Half Wave Rectifier Analysis

The Half wave rectifier is a circuit, which converts an ac voltage to dc voltage.
The Transformer in the Half wave Rectifier can be used to obtain the desired level of dc voltage (using step up or step down transformers).

The primary of the transformer is connected to ac supply. This induces an ac voltage across the secondary of the transformer.

During the positive half cycle of the input voltage the polarity of the voltage across the secondary coil , forward biases the diode.

As a result a current IL flows through the load resistor, RL. The forward biased diode offers a very low resistance and hence the voltage drop across it is very small.

Thus the voltage appearing across the load is practically the same as the input voltage at every instant.

During the negative half cycle of the input voltage the polarity of the secondary voltage gets reversed. As a result, the diode is reverse biased. Practically no current flows through the circuit and almost no voltage is developed across the resistor. All input voltage appears across the diode itself.

Hence we conclude that when the input voltage is going through its positive half cycle, output voltage is almost the same as the input voltage and during the negative half cycle no voltage is available across the load. This explains the unidirectional pulsating dc waveform obtained as output. The process of removing one half the input signal to establish a dc level is aptly called half wave rectification.

Ripple factor is defined as the ratio of rms value of ac component to the dc component in the output.

 Transformer Utilization Factor, TUF can be used to determine the rating of a transformer secondary.