Name: ac to dc conversion with full-wave rectifiers
Uploaded: 2025-05-22T09:06:19.000Z
Duration: 1 min 22 s
Channel: JoVE

Considérons un circuit redresseur à onde complète comprenant un transformateur à prise centrale, deux diodes dans une configuration à prise centrale et une résistance de charge.
L’enroulement secondaire du transformateur fournit deux tensions d’entrée égales avec des polarités opposées sur les deux moitiés de l’enroulement secondaire.
Pendant les demi-cycles positifs du signal d'entrée, lorsque la tension dépasse ou est égale à la chute de tension directe de la diode, la diode D1 conduit tandis que D2 est polarisée en sens inverse. La forme d’onde de sortie ressemble à celle d’un redresseur demi-onde.
À l'inverse, pendant le demi-cycle négatif, lorsque la tension d'entrée est inférieure à la chute de tension directe de la diode, la diode D1 est coupée tandis que D2 conduit. Encore une fois, la forme d’onde de sortie reflète celle d’un redresseur demi-onde.
Le courant traversant la résistance circule constamment dans la même direction, ce qui donne une sortie unipolaire.
L’efficacité accrue du redressement d’un redresseur à ondes pleines permet son utilisation dans les alimentations, les chargeurs de batterie, les amplificateurs audio et le traitement du signal.
La tension inverse de crête est le double de la tension d’entrée de crête moins la chute de tension directe de la diode, qui est environ le double de celle du boîtier du redresseur demi-onde.

redresseur pleine onde

Un redresseur double alternance est un dispositif qui convertit le courant alternatif (AC) en courant continu (DC) et est plus efficace que son homologue demi-onde. Il comprend généralement un transformateur à prise centrale, deux diodes et une résistance de charge. L'enroulement secondaire du transformateur est divisé pour fournir deux tensions égales de polarités opposées, ce qui constitue l'élément central du redressement double alternance. 
<img alt="Figure 1" src="/files/ftp_upload/15720/15720_Figure_1.svg" style="height: 200px;">
Le redresseur double alternance fonctionne en permettant à chaque diode de conduire pendant des demi-cycles alternés de l'entrée CA, en utilisant le cycle complet de la forme d'onde CA. Pendant le demi-cycle positif du signal alternatif, la diode D_1 devient polarisée en direct et conduit, tandis que la diode D_2 est polarisée en inverse et ne conduit pas. Cela crée une sortie positive similaire à celle d'un redresseur demi-onde.
Lorsque le signal alternatif entre dans le demi-cycle négatif, la diode D_1 est polarisée en inverse et non conductrice, tandis que la diode D_2 est polarisée en direct, permettant au courant de la traverser. Ce processus transforme la tension négative en tension positive à la sortie, garantissant que la tension de sortie est toujours de la même polarité. La résistance de charge voit un courant unidirectionnel, conduisant à une forme d'onde de sortie unipolaire.
Les redresseurs double alternance ont une efficacité de rectification plus élevée et sont largement utilisés dans les unités d'alimentation, les chargeurs de batterie, les amplificateurs audio et les applications de traitement du signal. La tension d'ondulation est inférieure et la fréquence d'ondulation est le double de celle d'un redresseur demi-onde, ce qui donne une sortie CC plus fluide avec moins de besoins de filtrage.
La tension inverse de crête (PIV) dans un redresseur double alternance est le double de la tension alternative d'entrée maximale (V_S) réduite par la chute de tension directe (V_D) des diodes.
<img alt="Equation 1" src="/files/ftp_upload/15720/15720_Equation_1.svg" style="height: 30px;">
Ce PIV est environ le double de celui rencontré dans un redresseur demi-onde, nécessitant des diodes capables de supporter des tensions inverses plus élevées pour garantir un fonctionnement sûr.

Redresseur pleine onde

Considérons un circuit redresseur à onde complète comprenant un transformateur à prise centrale, deux diodes dans une configuration à prise centrale et une résistance de charge.
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Full wave rectifier

ac to dc conversion with full-wave rectifiers

A full-wave rectifier converts alternating current, or AC, into direct current, or DC. It is more efficient than a half-wave rectifier. The circuit usually uses a center-tapped transformer, two diodes, and a load resistor.

