Transcript Instructional Design Document

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Welcome
This is a template to create an Instructional Design
Document of the concept you have selected for creating
animation.
This will take you through a 5 section process to provide the
necessary details to the animator before starting the
animation.
The legend on the left will indicate the current status of the
document. The Black coloured number will denote the
current section, the Turquoise color would denote the
completed sections, and the Sky blue color would denote
the remaining sections.
The slides having 'Instructions' would have a Yellow box, as
shown on the top of this slide.
Write the Title of the concept here
Switched Mode Power Supplies
Add Instructor/Instructors name here
Prof. Vivek Agarwal
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Definitions and Keywords
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Add the keywords with definitions which
are used in this concept
Duty cycle/ratio- The fraction of time for which the switch is ‘ON’ in one
complete switching cycle
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DCM (Discontinuous Conduction Mode)- The operating mode of the
converter when the current through the inductor is discontinuous with
respect to time i.e. it is zero for some finite duration in a switching cycle.
CCM (Continuous Conduction Mode)- The operating mode of the
converter when the current through the inductor is continuous with respect
to time i.e. it is never zero during the switching cycle.
Critical Conduction Mode- The operating mode of the converter when
the current through the inductor is just continuous (or just discontinuous)
with respect to time
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Add more slides if required
INSTRUCTIONS SLIDE
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Concept details:
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In this section, provide the stepwise detailed
explanation of the concept.
Please fill in the steps of the explanation of the
concepts in the table format available in the
slides to follow (see the sample below).
Resize the table dimensions as per your
requirements.
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Concept details
Step
number
Details of the step
Image / Diagram
D
L
Circuit diagram of a boost type dcdc converter
Text to be
displayed
S
Vi
R
C
VO
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IG
2
Operation of the circuit when the
switch ‘S’ is closed
IO
IL
S
Vi
Ip
IL
-
+
Show this as rising current
Ip
TON
Vi
VL
L
IL
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Operation of the circuit when the
switch ‘S’ is open
IO
S
R VO
C
Vi
di
=Vi
dt
Hence current through the
inductor increases. The
diode D is reverse biased
during this interval and
does not conduct
During this interval the
diode ‘D’ is forward
biased
di
=Vi -VO
dt
VO  Vi
L
Vi
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L
R VO
C
Vi
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The switch ‘S’ should open and
close with a time period of 0.5
sec
(VO  Vi )
L
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As the switch ‘S’ closes
and opens, the inductor
stores and releases energy
giving a boosted output
voltage
Action / Motion in
the step
Ip+
IL
Show this as falling current

-
Ip
T ON
T
T OFF
di
is negative
dt
 current through the
VL
Vi -V o
inductor decreases
The thickened arrows should
continuously move in the
direction of the “arrow heads”
as shown in both the loops
The current ILshould rise slowly
from its initial value (Ip-) to its
final value (Ip+)
The thickened arrows should
continuously move in the
direction of the “arrow heads”
as shown in both the loops
The current IL should fall
slowly from Ip+ to Ip- value in
the slot TOFF
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Concept details
Step
number
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Details of the step
Image / Diagram
Overall operation of the circuit
The output voltage expression:
Vo 
Text to be
displayed
Combination of operation
when the switch is ‘ON’ and
when the switch is ‘OFF’ as
given previously
Vi
1 d
Vo
1

Vi 1  d
 Vo  Vi ;
This is the output voltage expression
in case of CCM operation
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L
Case I
S
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Vi ×TON
(V -V )T
= i o OFF
TON +TOFF
TON +TOFF

