Hi @Ali,
Thank you for your detailed question about implementing the dual three-phase PMSM using the Motor-CAD import example. I understand you're looking to adapt the custom Simscape block from the six-phase machine example to work in motor mode with your Ansys Maxwell flux linkage LUTs. Let me address each of your concerns systematically.
Direct Usage as Motor vs. Generator
Yes, you can use the custom block directly as a motor without modifying the core equations. The fundamental electromagnetic relationships in the custom Simscape component are inherently bidirectional. The key difference between motor and generator operation lies in the energy flow direction and boundary conditions, not in the underlying flux linkage equations. Here's what you need to understand about the implementation:
Energy Flow Direction The custom block uses flux linkage tables (lambda= f(i,theta)) to compute electromagnetic torque and back-EMF. These relationships are physically bidirectional:
- Motor mode: Electrical power flows in → Mechanical power flows out
- Generator mode: Mechanical power flows in → Electrical power flows out
The block automatically handles this based on your simulation setup - specifically how you connect voltage sources and mechanical loads.
Practical Implementation Steps
1. Boundary Condition Changes Instead of modifying the block internals, simply change your simulation boundary conditions:
For Motor Operation: * Apply voltage inputs to the electrical terminals (rather than mechanical torque/speed) * Connect mechanical load to the shaft output * The block will naturally compute currents based on applied voltages and back-EMF
Current Generator Setup (from example): * Mechanical input drives the shaft * Electrical terminals see the generated voltages
2. Using Your Maxwell Flux Linkage Data The custom block expects flux linkage LUTs as functions of current and position angle - exactly what you have from Maxwell. You'll need to: * Replace the Motor-CAD flux linkage tables with your Maxwell data * Ensure your LUT format matches: lambda_abc = f(i_abc, theta_mech) * Verify the coordinate transformations align with your Maxwell model reference frame * Check units consistency (Wb-turns vs Wb, degrees vs radians)
3. Sign Conventions and Coordinate Systems Pay attention to the sign conventions in the custom block: * Positive torque typically indicates motor operation (counterclockwise when viewed from shaft end) * Current directions should be consistent with your Maxwell simulation setup * The mechanical angle reference should match between Maxwell and the Simscape implementation * Ensure phase sequence (ABC) matches your Maxwell model
Core Equations Remain Unchanged The fundamental equations in the custom block don't need modification because they represent physical relationships:
% Flux linkage from LUTs lambda = f(i, theta)
% Electromagnetic torque T_em = d(lambda)/d(theta) * i
% Voltage equation v = R*i + d(lambda)/dt
These equations are valid for both motor and generator modes - the sign of power flow determines the operating mode.
Recommended Implementation Approach
Phase 1: Direct Adaptation 1. Start with the existing custom block - don't modify the core equations initially 2. Replace the flux linkage data with your Maxwell LUTs 3. Change boundary conditions: Apply voltages instead of mechanical inputs 4. Run open-loop tests with simple voltage inputs
Phase 2: Validation Strategy To verify your motor operation is working correctly: * Compare no-load characteristics: Run the motor unloaded and compare speed vs. voltage relationship with Maxwell predictions * Validate torque production: Apply known load and verify steady-state torque matches Maxwell FEA results * Check flux linkage consistency: Monitor internal flux linkage values and compare with your Maxwell LUTs * Verify power balance: Ensure electrical input power = mechanical output power + losses
Phase 3: Control Integration Once validated, integrate with motor control: * The electrical terminals interface directly with voltage-source inverters * Current feedback is available for closed-loop control * Position/speed sensors connect to mechanical ports
Common Pitfalls to Avoid Data Format Issues * LUT extrapolation: Ensure your Maxwell LUTs cover the full operating range (current and angle) * Interpolation artifacts: Check for smooth transitions, especially near zero current * Saturation modeling: Verify high-current behavior matches Maxwell results
Simulation Setup * Initial conditions: Set realistic initial rotor position and flux linkage states * Solver selection: Use variable-step solvers for better accuracy during transients * Numerical conditioning: Watch for solver warnings related to flux linkage derivatives
Performance Considerations * Computational load: * Motor mode typically requires more iterations than generator mode due to voltage-driven operation * *Convergence: Start with lower bandwidth control to ensure stable operation
Dual Wye Configuration Specifics
Since you're working with dual three-phase windings: * Ensure your Maxwell flux linkage data accounts for both three-phase sets * The 30-degree phase shift between winding sets should be properly represented in your LUTs * Consider mutual coupling between the two three-phase systems if significant
Additional Recommendations
Control System Integration For typical motor drive applications, you'll want to: * Implement current controllers (PI or predictive) * Add flux-weakening capability for high-speed operation * Consider space vector modulation for the six-phase configuration
Model Validation Checklist
Before deploying in your main application: * No-load speed-voltage characteristic matches expectations * Torque-current relationship validated against Maxwell * Efficiency map reasonable compared to FEA predictions * Dynamic response (step torque/speed) behaves physically * Thermal behavior consistent (if included in model)
I recommend starting with the direct approach (changing boundary conditions only) and validate against a simple test case first. Begin with a basic R-L load to verify electrical behavior, then progress to mechanical loading.
The MathWorks development team designed this custom block architecture specifically to handle both operating modes seamlessly. Your Maxwell flux linkage data should integrate well with the existing framework.
Also, consider sharing your results with the motor drive community once you have a working implementation. Dual three-phase PMSM applications are growing, and your Maxwell-to-Simscape workflow could benefit other engineers facing similar challenges.
P.S. If you're planning to use this for real-time applications later, keep in mind the LUT size and interpolation requirements for code generation compatibility.
References
Import a Dual Three-Phase PMSM from Motor-CAD (Referenced example) https://www.mathworks.com/help/sps/ug/import-fem-motorcad-six_phase.html
