2. • Phase Locked Loop and micro-computer
control of DC drives
•Program flow chart for Constant torque
•Program flow chart for constant horse power
operations
•Speed detection and Current sensing circuits
and feedback elements.
Overview
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4. Microcomputer, an electronic device with a microprocessor
as its central processing unit (CPU).
Microprocessor- The microprocessor is also a general-purpose
processor that consists of a control unit, ALU, a bunch of registers
also called scratchpad registers, control registers and status
registers.
Microcontroller - Microchip Atmega328-AU, Microchip
P1C16F877A-I/P, Microchip P1C16F1503-I/P, Microchip
P1C16F671-I/SN, Microchip P1C18F45K22-I/P, etc.
Embedded Processor- It consists of several blocks they are the
processor, timer, an interrupt controller, program memory and data
memory, power supply, reset and clock oscillator circuits, system
application-specific circuits, ports and interfacing circuits.
Digital Signal Processor- T1 C5416, DSP 32C Processor
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Micro Computer
5. Reduces costs and Size
Provides Reliability and Control Performance
Flexible to change the control strategy
Extra Features can be added to meet performance
parameters.
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Advantages of Microcomputer Based DC Motor Drive
6. Speed Control
Current Control
Start and Stop of drive
Diagnostics for built-in fault finding
Protections
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Performs various desirable functions such as
8. FEATURES OF MICRO COMPUTER BASED CONTROL
Speed Signal is fed by use of D/A converter
An inner current –control loop is used to control the
armature current
Line Synchronizing Circuit - To Synchronize the
generation of the firing pulses with the supply line
frequency.
Pulse amplifier-- Provides the necessary isolation and
produces the gate pulses of required magnitude and
duration.
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10. The main function of the microprocessor is generating the
firing pulses with least possible asymmetry.
The accuracy in the calculation of current and speed loops.
The sampling periods of these loops are however larger than
those of the generating pulses. The error in computation must
be limited.
If extra accuracy is required in the speed loop the
microprocessor must be capable of floating point arithmetic in
order to handle large numbers. For this purpose a fast
microprocessor with optimised programs may be required.
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SELECTION OF A CONTROL OF DC DRIVE USING MICROPROCESSORS
11. chopper controlled four quadrant dc drives
using separately excited dc motor or dc series
motor.
multiphase chopper controlled dc drives
pulse width controlled dc drives
The multiple firing schemes for improving the
performance of dc drives, g., TRC and CLC.
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APPLICATIONS OF MICROPROCESSORS IN THE AREA OF DC
DRIVES