OBJECTIVE:
The aim of the project is to develop a speed control system for ac
motor. It is proposed to include the
start. Over-head no-volt protection also.Embedded microcontroller monitoring
the
Motor status and abnormal over load protection
systems
PRINCIPLE:
Since the speed of AC motor depends on stator-applied voltage. the speed can varied by varying stator voltage.
but if voltage is varied by keeping the frequency constant, the flux of the
machine will also vary. which is undesirable. It can be operated constant flux
condition.
TEAM DESCRIPTION:
The functional block diagram of AC motor speed control system is shown
in fig.1.
The controlled rectifier is a 3-phase half controlled bridge rectifier
constructed using SCRs and Diodes .the controlled is used to obtain variable DC
supply voltage. the variable DC supply
voltage is converted to 3 phase AC supply using else IGBT.
The speed adjust circuitry will firing angles of rectifier and rectifier
and inverter to achieve the desired speed =desired transformer(CT’s)are
provided to sense the over-load or no-volt condition and the firing pulses.
FEACTURES:
1.
No need of extra starter.
2.
soft start (while starting
the current will not exceed the full load current)
3.
consonant speeds or constant
torque operation.
4.
over-load and no-volt
protection.
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