PID BASED DC DRIVE USING

MICROCONTROLLER

ABDUL HASEEB SIDDIQI EE-42UMAIR JAMAL MANSURI EE-47

SYED ZOHAIB ALAM EE-56www.hasboo.co.nr

Hasboo86[at]gmail.com

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INTRODUCTION

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ELECTRIC DRIVEElectric drive for motor is used to draw electrical energy from

the mains and supply the electrical energy to the motor at whatever voltage, current and frequency necessary to

achieve the desired mechanical output.

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ELECTRIC DRIVENearly 65% of the total electric energy produced in the USA is consumed by electric motors (1).

Electric motors used in pumps, fans, compressors and in other commercial applications requiring considerable amount of power to operate waste this power by some kind of brake or throttle mechanism as they are not operated the way they were designed.

Their control is often implemented by inefficient systems and require to run the motor at full speed all the time.

By running a motor at full speed while throttling the output, is trying to control the speed of a car by keeping one foot on the accelerator and the other on brake.

Electric drives allow the selection of speeds within its operating range

(1) R. Krishnan, “Electric Motor Drives 4

Types

DC drives AC drives

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Open loop and Closed loop

Analog and

Digital

CONTROLLING METHODS

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PROPORTIONAL , INTEGRAL & DERIVATIVE CONTROLLER

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Proportional–integral–derivative controller (PID controller) is a control loop feedback mechanism widely used in industrial control systems. A PID controller attempts to correct the error between a measured variable and a desired set point by calculating and then

outputting a corrective action that can adjust the process accordingly.

Three separate parameters; the Proportional, the Integral and Derivative.

Proportional term calculates control action proportional to the error. Proportional control cannot eliminate the error completely

Integral control is the means to eliminate the remaining error or offset value, left from the proportional action, completely

Derivative control is sometimes added to introduce dynamic stability to the control loop

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• Starting Response

• Steady State• Changing

Loads• Varying

Proportional gainP controller

• Starting Response

• Steady State• Changing

Loads• Varying gainI controller

• Varying Loads• Varying gain

Combined Response of PI controller

• Starting Response

• Steady State• Changing

Loads• Varying D gainD controller

• Varying Loads• Varying gain

Combined Response of P and D controller

• Varying Loads• Varying gain

PID response

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DC DRIVE

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CONVENTIONAL DC DRIVE

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COMPONENTS OF DC DRIVE

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CONTROLLER

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SENSORS- SHAFT ENCODER

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MODULATOR

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Converter (H-Bridge)

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Source

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FLOW DIAGRAM

FLOW DIAGRAM

start

Input direction

Input reference

speedInitialize

timer

Initialize counter

Output DC motor with 50 % Duty

contd 21

After 30 seconds

interrupt is generated by

timer

Pulses of counter are

counted

Error = reference –

counted pulses

Sets the carry bit and PID acts

on error

Output = reference

signal +- PID answer

Output send to DAC

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ENHANCEMENTS

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ENHANCEMENTS

Self tuning PID

Controlling the field

Voltage

Over current

protection

Flux loss protectio

n

Interfacing with

PC/ remote user

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SIMULATION

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SPECIFICATIONS

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Atmel® 89C52, 8-bit MicrocontrollerDC shunt motor of 220V, 1/8 hp and 3000 rpm Speed range of 100 to 3000 rpmDC generator with Shaft encoder, 120 slot/rev

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COSTS

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THANKYOU