on-interval-builds-ripple - Electronic Circuits XIII & XIV: Power Supplies and Switching Energy Step by Step

An on-interval-builds-ripple scan holds the inductance and interval fixed and varies the switch-on voltage across three rows, checking that the upward ripple delta-I_on = V_on * delta-t / L tracks the on-voltage row by row. The arithmetic is exact only for the stated inductances, on-voltages, intervals, current changes, and rows in the ideal inductor and ideal switching model. Real converters add winding resistance, switch loss, diode drop, core saturation, ripple approximation, current-sense/probe calibration limits, finite precision, and measurement uncertainty.

A switch-on interval raises inductor current by a checked amount. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

On-time uses the positive inductor voltage

The inductance and interval are fixed. The positive switch-on voltage sets the upward ripple slope.

\Delta I_{\text{on}}={V_{\text{on}}\Delta t\over L}

Larger on voltage builds more ripple in the same time

Each row uses the same inductor and the same interval, so the current step follows voltage.

\begin{array}{c|c|c|c}L&V_{\text{on}}&\Delta t&\Delta I\\3\ \text{H}&3\ \text{V}&1\ \text{s}&1\ \text{A}\\3\ \text{H}&6\ \text{V}&1\ \text{s}&2\ \text{A}\\3\ \text{H}&9\ \text{V}&1\ \text{s}&3\ \text{A}\\\end{array}

The on interval builds a finite ripple current

The on-state inductor voltage is declared, then the current change is computed from that exact interval.

\Delta I_{\text{on}}=9\ \text{V}\cdot1\ \text{s}/3\ \text{H}=3\ \text{A}