EE Board Teaching Modules Covering Power Supply Topologies

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Nov 24, 2013 (3 years and 7 months ago)

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EE Board Teaching Modules
Covering

Power Supply Topologies

Team Dean

Christopher Stone, Christina Ells, Sean Mounts

Mentors: Scott Hanson, Clint Cole

Acknowledgements


Team

Dean

would

like

to

acknowledge

Clint

Cole,

Scott

Hanson,

and

Gene

Apperson

for

their

guidance

on

this

project,

as

well

as

Dr
.

Ali

Mehrizi
-
Sani

for

PSCAD

simulation

assistance
.

We

would

also

like

to

acknowledge

Digilent

Inc
.

and

the

WSU

facilities

for

their

support
.

Objective

Background

Impact Analysis


Digilent

needs

a

set

of

modules

that

will

demonstrate

a

set

of

power

supply

topologies

so

that

they

may

be

used

in

future

power

electronics

courses
.

The

modules

will

demonstrate

the

buck,

boost,

and

SEPIC

and

be

compatible

with

Digilent’s

Electronics

Explorer

Board
.

These

modules

will

allow

for

the

users

to

gauge

the

strengths

as

well

as

the

weaknesses

of

each

power

supply

topology

by

adjusting

not

only

the

loads,

but

the

reactive

components

of

each

module

(i
.
e
.

Inductors

and

capacitors)
.

These

modules

will

function

as

teaching

tools

for

the

user

so

that

they

may

not

only

see

how

each

power

supply

topology

works

but

also

how

it

loads

and

input

voltage

affect

it’s

noise,

latency,

and

efficiency
.



This

is

a

circuit

representation

of

a

buck

power

topology
.

It

is

meant

to

convert

the

voltage

V
in

into

a

lesser

voltage

using

the

inductor

and

capacitor

so

that

it

will

match

the

V
out


requirements

of

the

system

that

is

using

it
.

It

also

uses

a

transistor

and

diode

as

switches

in

order

to

transition

between

connecting

the

inductor

to

the

source

in

order

to

store

energy,

and

the

load

to

dissipate

energy
.



A

SEPIC

power

topology

is

one

that

function

like

a

buck

and

boost

topology

in

that

it

converts

the

output

voltage

so

that

it

can

be

less

than,

greater

than

or

equal

to

the

input

voltage

and

is

controlled

by

the

duty

cycle

of

the

transistor
.

It

is

useful

for

applications

in

which

the

input

voltage

may

vary

while

the

output

voltage

needs

to

remain

constant
.

This

setup

also

differs

from

a

buck
-
boost

setup

in

that

it

keeps

the

output

voltage

positive
.


The

boost

topology

is

the

opposite

of

the

buck

topology

in

that

it

steps

the

output

voltage

up

so

that

it

can

be

used

in

applications

such

as

rectifiers

and

DC

generators
.

It

uses

the

capacitor

to

store

the

energy

and

dissipate

it

at

a

more

normal

rate

in

order

to

reduce

any

rippling

in

the

voltage

that

may

occur
.



Since

these

modules

are

required

to

be

run

on

Digilent’s

EE

board,

this

would

require

the

user

to

not

only

purchase

the

modules

but

if

they

have

not

already

done

so

an

EE

board

as

well
.

While

this

does

make

the

cost

for

learning

and

testing

the

power

supply

topologies

much

higher,

it

still

gives

the

user

a

valuable

insight

into

how

each

of

the

topologies

work
.

By

using

these

modules

to

test

the

noise,

latency

and

efficiency

of

each

power

supply

topology,

they

will

be

able

to

determine

which

power

supply

topology

is

most

effective

for

various

situations
.



This

knowledge

will

help

to

lower

unnecessary

taxation

on

the

environment

and

therefore

reduce

the

wasted

materials
.

It

will

also

allow

for

users

such

as

students

to

understand

the

requirements

of

the

system

they

are

working

with

better

and

therefore

should

be

able

to

reduce

the

costs

of

building

devices

that

rely

on

these

power

supply

topologies

such

as

cell

phones

and

laptop

computers
.


Goals


The

goal

of

this

project

was

to

create

a

module

for

each

topology

that

would

not

only

simulate

their

function,

but

also

allow

for

the

user

to

be

able

to

modify

almost

every

parameter

in

order

to

see

how

they

affect

performance
.

