Full Wave Rectifier and Its Types

Last Updated on April 13, 2023 by Prepbytes

A rectifier is an electronic circuit which converts alternating current (AC) to direct current (DC). It is commonly used in power supplies for electronic devices that require DC voltage. Rectifiers can also be classified as either uncontrolled or controlled. Uncontrolled rectifiers are the most common and use diodes to convert AC to DC. Controlled rectifiers, on the other hand, use semiconductor devices like thyristors or transistors to control the output voltage and current.
There are mainly two types of rectifiers: half-wave rectifier and full wave rectifier. Here we will discuss full wave rectifier , types of full wave rectifier , working of full wave rectifier , full wave rectifier formulas, advantages and disadvantages of full wave rectifier

What is Full Wave Rectifier?

A full wave rectifier is an electronic circuit which converts an alternating current (AC) input signal into a direct current (DC) output signal. It does this by using diodes to only allow the positive portion of the AC signal to pass through, effectively converting the signal into a series of positive pulses. Compared to a half-wave rectifier, which only allows the positive half of the AC signal to pass through, a full wave rectifier produces a more constant DC output voltage with less ripple.

Types of Full Wave Rectifier

There are two main types of full wave rectifiers: the center-tapped full-wave rectifier and the bridge rectifier.

1) Centre-tapped Full Wave Rectifier

A center-tapped full wave rectifier is a type of full-wave rectifier that uses a center-tapped transformer as its input. The transformer has a center-tapped secondary winding, with two diodes connected to the ends of the winding and the other ends of the diodes connected to the load resistor.

Working of the Center-tapped Full Wave Rectifier
Steps of working of the center tapped full wave rectifier

• During the first half of the AC cycle, the voltage across the upper half of the secondary winding is positive, and the voltage across the lower half is negative.
• The diode connected to the upper half of the winding becomes forward-biased and conducts, allowing the current to flow through the diode and the load resistor.
• At the same time, the diode connected to the lower half of the winding becomes reverse-biased and blocks the current from flowing in that direction.
• During the second half of the AC cycle, the opposite happens. The voltage across the upper half of the winding is negative, and the voltage across the lower half is positive.
• The diode connected to the lower half of the winding becomes forward-biased and conducts, allowing the current to flow in the opposite direction through the load resistor.
• At the same time, the diode connected to the upper half of the winding becomes reverse-biased and blocks the current from flowing in that direction.

Advantages of Center-tapped Full Wave Rectifier
The main advantage of the center-tapped full-wave rectifier is that it produces a higher DC output voltage than a half-wave rectifier, while still being relatively simple and inexpensive. It also has a lower ripple voltage than a half-wave rectifier, which can be important for some applications.

Disadvantages of Center-tapped Full Wave Rectifier
There are also some disadvantages to using a center-tapped full-wave rectifier. One is that it requires a center-tapped transformer, which can be more expensive and difficult to find than a regular transformer. Additionally, it can waste power since only half of the secondary winding is being used at any given time.

2) Bridge Rectifier

A bridge rectifier is a type of full-wave rectifier that uses four diodes in a bridge configuration to convert an alternating current (AC) input signal into a direct current (DC) output signal.

Working of the Bridge Rectifier
Steps of working of the bridge rectifier

• During the first half of the AC cycle, the voltage across the upper two diodes is positive, while the voltage across the lower two diodes is negative. The two diodes connected to the upper side become forward-biased and conduct, allowing current to flow through the diodes and the load resistor.
• At the same time, the two diodes connected to the lower side become reverse-biased and block the current from flowing in that direction. During the second half of the AC cycle, the opposite happens. The voltage across the lower two diodes is positive, and the voltage across the upper two diodes is negative.
• The two diodes connected to the lower side become forward-biased and conduct, allowing the current to flow in the opposite direction through the load resistor.
• At the same time, the two diodes connected to the upper side become reverse-biased and block the current from flowing in that direction.

Advantages of the Bridge Rectifier
The main advantage of the bridge rectifier is that it produces a higher DC output voltage than a half-wave rectifier or a center-tapped full-wave rectifier. It also has a lower ripple voltage than a half-wave rectifier, making it suitable for many electronic applications. Another advantage is that it does not require a center-tapped transformer, making it more flexible and easier to use in a variety of applications.

Disadvantages of the Bridge Rectifier
It requires four diodes, which are more expensive than the two diodes used in a half-wave rectifier or the two diodes used in a center-tapped full wave rectifier. It also has a higher peak inverse voltage (PIV) than a half-wave rectifier, which can require a higher voltage rating of diodes in high-voltage applications.

