MAS

A vendor-neutral data model for describing magnetic components used in power electronics: their design requirements, physical construction, and computed performance. MAS is incubated at OpenMagnetics and is being prepared for transfer to the PSMA Magnetics Committee for further stewardship.

Status

Aspect	Value
Specification version	pre-1.0, see CHANGELOG.md
Schema dialect	JSON Schema draft 2020-12
Stewardship	OpenMagnetics maintainers (incubation phase)
Roadmap	OpenMagnetics → proposed PSMA Magnetics Committee Working Group. See GOVERNANCE.md.
License	Apache-2.0 (see LICENSE.md)
Open work items	numbered RFCs under proposals/

Scope

MAS describes magnetic components used in power-electronic converters: transformers, inductors, chokes, current transformers and the operating points and outputs associated with them. A MAS document has three top-level parts:

Part	What it describes
inputs	Design requirements and operating conditions — what the magnetic must do.
magnetic	Physical construction — core, coil, materials, gaps, insulation, bobbin.
outputs	Computed results — core and winding losses, inductance, temperature rise, stray capacitance, insulation coordination.

In scope:

• Cores: ferrite, powder, amorphous, nanocrystalline; ungapped and gapped.
• Coils: single and multi-winding, round / rectangular / foil / planar / litz wires.
• Insulation: temperature classes, dielectric strength, creepage, reinforced and double insulation per IEC 62368-1 / IEC 61558.
• Twenty-five converter topologies, from buck and boost through LLC, CLLC, dual-active-bridge, push-pull and PFC.

Out of scope:

• PCB layout and routing (covered by IPC formats).
• Thermal-management hardware beyond the magnetic itself.
• Rotating machines (motor / generator construction).

Normative references

MAS defers to existing international standards wherever possible. docs/normative-references.md is the master mapping. Highlights:

• Core shapes: IEC 62317 series, IEC 63093 series.
• Effective parameters Aₑ, lₑ, Vₑ, C₁: IEC 60205.
• Core terminology and nomenclature: IEC 60401-1 / -3.
• Wire enamel grades: IEC 60317 series; NEMA MW 1000 (US-market).
• Conductor sizes: IEC 60228 (metric), ASTM B258 (AWG).
• Insulation thermal classes: IEC 60085.
• Comparative Tracking Index: IEC 60112.
• Insulation coordination (clearance, creepage): IEC 60664-1.
• Vocabulary: IEC 60050-151 (electrical and magnetic devices), IEC 60050-221 (magnetic materials and components). Verbatim definitions reproduced in docs/normative-references.md §6b.
• Test methods: IEC 60205, IEC 61007, IEC 62044, IEEE Std 393.
• Identifier registries: ISO/IEC 11179-6 (IRDI), IEC 61360-4 / IEC CDD.

Where no standard exists — power-electronics ferrite grade nomenclature (N87, 3C95, …), powder-core alloy families (MPP, High Flux, Kool Mµ), litz wire construction — MAS encodes the data pragmatically. See docs/normative-references.md "Standardisation gaps".

Units and vocabulary

docs/units.md is the normative units table. All numeric fields carry SI units fixed by that document; values are bare numbers, not {value, unit} objects. Highlights: frequency in Hz, length in metres, temperature in degrees Celsius (per ISO 80000-5, which permits °C alongside K and recommends °C for everyday temperatures), magnetic flux density in tesla.

Vocabulary follows IEV 60050-151 and 60050-221. Each MAS field description that introduces a domain term cites the relevant IEV reference number.

Reference implementation

The MAS.hpp header is a C++ reference binding generated from the schemas via quicktype and consumed by the OpenMagnetics MKF library and its Python bindings (PyMKF). Conforming implementations need not use this binding — they need only consume MAS documents that validate against schemas/MAS.json. Build instructions for the reference implementation are in BUILD.md.

Reading the schema

• docs/quickref.md — at-a-glance index of every field.
• docs/schema.md — guided tour of the schema hierarchy.
• docs/inputs.md — detailed walk-through of the inputs section.
• docs/magnetic.md — detailed walk-through of the magnetic section.
• docs/units.md — normative units table.
• docs/glossary.md — definitions of every term used in MAS, with IEC/IEV citations.
• docs/normative-references.md — mapping of every MAS area to the standards it defers to.

Examples

Eight complete MAS documents under samples/complete/ cover buck, boost, flyback, forward (single-switch / two-switch / active-clamp), push-pull, isolated buck, isolated buck-boost and current transformer designs. Each one validates against schemas/MAS.json.

A bundled component database under data/ contains 410+ ferrite and powder materials, 300+ standard core shapes, 4 350+ wires and 300+ bobbins, all referenced by name from MAS documents.

Governance and contributing

• GOVERNANCE.md — stewardship roadmap, decision rules, IPR.
• CONTRIBUTING.md — DCO sign-off, PR checklist, schema conventions.
• MAINTAINERS.md — current maintainers.
• SECURITY.md — how to report security or IPR concerns.
• proposals/ — RFCs for non-trivial changes.

The project follows Semantic Versioning. Pre-1.0 minor breaks are permitted but flagged in CHANGELOG.md; from 1.0 onward, breaking changes require a MAJOR bump and a documented migration path.

License

Apache-2.0. See LICENSE.md. Each schema file carries an SPDX header. The patent grant in §3 of the licence is intended to keep the specification clear of IPR encumbrance for downstream users.

History

MAS began at OpenMagnetics as a working data model for an inductor-design tool. As coverage grew it became useful as a standalone specification, independent of any one tool. Transfer to the PSMA Magnetics Committee is the next step. The schema lives openly on GitHub under Apache-2.0.