Half Wave Rectifier – Definition, Working, Circuit Diagram, Theory & Applications

Hello, friends, I hope all of you are enjoying your life. In today’s tutorial, we will discuss What is Half Wave Rectifier. The diode is a device that used to transform ac current into dc current. The circuit used diodes to convert AC into DC is known as a rectifier. There are normally two types of halfwave rectifiers and full-wave rectifier. In half-wave rectifier, a half cycle of ac waveform is transformed into direct current and in a full-wave rectifier, both cycle or complete waveform of AC current is transformed into the direct current.

In today’s post, we will have a detailed look at half-wave rectifier its circuit, applications, and some other related parameters. There are mostly electronic devices that operate on DC as our power system is AC. So these rectifier circuits help us to operate these devices. So let’s get started with the Half Wave Rectifier.

What is Half Wave Rectifier?

• The rectification is a process that used to transform AC signal into DC and the circuit used to transform AC into DC is known as a rectifier.
• Almost every electronic device that operates on dc power supply and input source of dc supply is ac uses rectifier circuits to transform ac into dc.

• For a practical understanding of half-wave rectifier, first of all, we discuss the operation DC supply.

Basic DC Power Supply

• All active devices such as a transistor, TRIACs, etc operate on direct current, and direct current they needed dc power supply or battery.
• The input of dc supply is ac one twenty standard volts that convert into the direct current.
• Nowadays in electronic engineering and circuits the circuitry of dc power supply is very common to us so its knowledge is compulsory for the understanding of other circuits.
•  The devices that operate at dc current are TVs, computers, DVD players, etc. The output voltage of a dc supply depends on the devices for which it is designed normally voltage power supplies are designed.
• In the given figure the block diagram if the dc power supply is shown.

• In the figure, you can see different parts of dc power supply in the first part input AC supply is provided to the transformer that steps down at the required level.

• In some cases, a step-up transformer is used to increase the voltage level
• The output of the transformer goes to the rectifier circuit that converts it into the dc voltage. it is shown in below figure.

• After that dc output of the rectifier goes to a filter circuit that removes the fluctuation and makes pure dc output.
• With the filter circuit regulator circuit is connected that maintains the required voltage level and then the specified voltage goes to the load.

Half-Wave Rectifier Operation

• In the given figure the circuit of a half-wave rectifier is shown. In this circuit, an input ac supply is provided to the diode and resistance as load is attached in series with the diode.

• For the understanding of half-wave rectification, we discuss both half of ac signal one by one.
• When the first half of AC wave passes through the diode it operates as forward biased and this part of the signal is rectified into the dc. This process is denoted (a) figure.
• When the negative half of the diode passes through the diode it now in reversed biased condition and no current passes through the diode. This process is denoted as (b) in the above figure.
• In figure denoted as (c) the output of the halfwave rectifier is shown.

Average Value of the Half-Wave Output Voltage

• The value of voltage measured by the voltmeter is known as the average value of the half-wave
  rectified output voltage.
• It can also determine by calculating the area of the curve obtained after the rectification process as it is shown in a given figure.

•  After finding area divide it by the numbers of radians in the output rectified complete cycle.
• The average value of voltage is shown in the below equation.
• From this equation, you can see that the V_AVG  is almost 31.8 percent of V_P of the half-wave rectified voltage.

V_AVG =V_p/Π

Barrier Potential Effect on Half-Wave Rectifier Output

• During the positive half of the ac wave, 0.7 volts are used to cross the potential barrier of a diode.
• So, as a result, the half-wave peal output is equal to 0.7 less than the peak value of input as shown in a given figure. 2–23
• The equation for peak output voltage is mentioned here.

Vp_(out) =Vp_(in) -0.7 V——–(a)

• In an ideal diode, the potential barrier is not considered so we get the output without 0.7V loss.
• While in case of a practical diode potential barrier effect can not be neglected.

Peak Inverse Voltage (PIV)

• The value of peak inverse voltage is similar to the peak value of an input voltage and the diode should have the ability to bear this repetitive reverse voltage.
• In the given figure, you can see that, the extreme value of reverse voltage denoted as (PIV) exits at the peak of every negative repetition of the input voltage when the diode is in reverse bias condition.

• The rating of diode should be twenty percent greater than the PIV value.