Full Wave Rectifier Formula

The formula for the output voltage of a full wave rectifier is:

Vout = Vpeak / (2 * sqrt(2)) - Vd

where:

Vout is the DC output voltage of the rectifier
Vpeak is the peak voltage of the AC input signal
sqrt(2) is the square root of 2, which is approximately 1.414
Vd is the forward voltage drop across the diodes in the rectifier

Peak Inverse Voltage (PIV):
PIV = Vpeak
where Vpeak is the peak voltage of the AC input signal.

DC Output Voltage:
Vout = (2 Vrms / π) – 2 Vd
where Vrms is the RMS value of the AC input voltage and Vd is the forward voltage drop across the diodes.

RMS Value of Current:
Irms = Idc / sqrt(2)
where Idc is the DC current flowing through the load resistor.

Form Factor:
Form Factor = Vrms / Vavg
where Vavg is the average value of the rectified output voltage.

Peak Factor:
Peak Factor = Vpeak / Vrms

Rectification Efficiency:
Rectification Efficiency = (DC power output / AC power input) * 100%

Advantages of Full Wave Rectifier

Here we have the advantages of a full wave rectifier include:

• Higher average output voltage: A full-wave rectifier produces a higher average output voltage compared to a half-wave rectifier, which makes it more efficient for many applications.
• Higher rectification efficiency: The full-wave rectifier has a higher rectification efficiency compared to a half-wave rectifier, as it uses both halves of the input signal cycle to produce a DC output voltage.
• Lower ripple voltage: The full-wave rectifier produces a lower ripple voltage compared to a half-wave rectifier, as it uses both halves of the input signal to produce a smoother DC output voltage.
• Flexibility: A full-wave rectifier can be constructed using either a center-tapped transformer or a bridge rectifier configuration, making it more flexible and easier to use in a variety of applications.
• More precise regulation: Full-wave rectifiers are typically used in voltage regulation circuits, as they produce a more stable DC output voltage with less ripple, which is important for sensitive electronic circuits.
• Smaller filter capacitor: A full-wave rectifier requires a smaller filter capacitor compared to a half-wave rectifier, as it produces a smoother DC output voltage with less ripple. This reduces the size and cost of the filter capacitor.

Disadvantages of Full Wave Rectifier
Here we have disadvantages of full wave rectifier

• More expensive: A full-wave rectifier requires four diodes, which can make it more expensive than a half-wave rectifier that only requires two diodes.
• More complex: The full-wave rectifier circuit is more complex compared to a half-wave rectifier, as it requires more diodes and a center-tapped transformer or a bridge rectifier circuit.
• Higher power loss: The full-wave rectifier has a higher power loss compared to a half-wave rectifier, as it has two diodes conducting current at any given time, which leads to a higher voltage drop across the diodes.
• Higher peak inverse voltage (PIV): The full-wave rectifier has a higher PIV compared to a half-wave rectifier, as it uses both halves of the input signal cycle to produce a DC output voltage, which can result in higher voltage stress on the diodes and the transformer.

Conclusion
In conclusion, we can say that a full wave rectifier is an important component in many electronic devices. It is widely used in power supplies and battery chargers because of its ability to convert AC voltage into DC voltage efficiently and effectively. The two most common types of full wave rectifiers are the bridge rectifier and the center-tapped rectifier. The bridge rectifier uses four diodes to form a bridge circuit, while the center-tap rectifier uses a transformer with a center-tapped secondary winding and two diodes.

Frequently Asked Questions(FAQ)

Q1. What are the advantages of using a full wave rectifier over a half-wave rectifier?
Ans. A full wave rectifier produces a smoother output voltage with less ripple and has a higher average output voltage and higher output power than a half-wave rectifier.

Q2. What are the two most common types of full wave rectifiers?
Ans. The two most common types of full wave rectifiers are the bridge rectifier and the center-tapped rectifier.

Q3. How does a bridge rectifier work?
Ans. A bridge rectifier uses four diodes to form a bridge circuit that rectifies both halves of the AC waveform.

Q4. How does a center-tap rectifier work?
Ans. A center-tap rectifier uses a transformer with a center-tapped secondary winding and two diodes to rectify both halves of the AC waveform.

Q5. What are some applications of full wave rectifiers?
Ans. Full wave rectifiers are used in power supplies, battery chargers, and other electronic devices that require a DC voltage output.

Q6. Can a full wave rectifier convert DC voltage into AC voltage?
Ans. No, a full wave rectifier is designed to convert AC voltage into DC voltage and cannot be used to convert DC voltage into AC voltage.

Q7. Can a full wave rectifier work with any frequency of AC voltage?
Ans. Yes, a full wave rectifier can work with any frequency of AC voltage, although the components used may need to be adjusted for higher frequencies.