Power Electronics
An inverter produces AC from DC — this is the road from a solar panel to the grid, or from an electric car’s battery to its motor. In a half-bridge, two switches connect the output alternately to the + and − rail; when the resulting fast square pulses pass through an LC filter, a smooth sine wave remains.
The way to "draw" the sine is SPWM: the duty is varied continuously along with the desired sine — d(t) = ½(1 + m·sin(2πf₀t)). At the sine’s crest the pulses widen; in its trough they narrow. m (the modulation depth) is the volume knob for the output amplitude.
A deadly trap: if the two switches in the same leg conduct together for even an instant, they short-circuit the supply (shoot-through). The cure is a microsecond-scale dead time during every transition in which both stay off. Drive three half-bridges 120° apart in phase and you get three-phase power.
⚡ Open this lesson in the simulator — free