How to select and design magnetic components for industrial AC/DC power supplies and DC/DC converters
Introduction
Industrial switch-mode power supplies (SMPS) must operate 24/7 for 10+ years, withstand wide temperature ranges, and meet stricter EMC and safety standards. At the heart of every industrial SMPS are magnetic components—boost PFC inductors, main transformers, output filter inductors, and EMI filter chokes.
Shaanxi SiRui Technology Co., Ltd. supplies magnetic cores and custom magnetic components for industrial power supply manufacturers.
1. Industrial SMPS Topology Overview
- Single-Phase AC/DC (100W–3kW): Two-stage: PFC + isolated DC/DC. Used for PLC power, instrumentation.
- Three-Phase AC/DC (3kW–30kW+): Large industrial drives, factory automation.
- DC/DC Bus Converters: Distributed power architecture, 48V bus.
2. PFC Boost Inductor
Powder cores (Sendust, High Flux, MPP) dominate PFC inductors. Their distributed air gap handles DC bias without fringing flux loss, low audible noise, and stable inductance across wide current range. Ferrite is cheaper but has gap fringing loss and noise.
3. Main Isolation Transformer
- Flyback (<200W): Simple, cheap, low power auxiliary supplies.
- LLC Resonant (>500W): ZVS, high efficiency, compact. Dominant modern topology.
- Phase-Shifted Full-Bridge (>1kW): High power, ZVS over wide load range.
- Core material: Mn-Zn ferrite (PQ/ER/ETD) most common. Nanocrystalline for premium high-density designs.
4. EMI Filter for Industrial
Industrial equipment must meet EN 61000-6-4 (emission) and EN 61000-6-2 (immunity). Nanocrystalline CMCs are increasingly used for high-performance industrial filters.
5. Reliability Considerations
Industrial SMPS operate -40°C to +70°C ambient with 10+ year lifetime. Design with thermal margin (20–30°C lower than max rating), derate components to 70–80%, and use industrial-grade (not consumer-grade) magnetic cores.
6. Industrial vs Consumer SMPS
| Parameter | Consumer | Industrial |
|---|---|---|
| Lifetime | 3–5 years | 10+ years |
| Temperature Range | 0°C – 40°C | -40°C – 70°C |
| Core Quality | Consumer grade | Industrial grade |
7. Custom Cores from SiRui-Tech
At Shaanxi SiRui Technology Co., Ltd., we supply Sendust powder cores for PFC inductors, Mn-Zn ferrite cores for main transformers, nanocrystalline cores for premium CMCs, and finished inductors for industrial SMPS applications.
Conclusion
Industrial SMPS magnetic design is all about reliability and long lifetime. As industrial automation pushes toward higher efficiency and higher power density, magnetic material selection becomes even more critical.