PIV= V_p(in)—(b)

Half Wave Rectifier Transformer Coupling

• In the given figure, you can see the transfer coupled with the rectifier circuit. There are 2 advantages of a transformer with a rectifier circuit.

• First is that we can vary the value of voltage according to circuit requirements and the second is that the transformer provides protection to the rectifier circuit from the input source.
• The value of the voltage step down by the transformer can calculate from the turn ratio of the transformer.
• Turn ratio is the ratio between the number of turns of secondary windings to the number of turns of the primary winding.
•  The transformer having a turn ratio less than one is called a step-down and a transformer having a turn ratio greater than one is called a step-up.
• The relation between turn ratio and voltage value at the transformer windings is shown below.

V_sec = nV_pri

• If the value of n (turn ratio) is larger than one then the value of the secondary voltage is larger than the primary voltage.
• If n is less than one than the secondary voltage is less than the primary voltage.
• If the ratio is equal to one than the voltage at primary and secondary winding will be equal.
• The value of peak secondary voltage Vp(sec) in a rectifier circuit having a transformer is equal to the equation denoted as a.

• So this equation can be written as.

V_p(out) = V_p(sec) – 0.7 V

• The equation (b) can also be written as.

PIV= V_p(sec)

Half Bridge Rectifier

The half-bridge rectifiers transform AC single into DC signal through a negative or positive half cycle of signal and block the other half.For the creation of half-bridge rectifiers single diode is used but it has less efficiency then full-wave rectifiers.

Difference Between Half Wave and Full Wave Rectifier

• These are some differences between half-wave and full-wave rectifier.

Half Wave Rectifier	Full Wave Rectifier
In half-wave rectification positive half of input, ac wave is converted into dc.	In full-wave rectifier complete ac waveform is converted into the dc current.
The rectification efficiency of a half-wave rectifier is 40.6 percent.	Its efficiency is 81.2 percent.
Its ripple factor is 1.21.	Its ripple factor is 0.482.
0.286 is the transformer utilization factor of a half-wave rectifier.	Its transformer utilization factor is 0.692
It provides voltage regulation of good quality.	Its voltage regulation is better than the half-wave rectifier.
Its ripple fundamental frequency is equal to the input supply frequency.	Its ripple frequency is double the input supply frequency.
Its form factor is 1.57	Its form factor is 1.11
Its peak factor is two.	Its peak factor is 1.414
Its circuit uses only a single diode.	Its circuit has two to four diodes.

Half Bridge vs Full Bridge Rectifier

Half Wave Rectifier

• In this circuit, half AC signal is converted into dc current
• It not come with any sub-types
• It uses a single diode
• It only rectifies half cycle of the AC
• The frequency of ripple output is equal to the input frequency
• The maximum efficiency of rectification is 40.6%.
• 1.21. is ripple factor
• 1.57 is form factor value
• Peak inverse voltage is equal to the highest value of input voltage, V_m
• It has 2 peak factor
• The transformer utilization factor is 0.2865.
• Low cost use of single diode

Full Wave Rectifier

• In this circuit, a complete AC signal is converted into DC.
• There are two types of full wave rectifiers center-tapped FWR and bridge FWR.
• It uses 2 diodes for Center-tapped and 4 diodes for Bridge FWR
• In this circuit continuous current flow.
• peak inverse voltage is two times of maximum input voltage. 2V_m.
• Its frequency is double than input signal frequency
• Its efficiency is 81.2%
• The ripple factor is 0.482 and the form factor is 1.11
• The peak factor is 1.414.
• It has larger number of diodes so costly design

 

FAQs:

How Does a Half-Wave Rectifier Work?

• The half-wave rectifier transforms the AC signal to DC by allowing the negative or positive half of the wave and blocking the other half. This circuit uses single diode and has less efficiency than full-wave rectifiers

Where is a Halfwave Rectifier Used?

• The half-wave rectifier is used for soldering iron circuits and is also part of mosquito repellent for creating lead fumes.It is also used for electric welding for steady and polarized DC voltage.

What are Half-Wave and Full-Wave Rectifiers?

• The half-wave rectifier is used to convert one-half of ac input into dc output and full wave rectifier converts both halfs of ac into DC output.

So friends that is the detailed post on the half-wave rectifier I have each and every parameter related to the half-wave rectifier. If you have any queries about this post ask in comments. Thanks for reading. See you in the tutorial.

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