Ethernet interface gives power supply functionality of Arbitrary Waveform

Paul Boughton

Classically, power supplies were always optimised for stability and low ripple. Electronic circuits required these features. Since electronic circuits were introduced in cars there is a demand for unstable voltages again. Electronics in cars experience a deep dip during engine start-up, peaks and dips during switching of loads like lamps and motors, voltage overshoots when the battery fails.

More and more safety sensitive parts ­ ABS, ASR, electric steering and electric braking ­ are powered by the car battery, they have to withstand all combinations of fast and very slow changes in voltage.

Extensive testing of these sensitive parts in a harsh environment has to be carried out.  A power supply, which can simulate any unstable voltage of a car battery, is required (Fig.1).

Theoretically a desired waveform could be generated by programming a power supply by a CPU, unfortunately the communication between a computer and the power supply controller is usually not fast enough to generate high speed transitions.

The new card (Fig. 2) solves this problem by executing the sequence on the interface card. Even stand-alone generation (without computer) is possible, the wave can be started or stopped by a contact or logical signal.

With the PSC-ETH card, the power supply can carry out automation tasks without additional external modules like a PLC, current shunts, etc. Just some wires will do.

The integrated sequencer can be programmed with the simple internal programming language. A programmed step (program line) can set the output voltage, current, a digital output, an interval variable or internal timer. Even conditional jumps to a defined step number are possible, depending on the status of a digital in- or output, or value of output voltage or  output current. This conditional branching makes it possible to create more complex tasks.

Ethernet can be seen as the successor of the IEEE488 industry standard. It allows use of smaller connectors, inexpensive UTP cabling and standard low cost hubs and switches (Fig. 3). Another advantage is that Ethernet suffers less from compatibility problems.

Ethernet makes it possible to use existing local area networks and internet connections.

Enquiry details

Delta Elektronika BV, Zierikzee, Netherlands. www.DeltaPowerSupplies.com

"

Recent Issues