This document discusses uncontrolled rectifiers, which use power diodes to convert AC input voltage to DC output voltage. Uncontrolled rectifiers cannot control the on/off timing of the diodes. As a result, the average output voltage is fixed and cannot be controlled. The document then examines various rectifier circuit configurations including single phase half wave and full wave rectifiers, and three phase half wave and full wave rectifiers. It analyzes the operation of these rectifiers with resistive and resistive-inductive loads.

1. UEEC010 – Power Electronics
Uncontrolled Rectifiers
Poornima D, Assistant Professor/EEE,
Sri Ramakrishna Institute of Technology, Coimbatore 1

2. Rectifiers
Rectifiers –converts ac input voltage to dc output voltage
Uncontrolled Rectifiers:
– Uses Power Diodes
– called so because the on/off of the diode cannot be controlled
– Average output voltage is a fixed voltage, cannot be controlled
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3. Power Diodes
 Power Diodes are such semiconductor
devices used in rectifier circuitries to rectify
higher value current.
 This diode has a larger area of PN junction
then other diodes, due to this ability is used
to rectifier higher value current and voltage,
like hundred amperes and thousand
kilovolts.
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4. Single Phase Half Wave Rectifier
-Simplest type
-Poor performance
-For one cycle of supply voltage there is one half cycle of output-
called single phase one pulse rectifier
-Load can be R,RL or RL with freewheeling diode
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5. Single Phase Half Wave Rectifier with R Load
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6. Single Phase Half Wave Rectifier RL Load
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7. Single Phase Half Wave Rectifier RL Load with free wheeling diode
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8. Single Phase Half Wave Rectifier RLE Load
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9. Single Phase Full Wave Rectifier
• Utilises both halves of the input sinusoidal waveform to provide a
unidirectional output
• The output voltage is more consistent
• Has a higher average output voltage
• The input frequency is doubled by the process of rectification
• Requires a smaller capacitance value smoothing capacitor
• Applications in variable voltage power supplies and motor control.
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10. Single Phase Full Wave Rectifier with R Load
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11. Single Phase Full Wave Rectifier with RL Load
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12. Single Phase Full Wave Rectifier RLE Load (Continuous
current)
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13. Single Phase Full Wave Rectifier RLE Load (Discontinuous
current)
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14. Three Phase Half Wave Rectifier R Load
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15. Three Phase Half Wave Rectifier RL Load
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16. Three Phase Full Wave Rectifier R Load
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17. Three Phase Full Wave Rectifier RL Load
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