Rectifiers and Battery Chargers - Part B

Question 1

How many types of rectifiers are there and what are they?

Answer 1

1. half-wave rectifiers
2. full-wave rectifiers

Question 2

What is a single-phase half-wave rectifier?

Answer 2

• The simplest rectifier
• consists of a single diode placed in series with the laod
• The average voltage output of a half-wave rectifier is 31.8%(0.318) of the peak voltage
• V_dc = V_peak X 0.318
• V_dc - V_peak X (1/π)
• The diode current equals the load current
• the pulsating DC voltage at the load has a “ripple frequency” that is equal to that of the supply voltage

Question 3

What is a Centre-Tapped Full-Wave Rectifier?

Answer 3

• A centre-tapped transformer with two diodes, which results in the load seeing a voltage during both alternations of the sine wave, this is called full-wave rectification
• The conversion factor for a single-phase, full-wave rectifier is 0.637 of the peak value of the rectifier voltage
• The average DC voltage output is 63.7% of the peak value of instantaneous voltage
• V_dc = V_peak X 0.637
• V_dc = V_peak X (2/π)
• F_load = 2 X f_supply
• The peak load voltage is one half of the peak secondary voltage
• The diodes must block the entire transformer secondary voltage when reverse biased
• Each diode carries the full load current half of the time, which means that the average diode current is half of the average load current
• The ripple frequency of the load voltage is double that of the supply

Question 4

What is a Single-Wave, Full-Wave Bridge Rectifier?

Answer 4

• The most commonly used single-phase rectifier
• Uses four diodes
• Vdc = Vpeak X 0.637 or Vdc = Vpeak X (2/π)The frequency of the load is equal to two multiplied by the frequency of the supply - Fload = 2 X Fsupply
• You can determine the load that each diode has to carry by dividing the average DC voltage by the resistance of the load and then dividing your answer by two because each diode carries the load only half at a time
• Bridge Rectifiers are available in a modular assembly that contains all four diodes, the assembly has all four leads, two AC input leads and two DC output leads

Question 5

What is an Integrated Circuit Rectifier?

Answer 5

• These rectifiers are preassembled and are an alternative to using two, four or six diodes to assemble a rectifier. They’re compact and easy to install
• The peak load voltage is the same as the peak supply voltage
• each diode carries the entire load current half of the time, which means that the average diode current is half of the average load current
• the ripple frequency of the load voltage is double that of the supply
• the conversion factor for a single-phase, full-wave rectifier is 0.637 times the Peak Voltage (Vpeak)

Question 6

What is the peak load voltage of a Centre Tapped Full-Wave Rectifier?

Answer 6

One half of the Transformer’s Secondary peak voltage

Question 7

What is the formula for finding the peak voltage of an AC waveform?

Answer 7

V_peak = V_ac / 0.707

Vpeak = V_ac X (square root of 2)

Question 8

What is the formula for find the average dc output of a single-phase, half-wave rectifier?

Answer 8

V_dc = V_peak X 0.318

V_dc = V_peak X ( 1 / π )

Question 9

What is the formula for finding the average DC output of a Full-Wave Rectifier?

Answer 9

V_dc = V_peak X 0.637

V_dc = V_peak X ( 2 / π )

Question 10

What is the average DC output of a full-wave rectifier?

Answer 10

The average DC output of a full-wave rectifier is 63.7% of the peak voltage

Question 11

What is the average DC output of a half-wave rectifier?

Answer 11

The average DC output of a half-wave rectifier is 31.8% of the peak voltage