Half wave and full wave rectifier practical pdf

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half wave and full wave rectifier practical pdf

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A simple Half Wave Rectifier is nothing more than a single pn junction diode connected in series to the load resistor. As you know a diode is to electric current like a one-way valve is to water, it allows electric current to flow in only one direction. This property of the diode is very useful in creating simple rectifiers which are used to convert AC to DC. If you look at the above diagram, we are giving an alternating current as input. The output voltage is measured across load resistor RL.

Rectifier Circuits

A rectifier is an electrical device that converts alternating current AC , which periodically reverses direction, to direct current DC , which flows in only one direction. The reverse operation is performed by the inverter. The process is known as rectification , since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes , wet chemical cells, mercury-arc valves , stacks of copper and selenium oxide plates, semiconductor diodes , silicon-controlled rectifiers and other silicon-based semiconductor switches.

Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios , used a " cat's whisker " of fine wire pressing on a crystal of galena lead sulfide to serve as a point-contact rectifier or "crystal detector". Rectifiers have many uses, but are often found serving as components of DC power supplies and high-voltage direct current power transmission systems.

Rectification may serve in roles other than to generate direct current for use as a source of power. As noted, detectors of radio signals serve as rectifiers.

In gas heating systems flame rectification is used to detect presence of a flame. Depending on the type of alternating current supply and the arrangement of the rectifier circuit, the output voltage may require additional smoothing to produce a uniform steady voltage. Many applications of rectifiers, such as power supplies for radio, television and computer equipment, require a steady constant DC voltage as would be produced by a battery.

In these applications the output of the rectifier is smoothed by an electronic filter , which may be a capacitor , choke , or set of capacitors, chokes and resistors , possibly followed by a voltage regulator to produce a steady voltage. More complex circuitry that performs the opposite function, that is converting DC to AC, is called an inverter.

Before the development of silicon semiconductor rectifiers, vacuum tube thermionic diodes and copper oxide- or selenium-based metal rectifier stacks were used. For power rectification from very low to very high current, semiconductor diodes of various types junction diodes , Schottky diodes , etc.

Other devices that have control electrodes as well as acting as unidirectional current valves are used where more than simple rectification is required—e. High-power rectifiers, such as those used in high-voltage direct current power transmission, employ silicon semiconductor devices of various types. These are thyristors or other controlled switching solid-state switches, which effectively function as diodes to pass current in only one direction. Rectifier circuits may be single-phase or multi-phase.

Most low power rectifiers for domestic equipment are single-phase, but three-phase rectification is very important for industrial applications and for the transmission of energy as DC HVDC. In half-wave rectification of a single-phase supply, either the positive or negative half of the AC wave is passed, while the other half is blocked. Mathematically, it is a step function for positive pass, negative block : passing positive corresponds to the ramp function being the identity on positive inputs, blocking negative corresponds to being zero on negative inputs.

Because only one half of the input waveform reaches the output, mean voltage is lower. Half-wave rectification requires a single diode in a single-phase supply , or three in a three-phase supply. Rectifiers yield a unidirectional but pulsating direct current; half-wave rectifiers produce far more ripple than full-wave rectifiers, and much more filtering is needed to eliminate harmonics of the AC frequency from the output.

The no-load output DC voltage of an ideal half-wave rectifier for a sinusoidal input voltage is: [2]. A full-wave rectifier converts the whole of the input waveform to one of constant polarity positive or negative at its output. Mathematically, this corresponds to the absolute value function.

Full-wave rectification converts both polarities of the input waveform to pulsating DC direct current , and yields a higher average output voltage. Two diodes and a center tapped transformer , or four diodes in a bridge configuration and any AC source including a transformer without center tap , are needed. For single-phase AC, if the transformer is center-tapped, then two diodes back-to-back cathode-to-cathode or anode-to-anode, depending upon output polarity required can form a full-wave rectifier.

Twice as many turns are required on the transformer secondary to obtain the same output voltage than for a bridge rectifier, but the power rating is unchanged.

The average and RMS no-load output voltages of an ideal single-phase full-wave rectifier are:. Very common double-diode rectifier vacuum tubes contained a single common cathode and two anodes inside a single envelope, achieving full-wave rectification with positive output.

Single-phase rectifiers are commonly used for power supplies for domestic equipment. However, for most industrial and high-power applications, three-phase rectifier circuits are the norm. As with single-phase rectifiers, three-phase rectifiers can take the form of a half-wave circuit, a full-wave circuit using a center-tapped transformer, or a full-wave bridge circuit.

Thyristors are commonly used in place of diodes to create a circuit that can regulate the output voltage. Many devices that provide direct current actually generate three-phase AC. For example, an automobile alternator contains six diodes, which function as a full-wave rectifier for battery charging. An uncontrolled three-phase, half-wave midpoint circuit requires three diodes, one connected to each phase.

