The center tapped full wave rectifier as well as bridge rectifier converts efficiently. A bridge rectifier circuit is a common part of the electronic power supplies. Many electronic circuits require a rectified DC power supply for powering the various electronic basic components from available AC mains supply. We can find this rectifier in a wide variety of electronic AC power devices like home appliances , motor controllers, modulation process, welding applications, etc.
This article discusses an overview of a bridge rectifier and its working. Bridge Rectifiers are widely used in power supplies that provide necessary DC voltage for the electronic components or devices. They can be constructed with four or more diodes or any other controlled solid-state switches.
Depending on the load current requirements, a proper bridge rectifier is selected. The bridge rectifier construction is shown below. The connection of these diodes can be done in a closed-loop pattern to convert the AC alternating current to DC Direct Current efficiently. The main benefit of this design is the lack of an exclusive center-tapped transformer. So, the size, as well as cost, will be reduced.
The arrangement of two diodes can be made in such a way that the electricity will be conducted by two diodes throughout every half cycle. The main advantage of the bridge rectifier is that it produces almost double the output voltage as with the case of a full-wave rectifier using a center-tapped transformer.
The bridge rectifier circuit diagram consists of various stages of devices like a transformer, Diode Bridge, filtering, and regulators. Generally, all these blocks combination is called a regulated DC power supply that powers various electronic appliances. The first stage of the circuit is a transformer which is a step-down type that changes the amplitude of the input voltage. The next stage is a diode-bridge rectifier which uses four or more diodes depending on the type of bridge rectifier.
Choosing a particular diode or any other switching device for a corresponding rectifier needs some considerations of the device like Peak Inverse Voltage PIV , forward current If, voltage ratings, etc. It is responsible for producing unidirectional or DC current at the load by conducting a set of diodes for every half cycle of the input signal. Since the output after the diode bridge rectifiers is of pulsating nature, and for producing it as a pure DC, filtering is necessary.
Filtering is normally performed with one or more capacitors attached across the load, as you can observe in the below figure wherein smoothing of the wave is performed. This capacitor rating also depends on the output voltage. The last stage of this regulated DC supply is a voltage regulator that maintains the output voltage to a constant level.
Suppose the microcontroller works at 5V DC, but the output after the bridge rectifier is around 16V, so to reduce this voltage, and to maintain a constant level — no matter voltage changes in the input side — a voltage regulator is necessary.
As we discussed above, a single-phase bridge rectifier consists of four diodes and this configuration is connected across the load.
When the voltage, more than the threshold level of the diodes D1 and D2, starts conducting — the load current starts flowing through it, as shown in the path of the red line in the diagram below. During the negative half cycle of the input AC waveform, the diodes D3 and D4 are forward biassed, and D1 and D2 are reverse biased. Load current starts flowing through the D3 and D4 diodes when these diodes start conducting as shown in the figure. This process is known as filtration, and the capacitor acts as a filter.
The capacitor has improved the pulsating nature of the output voltage, and it will now only have ripples. This waveform shape is now much closer to a pure DC voltage waveform.
The waveform can be further improved by using other types of filters such as an L-C filter and pie filter. The bridge rectifier just discussed is a single-phase type, however, it can also be extended to a three-phase rectifier. These two types can be further classified into full controlled, half controlled, or uncontrolled bridge rectifiers.
The circuit that we just discussed is uncontrolled since we cannot control the biasing of the diode, but if all the four diodes are replaced with a thyristor , its biasing can be controlled by controlling its firing angle via its gate signal. It results in a fully controlled bridge rectifier.
In a half controlled bridge rectifier, half of the circuit contains diodes, and the other half has thyristors. Your Name required. Your Email required. All Rights Reserved.
Peak inverse voltage: It is very important to ensure that the peak inverse voltage of the bridge rectifier, or individual diodes is not exceeded otherwise the diodes could break down. The PIV rating of the diodes in a bridge rectifier is less than that required for the two diode configuration used with a centre tapped transformer. If the diode drop is neglected, the bridge rectifier requires diodes with half the PIV rating of those in a centre-tapped rectifier for the same output voltage.
This can be another advantage of using this configuration. The peak inverse voltages across the diodes are equal to the peak secondary voltage V sec because over one half cycle the diodes D1 and D4 are conducting and the diodes D2 and D3 are reverse biassed. Assuming perfect diodes that have no voltage drop across them - a good assumption for this explanation. Using this, it can be seen that points A and B will have the same potential, as will points C and D. This means that the peak voltage from the transformer will appear across the load.
The same voltage also appears across each non-conducting diode. Bridge rectifiers are an ideal way of providing a rectified output from an alternating input. The bridge rectifier provides a full wave rectified output which enables better performance to be achieved in many instances.
For many circuits like operational amplifiers, split supplies may be needed from a linear power supply. It is possible to create a split supply for these and other applications very easily using a full wave bridge rectifier.
Although it returns to the use of a split transformer, i. The circuit operates effectively and efficiently because both halves of the input waveform are used in each section of the transformer secondary winding. The dual supply bridge rectifier solution does require the use of a centre tapped transformer, but a second winding would often be required anyway to provide the dual supply.
The full wave rectifier circuit based around the bridge of diodes performs well and is used in most full wave rectifier applications. It uses both halves of the waveform in the transformer winding and as a result reduces heat losses for a given level of output current when compared to other solutions.
Also this solution does not require a centre tapped transformer except for the dual supply version and as a result the costs are reduced. The bridge rectifier is probably most known for its use in switch mode power supplies and linear power supplies, but it is also used in many other circuits as well. Typical PCB mount bridge rectifier Bridge rectifier circuits A diagram of the basic bridge rectifier circuit has a bridge rectifier block at the centre.
Full wave rectifier using a bridge rectifier The bridge rectifier provides full wave rectification and has the advantage over the full wave rectifier using two diodes that no centre tap is required in the transformer.
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