Lcr meter measurements

Thread Starter

myil

Joined May 2, 2020
145
Hi Everyone,

I bought a new and fairly cheap LCR meter that is capable of measuring paralel and series of resistance, inductance and capacitance with a frequency up to 2mhz. I would like to use it for dc-dc converter designs. But I don't know what kind of capacitor and inductor models with parasitic elements I need to choose to simulate it on MATLAB. And also, switching frequency of my one of design is to be chosen 62.5khz. Should it also be my test frequency?

Thanks and Best regards
 

Papabravo

Joined Feb 24, 2006
21,159
How many different kinds of inductor and capacitor models do you know of?

Here is one for an inductor:
1658947342818.png
Here is one for a capacitor:
1658947399879.png
Is that what you were looking for?
 

Thread Starter

myil

Joined May 2, 2020
145
How many different kinds of inductor and capacitor models do you know of?

Here is one for an inductor:
View attachment 272370
Here is one for a capacitor:
View attachment 272371
Is that what you were looking for?
I don't know any actually. Just did a quick search on web. What do you recommend me to use for MATLAB model? I would like to keep it as simple as possible but accurate as well. Thanks for your reply.
 

Papabravo

Joined Feb 24, 2006
21,159
I don't know any actually. Just did a quick search on web. What do you recommend me to use for MATLAB model? I would like to keep it as simple as possible but accurate as well. Thanks for your reply.
It has been two decades since I have used MATLAB and I'm not sure it even comes close to being the best tool. However, I can recommend an alternative for this purpose.
 

Thread Starter

myil

Joined May 2, 2020
145
These inductor and capacitor values from a boost converter. Would you mind sharing the equivalent capacitor and inductor models of the boost converter with these values? :)
 

Papabravo

Joined Feb 24, 2006
21,159
These inductor and capacitor values from a boost converter. Would you mind sharing the equivalent capacitor and inductor models of the boost converter with these values? :)
I'm sorry to tell you that your units are wrong for the capacitor pictures. Henries are for inductors, and Farads are for capacitors. You also need a few other things for a boost converter like an input voltage and an output voltage and some idea of output power. Here is a generic boost converter with a light load which leads it to operate in DCM.
1658957398906.png
 

Thread Starter

myil

Joined May 2, 2020
145
Thanks. You are right about units. Probably I have a problem with calibration. But Can you provide me a schematics with parasitic elements by using parallel and series values on my scope? I know the capacitor measurement wrong but you can replace a capacitor for capacitance measurement. I would like to see how to draw a model. So I can plug these elements to matlab.

Regards
 

Papabravo

Joined Feb 24, 2006
21,159
Sure. Here is a schematic for an open loop buck converter. The inductor L1 has a DC resistance, Rser=0.05Ω, and capacitor C1 has an Equivalent Series Resistance, Rser of 0.15Ω. The duty cycle is 50%. The output should be about 4.52V@2.38 Amperes because of the losses in the inductor, capacitor, switch, and diode.
1659016697182.png
 

Thread Starter

myil

Joined May 2, 2020
145
Sure. Here is a schematic for an open loop buck converter. The inductor L1 has a DC resistance, Rser=0.05Ω, and capacitor C1 has an Equivalent Series Resistance, Rser of 0.15Ω. The duty cycle is 50%. The output should be about 4.52V@2.38 Amperes because of the losses in the inductor, capacitor, switch, and diode.
View attachment 272436
Thank you :)
 
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