fpga based motor controller

A

Seminar

On

“FPGA BASED MOTOR CONTROLLER”

Introduction

The recent advances in FPGA (Field

Programmable Gate Array) technology have made

it possible to implement digital control algorithms

in hardware solution with low costs.

FPGA In motor control

FPGA are being more popular in motor

control

Wide integration capabilities

Higher performance, reduce latency

Cost reduction

FPGA Principles

A Field-Programmable Gate Array

(FPGA) is an integrated circuit that can

be configured by the user to emulate

any digital circuit as long as there are

enough resources

An FPGA can be seen as an array of

Configurable Logic Blocks (CLBs)

connected through programmable

interconnect (Switch Boxes)

FPGA-Xilinx Spartan-3E Starter

Kit

FPGA

buttonsswitches

LEDs

FPGA structure

CLB SB

SB SB

CLB

SB

CLB SB CLBConfigurable Logic Blocks

Interconnection Network

I/O Signals (Pins)

Simplified CLB Structure

CLB SB

SB SB

CLB

SB

CLB SB CLBConfigurable Logic Blocks

Interconnection Network

I/O Signals (Pins)

Look-Up

Table

(LUT)

Q

QSET

CLR

D

MUXLook-Up

Table

(LUT)

Q

QSET

CLR

D

MUX

CLB SB

SB SB

CLB

SB

CLB SB CLBConfigurable Logic Blocks

Interconnection Network

I/O Signals (Pins)

Configuration

bits 1

0

0

0

00

Interconnection Network

Design Flow

Pulse Width Modulated

(PWM)

what is it?

Output signal alternates between on and

off within specified period

Controls power received by a device

The voltage seen by the load is directly

proportional to the source voltage

Definition

LOWHIAVG VDDVV )1(

Duty Cycle: on-time / period

Vlow is often zero

PWM signals of varying duty

cycles

Three Phase AC motors with PWM

3 different AC currents at different

phases

Phase: 120 degrees apart

Creates constant power transfer

Rotating magnetic field

Pulses substitute for AC current

Principles of PWM Motor

Drives

Phase A modulated pulse

Given to motor

Phase B modulated pulse

Given to motor

Average voltage

The net voltage across one motor

winding

Motor current

OPTOCOUPLER

An opto-isolator, also called an optocoupler,

photocoupler, or optical isolator, is a

component that transfers electrical signals

between two isolated circuits by using light.

Opto-isolators prevent high voltages from affecting the system receiving the signal.

Commercially available opto-isolators withstand input-to-output voltages up to 10 Kvand voltage transients with speeds up to 10 kV/μs.

Working of

OPTOCOUPLER

ADVANTAGES

High motor efficiency

Fast control response

Lower motor torque ripple

Close to ideal sinusoidal motor current

waveform

CONCLUSION

By controlling the amplitude and

frequency of the modulating waveforms,

the PWM drive can output to the motor a

three phase supply with the use of

optocoupler at the necessary voltage

and frequency to drive the motor at any

required speed.