This is the simplest type of three-phase rectifier but suffers from relatively high harmonic distortion on both the AC and DC connections. This type of rectifier is said to have a pulse-number of three, since the output voltage on the DC side contains three distinct pulses per cycle of the grid frequency:.

If the AC supply is fed via a transformer with a center tap, a rectifier circuit with improved harmonic performance can be obtained. This rectifier now requires six diodes, one connected to each end of each transformer secondary winding. This circuit has a pulse-number of six, and in effect, can be thought of as a six-phase, half-wave circuit.

Before solid state devices became available, the half-wave circuit, and the full-wave circuit using a center-tapped transformer, were very commonly used in industrial rectifiers using mercury-arc valves. With the advent of diodes and thyristors, these circuits have become less popular and the three-phase bridge circuit has become the most common circuit.

For an uncontrolled three-phase bridge rectifier, six diodes are used, and the circuit again has a pulse number of six. For this reason, it is also commonly referred to as a six-pulse bridge. The B6 circuit can be seen simplified as a series connection of two three-pulse center circuits. For low-power applications, double diodes in series, with the anode of the first diode connected to the cathode of the second, are manufactured as a single component for this purpose.

Some commercially available double diodes have all four terminals available so the user can configure them for single-phase split supply use, half a bridge, or three-phase rectifier. For higher-power applications, a single discrete device is usually used for each of the six arms of the bridge. For the very highest powers, each arm of the bridge may consist of tens or hundreds of separate devices in parallel where very high current is needed, for example in aluminium smelting or in series where very high voltages are needed, for example in high-voltage direct current power transmission.

If the three-phase bridge rectifier is operated symmetrically as positive and negative supply voltage , the center point of the rectifier on the output side or the so-called isolated reference potential opposite the center point of the transformer or the neutral conductor has a potential difference in the form of a triangular common-mode voltage. For this reason, these two centers must never be connected to each other, otherwise short-circuit currents would flow.

The ground of the three-phase bridge rectifier in symmetrical operation is thus decoupled from the neutral conductor or the earth of the mains voltage. Powered by a transformer, earthing of the center point of the bridge is possible, provided that the secondary winding of the transformer is electrically isolated from the mains voltage and the star point of the secondary winding is not on earth.

In this case, however, negligible leakage currents are flowing over the transformer windings. The common-mode voltage is formed out of the respective average values of the differences between the positive and negative phase voltages, which form the pulsating DC voltage.

The RMS value of the common-mode voltage is calculated from the form factor for triangular oscillations:. If the circuit is operated asymmetrically as a simple supply voltage with just one positive pole , both the positive and negative poles or the isolated reference potential are pulsating opposite the center or the ground of the input voltage analogously to the positive and negative waveforms of the phase voltages.

However, the differences in the phase voltages result in the six-pulse DC voltage over the duration of a period. The strict separation of the transformer center from the negative pole otherwise short-circuit currents will flow or a possible grounding of the negative pole when powered by an isolating transformer apply correspondingly to the symmetrical operation.

The controlled three-phase bridge rectifier uses thyristors in place of diodes. Or, expressed in terms of the line to line input voltage: [5]. The above equations are only valid when no current is drawn from the AC supply or in the theoretical case when the AC supply connections have no inductance. The effect of supply inductance is to slow down the transfer process called commutation from one phase to the next.

As result of this is that at each transition between a pair of devices, there is a period of overlap during which three rather than two devices in the bridge are conducting simultaneously. Although better than single-phase rectifiers or three-phase half-wave rectifiers, six-pulse rectifier circuits still produce considerable harmonic distortion on both the AC and DC connections. For very high-power rectifiers the twelve-pulse bridge connection is usually used.

This cancels many of the characteristic harmonics the six-pulse bridges produce. The degree phase shift is usually achieved by using a transformer with two sets of secondary windings, one in star wye connection and one in delta connection.

The simple half-wave rectifier can be built in two electrical configurations with the diodes pointing in opposite directions, one version connects the negative terminal of the output direct to the AC supply and the other connects the positive terminal of the output direct to the AC supply.

By combining both of these with separate output smoothing it is possible to get an output voltage of nearly double the peak AC input voltage. This also provides a tap in the middle, which allows use of such a circuit as a split rail power supply. A variant of this is to use two capacitors in series for the output smoothing on a bridge rectifier then place a switch between the midpoint of those capacitors and one of the AC input terminals. With the switch open, this circuit acts like a normal bridge rectifier.

With the switch closed, it acts like a voltage doubling rectifier. However, for a given desired ripple, the value of both capacitors must be twice the value of the single one required for a normal bridge rectifier; when the switch is closed each one must filter the output of a half-wave rectifier, and when the switch is open the two capacitors are connected in series with an equivalent value of half one of them.