The center-tapped transformer is the key part of the circuit. Its secondary winding is split into two equal voltages with opposite polarities. That split lets the rectifier use both halves of the AC input waveform.

During the positive half-cycle of the AC signal, diode D1 is forward-biased and conducts. At the same time, diode D2 is reverse-biased and does not conduct. The output stays positive, much like the output of a half-wave rectifier.

During the negative half-cycle, D1 becomes reverse-biased and stops conducting. D2 then becomes forward-biased and carries the current. This action turns the negative half-cycle into a positive output, so the load resistor receives a unidirectional current and a unipolar waveform.

Full-wave rectifiers are widely used in power supply units, battery chargers, audio amplifiers, and signal-processing applications. They produce lower ripple voltage, and the ripple frequency is twice that of a half-wave rectifier. That gives a smoother DC output and usually means less filtering is needed. The peak inverse voltage, or PIV, is about twice the maximum input AC voltage minus the diode forward voltage drop, so the diodes must handle higher reverse voltage safely.

AC to DC Conversion with Full-Wave Rectifiers

ac-to-dc-conversion-with-full-wave-rectifiers

the ideal diode

Ideal Diode I-V Curve and Rectification

An ideal diode is a simple model of a semiconductor diode used to show how current moves through circuits. A diode has two terminals. The anode is positive, and the cathode is negative. In this model, current can flow only in one direction. When a positive voltage is applied to the anode relative to the cathode, the diode is forward-biased. In that state, it conducts current. When the cathode is at a higher potential than the anode, the diode is reverse-biased. It then blocks current and acts...

diode: forward bias

Diode Current in Forward Bias

Diode current in forward bias depends on how the p-type and n-type regions are connected to a battery. When the p-type region is tied to the positive terminal and the n-type region to the negative terminal, the diode is forward-biased. This setup lowers the potential barrier inside the diode and lets current move easily from the p-type side to the n-type side. The current-voltage behavior of a forward-biased diode is described by its I-V characteristics. These characteristics depend on the...

diode: reverse bias

Diode Reverse Current and Breakdown

A diode in reverse bias blocks current flow and widens its depletion region. In this setup, the positive terminal of the power source connects to the n-type material, and the negative terminal connects to the p-type material. The reverse connection also raises the barrier potential, so current stays very small. The small reverse current is called leakage current. It comes mainly from minority charge carriers. At room temperature, once the reverse voltage is above the thermal voltage, the...

zener diodes

Zener Diode Voltage Regulation

Zener diodes are semiconductor devices used to hold voltage steady in reverse bias. In reverse breakdown, current flows into the cathode and makes it positive relative to the anode. This behavior is different from a conventional diode and is the reason Zener diodes are useful in voltage regulation. A Zener diode has a nearly vertical current-voltage, or I-V, curve above a threshold called the knee current. That shape lets it keep a fairly stable voltage over a wide range of currents.

modeling of diode forward characteristics

modeling-of-diode-forward-characteristics

Diode Forward Bias: I-V Curve and Models

Diode forward bias is analyzed with the current-voltage, or I-V, curve and two common circuit models. These models help describe how a diode behaves when current flows in the forward direction. They are useful for electronic circuit design and analysis. The exponential diode model is used when the source voltage rises above 0.5 volts. At that point, the diode current increases exponentially above the saturation current. The I-V curve shows this nonlinear response as the forward voltage...