where, d lies between 0 and 1.
Hence, the output voltage gets boosted
up
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Average voltage across the
inductor during a cycle = 0.
Therefore:
Effect of duty cycle on the operation
of the circuit keeping inductor value
constant
C
Vi
a) CCM operation
R
For a given inductor
value and reasonably
large duty cycle, the
current through the
inductor is continuous (as
shown) i.e. CCM
operation
IG
Ip+
IL Ip
TON
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TOFF
Sequentially show the
animation of both modes i.e.
when the switch is ‘ON’ and
when the switch is ‘OFF’ as in
the previous two circuits – i.e.
the animation toggles between
the two states
The duty cycle needs to be
animated here. Starting with a
reasonably high duty cycle (as
shown in the figure), the inductor
current should rise from the initial
value Ip- and reach a peak value
Ip+ at the end of the ON period
then slowly decrease back to Ip- at
the end of the OFF period as
shown in the figure, thereby
resulting in a continuous current
mode of operation
T
IG
b) Critical Conduction Mode of
operation
Ip
IL
TON
TOFF
T
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Action / Motion in
the step
With the same inductor
value, the duty cycle is
now reduced such that
the current through the
inductor becomes just
continuous – Critical
Conduction Mode
The duty cycle should then be
slowly reduced till a point when
the inductor current starts from the
initial value of 0, reaches a peak
Ip at the end of the ON period and
then decreases slowly back to 0
exactly at the end of the OFF
period as shown in the figure,
thereby resulting in a just
continuous (or critical) current
mode of operation
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Concept details
Step
number
Details of the step
c) DCM operation
Image / Diagram
IG
Ip+(new)
IL
TOFF
T
TON
L
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Case II
Action / Motion in
the step
Without changing the
inductor value, the duty
cycle is further reduced
till the inductor current
becomes fully
discontinuous i.e. DCM
operation.
Ip+(new) >Ip> Ip+
Next, the duty cycle should be
further reduced till a point is
reached when the inductor
current starts from the initial
value of 0, reaches a peak
Ip+(new) at the end of the ON
period and then decreases slowly
back to 0 before the end of the
OFF period as shown in the
figure, thereby resulting in a
discontinuous current mode of
operation
D
Big sized
inductor
S
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C
Vi
Effect of inductor value on the
operation of the circuit keeping duty
cycle fixed
a) CCM operation
For a given (fixed) duty
cycle and a reasonably
large inductor value, the
current through the
inductor is continuous i.e.
CCM operation
IG
Ip+
IL
Ip-
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TOFF
T
D
L
b) Critical Conduction Mode of
operation
R VO
IG
TON
Normal sized
inductor
S
C
Vi
IG
IG
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Text to be
displayed
Ip
IL
TON
TOFF
T
R VO
With the same (fixed)
duty cycle, the inductor
value is now reduced till
the point when the
inductor current becomes
just continuous – Critical
Conduction Mode
Here, the inductor size needs to be
animated giving the waveforms
according to the size of the
inductor used in the circuit.
Starting with a high value of
inductor (shown in the figure with
a bigger size), the inductor current
should rise from the initial value
Ip- and reach a peak value Ip+ at
the end of the ON period then
slowly decrease back to Ip- at the
end of the OFF period as shown in
the figure, thereby resulting in a
continuous current mode of
operation
The inductor size should be slowly
reduced till a point is reached
when the inductor current starts
from the initial value of 0, reaches
a peak Ip at the end of the ON
period and then decreases slowly
back to 0 exactly at the end of the
OFF period as shown in the figure,
thereby resulting in a just
continuous (or critical) current
mode of operation
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Concept details
Step
number
Details of the step
Image / Diagram
c) DCM operation
S
C
Vi
IG
Ip+(new)
IL
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Action / Motion in
the step
With the same (fixed)
duty cycle, as the
inductor
value
is
reduced there comes a
point when the current
through the inductor
becomes discontinuous DCM operation
Ip+(new) >Ip> Ip+
Next, the inductor size should be
further reduced (as depicted in
the figure) till a point when the
inductor current starts from the
initial value of 0, reaches a peak
Ip+(new) at the end of the ON
period and then decreases slowly
back to 0 before the end of the
OFF period as shown in the
figure, thereby resulting in a
discontinuous current mode of
operation
D
L
Small sized
inductor
IG
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Text to be
displayed
TON
TOFF
T
R VO
INSTRUCTIONS SLIDE
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Interactivity and Boundary limits
expected in the animation

In this section provide, interactivity options for all the
parameters/components of the concept.
For example:
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
Numerical values to change the state of the component: By providing input boxes
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Drag and drop of components: To test the comprehension of the users
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Movement of objects: To explain the action of the components
Interactivity option
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number
Details of
Image /
Text to be
Boundary limit
Provide the boundary
of the parameters,
which
will
interactivity limits
Diagram
displayed
balloon is
....
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The user canof the results ofWhen
enable
correctness
thethein experiment.
placed
high
move the
‘balloon’ of gas
in the resonator
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gas
pressure region, it
would shrink and its
temperature will rise
(it will become red).
When moved to low
pressure region, it
expands becoming
cold (blue)
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Interactivity and Boundary limits
Interactivity
option number
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Details of
interactivity
Image /
Diagram
Text to be
displayed
Boundary
limit
INSTRUCTIONS SLIDE
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Questionnaire to test the user
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A small, (5 questions) questionnaire can
be created in the next slide, to test the
user's comprehension.
This can be an objective type
questionnaire.
It can also be an exercise, based on the
concept taught in this animation.
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Questionnaire
1. For a Boost type DC-DC converter, VO (output voltage) is:
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Answers: a) <Vi
b) >Vi
c) =Vi
d)0
2. The range of duty cycle (d) for DC-DC converters is:
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Answers: a) 0  d  0.5
b) d  1
c) d  0
d) 0  d  1
3. For a given power output, the peak current in the inductor of a
DCM operated DC-DC boost converter is:
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Answers: a) less than the peak current in case of CCM
b) equal
to the peak current in case of CCM
c) greater than the peak
current in case of CCM d) none of the above
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Questionnaire
4. The ripple in the inductor current of a CCM operated DC-DC
boost converter is:
Answers: a) greater than the current ripple in case of DCM
b) equal to the current ripple in case of DCM c) less than
the current ripple in case of DCM
d) none of the above
5. The expression of the output voltage of the Boost DC-DC
converter operating in DCM is :
Vi
Answers: a) Vo 
b) Vo is a complex expression of R, L
1 d
d
and d c) Vo  
Vi d) none of the above
1 d
Answer key: 1(b), 2(d), 3(c), 4(c), 5(b)
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INSTRUCTIONS SLIDE
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Links for further reading
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In the subsequent slide, you can provide
links, which can be relevant for the user
to understand the concept further.
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Add more slides in necessary
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Links for further reading
[1] “DC-DC Switching Regulator Analysis”, by Daniel M. Mitchell, McGraw-Hill
Book Company, 1988.
[2] “Power Electronics: Converters, Applications and Design” , by Ned Mohan,
Tore M. Undeland and William P. Robbins, Third edition, John Wiley & Sons.
Thank you