Hi,

I am working on Ultrasonic welding Power supply . Freq 20khz, Power is 1kw in full bridge.
Although I have tried with PLL 4046 ,PLL is doing its job fine but it is not exactly locking to required resonance freq.

Here are some points when resonance occurs:

1> voltage & current become in phase ,but practically have seen this condition when there is no resonance at all .

2> voltage & current of transducer will be minimum.

Can anybody suggest me better method to track resonance of ultrasonic transducer. .

Regards.