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Diode Bias and Small-Signal Response

Diode bias and small-signal response describe how a diode behaves when a steady DC voltage and a tiny changing signal act on the same circuit. The DC bias sets the diode’s operating point, or Q point. Around that point, the diode current and voltage follow an exponential I-V relationship. A small time-varying signal can be added on top of the DC bias to study how the diode responds to small changes. When the signal voltage is much smaller than the thermal voltage, the diode’s behavior can be...

modeling of diode reverse characteristics

modeling-of-diode-reverse-characteristics

Zener Diode Load-Line Modeling

Zener diode load-line modeling shows how a reverse-biased diode sets a steady voltage in a circuit. Zener diodes use reverse breakdown in a controlled way, so they can hold a fixed voltage across their terminals. This makes them useful for voltage regulation. When the reverse voltage rises above the Zener voltage, or VZ, the diode enters the breakdown region. In this region, the current-voltage, or I-V, curve becomes nearly vertical after the knee current, IZ, is reached. That means the...

half wave rectifier

Single-Diode AC to DC Conversion

Single-diode AC to DC conversion uses a half-wave rectifier to change alternating current into a unidirectional voltage. The circuit is simple. It uses one diode in series with a load resistor and an AC power source. The diode controls the current because it allows flow in only one direction. During the positive half-cycles of the AC input, the diode is forward-biased. When the input voltage is greater than the diode threshold, current flows and an output voltage appears across the load...

full wave rectifier

A full-wave rectifier converts alternating current, or AC, into direct current, or DC. It is more efficient than a half-wave rectifier. The circuit usually uses a center-tapped transformer, two diodes, and a load resistor. The center-tapped transformer is the key part of the circuit. Its secondary winding is split into two equal voltages with opposite polarities. That split lets the rectifier use both halves of the AC input waveform. During the positive half-cycle of the AC signal, diode D1...

bridge rectifier

AC to DC Conversion with Bridge Diodes

A bridge rectifier converts alternating current (AC) into direct current (DC) using four diodes arranged in a bridge layout. It is used to turn both halves of the AC waveform into a single-direction output. That makes it an important part of many electronics circuits. During the positive half-cycle, diodes D1 and D2 conduct. Current then flows through the load resistor R. At the same time, D3 and D4 are reverse-biased, so they do not conduct. The action switches during the negative half-cycle.

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Dual Diode Wave Clipping

Dual diode wave clipping uses diodes and biasing batteries to reshape an AC signal. A clipper circuit is a wave-shaping device that changes waveform parts without changing the whole signal. It is commonly used in television and radar communication systems to improve waveform modulation in transmitters and receivers. A dual-clipper setup uses two ideal diodes, two biasing batteries, and a resistor connected in parallel. The circuit works by responding to the phase of the input AC signal. The...

clamper circuit

DC Restorer for Waveform Level Shifting

A clamper circuit, or DC restorer, shifts a waveform up or down by adding a DC level. It is a special form of rectifier circuit. In this setup, the output is taken across the diode instead of across the capacitor. The circuit works well with square wave inputs and other pulse signals. The diode direction lets the capacitor charge to the most negative peak of the input signal. After that, the diode stops conducting. The capacitor then holds that voltage at a steady value. As a result, the...

voltage doubler circuit

How a Voltage Doubler Raises AC Output

A voltage doubler circuit raises the output voltage by using a clamping section and a rectifier section. The clamping section includes a capacitor, C1, and a diode, D1. The rectifier section includes a second diode, D2, and a capacitor, C2. The circuit starts working when a sinusoidal input signal enters the clamping section. Under ideal conditions, this stage clamps the positive peaks at zero volts. It also lets the negative peak reach a magnitude that is twice the input amplitude. That...

schottky barrier diode

Fast Switching in Schottky Diodes

Schottky barrier diodes use a metal-semiconductor junction to control current flow. They are built by combining a metal layer with a moderately doped n-type semiconductor. This contact creates the Schottky barrier, which gives the diode its one-way current behavior. When the metal touches the semiconductor, charge transfer occurs. The Fermi levels of the two materials align, and a depletion region forms near the contact area. In an n-type semiconductor, this region contains uncompensated...

key terms and concepts

See how a full-wave rectifier uses a center-tapped transformer and two diodes to convert AC to smoother DC with lower ripple and higher efficiency.

AC to DC Conversion with Full-Wave Rectifiers | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

AC to DC Conversion with Full-Wave Rectifiers

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