1. Example #6 Buck Converter with Simplorer
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.

2. 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
SimplorerPExprt
PEmag
Simplorer

3. Step 1: Select the topology
Buck Converter
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Decide to use
either average
or switch level
Buck Converter

4. 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
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Open e06a_Buck.SSH

5. 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
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.

6. Step 3 (cont): Design Inductor with PExprt
Run the PExprt
model and select
the design
you prefer
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
PExprt design results, including constructive data

7. Step 4: Generate Model with PExprt Modeler [PEmag]
Generate a
1D Analytical
or a 2D FEA
based model
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Can include core non-linear effects
using Jiles-Atherton model if the core
is operating in the nonlinear range
(usually this is a bad design)
Open e06c_Buck.pmg

8. Step 5: Import PExprt Model into Simplorer
Use Simplorer PExprt
link to substitute ideal
inductor with
PExprt model
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.

9. Step 6: Simplorer Simulation With PExprt Model
PExprt Model and Symbol
Simulate the PExprt
model in Simplorer
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Open e06d_Buck.SSH

10. Step 7: Load Step Test: Feedback loop is needed
reduces current
and device moves
to discontinuous
mode
Non-Regulated
Output Voltage
Spike occurs
since no control
loop is used
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Open e06e_Buck.SSH

11. Step 8: Design Feedback Loop in frequency domain
This controls
duty cycle of
switch to
maintain
constant
output voltage
Add PID
controller
from the
SMPS library
Design of the control loop
with AC analysis of the Converter
Specifically, select R and C
in the PID controller
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Open e06f_Buck.SSH

12. 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
Designing a new 42-volt automotive power system requires knowledge of components, electronics and controls. It has become a truly multi-disciplinary engineering task. Ansoft's Electromechanical System Design Suite is a powerful combination of software simulation technology including electromagnetics, circuits, block diagrams, state machines, and specialized design programs which allow an engineer to successfully design and analyze a complete 42V system from start to finish.
Open e06g_Buck.SSH