In this blog post, we’ll explore how to design a 3-phase inverter using Ansys Simplorer and couple it with an electromagnetic FEA model in Ansys Maxwell to achieve accurate system-level results.
Ansys Electronics offers a robust ecosystem for multi-domain simulation, enabling seamless integration across various physics domains. Maxwell is used for electromagnetic finite element analysis (FEA), Simplorer (Twin Builder) for system-level inverter and controller design, and Icepak for thermal simulations in electronics.
As an example, we’ll walk through the inverter design process for a 160 kW, 8-pole Permanent Magnet Synchronous Motor (PMSM) using Simplorer. Let’s get started!
There are two common topologies for implementing a 3-phase inverter:
Battery-fed Inverter: Power is delivered from a DC battery to the motor through an inverter—commonly used in electric vehicles.
In this post, we’ll demonstrate how to build both cases in Ansys Simplorer.
Launch Ansys Simplorer within the Electronics Desktop.
2. From the Component Libraries, go to:
3. Drag the Voltage Source block into the workspace. Double-click it, rename it to “Battery,” and set the DC link voltage (e.g., 450 V).
Search for TPRC (Three-Phase Resonance Converter).
Drag and drop it onto the canvas.
Connect the battery to the inverter.
Double-click the inverter block and go to the Output/Display tab. Uncheck signals ctrl11/12/21/22/31/32 to reduce wire clutter.
At this point, your battery is connected to the switching unit. The control signals will be generated later.
Let's connect the 3-phase inverter to an electric motor. In this blog we will show how to couple FEA model, in next blogs we will show how to extract the equivalent circuit of an electric motor to use in Simplorer for faster simulations.
Before proceeding, note the following:
If your windings are set as stranded, Maxwell does not calculate resistance and inductance.
You will need to manually insert:
Resistance = 5 mΩ
Inductance = 5 µH
Use the Component Libraries to add these elements, along with an Ammeter to measure phase currents—this will help with controller feedback.
Note: If your windings are solid (e.g., hairpin type), Maxwell will calculate resistance and inductance automatically, and this step can be skipped.
Open your motor model in Maxwell.
Ensure both Simplorer and Maxwell designs are under the same project.
In Maxwell:
Go to Maxwell 2D > Design Settings > Advanced Product Coupling
Enable Transient–Transient Link
In Simplorer:
Go to Twin Builder > Add Component > Maxwell Component > Add Transient Cosimulation…
Ensure the correct Maxwell project and solution are selected, then click OK.
4. Connect the phase terminals and configure the motor as star-connected (or delta as needed).
To simulate the motor’s motion:
Search V_ROTB in the component library.
Connect it to MotionSetup1_in to provide angular velocity (e.g., 3000 rpm).
Set the initial angle to 7.5°.
To measure rotation:
Add VM_ROTB parallel to the rotation input.
Add FM_ROTB in series if you want to observe torque.
To convert mechanical angle to electrical:
Use:
One SUM block to subtract the 7.5° offset.
One GAIN block to multiply by the number of pole pairs.
One final SUM block for phase correction.
The first summation block is used to correct the initial electrical angle of the motor, which we previously set as 7.5°. To adjust this:
Double-click the block, change the ‘+’ sign to ‘–’ to subtract the offset,
Enter 7.5*PI/180 for Signal 2,
Uncheck "Show Pin" for a cleaner layout.
The Gain block is used to convert the mechanical angle to electrical angle by multiplying it with the number of pole pairs.
The final summation block applies phase inversion, which is required for the Clarke/Park transformation.
Your final configuration should look like the images below.
Since we already have the rotational position of the rotor, we can convert the ABC phase currents to DQ components, which are commonly used in control algorithms.
Ansys Simplorer provides a ready-to-use block for this:
Search for abc2dq in the component library.
Drag it into your circuit workspace and connect it as shown to the phase current signals.
(Tip: You can use pin names instead of wires to keep the diagram visually clean and organized.)
This will enable you to work with DQ currents in your controller design.
To control id and iq currents:
Search PI_ and drag two blocks.
Connect outputs of abc2dq to PI controllers.
