# Presentation: 026018

## SOFTWARE INTEGRATIONUSING STEP AP210

**Prof. Jan Helge Bøhn**
*Virginia Tech, Mechanical Engineering*
*Blacksburg, Virginia 24061, USA*
- Tel: +1-540-231-3276, Fax: +1-540-231-9100
- E-mail: bohn@vt.edu, Mobile: +1-540-819-0326
- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Presentation Outline

- CPES overview
- Why software integration?
- Sample demonstration case
- A first generation implementation
- Current activities
- STEP AP210 mini-consortium

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## CPES Overview

- National Science Foundation (NSF) Engineering Research Center (ERC)
- Five universities
- Virginia Tech, Univ. Wisconsin (Madison),
- RPI, NC A&T, Univ. Puerto Rico (Mayagüez)
- 85+ corporate members
- $120M budget over 10 years (year 3)

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## CPES Vision

- Improve the competitiveness of US power electronics industry by developing an integrated systems approach via **Integrated Power Electronics Modules** (IPEMs)
- 10 x improvement in quality, reliability, and cost effectiveness of power electronics systems

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Why Software Integration?

- To achieve these goals, we must
- push existing technologies to their limits and develop new ones as needed
- use a multi-disciplinary set of software tools for design, modeling, and analysis, to optimize performance
**integrate our software tools**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## The Multi-Disciplinary Analysis

**Geometric**
**Modeling**

**Electrical**
**Circuit**
**Simulation**

**Cost**
**Modeling**

**The Multi-Disciplinary Analysis**
**and Design Process**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

**Notes:**
If we look at today’s design process, it typically begins with an engineer...that gets an idea on how to solve a problem.
...He then begins to develop a circuit diagram...using an electric circuit simulation tool...which provides feedback to the engineer.
...He then begins to look at the mechanical layout...using a geometric modeling system.
...Taken together, the engineer now begins to have a prototype design
...on which  he can do thermal analysis...electromagnetic field analysis...stress and strain analysis...and, at some point, costs analysis.

Today this process is completed on an ad hoc basis, and it is not uncommon that data is re-entered seven or eight times during the design process, with all the inefficiencies and problems this generates.

We want to streamline this process.  We want to make the the prototype data model the core of our process so the engineer can concentrate on the flow of design and analysis activities
...while the applications interact with the model to extract the necessary data

## The CPES Solution

**Software integration should rely on open international standards**

**The CPES Solution**

- STEP AP210

**— ****and in particular**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## CPES Solution: Target Platforms

***STEP***
- Product
- Database

**Program**
**Flow Control**
***iSIGHT***

- Model and Analysis Data Flow

***AP 210***

**Cost**

**Reliability**
**(CALCE)**

**Electro-**
**Dynamic**
***SABER***

**Thermal**
***FLOTHERM ***

**3D**
**Solid Modeling**
***I-DEAS***

**Electro-**
**Magnetic**
***MAXWELL***

**Mechanical**
***ABAQUS***

**CPES Solution: Target Platforms**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Sample Demonstration Case

**3D solid modeling**
**Electrical modeling and analysis**
**Thermal modeling and analysis**
**Automated optimization**
**Experimental verification**

**OBJECTIVE:**   Sample demonstration case to illustrate usefulness of integration of software tools for design, modeling, and analysis of an IPEM:

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Sample Demonstration Case

**IPEM Design**

**APEP**

**Sample Demonstration Case**

**IPEM:**  Two MOSFETs in a   half-bridge structure as part of   a front-end converter in a distributed power system (DPS).

**Mechanical CAD**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Sample Demonstration Case

- The two MOSFETs are soldered on one side of a Al2O3 Direct Bonded Copper (DBC) board.
- The copper substrate of the DBC is etched to give it the desired pattern.
- Wire-bonding is used to connect the MOSFETs to the copper substrate.
- The copper substrate on the other side of the DBC is attached directly to the heat sink.

**Sample Demonstration Case**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Parasitic Inductance

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- Voltage waveform of the
- bottom switch at turn off

- Voltage waveform of the
- bottom switch at turn off

- Ideal Case

- Non-ideal Case

- To minimize the parasitic inductance, we want to place these two MOSFETs as close together as possible...

