11.9:
Full wave rectifier
Consider a full-wave rectifier circuit comprising a center-tapped transformer, two diodes in a center-tapped configuration, and a load resistor.
The secondary winding of the transformer supplies two equal input voltages with opposite polarities across the two halves of the secondary winding.
During the positive half-cycles of the input signal, when the voltage exceeds or equals the diode's forward voltage drop, diode D1 conducts while D2 is reverse-biased. The output waveform resembles that of a half-wave rectifier.
Conversely, during the negative half-cycle, when the input voltage is lower than the diode's forward voltage drop, diode D1 is cut off while D2 conducts. Again, the output waveform mirrors that of a half-wave rectifier.
The current through the resistor consistently flows in the same direction, resulting in a unipolar output.
The increased rectification efficiency of a full wave rectifier enables its use in power supplies, battery chargers, audio amplifiers, and signal processing.
The peak inverse voltage is twice the peak input voltage minus the diode forward voltage drop, which is approximately twice that of the half-wave rectifier case.
11.9:
Full wave rectifier
A full-wave rectifier is a device that converts alternating current (AC) to direct current (DC) and is more efficient than its half-wave counterpart. It typically includes a center-tapped transformer, two diodes, and a load resistor. The secondary winding of the transformer is divided to provide two equal voltages of opposite polarities, which is the pivotal element of full-wave rectification.
The full-wave rectifier operates by allowing each diode to conduct during alternate half-cycles of the AC input, utilizing the full cycle of the AC waveform. During the positive half-cycle of the AC signal, diode D1 becomes forward-biased and conducts, while diode D2 is reverse-biased and does not conduct. This creates a positive output similar to that of a half-wave rectifier.
When the AC signal enters the negative half-cycle, diode D1 is reverse-biased and non-conductive, while diode D2 is forward-biased, allowing the current to flow through it. This process flips the negative voltage to a positive one at the output, ensuring that the output voltage is always of the same polarity. The load resistor sees a unidirectional current, leading to a unipolar output waveform.
Full-wave rectifiers have higher rectification efficiency and are extensively used in power supply units, battery chargers, audio amplifiers, and signal-processing applications. The ripple voltage is lower, and the ripple frequency is double that of a half-wave rectifier, yielding smoother DC output with less filtering requirement.
The peak inverse voltage (PIV) in a full-wave rectifier is twice the maximum input AC voltage(VS) reduced by the diodes' forward voltage drop (VD).
This PIV is approximately double that encountered in a half-wave rectifier, requiring diodes that can sustain higher reverse voltages to ensure safe operation.