You can assign the values as shown below for the d-axis and q-axis PI controllers. In this setup, the input signals for the d and q currents are assigned manually. However, you can further advance the model by implementing a Field-Oriented Control (FOC) algorithm to dynamically predict the current references based on your torque or speed commands, and connect those outputs to the reference inputs of the PI controllers.
Please note that the PI values provided are tuned for this specific motor and inverter combination—you may need to adjust them to suit the parameters of your own system.
To generate switching signals:
Add dq02abc and SVPWM blocks.
Connect them in the following order:
3. In SVPWM:
Uncheck “z” pin and zero input.
Set:
freq = 10,000 Hz
dead_time = 1e-6
v_dc = Vdc_bus (parameter set earlier)
v
Now we have ended the circuit of the 3-phase SVPWM inverter coupled with FEA.
Double-click the TPRC inverter block.
Assign: svpwm1.t1 , svpwm1.t2 and so on for the switching signals.
3. Set analysis parameters:
End Time = 10 ms
Min/Max Step Size = 4 µs
Your simulation setup is now complete and ready to run!
Go ahead and run the simulation. Depending on your step size, solver settings, and model complexity, the simulation may take anywhere from 10 to 60 minutes.
The phase currents for both pure sinusoidal excitation and the inverter-fed excitation are plotted below. As seen from the results, the fundamental magnitudes are identical, confirming that the inverter is functioning correctly and generating the required waveform.
The torque output was also analyzed at 3000 rpm under both excitation methods:
The average torque remains consistent across both simulations.
However, the inverter-fed model exhibits higher torque ripple, with approximately 15% more peak-to-peak variation compared to the pure sinusoidal case.
This increased ripple is due to the harmonic content introduced by the switching behavior of the inverter.
When comparing the core losses between the two excitation scenarios:
The inverter-fed model results in approximately 24% higher core loss than the pure sinusoidal excitation.
This increase can be attributed to the additional high-frequency harmonics generated by the pulse-width modulation (PWM) switching, which elevates local eddy currents and hysteresis effects in the magnetic core.
To model a grid-fed inverter system, we’ll replace the DC battery source with an AC grid input and add a rectification stage.
Remove the DC voltage source (Battery) used in the previous section.
From the Component Library, search for and add a 3-phase AC voltage source.
Then, search for rectifier_6pulse and drag it onto the workspace.
Add a filter capacitor (e.g., 1 mF) between the rectifier output terminals.
Connect the AC source to the rectifier input and the capacitor across the rectifier output.
Add a voltmeter across the capacitor to monitor the DC link voltage.
Rename the measured value to VM1.V and use this as the reference for Vdc_bus in your inverter settings instead of the fixed 450 V.
This setup converts the 3-phase AC input into a smoothed DC voltage that feeds the inverter.
Congratulations! Your inverter is now connected to the grid and ready for simulation.
This blog demonstrated how to build a 3-phase inverter system in Ansys Simplorer and couple it with a detailed electromagnetic model from Ansys Maxwell. The results confirmed that the inverter-fed system performs equivalently in terms of average torque compared to a pure sinusoidal source, while also highlighting important differences in torque ripple and core losses due to PWM switching.
Coupling system-level control and drive circuitry with detailed finite element models is crucial for accurately capturing real-world behaviors, especially in electric motor applications. This workflow not only enables more precise loss and torque analysis but also supports the development of advanced control strategies like FOC (Field-Oriented Control).
Ansys Simplorer and Maxwell offer powerful capabilities for co-simulation, providing a unified environment to evaluate the electrical, magnetic, and control interactions within your design. Whether you're optimizing performance, validating control logic, or exploring thermal and NVH impacts in future stages, this flexible and integrated toolchain ensures you can do it all—efficiently and accurately.
Stay tuned for the next blog, where we’ll show how to extract an equivalent circuit model from Maxwell and use it in Simplorer for faster simulations.
Ozen Engineering Inc. leverages its extensive consulting expertise in CFD, FEA, optics, photonics, and electromagnetic simulations to achieve exceptional results across various engineering projects, addressing complex challenges such as antenna design, signal integrity, electromagnetic interference (EMI), and electric motor analysis using Ansys software.
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