There were no workable methods for raising or lowering DC transmission voltages when engineers and scientists were first developing strategies for the distribution of electric power. In contrast, a transformer made it simple to step up or step down AC transmission voltages. Consequently, AC emerged as the global norm for the transmission of electric power.For light bulbs and motors, the two load types that were the main concern in the early days of electric power, AC voltage is more than sufficient. George Westinghouse, arguably the most significant advocate of AC distribution in history, probably had no idea how much trouble engineers working in the age of digital electronics would face with AC voltages. Although motors and light bulbs are still necessary, many of the gadgets in our daily life today also demand steady DC supply voltages. In the meantime, AC transmission still dominates even with the advent of high-voltage DC (HVDC) power systems. Therefore, rectification, or the conversion of AC to DC, is a basic electrical engineering activity. Therefore, the circuits that carry out rectification are essential parts of electrical engineering. The most popular of these parts—the full-wave bridge rectifier, sometimes referred to as the full-bridge rectifier or just the bridge rectifier—will be covered in this article. We must first comprehend the operation of both full-wave and half-wave rectification in order to comprehend why this circuit is so helpful.
What Is Transformer Protection?
The full-wave rectifier uses four rectification diodes to transform both halves of each waveform cycle into a pulsing DC signal. We covered how to connect smoothing capacitors across the load resistance to reduce ripple or voltage changes on a direct DC voltage in the last power diodes tutorial. This approach is inappropriate for applications that require a "steady and smooth" DC supply voltage, even though it might work well for low-power applications. Using the input voltage every half-cycle rather than every other half-cycle is one way to enhance this. The full-wave rectifier is the circuit that enables us to accomplish this.
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| Full-Wave Bridge Rectifier Source: lastminuteengineers.com |
How does a Full-wave Bridge Rectifier work?
Only two of the four diodes, designated D1 through D4, carry
current throughout each half cycle, forming "series pairs." Diodes D1
and D2 conduct in series during the supply's positive half cycle, whereas
diodes D3 and D4 are reverse biased, allowing current to pass through the load
as illustrated below.
The Positive Half-cycle
Diodes D1 and D2 conduct throughout the source's positive half cycle, whereas D3 and D4 are reverse biased. As a result, the load resistor experiences a positive load voltage.
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| Positive Half-cycle Source: lastminuteengineers.com |
The polarity of the source voltage changes during the subsequent half-cycle. D1 and D2 are now reverse biased, but D3 and D4 are forward biased.
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| Negative Half-cycle Source: lastminuteengineers.com |
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| Bridge Rectifier Wave Form Source:lastminuteengineers.com |
Full-Wave Rectifier With Smoothing Capacitor
The single phase half-wave rectifier, as we saw in the previous section, generates an output wave every half cycle, making it impractical to utilize this kind of circuit to generate a constant DC supply. Though the output waveform is twice as high as the input supply frequency, the full-wave bridge rectifier provides us with a higher mean DC value (0.637 Vmax) and less superimposed ripple. By filtering the output waveform with smoothing capacitors, we can increase the rectifier's average DC output while simultaneously decreasing the rectified output's AC fluctuation. Because smoothing or reservoir capacitors function as storage devices, as seen below, connecting them in parallel with the load across the full wave bridge rectifier circuit's output raises the average DC output level even further.
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| Output of Full-Wave Rectifier with Smoothing Capacitor Source: www.electronics-tutorials.ws |
Why is a Full-Wave Rectifier better than a Half-wave Rectifier?
One glaring flaw in the single-diode method is that it
discards the negative half of the source waveform while keeping the positive
half. This results in significant gaps in the output waveform and is referred
to as half-wave rectification. Finding a method to correct the input signal
without wasting half of it would be preferable, and a full-wave rectifier
accomplishes just that. Given the same transformer, we get twice as much peak
voltage and twice as much dc voltage with a bridge rectifier as with a
center-tapped full-wave rectifier. That is why bridge rectifiers are used much
more than full-wave rectifiers.
Disadvantage of Bridge Rectifier
TThe output voltage of the bridge rectifier is 1.4V lower than the input voltage, and this is its only drawback. TThis drawback only affects power supplies that operate at extremely low voltages. FFor example, if the source voltage is at its highest of 5V, the load voltage will only peak at 3.6V. HHowever, if the peak source voltage is 100 V, the load voltage will be nearly ideal full-wave with minimal diode losses.
Conclusion
OThe bridge rectifier is a key element that contributes to converting alternating current (AC) to direct current (DC) in the field of electronics. It has eliminated the center-tapped transformer. This article examines the idea of a bridge, including its construction, operation, advantages and disadvantages, various types that are available, crucial parameters, and features to take into account real-world applications where it is utilized in practical examples and with visual aids to help comprehension.
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