Core loss, proximity and skin loss
Currently I am working on a boost converter thesis project and my task is to find losses in the inductor. Its hardware based work.
I have three questions regarding inductor losses
1- For the given coil, core material properties are not given in the data sheets and I also contaced coil supplier but no response from them perhaps they do not want to disclose. Then I broke the inductor and fond the number of turns, number of layers,height of the layer,width of the layer. After getting this information I use dowells equation to find the proximity loss. Can anyone tell me is that the right approach? the equation cabn be seen in the following link (heading of the chapter is the euation)
http://ridleyengineering.com/images/...ity%20loss.pdf
2- How can I find the core losses with out corematerial properties? The coil that I am using is from Vishay 10UH
3- This is the most important question. I choosed an indirect approach to find the coil losses in the boost converter by subtracting the mosfet losses and DC loss of the coil from the total losses of the converter and rest are the AC losses in the coil. I did not choosed the direct approach because its difficult and I do not know the equipment required for direct measurement. Every time I go for meeting with my professor he ask why indirect approach why not direct. I need to answer this quetion please help me.
Your professor's questions makes only sense if you have the required equipment (current probe, digital oscilloscope with respective math features) available in the lab.
An alternative method to determine the total coil losses is to measure the coil overtemperature in steady state and find out which DC current will produce the same temperature.
First you need to determine the B-H curve using conventional tools and and determine the hysteresis curve and determine the hysteresis loop area and estimate the hysteresis loss;
Next you determine the copper losses (both skin effect and proximity losses) experimentally. Using the current and voltage close to the field values, measure the power loss - by determining the phase angle.
You also need to calculate the expected losses (proximilty losses will be low for small currents) and compare the results.