AN ARTIFICIAL LOGIC CONTROLLER IMPLEMENTATION OF HIGH PERFORMANCE VARIABLE FREQUENCY DRIVER WITH INTERLEAVED CONVERTER
Abstract : Variable frequency drive uses power electronics vary the frequency of input power to motor, thereby controlling motor speed.
AC motor drives are widely used to control the speed of ACs,pumps, blower speeds, machine tool speeds, conveyor systems speeds and others applications that require variable speed with variable torque.
This paper proposes a compact VFD circuit design using advanced ALU(artificial logic controller).
The system completely designed with interleaved converter and reduced components.
The controlling can be done by fuzzy logic control system.
Before semiconductor devices were introduced (<1950):
AC motors for fixed speed applications
DC motors for variable speed applications
After semiconductor devices were introduced (1950s)
Variable frequency sources available – AC motors in variable speed applications
Coupling between flux and torque control
Application limited to medium performance applications – fans, blowers, compressors – scalar control
High performance applications dominated by DC motors – tractions, elevators, servos, etc
In 1980s vector controlled semiconductor drives were introduced
Bulky, Inefficient, inflexible.
Switching stress is high.
System efficiency is low.
The operation of the drive is as follows :
Power first goes into the rectifier, where the 3-phase AC is converted into a rippling DC voltage.
The intermediate circuits (interleaved converter) then smoothes and holds the DC Voltage at a constant level or energy source for the inverter.
The last section, the inverter, uses the DC voltage to pulse the motor with varying levels of voltage and current depending upon the external temperature conditions.
The control section uses the frequency, voltage and phase angle to control the inverter.
And also fuzzy logic based control system is implemented for better performance and also reducing components.
Reducing I2R losses and inductor AC losses.
Higher efficiency
Switching loss is less.
Advanced controller is used.
Good modulation technique.
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