Electronics

Electrical Rectification

It’s a process of transforming alternating current (AC) to direct current (DC). There are different types of rectifier devices; solid state, vacuum tube, dry disk and the most common semiconductor rectifiers, Diode. Rectifiers are supplied with power for aircrafts to require high strength of electrical current and low voltage for dc operation.

Rectifier Circuits (Diodes)

Half-wave rectifiers are the simplest form of rectifier circuit because it uses a single diode and operate on either negative or positive half-cycles of supply. However, half-wave rectifier circuit is less efficient because conduction takes place only on alternate half-cycles. Full-wave rectifier circuit are in fact a better arrangement because it makes use of both positive and negative half-cycles and the circuit offers a good improvement over their half-wave counterparts.

The frequency of the vibration produced (ripple) on the DC output of a half-wave power supply will be the same as frequency of AC input. Therefore, in full-wave power supply, frequency of ripple voltage on DC output will be double of the AC input.

To rectify AC power by obtaining the complete use of both cycles is center-tap design, which consists of a transformer with a center-tapped secondary winding and two diodes.

Figure [ 1 ] Full-wave rectifier center-tapped design

From the picture above, it can be seen that it is one half-cycle at a time. The source voltage polarity is positive on top and negative on bottom. At this stage, it is only the top diode which is conducting, and the bottom one in simply blocking current. Top half of secondary winding is carrying current during this half-cycle.

In the next stage of the circuitry, AC polarity reverses. And the latter diode and other half of the transformer winding carry current. From the previous half-cycle, the portion of the circuit which was carrying current is not in action. Therefore, the full-wave rectifier can be reversed by...