Field-Circuit Co-Simulation

Circuit Coupling in EMWORKS

Circuit coupling integrates the 3D electromagnetic field model with an electrical schematic for accurate system-level simulation.

How Coupled Simulation Works

During the solution, two solvers interact continuously:

• Electromagnetic Solver: Computes flux linkage, induced voltage, current distribution, and power losses in the 3D geometry.

• Circuit Solver: Uses these electromagnetic values as port quantities within the schematic. Currents and voltages from the circuit then become boundary conditions for the next electromagnetic calculation.

This exchange creates a two-way interaction, capturing real-world effects like saturation, back-EMF, and non-linear inductance.

Simulation Workflow

• Define 3D EM Model: Assign materials, coil and conductor regions, sources, and boundary conditions to the geometry.

• Assign Circuit Ports: Coils or conductive paths in the 3D geometry are defined as electrical terminals. These terminals exchange voltage and current with the circuit model.

• Build External Circuit: Create the schematic using sources, loads, passive elements, switching devices, and control elements. Connect the electromagnetic ports to the appropriate nodes in the circuit.

• Solve Coupled Problem:

  • Time-Domain: The EM solver and circuit solver exchange values at each time step (Transient analysis).

  • Frequency-Domain: The EM solver provides impedance or port parameters for AC analysis.

• Postprocess Results: Review both circuit and field data simultaneously.

Key Capabilities

• Two-Way Field–Circuit Interaction: Circuit conditions drive the EM model, while EM quantities (like induced voltage) feed back into the circuit.

• Analysis Support: Supports Transient (time-domain) analysis for motors, converters, and switching systems, and Steady-State AC (frequency-domain) analysis for impedance and resonance studies.

• Winding and Port Representation: Coils, conductors, and terminals in the 3D model are represented as electrical ports with defined current and voltage.

• Multiphysics Integration: Circuit coupling can be combined with other studies (motion, thermal, or structural) to analyze fully interacting physical behaviors.

• Typical Applications

  Circuit coupling is required when the electromagnetic device performance depends directly on its connected electrical system:

• Transformers and Inductors: Analysis of magnetizing current, leakage inductance, and core losses under connection to rectifiers or switching circuits.

• Motors and Generators: Study of back-EMF, torque, and transient startup when windings are connected to inverters, drives, or controllers.

• Wireless Power Systems: Simulation of resonant tank circuits and compensation networks linked to transmitter/receiver coils to determine efficiency and sensitivity.

• Inductive Sensors and Sensing Coils: Calculation of output voltage or current from pickup coils and sensing elements based on the electromagnetic field they measure.

Results and Data Output

Coupled simulations provide a complete set of circuit and field results:

• Circuit Quantities: Voltage, current, power flow, losses, and efficiency versus time or frequency.

• Field Quantities: Fields, losses (eddy current, hysteresis, copper), and flux in the electromagnetic model.