I wil be doing repeated measurements for averaging, but, only with my previous idea of a single current ramp. My main motive for this is power - once energy is put into the inductor on the rising ramp, how can I recover that whilst stll maintaining the same voltage over the inductor? As in, the ramp up and ramp down are symmetrical. With my original idea, I'll be doing say 8 tests for each current threshold, and averaging these, but each time, only charging the inductor, and allowing it to discharge back into a cap bank (which is used to provide ~5V to the linear regulator, so the power input doesn't have to provide more than say 200mA at a time to replenish the cap bank which will deplete due to losses). Allowing it to discharge this way, means that the voltage across it isn't fix, so the 'down ramp' would be steeper, and dependent on the cap banks voltage.
I do see what you're saying, and it does seem a much better way, one could time the entire sequence (basically making an oscillator, but with higher currents), starting from 0, then turning off the voltage once the inductor current reaches a threshold, then one times how long this takes to get back to 0, rinse, repeat etc.. If you can explain in further detail your idea, I would be very interested! My original idea has its issues and many sources of error, its a kind of brute force approach for getting saturation current.
I do like the idea of 'burst tests', as that is what I've been on about, not continuously using the inductor in an oscillator, but a fixed number of tests that are averaged, and then parameters changed, and it does another few tests, eventually giving a fairly good idea of whats happening.
I also like the idea of going through the BH curve for cores. However, I fear we're approaching the sort of test that would require an oscilloscope (to visualise) or heavy processing to extract such information from the test above. There are of course precision test gear for such things, but I was going to strip down the design to very basic, and buildable (using AVR or PIC) whilst still maintaining some accuracy.
I think I have got to the point where I'm going to have to lean less on simulations, and actually build something, get my scope out, and see what happens
I do see what you're saying, and it does seem a much better way, one could time the entire sequence (basically making an oscillator, but with higher currents), starting from 0, then turning off the voltage once the inductor current reaches a threshold, then one times how long this takes to get back to 0, rinse, repeat etc.. If you can explain in further detail your idea, I would be very interested! My original idea has its issues and many sources of error, its a kind of brute force approach for getting saturation current.
I do like the idea of 'burst tests', as that is what I've been on about, not continuously using the inductor in an oscillator, but a fixed number of tests that are averaged, and then parameters changed, and it does another few tests, eventually giving a fairly good idea of whats happening.
I also like the idea of going through the BH curve for cores. However, I fear we're approaching the sort of test that would require an oscilloscope (to visualise) or heavy processing to extract such information from the test above. There are of course precision test gear for such things, but I was going to strip down the design to very basic, and buildable (using AVR or PIC) whilst still maintaining some accuracy.
I think I have got to the point where I'm going to have to lean less on simulations, and actually build something, get my scope out, and see what happens