Bridge Rectifier Circuit with Working Operation and Their Types

Bridge Rectifier Circuit
with Working Operation
and Their Types

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Bridge Rectifier Circuit with Working
Operation and Their Types
Introduction:
 A bridge rectifier circuit is a common part of the electronic power
supplies. Many electronic circuits require 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.

What is a Bridge Rectifier?
 A Bridge rectifier is an Alternating Current (AC) to Direct Current (DC)
converter.
 Bridge Rectifiers rectifies mains AC input to DC output.
 Bridge Rectifiers are widely used in power supplies.
 It provide necessary DC voltage for the electronic components or devices.

 Bridge Rectifier 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.
What is a Bridge Rectifier?

Types of Bridge Rectifiers
 Bride rectifiers are classified into several types based on these factors.
 Type of supply, controlling capability, bride circuit’s configurations, etc.
 Bridge rectifiers are mainly classified into Single and Three phase rectifiers.
 Both these types are further classified into Uncontrolled, Half Controlled
and Full Controlled rectifiers.

Single Phase and Three Phase Rectifiers

Single Phase and Three Phase Rectifiers
 A single phase or three-phase supply decides these rectifiers.
 The Single phase bridge rectifier consists of four diodes for converting
AC into DC.
 A three phase rectifier uses six diodes.
 These can be again uncontrolled or controlled rectifiers depending on
the circuit components such as diodes, thyristors, and so on.

Uncontrolled Bridge Rectifiers

 Uncontrolled bridge rectifier uses diodes for rectifying the input.
 The diode is a unidirectional device that allows the current flow in one
direction only.
 With this configuration of diodes in the rectifier.
 It doesn’t allow the power to vary depending on the load requirement.
 This type of rectifier is used in constant or fixed power supplies.
Uncontrolled Bridge
Rectifiers

Controlled Bridge Rectifier

Controlled Bridge Rectifier
 In Controlled Bridge Rectifier, AC/DC converter or rectifier.
 Controlled solid state devices like SCR’s, MOSFET’s, IGBT’s, etc. are used to
vary the output power at different voltages.
 By triggering these devices at various instants, the output power at the load
is appropriately changed.

Bridge Rectifier Circuit Diagram

 Bridge rectifier circuit doesn’t need center tapped transformer so it
resembles low-cost rectifier.
 The bridge rectifier circuit diagram consists of various stages of devices.
 Devices like transformer, Diode Bridge, filtering and regulators.
 All these blocks combination is called as regulated DC power supply
that powers various electronic appliances.

 The first stage of the circuit is a transformer which is a step-down type.
 It changes the amplitude of the input voltage.
 Most of the electronic projects uses 230/12V transformer to step-down
the AC mains 230V to 12V AC supply.
 Next stage is a diode-bridge rectifier which uses four or more diodes.
 It depending on the type of bridge rectifier.

 Choosing a particular diode or any other switching device for a
corresponding rectifier.
 It needs some considerations of the device like Peak Inverse Voltage
(PIV), forward current If, voltage ratings.
 It is responsible for producing unidirectional or DC current at the load.
 Conducting a set of diodes for every half cycle of the input signal.
 The output after the diode bridge rectifiers is of pulsating nature.

 For producing it as a pure DC, filtering is necessary.
 Filtering is normally performed with one or more capacitors attached
across the load.
 Capacitor rating also depends on the output voltage.
 The last stage of this regulated DC supply is a voltage regulator.
 It maintains the output voltage to a constant level.
 A voltage regulator is necessary in Bridge Rectifier.

Bridge Rectifier Working
Principle
 A single-phase bridge rectifier consists of four diodes and this
configuration is connected across the load.
 During the Positive half cycle of the input AC waveform diodes D1 and D2
are forward biased.
 Diodes D3 and D4 are reverse biased.
 When the voltage, more than the threshold level of the diodes D1 and
D2, starts conducting.
 The load current starts flowing through it.

Bridge Rectifier Working Principle
 During the negative half cycle of the input AC waveform.
 The diodes D3 and D4 are forward biased, and D1 and D2 are reverse
biased.
 We can observe that in both the cases, the load current direction is
same, i.e Unidirectional, which means DC current.
 Using bridge rectifier, the input AC current is converted into a DC
current.

Bridge Rectifier Working Principle
 The output at the load with this bridge wave rectifier is pulsating in
nature.
 But for producing a pure DC requires additional filter like capacitor.
 The same operation is applicable for different bridge rectifiers.
 In case of controlled rectifiers thyristors triggering is necessary to
drive the current to load.

Advantage of Bridge Rectifier
 The main advantage of this bridge circuit is that it does not require a
special centre tapped transformer.
 Higher output voltage, higher output power and higher Transformer
Utilization Factor (TUF) in case of a full-wave rectifier.
 Transformer utilization factor, in case of a bridge rectifier, is higher than
that of a centre-tap rectifier.

Disadvantage of Bridge Rectifier
 The main disadvantage of a bridge rectifier is that it needs four diodes.
 Total voltage drop in diodes becomes double of that in case of centre-tap
rectifier.
 Losses are increased and rectification efficiency is somewhat reduced.
 Another disadvantage of bridge rectifier is that the load resistor RL and
the supply source have no common point which may be earthed.

Application of Bridge Rectifier
 The main application of bridge rectifier is to convert AC Power to DC
Power.
 Because of their low cost compared to center tapped they are widely
used in power supply circuit.
 This can be used to detect the amplitude of modulated radio signal.
 Bridge rectifiers can be used to supply polarized voltage in welding.

Bridge Rectifier Circuit with Working Operation and Their Types

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Bridge Rectifier Circuit with Working Operation and Their Types