Hi, everyone.

I am doing a project about buck converter.

I want to inject a stimulus signal to observe the deviation of the component and estimate the stability of the whole system.

example: observe the ESR variation of the output capacitor, if the ESR value becomes larger, the system would be unstable?

or another component parameter variation influences the system stability.

But I don't know how to implement on my circuit.

Thanks for the reply!

 

Welcome to AAC!
Is this a real world buck converter, a simulated one, or a merely hypothetical one?

 

It's just in the conception stage now.

After that, I will turn it into an integrated circuit.

Briefly speaking, I want to inject a stimulus signal into the circuit and observe the response.

Therefore I can know the health status of switch mode power supply, and then predict the remaining useful life of SMPS.

But I have no idea how could I do.

Thanks for the reply.

 

What are the stimulus signal characteristics?

 

One way is to inject a small signal through a high value resistor in series with a capacitor into a low impedance point in the feedback loop (such as the minus input of an op amp).
Injecting a sinewave frequency sweep and measuring the output phase and amplitude will give a Bode plot to check the loop stability.
Injecting a step or pulse will check the transient response for any significant ringing, which also is a measure of loop stability.

 

I am still thinking not sure, maybe the voltage or current stimulus signal.

Take this as example: http://ieeexplore.ieee.org/document/5351978/

The author injects a white noise as stimulus signal and uses identification method to measure the diagnostic indicator.

But I want to do it more easily.

Inject a stimulus signal then observe the response characteristics.

Maybe the characteristics behavior is slew rate, settling time, overshoot, etc..

Thanks for the reply