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LTSpice - realtime frequency to voltage conversion

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ACharnley

Member
Hi,

I have a buck circuit where the control factor is the input voltage (MPPT tracking) not the output. It's different from the usual buck as there's no pwm input, it resonates based on input/output capacitance and the inductor. All is working well except that the inductor can still enter discontinuous mode when the input is too low which causes a bit of backflow. In real-life I'll analyse the pulse using a PIC SMT and cut off the async lower FET's to prevent backflow. The question is how to do this in LTSpice.

A visual representation may make more sense.

Here you can see DCM with backflow.

Screenshot_2019-05-12_07-22-17.png

If I convert the PWM to voltage I can cut the FET's off.

Screenshot_2019-05-12_07-24-48.png

I'm doing this at 98.4ms using the circuit on the right, but it's not perfect and perhaps there's a better way?

Screenshot_2019-05-12_07-23-01.png


Cheers, Andrew
 

crutschow

Well-Known Member
Most Helpful Member
There is no inductor in your schematic so where is the backflow coming from?
Please show the complete circuit.
 
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