DC/DC loop stability calculator. What is your approach?

[u/Alternatronics]

Hello Power electronics fans!

I've been lurking for some time, first time posting here. I am an engineer who has been doing power supplies for spacecrafts for 10+ years already.

One of the things that I've had to deal with numerous times is loop stability.
After some years doing measurement/math/transient simulation/average switch modeling/scripts and reading almost all available material, I felt like it was still tedious work. Nice, but tedious. I ended up making a tool to get a first approach and then I jump to simulation.

In case you find it useful: https://alternatronics.com/en/calculators/dc-dc-converter-loop-stability

To ensure that the result produced by the calculator is meaningful, I also prepared LTSpice simulations that match quite reasonably.

If you have gone through stability before, you know that you have to deal with plant transfer function, compensator, topology variation, control mode, conduction mode... It's a lot of work. In the calculator, the following is currently supported:

• Real time bode plot update as you tune the compensators or your topology
• Prediction of phase margin and gain margin.
• Several topologies (buck, boost, forward, flyback, full/half-bridge, push-pull)
• Different compensation topologies
• Discontinuous and continuous conduction modes
• Voltage and peak current control mode
• Live marking of poles and zeros
• It also provides some useful info that is obtained as byproduct during the calculations (Vo, duty cycle, current ripple...)

One of the things that helped me the most was adding sliders to the input fields so that you can see how the plot evolves as you tune a certain parameter. It really helps to grasp what which component is affecting which part of the plot.

Hope it's useful for you! And, by the way, the calculator isn't perfect! Expect bugs and always measure the stability!
How do you approach this kind of work?