Download Buck Converter Design Process

Example #6
Buck Converter with Simplorer
Buck Converter Design Process
1) Manually select the topology
2) Use Simplorer to simulate the SMPS model
3) Use PExprt to design inductor
4) Use PEmag to generate detailed netlist model
5) Import PEmag model into Simplorer
6) Use Simplorer to simulate the PEmag model
7) Use Simplorer (transient) for load step test
8) Use Simplorer (AC) to design feedback loop
9) Use Simplorer (transient) to do feedback loop
test and verify performance
9/1/04
Pg. 2
Simplorer
PExprt
PEmag
Simplorer
Step 1: Select the topology
Buck Converter
Decide to use
either average
or switch level
Buck Converter
Step 2: Simulate in Simplorer with SMPS library
Use switch level Buck Converter from SMPS library
Change duty cycle
and inductor value
to achieve desired
output voltage
Open
e06a_Buck.SSH
Step 3: Design Inductor with PExprt
Easy transition from
Simplorer to PExprt
Build a waveform
based inductor or
buck converter
in PExprt
Open
e06b_Buck.cia
Step 3 (cont): Design Inductor with PExprt
Run the PExprt
model and select
the design
you prefer
PExprt design results, including constructive data
Step 4: Generate Model with PExprt Modeler [PEmag]
Generate a
1D Analytical
or a 2D FEA
based model
Can include core non-linear effects
using Jiles-Atherton model if the core
is operating in the nonlinear range
Open e06c_Buck.pmg
(usually this is a bad design)
Step 5: Import PExprt Model into Simplorer
Use Simplorer PExprt
link to substitute ideal
inductor with
PExprt model
Step 6: Simplorer Simulation With PExprt Model
PExprt Model and Symbol
Simulate the PExprt
model in Simplorer
Open e06d_Buck.SSH
Step 7: Load Step Test: Feedback loop is needed
Non-Regulated
Output Voltage
Spike occurs
since no control
loop is used
Open e06e_Buck.SSH
Load step
reduces current
and device moves
to discontinuous
mode
Step 8: Design Feedback Loop in frequency domain
Add PID
controller
from the
SMPS library
This controls
duty cycle of
switch to
maintain
constant
output voltage
Design of the control loop
with AC analysis of the Converter
Specifically, select R and C
in the PID controller
Open
e06f_Buck.SSH
Step 9: Feedback Loop Test: Simplorer Time Domain
Finally, return to the time domain analysis
to see how the buck converter performs
PID regulator from the SMPS library
Load Step
Regulated Output Voltage
Open
e06g_Buck.SSH