Estimation of Parasitic Inductances of a Two-Phase Interleaved Buck Converter with Coupled Inductors Through Detailed Experiments

This paper presents the experimental determination of parameters, especially the leakage inductance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(L_{lk})$</tex> of coupled inductors (CIs) due to the leakage flux of the CIs <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\phi_{lk})$</tex>, in a two-phase interleaved synchronous buck converter (ISBC) with a 200 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V$</tex> input feeding a 75 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$V$</tex>, 1.5 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$A$</tex> load at a nominal rating of 110 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$W$</tex>. The CIs have been designed to operate at a frequency of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$100\ kHz$</tex>. It is identified that the performance of the CIs are heavily influenced by <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L_{lk}$</tex> and the coupling coefficient <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(k)$</tex> of the CIs. A simple, yet novel method of determining <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L_{lk}$</tex> from the experimental waveforms has been proposed. Besides <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{L}_{l k}$</tex> of the CIs, the parasitic inductances <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(L_{pr})$</tex> in the actual hardware prototype contribute to the total inductance <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(L_{uc})$</tex> that does not couple the two phases of the CIs. This distorts the voltage waveform across the CIs. An analytical exercise is carried out to evaluate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$L_{pr}$</tex> from the experimental waveforms and then validated through circuit simulations. Further, the various losses in the CIs have been calculated from the experimental results as a part of the performance validation exercise. The experimental and simulation results are found to be in good agreement.