Cascaded diode and capacitor stages can be added to make a voltage multiplier Cockroft-Walton circuit. These circuits are capable of producing a DC output voltage potential up to about ten times the peak AC input voltage, in practice limited by current capacity and voltage regulation issues. Diode voltage multipliers, frequently used as a trailing boost stage or primary high voltage HV source, are used in HV laser power supplies, powering devices such as cathode ray tubes CRT like those used in CRT based television, radar and sonar displays , photon amplifying devices found in image intensifying and photo multiplier tubes PMT , and magnetron based radio frequency RF devices used in radar transmitters and microwave ovens.

The two primary measures are DC voltage or offset and peak-peak ripple voltage, which are constituent components of the output voltage. The ratio can be improved with the use of smoothing circuits which reduce the ripple and hence reduce the AC content of the output.

Conversion ratio is reduced by losses in transformer windings and power dissipation in the rectifier element itself. This ratio is of little practical significance because a rectifier is almost always followed by a filter to increase DC voltage and reduce ripple. In some three-phase and multi-phase applications the conversion ratio is high enough that smoothing circuitry is unnecessary. Three-phase rectifiers, especially three-phase full-wave rectifiers, have much greater conversion ratios because the ripple is intrinsically smaller.

The transformer utilization factor TUF of a rectifier circuit is defined as the ratio of the DC power available at the input resistor to the AC rating of the output coil of a transformer. A real rectifier characteristically drops part of the input voltage a voltage drop , for silicon devices, of typically 0. Unlike an ideal rectifier, it dissipates some power. An aspect of most rectification is a loss from the peak input voltage to the peak output voltage, caused by the built-in voltage drop across the diodes around 0.

Half-wave rectification and full-wave rectification using a center-tapped secondary produces a peak voltage loss of one diode drop. Bridge rectification has a loss of two diode drops. This reduces output voltage, and limits the available output voltage if a very low alternating voltage must be rectified. As the diodes do not conduct below this voltage, the circuit only passes current through for a portion of each half-cycle, causing short segments of zero voltage where instantaneous input voltage is below one or two diode drops to appear between each "hump".

half wave and full wave rectifier lab manual pdf

A rectifier is an electrical device that converts alternating current AC , which periodically reverses direction, to direct current DC , which flows in only one direction. The reverse operation is performed by the inverter. The process is known as rectification , since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes , wet chemical cells, mercury-arc valves , stacks of copper and selenium oxide plates, semiconductor diodes , silicon-controlled rectifiers and other silicon-based semiconductor switches. Historically, even synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios , used a " cat's whisker " of fine wire pressing on a crystal of galena lead sulfide to serve as a point-contact rectifier or "crystal detector".

That means the full wave rectifier converts AC to DC more efficiently than the half wave rectifier. Manufacturing of the center-tapped transformer is quite expensive and so Full wave rectifier with center-tapped transformer is costly. Consider the half-wave rectifier circuit with resistive load. Besides the general rules above, specific guidelines for this lab: 1. Rectifier broadly divided into two categories: Half wave rectifier and full wave rectifier. This DC is not constant and varies with time.

Full Wave Bridge Rectifier Experiment Pdf

Now we come to the most popular application of the diode : rectification. Simply defined, rectification is the conversion of alternating current AC to direct current DC. This involves a device that only allows one-way flow of electric charge.

Operation of a 3 phase full wave uncontrolled bridge rectifier supplying an R — L — E load This type of load may represent a dc motor or a battery. Usually for driving these loads a variable output voltage is required. This requirement has to be met by using a variable ac source. Full Wave Bridge Rectifier.

Home Events Register Now About. Bridge Rectifier Lab Manual Author: gallery. Ripple factor for Half wave recifier is … Rectifiers R. Ans: The peak inverse voltage is either the specified maximum voltage that a diode rectifier can block, or, alternatively, the maximum that a rectifier needs to block in a given application. Ans:Ripple factor can be defined as the variation of the amplitude of DC Direct current due to improper filtering of AC power supply.

experiment 2 half-wave & full- wave rectification - faraday

To understand the effect of a reservoir capacitor upon the rectified waveform and its mean value. Half wave rectifier has around 0. Design the circuit diagram.

Main menu. Tech Lab Home; Manuals. It has very low performance when it is compared with the other rectifiers. Although the half wave rectifier is not a useful circuit for high power applications, it nevertheless permits a number of useful principles to be explained in their simplest terms. Half Wave Rectifier.

To understand the effect of a reservoir capacitor upon the rectified wave form and. Construct the circuit of Fig. Note that the resistor limits the. Sketch the wave form and label it to show the periods when the diode is conducting. Hint: The mean value of a half -sinusoid can be shown by geometry to be :. But at every half -cycle the voltage is zero.

Experiment No. performance of the full-wave rectifier will be studied and measured as well as that of the Half-wave rectifiers can be used, but they are highly.

half wave rectifier experiment observations with conclusion

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