Extracting Busbar Inductance in Q3D

Introduction to Busbars and Design Considerations

Busbars are metallic conductors used for power distribution that offer design advantages over traditional wiring in many applications. When designing a busbar, several important considerations must be addressed:

• Low inductance: Higher frequency switching content can lead to reactive losses that reduce efficiency
• Capacitance: Managing the capacitive effects between conductors
• Isolation: Ensuring proper separation to prevent arcing
• Thermal specifications: Ensuring the busbar can withstand operational temperatures

Understanding Q3D Concepts

Q3D Extractor is an ANSYS tool for extracting parasitic parameters from 3D models. Key concepts include:

• Nets: All physically connected metal components (e.g., an aluminum strip or copper welded to steel)
• Terminals: Inputs or outputs for a net, classified as:
  • Sources: A net can have multiple sources
  • Sinks: A net can only have one sink

Simulation Requirements

• Capacitance analysis only requires net information
• Inductance analysis requires both nets and terminals

Step-by-Step Guide to Busbar Analysis in Q3D

1. Initial Setup

1. Open ANSYS Electronics Desktop
2. Navigate to File > Open and select your model file or create a new design

2. Defining Nets

1. Right-click on "Nets" in the Project Manager and select "Auto Identify Nets"
2. This will identify all electrically connected components as distinct nets

3. Modifying Material Properties (Optional)

1. Select your component in the model tree
2. In the Properties window, find the Material row and click "Edit"
3. Choose the desired material (e.g., changing from copper to aluminum)
4. Confirm your selection

4. Adding Terminals to Nets

1. Enter Face Selection mode (press F key or right-click > Selection Mode > Faces)
2. Select the desired face where you want to place a terminal
3. Right-click and select Assign Excitation > Source (or Sink)
4. You can assign multiple sources but only one sink per net
5. For faces on the opposite side, you can use the B key (Next Behind) to select faces without rotating the model

5. Setting Up the Analysis

1. Add a Solution Setup by right-clicking on "Analysis" in the Project Manager
2. Select "Add Solution Setup"
3. Set your desired frequency (typical range is from DC to MHz depending on application)
4. Select solution types (Capacitance/Conductance, DC Resistance/Inductance, AC Resistance/Inductance)
5. Click OK to confirm

6. Adding a Frequency Sweep (Optional)

1. Select your setup in the Project Manager
2. Right-click and select "Add Frequency Sweep"
3. Set sweep type to "Interpolating"
4. Define your frequency range (e.g., Log Scale from 1Hz to 1MHz)
5. Click OK to confirm

7. Running the Simulation

1. Right-click "Analysis" and select "Analyze All"
2. Monitor progress in the progress window

8. Viewing and Interpreting Results

1. Right-click "Results" in the Project Manager
2. Select "Create Matrix Report" > "Data Table" or "Rectangular Plot"
3. Choose parameters to display (e.g., DCL Matrix for DC inductance)
4. For frequency-dependent plots, you can change the X-axis to log scale for better visualization

Understanding Inductance Results

When analyzing inductance across frequencies, you'll notice that DC inductance is typically higher than AC inductance. This occurs because:

1. At DC, current flows throughout the cross-section of the conductor
2. At higher frequencies, current concentrates at the surface (skin effect)
3. This surface concentration reduces the effective inductance as frequency increases

Summary

By following this guide, you should be able to effectively analyze busbar designs in Q3D Extractor, extract parasitic parameters, and optimize your designs for your specific application requirements. For more details, check out the associated youtube video below: