Rectifier Efficiency

Formula

Description

Rectifier conversion efficiency is the ratio of useful DC output power to the AC input power. It has a theoretical ceiling because the rectified waveform contains AC harmonics that do not contribute to the DC term: about 40.6% for an ideal half-wave rectifier and 81.2% for a full-wave rectifier. Real efficiency is lower still due to diode drops and transformer losses.

Variables

• η — Conversion efficiency (fraction)
• Pdc — DC power delivered to the load (W)
• Pac — AC power drawn from the source (W)

Practical Notes

The full-wave maximum (81.2%) is double the half-wave value because both half-cycles deliver power. This ceiling is why linear supplies are inefficient and switch-mode designs dominate above a few watts.