The JMAG alternative for WPT coils.
JMAG-Designer grew up designing motors, and it shows: steel, magnets, motion and loss are where it shines. AirInduct Sim is built for the opposite problem — air-core wireless power coils, with no iron at all — and answers it in seconds in a browser.
Last reviewed: October 2026
What JMAG-Designer does well
JMAG is developed by JSOL Corporation in Japan and has been in development since 1983, when it began as a 3D magnetostatic tool for motors and actuators. Today JMAG-Designer is a standard finite element tool in electric motor teams.
Its strengths follow from that heritage: nonlinear steel and magnets from a large measured material database, lamination iron loss, demagnetisation, rotation and skew, and coupling to drive circuits. JMAG-RT turns a solved machine into a plant model for system simulation. The same machinery serves transformers and reactors, and JSOL publishes WPT application notes on coil arrangement optimisation and on transmission between opposing cores.
Where AirInduct Sim is faster for WPT coils
A motor-centred tool is an odd fit for an air-core coil. Saturation, lamination loss, magnets and motion never appear when there is no iron, yet the air region still has to be meshed finely around thin conductors. AirInduct Sim drops the mesh: closed-form Biot–Savart for the field, the Neumann integral for coupling.
- Eight WPT presets — circular and square Helmholtz, descending-turn (DTC) planar spirals and cross pairs — instead of a rotor-and-stator template set.
- Self-inductance, mutual inductance M and coupling k on every run, with no study or circuit to configure.
- Gap, lateral offset and turn-count sweeps plus a genetic optimizer, solved in seconds rather than as queued FEM cases.
- Runs in a browser or on iOS and Android, without a seat on your motor team's licence.
- An AI Copilot that drives the app and runs the real solver, and an MCP server for agents.
It is free to start: the free plan covers the Helmholtz topology with 3 simulations a month, and AirInduct Pro unlocks every topology, the AI Copilot and unlimited runs (see pricing).
JMAG-Designer vs AirInduct Sim at a glance
A motor-design FEM suite and an air-core coil solver, on the tasks a WPT engineer actually runs.
| Criterion | AirInduct Sim | JMAG-Designer |
|---|---|---|
| Solver method | Closed-form Biot–Savart field + Neumann mutual inductance, no mesh | Finite element method: magnetic field, transient, frequency-response and thermal studies |
| 3D | Full 3D B and H fields, interactive 3D plots | 2D and full 3D models |
| Install | None — runs in the browser, plus iOS and Android apps | Desktop install, Windows and Linux; network licence server |
| Licence / price model | Free plan + Pro subscription | Commercial licence, quote-based; trial version and academic packages on application |
| Time to first result | Seconds from a topology preset | Minutes to hours: geometry, materials, conditions, circuit, mesh, solve |
| WPT outputs (L, M, k) | Self-inductance, mutual inductance M and coupling k on every run | Inductance analysis yields L, M and k; you build the study and the extraction |
| Home turf | Air-core WPT coil pairs | Motors, actuators, transformers and reactors with nonlinear steel and magnets |
| Motion and rotating machines | Not modelled — coils are static | Yes: rotation, translation, skew, magnetisation and demagnetisation |
| Ferrite, cores and eddy currents | Not modelled — air-core coils only | Yes, with a large measured material database and iron-loss models |
| Sweeps and optimisation | Parameter sweeps + genetic optimizer built in | Parametric cases and built-in optimisation tools |
| Export | PDF report, KiCad, DXF, SPICE | Native project files, plant models for circuit simulators (JMAG-RT) |
| AI assistance | AI Copilot that drives the app and runs the real solver; MCP server for agents | Scripting and macros for automating studies |
Competitor details are taken from public vendor pages and documentation, last reviewed October 2026. Product names are trademarks of their respective owners and are used only to identify them. AirInduct is not affiliated with, endorsed by or sponsored by any of these vendors.
When to stay with JMAG-Designer
Stay with JMAG the moment magnetic material enters the design. An EV pad with ferrite bars, opposing cores or a gapped-core transformer are transformer-style problems, and JMAG's material and loss models apply directly. AirInduct Sim does not model ferrite or shields.
It also makes sense when the coil sits inside a motor project — a contactless power feed to a rotor, say — where motion and nearby steel matter and your team already lives in JMAG.
Using AirInduct Sim alongside JMAG
The practical split is air-core first, materials second:
- Choose a preset in AirInduct Sim, then sweep turns, outer radius and offset at your target gap to map M and k.
- Let the genetic optimizer refine it and save the PDF report.
- Export the coil outline as DXF and load it in the JMAG Geometry Editor.
- Run an air-core inductance study first and check it against the report, then add ferrite, shielding and the drive circuit.
See the export formats or how the solver is validated.
Which should I use?
Use AirInduct Sim to size air-core wireless power coils, and JMAG-Designer once the coil meets ferrite, a core or a moving machine. JMAG is a motor-design tool at heart, refined since 1983 for steel, magnets, motion and loss, and those strengths pay off for cored transmitters, reactors and transformers. For a bare copper coil pair, they mostly sit idle while you build a mesh around empty air. AirInduct Sim gives inductance, mutual inductance and coupling in seconds, sweeps gap and offset instantly and runs in a browser, so a WPT side project does not need a seat on your motor team's licence. If your coils stay air-core — research links, implant prototypes, sensor power, teaching — AirInduct Sim may be all you need. If they end up on a ferrite-backed pad, pick the geometry in AirInduct Sim and finish it in JMAG.
Compare with other tools
See all 20 AirInduct Sim alternatives and comparisons →Size the coil before you book the licence.
Frequently asked questions
Can JMAG-Designer simulate wireless power transfer coils?
Yes. JSOL publishes WPT application notes, including coil arrangement optimisation and transmission with opposing cores. The tool is capable; the question is whether a motor-centred FEM workflow is the quickest route for an air-core coil.
Why would a motor engineer use AirInduct Sim instead of JMAG?
When the job is a side project — an air-core charging coil or a sensor link — and you need L, M and k quickly. AirInduct Sim gives those in seconds without a JMAG licence or a mesh.
Is JMAG free for students?
JMAG-Designer is commercial. JSOL offers a trial on application and educational packages for universities, and JMAG-Express Online is a free browser tool for motor sizing, not coils. AirInduct Sim is free to start with the Helmholtz topology and 3 simulations a month.
Can I import an AirInduct Sim coil into JMAG?
Yes, via DXF. The JMAG Geometry Editor reads DXF files, so you can bring in the planar coil outline, add ferrite or a core, and compare the air-core inductance against the PDF report before adding materials.