Is there a way to toggle between two switching frequencies?

Thread Starter

SiCEngineer

Joined May 22, 2019
81
I am posting here because I suppose it is not just related to power electronics and SMPS.

Is there any way to toggle between two switching frequencies, rather than navigating linearly from a min > max frequency?

I know with a voltage controlled oscillator the frequency depends on the input voltage - is there a way to design this to toggle between two frequencies, for example 50kHz and 150kHz?
 

Dodgydave

Joined Jun 22, 2012
8,469
Yes if you use a switching chip like CD4016, then you can just put in the resistance values you want, or use transistors to pull in the resistors, best chip for a smps oscillator is TL494.
 

crutschow

Joined Mar 14, 2008
23,502
Now you added duty-cycle which, is an added requirement.

What will generate the signal to change the FREQ/DUTY of the signal?
 

atferrari

Joined Jan 6, 2004
3,486
What about an FPGA? Any recommendations for a micro/FPGA? I would need control of FREQ/DUTY control of 3 FETs.
FPGA? No idea.

Look at the PIC 18F4431 (Microchip).
Do not let the complexity to overwhelm you.

BTW, are you sure that you will need toggling between two frequencies? Isn't maybe between two duty cycles? Most probably this last, I suspect.

Not the way to learn how the micro works but once in the .pdf, do a search (Ctrl F) for "on the fly". That will put you in the ballpark.

A powerful beast.
 

Thread Starter

SiCEngineer

Joined May 22, 2019
81
Now you added duty-cycle which, is an added requirement.

What will generate the signal to change the FREQ/DUTY of the signal?
I would need to control both the frequency and the duty cycle of the converter. I am unsure, that's why I have posted here. I have seen power converters that use dual control of FREQ and DUTY but I am unsure whether it can be implemented in analog - most likely a PIC will be better as above, which is fine. Basically, I have a resonant converter which only operates at full load (or thereabouts) or zero load when pulsed OFF. Therefore I thought of having two fixed frequencies for each load, then regulate the duty cycle to regulate the output voltage. Might not be feasible but I was interested to find out about the possibility of toggling between two frequencies anyway!
 
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