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**Parasitic Inductance**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Thermal Considerations

- We therefore
- Need electrical and thermal models that are based on 3D solid geometry to address these issues
- Need to integrate the electrical and thermal analysis tools to quantify these effects

- But if we place these two MOSFETs _too_ close together, then the thermal interaction between them may cause the junction temperature to become too high

**Thermal Considerations**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## I-DEAS 3D Solid Model

- I-DEAS 3D Solid Model of the IPEM

**I-DEAS 3D Solid Model**

**Step 1**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Maxwell Q3D Model

- Maxwell Q3D Model of the IPEM

**Maxwell Q3D Model**
- (Parasitic Parameter Extraction)

- Parasitic Inductance

- With Maxwell Q3D Extractor we can calculate the inductance from the geometry
-  { using the partial element equivalent circuit (PEEC) method }

- L2

- L1

- M23

- L3

- M12

- M13

**Step 2**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Saber Model (losses, EMI)

- With Saber we can determine losses and EMI
- { using the equivalent inductance matrix obtained from Maxwell }

**Saber Model **(losses, EMI)

**Step 3**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Experimental Verification

**Experimental Verification**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Thermal Modeling

- The thermal analysis is based on:
- Device power loss provided by Saber
- Geometry provided by I-DEAS
- Boundary condition, such as air flow rate and ambient temperature

- Air flow

- FLOTHERM uses computational fluid dynamics (CFD) to predict air flow and heat transfer in and around the electronic systems

**Thermal Modeling**

**Step 4**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Results:  Thermal Modeling

**OBSERVATIONS:**
- The thermal resistance of the heat sink is much larger than that of any other package component
- The heat sink size is determined by the device loss

**Results:  Thermal Modeling**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Results:  IPEM Geometry

- CASE STUDY:  Reduce the size of the IPEM
- Does not affect the parasitic inductance since both the length and width of the trace are reduced

- Large-Sized IPEM

- Small-Sized IPEM

- L: 4~16nH

- L: 6~12nH

**Results:  IPEM Geometry**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Results:  IPEM Geometry

- CASE STUDY:  Reduce the size of the IPEM
- Does not affect the power density since the size of heat sink is mainly determined by the power loss

**Results:  IPEM Geometry**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Sample Conclusions

- To minimize the parasitic inductance of the layout, we should keep the width of the copper trace as large as possible, but minimize the length of the trace.
- Scaling down the size of the IPEM may not increase the high power density, because the heat sink size is mainly determined by the power loss.

**Sample Conclusions**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## A First Generation Implementation of
IPEM Design, Modeling, and Analysis
Software Tools Integration

**IPEM Design, Modeling, and Analysis**
**Software Tools Integration**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Flow Controlled by iSIGHT

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Data Flow and Storage

**Data Flow and Storage**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Vary the Heat Sink Thickness

- the tradeoff between EMI and device temperature.

**Vary the Heat Sink Thickness**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Conclusions

**MOTIVATION:**  Once a model is defined, it is practical to optimize via an automatically driven sequence of analysis-redesign iterations.
**NEED:**  We need to optimize our IPEMs in order to reach our 10x improvement targets.
**PROBLEM:**  Lack of implemented standards for data exchange between our software tools makes it impractical to set up such a model...

- 

****

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Current Activities

- Examine how STEP AP210 can represent IPEM models
- What are the limitations?
- How can we work around them?
- What must be changed?
- Establish a STEP AP210 mini-consortium within CPES to drive the deployment of AP210 among MCAD and ECAD vendors
- Test case:  1kW DC/DC power conversion module for server and low-end telecommunication systems.

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Acknowledgements

**CPES STEP AP210 Team:**
- Yingxiang Wu, MS ME / MS CPE
- Jonah Z. Chen, Ph.D. EE
- Li Ma, Ph.D. EE
- Christelle Gence, visiting scholar
- Prof. Jan Helge Bøhn, ME
- Prof. Dushan Boroyevich, EE
- Prof. Elaine Scott, ME

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA

## Acknowledgements

- This work was supported primary by the ERC Program of the National Science Foundation under Award Number EEC-9731677

**Acknowledgements**

- NASA's STEP for Aerospace Workshop • January 16-19, 2001 • JPL, Pasadena, CA