DISCRIPTION The output voltage of an alternator is prop

DISCRIPTION
The output voltage of an alternator is proportional to the field excitation voltage. So by varying field voltage it is possible to get the desired output voltage. It is proposed to excite the field of the alternator by a chopper constructed using MOSFET/SCR. The output voltage of the chopper is varied by varying the ON time of the MOSFET/SCR .We can change duty cycle and get different output voltage of the alternator by modification of the ckt.
Initially the alternator is excited by an external DC supply through Relay-1 so that an EMF is induced in armature. This induced EMF is rectified and fed to chopper to generate variable DC supply for field. After a delay the output of chopper is also fed to field through Relay-2 so that external supply and the output of chopper are in parallel. When the voltage output of chopper exceeds the external DC voltage Relay-1 is de-energized to cut the external DC supply.
The system has provision to sense the generated voltage and current using PT and CT and these signals are used as feedback signals in order to compare with set values. The system has provision to enter set values through keyboard. The Microcontroller computes the error between set value and feed back signal. The error signal is used to generate the PWM pulse to fire the MOSFET/SCR using PID/Fuzzy algorithm.
I to V converterAlternator fieldAlternator statorPNloadRectifierRectifier8 channel ADC89C52MCSignalConditioningCircuitRelay-1RectifierRYB8CTPTDCSingle quadrant chopperRectifierDCACPulsesChange over signalKeyboard/Display interfaceKeyboardDisplayRelay-2
Block diagram of Voltage regulation of alternator using 89C52

Attachments: