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 half-wave and full-wave rectifier. In half-wave rectifier,a half cycle of ac waveform is transformed into direct current and in 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.
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 the 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.
- Now a day 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 dc supply depends on the devices for which it designed normally less voltage power supplies are designed.
- In the given figure the block diagram if 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 half-wave rectification we discuss both half of ac signal one by one.
- When first half of ac wave passes through the diode it operates as forward biased and this part of signal rectified into the dc. This process is denoted (a) figure.
- When negative half of 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 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 diode should have 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 every negative repetition of the input voltage when the diode is 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 requirement and second is that 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 transformer.
- Turn ratio is the ratio between the number of turns of secondary windings to the numbers of turns of the primary winding.
- The transformer has turn ration less than the one is called step down and a transformer having turn ratio greater than one is called step up.
- The relation between turn ration 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 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 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 written as.
PIV= V_{p(sec)}
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. |
So friends that is the detailed post on 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.