The

modules

will

not

only

be

effective

teaching

tools,

but

also

be

user

friendly
.

Since

the

user

needs

to

understand

what

each

topology

does,

the

easier

it

is

to

interact

with

the

faster

the

user

can

better

understand

the

topology
.

PCB Design

Module Design


A

duty

cycle

is

defined

as

the

duration

of

the

event

in

a

signal

over

the

entire

period

of

the

signal,

or

in

the

case

of

the

power

supplies

how

long

it

takes

to

turn

on

and

off
.

By

changing

how

long

a

power

source

is

considered

“active”

it

is

possible

to

change

the

duty

cycle
.


All three circuit diagrams were obtained from the Texas Instruments Power Supply
Topology poster, “http://dc417.4shared.com/doc/OoBfQonF/preview.html”


Global

Economical

Societal

Environmental

Ethical

Manufacture

X

X

X

Use

X

X

Disposal

X

X

X

X


The

EAGLE

software

was

used

in

order

to

translate

the

buck,

boost,

and

SEPIC

design

into

something

that

could

be

interpreted

by

a

PCB

manufacturing

company
.

First,

a

schematic

with

all

the

necessary

components

and

their

interconnections

were

created
.

Then,

a

board

drawing

would

be

created

from

these

parts

and

it

is

the

job

of

the

designer

to

arrange

components

and

connect

traces

as

appropriate
.

There

are

many

inherent

rules

associated

with

PCB

design

that

must

be

followed

in

order

to

not

only

to

make

the

resulting

board

work,

but

keep

it

from

being

sent

back

by

the

manufacturing

company
.


As

far

as

our

design

is

concerned,

these

rules

need

to

be

taken

into

account

considering

the

module

designs

we

came

up

with
.

The

most

important

rule

is

that

the

copper

traces

that

connect

each

component

together

be

wide

enough

to

accommodate

the

maximum

amount

of

current

that

could

flow

through

them
.

A

maximum

current

rating

of

1
.
5
A

from

the

EE

board

could

be

assumed

for

most

traces

throughout

the

board

and

calls

for

about

56

mil

width

on

these

traces
.

However,

most

cases

allowed

for

the

use

of

planes

which

introduces

a

large

conducting

surface

that

connects

all

component

parts

of

a

particular

node
.

This

provided

decreased

resistivity

for

all

cases
.

Solution

Adjustable Reactive
Components?


All topologies must have adjustable inductive and capacitive values. To solve this issue a set of inductors/capacitors will
be set up in parallel with a
jumper in series with each one. By connecting contacts at each jumper and even doing combinations of them in parallel, diffe
ren
t values can be achieved.

Jumpers

Solution

PWM control of
switch gate?


Output voltage control is a key design aspect of all the suggested topologies as it is the key component to a user’s underst
anding of the topology. Basic
analysis of the each topology shows a relationship to duty cycle, however letting the user directly control that aspect seeme
d t
o overcomplicate. By
using a prepackaged switching regulator the voltage can simply be controlled through a feedback network (i.e. a high resistan
ce
voltage divider). This
feedback network would be controlled by the student using a variable resistor connected from the EE board itself.

Switching Regulators
w/ Feedback Resistors

Solution

EE Board
Compatibility


All topologies must be able to mount the Electronics Explorer Board to allow for easy measurements and analysis of data. Thi
s issue was
easily resolved by using a two single
-
row jumper pins and mounting them to the bottom of the board with enough spacing between t
hem to
accommodate the pin spacing of the EE Board. Doing so will provide a snug fit and all the nodes that require user interactio
n c
an be
connected via these jumper pins.

Bottom Mounted
Jumper Pins

Buck Topology

SEPIC Topology

Boost Topology


Digilent’s

Electronics

Explorer

(EE)

Board

is

essentially

a

“smart

breadboard”
.

Through

a

USB

connection

and

software,

signals

can

be

generated,

measured,

and

analyzed

right

from

the

user’s

computer
.

Electronics Explorer (EE) Board

Finished Boost Board

Finished SEPIC Board

Finished Buck Board

Convert
to Board

Draw Copper
Traces and
Planes


Buck Board with components
optimally arranged


Schematic of the Buck topology designed by Team Dean