes through zero and has an amplitude. Doesn't it pass through the MOS tube? Does it have no effect on the current of the MOS tube? Or when the excitation inductor does not participate in the resonance, what is the path of the excitation current? Does it not pass through the MOS tube?

Second, when there is current in IQ2/IQ3 on the right side, why does the current direction go to the positive half axis instead of being the same as the resonant current waveform? I don't understand.

maychang

[First, when the MOS tube is turned on, is the current waveform passing through the MOS tube exactly the same as the resonant current waveform? For example, when the tube current passes through zero, I see that the resonant inductor current also passes through zero, and the excitation current also passes through zero and has an amplitude, so doesn't it pass through the MOS tube? ]

This circuit is not yet a distributed parameter system, and Kirchhoff's laws are still valid.

不亦心

1. Resonant current = MOS current = excitation current + load current

2. Take the direction of the current arrow in the figure as the reference direction. The current of Q2 and Q3 is like this. Is it not clear if you draw it yourself?

西里古1992

Bu Yixin published on 2023-4-12 23:23 1. Resonant current = MOS current = excitation current + load current 2. Taking the direction of the current arrow in the figure as the reference direction, the current of Q2 and Q3 is obtained in this way. You can calculate it yourself...

I understand that the DS of the MOS tube is the positive half cycle, but the standard of the resonant current is clockwise and counterclockwise, which leads to the difference