Single-phase full-wave diode rectifier
Single-phase diode rectifier, converting ac signal into a dc voltage, exist in two types – half-wave and full-wave one. Half-wave diode rectifier was mentioned before.
Full-wave diode rectifier can be two types as well – with a centre-tapped transformer and bridge rectifier. Both of them are depicted on the figure below.
In the case of center-tapped transformer, we have two half-wave rectifiers, combined. The DC currents of these half-wave transformers are equal but opposite. Each diode conducts in corresponding half-cycle of transformer. Below you can see the current and voltage wave-forms for this rectifier.
Bridge rectifier circuit is depicted below. Here we have four diodes instead of two. So in each half-cycle of transformer we have two conducting diodes. Below you can see voltage and current wave-forms for this rectifier.
The average voltage is .
So . Root-mean-square (RMS) value is
The average value of load current . And the RMS value of load current is .
The rectification ratio (RF), measures of rectification effectiveness .
Form factor (FF) is a ratio of root-mean-square value of voltage or current to it’s average value. and . For full-wave rectifier .
Ripple factor (RF) is the measure of ripple , where . Making several mathematical simplifications .
Transformer utilisation factor (TUF) is a transformer merit measure where and are rms voltage and rms current ratings of secondary transformer. Where for full-wave transformer .
Reader must note that only half-wave rectifier with resistive load produce harmonic currents in their transformers.
Datasheets of industrial single-phase full-wave diode rectifiers contain following important parameters:
- Peak repetitive reverse voltage ;
- Ripple factor;
- RMS input voltage per transformer leg ;
- Diode average current ;
- Rectification ratio;
- Output ripple frequency ;
- Peak repetitive forward current ;
- Transformer rating primary VA;
- Diode RMS current ;
- Form factor;
- Transformer rating secondary VA;
- Form factor of diode current .
For instance, Digi-Key Electronics offers great range of single-phase full-wave and bridge rectifiers.