The capacitor will charge during the positive cycle and discharge during the negative cycle to give out a smooth output signal. A full wave rectifier converts both positive and negative half cycles of the AC alternating current into DC direct current. It provides double output voltage compared to the halfwave rectifier. A full wave rectifier is made up of more than one diode. There are two types of full wave rectifier. A bridge rectifier uses four diodes to convert both half cycle of the input AC into DC output.
In this type of rectifier, the diodes are connected in a specific form as given below. But the polarity across the load resistor RL remains the same and provides a positive output across the load. Working of Bridge Rectifier Circuit. From the circuit diagram it is apparent that the diodes are connected in a particular fashion. This unique arrangement gives the converter its name. In bridge rectifier, voltage that is given as the input can be from any source.
It can be from a transformer that is used to step up or down the voltage or it can be from the mains of our domestic power supply. In this article, we are using a centre tapped transformer for providing AC voltage.
In the first phase of working of the rectifier, during the positive half cycle, diodes D3-D2 get forward biased and conducts. Diodes D1-D4 gets reversed biased and do not conduct in this half cycle, acting as open switches. Thus, we get a positive half cycle at the output. Conversely, in the negative half cycle, diodes D1-D4 get forward biased, and start conducting whereas diodes D3-D2 gets reversed biased and do not conduct in this half cycle.
Again, we get a positive half cycle at the output. At the end of the rectification process, the negative part of the AC current is converted into a positive cycle. The output from the rectifier is two half-positive pulses with the same frequency and magnitude as that of the input.
In contrast to the working of a half-wave rectifier, the full bridge rectifier has another branch which allows it to conduct for the negative half of the voltage waveform which the half-bridge rectifier had no means of doing.
So the average voltage at the output of the full bridge rectifier is double than that of the half-bridge rectifier. The output voltage waveform after the rectification is not a proper DC, so we can try to make it more into a DC waveform using a capacitor for filtering purpose. Smoothing or reservoir capacitors that are connected in parallel with the load across the output of the full wave bridge rectifier circuit increases the average DC output level to the required average DC voltage at the output because the capacitor not only acts as a filtering component, but it also periodically charges and discharges effectively increasing the output voltage.
Capacitor charge till the waveform goes to its peak and discharges uniformly into the load circuit when waveform starts going low. So when the output is going low, capacitor maintains the proper voltage supply into the load circuit, hence creating the DC. Advantages of a Bridge Rectifier:. Disadvantages of Bridge Rectifier:. The T2 terminal is connected to the center of the output coil which acts as a reference ground o volt reference. The T1 terminal produces positive voltage and the T3 terminal produces negative voltage with respect to the T2.
The design of the center-tap rectifier is given below:. Postive Half Cycle:. During the input positive half cycle, the T1 will produce positive and T2 will produce a negative voltage. This makes a close path from T1 to T2 through the load resistor RL as shown below.
But the polarity across the load resistor RL is still the same as the current takes the path from T3 to T1 as shown in the figure below. A capacitor at the output will remove the ripple and make a steady DC output. A type of rectifier whose output voltage can be varied or changed is called controlled rectifier. The need for a controlled rectifier is apparent when we look into the shortcomings of an uncontrolled bridge rectifier. These are generally more preferred than their uncontrolled counterparts.
An SCR , also known as thyristor is a three-terminal diode. Just like a simple diode an SCR conduct in forward bias and blocks current in reverse bias but it only starts forward conduction when there is a pulse at the gate input. So the output voltage can be controlled using the gate input.
Types of controlled rectifier. There are two types of controlled rectifier. Rectification can be done through the basic diode. It may be current or voltage the AC values will be converted into DC. The basic property of the diode is that it can establish the path for the flow of current in one direction that is possible during forwarding bias.
However, during reverse bias, the diode remains in non-conducting mode. Hence this made the diode to utilize it for rectification. This article covers the basics of Rectifier, its working theory, functioning, circuit diagram, equations and furthermore its applicstions. Definition : A normal diode with its junction formed due to p-type and n-type interaction is utilized for the purpose of conversion of alternating currents into direct currents.
This process is referred to as rectification and the respective circuitry designed for rectification is defined as a rectifier. As the property of diode suggests, whether a diode with the junction as p-n can operate in forwarding bias or block the flow during reverse bias. The diode in forwarding bias is in conducting mode because the p-type is connected to the positive part of the supply and the n-type is connected to the negative part of the supply.
There is the movement of electrons from the n-side towards the p-side and the holes movement can be evident from the p-side towards the n-side.
As these are the majority charge carriers from both sides. Their movement makes to generate the current that is referred to as forwarding current. If the diodes p-type is connected to the negative part of the supply and n-type is connected to the positive part of the supply.
This type of connection makes the diode to be in reverse bias. Hence the majority of the charge carriers get attracted towards the respective terminals of the battery. Then the existence of minority carriers makes the presence and the reverse saturation current flows in the circuit. But the reverse current in the diode is because of the influence of minority charge carriers. So that it can be neglected. Hence these conditions are utilized and make the diode as the part of the application.
Traditional telecommunications equipment generally requires DC input power but mains power runs off AC. Such power systems consist of multiple rectifiers that convert AC power to DC power, so they can operate.
Without the right rectifier, there is little chance of configuring your ideal system. They are the heart of a power system as they offer optimised solutions for each application. Using rectifiers means that you can tailor your power system without having to rebuild every element. So, it is clear that rectifiers are a key component to any network system but we need to dip deeper to understand the carious types. Depending on the situation, different rectifiers are used conditional to the system it is used in.
The top two levels are single phase and three phase, which indicate how many diodes are used in the circuit. Then we come to half wave, full wave and bridge rectifiers, which affect what half cycles are produced. Single phase rectifiers have an input of one phase AC power.
The structures are very simple, needing one, two or four diodes dependent on the type of system. This means that the single phase rectifier delivers a small amount of power and has less transformer utilisation factor TUF. A single phase rectifier uses only single phase of transformer secondary coil for the conversion and diodes are connected to the secondary winding of single phase transformer.
This causes high ripple factor. Three phase rectifiers have an input of three phase AV power. Structures need three or six diodes and these are connected to each phase of the transformer secondary winding. Three phase rectifiers are used in place of single phase rectifiers to reduce ripple factor. Comparing the two types of rectifiers, three phase is preferred when using large systems.
This is because they can deliver large amounts of power and do not require any additional filter to reduce ripple factor. Because of this, three phase rectifiers are more efficient and have more transformer utilisation factor. Half wave rectifiers convert one half cycle on the AC input into pulsating DC output. This allows half cycle of the AC input while blocking the other half cycle. The half cycle can be either positive or negative.
It is the simplest rectifier as only one single diode is used. Figure 1 below shows a positive half wave rectifier whereas a negative half wave rectifier would show the diode being reverse biased facing the opposite way. Due to the pulsating nature of the direct current, ripple factor is high.
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