Hi, I’m wondering if anyone has any ideas that might help me. I’m working on a 20V - > 20-40V boost converter. I’ve run into difficultly recently by saturating my 10uH inductor, which will happen at ~25A. In continuous mode I have no idea in which way the avg and peak L1 current is trending. I’d like to introduce some direct current sensing method so that I can achieve maximum power transfer through the converter while maintaining good efficiency. So far the best solution I’ve come up with is introducing a hall sensor to GND in series with L1. ACS712ELCTR-20A-T is on my radar because it’s rated to 20A. Other ideas I’ve considered are:
- Measuring the initial dV/dt of the FET’s parasitic drain-source capacitance when the charge phase ends. dV/dt here would be ~1V/ns so it’d be necessary to have some sort of peak detect circuit of a capacitor and diode to allow an ADC to derive the dV/dt. I suspect the error terms would be very large and it would be necessary to add a 10nF fixed capacitor across Source-Drain due to the variability of the FETs capacitance.
- Measuring the initial dV/dt across the output capacitor C1 as L1 discharges into it. dV/dt here would be ~0.01V/us so is measurable directly by the ADC. The capacitance is better known but still varies with temp. and the current sinked by the output can vary and cause error.
- Adding an enameled strand around L1's core and measure the induced voltage which should round off as saturation starts. No idea how I'd determine this though.