Industrial power supplies need to fulfill special requirements, such as low losses (to reduce efforts on cabinet cooling), high power density (to reduce space requirements), but also high reliability and ruggedness, along with features not commonly found in standard power supplies such as easy paralleling, remote control, and certain overload and protection features. At the same time, the EMI and stability requirements are more stringent than in other applications.
This picture shows the inside of a cabinet, with power supplies and control circuits mounted on standardized rails, as well as the high- and low power wiring to connect to the machines to be controlled. Siemens AG 2008, Alle Rechte vorbehalten
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And, with the new EuP guidelines coming up, additional requirements are coming up that impact the design of these power supplies. The main improvements must include reduced component count, weight, and size, as well as efficiency across the whole output power range and low standby consumption.
In this article, a design example of a 400W power supply is being analyzed in detail, showing the use of power supply modules for both the primary and secondary side, as well as other ways of improving the performance. Beyond all improvements on the electrical side, the identical form factor of the modules allows for a very elegant and compact mechanical design, as well as a reduction of mounting and logistics cost. The fact that both modules are available in different power ratings does significantly shorten the time-to-market, should a different output power requirement come up.
This diagram shows the different stages of a industrial power supply, indicating the main characteristics each stage impacts.
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