Background: In the manufacture of semiconductors, certain products are subjected to Rapid Temperature Processing or RTP. The heat source for this technique is typically an array of very high power quartz halogen lamps. Each array consists of up to 12 groups of lamps at about 12-15 kilowatts per group. The process requires the temperature of each lamp group to be cycled from minimum to maximum or any point in between with great speed and accuracy.

Project: The project was to design and build a power supply to convert 240 volt AC 3 phase power to 12 outputs, each with independently variable output voltage from zero to 200 volts at a current of 60 amps per channel. Multiple phase firing circuits operating on the same AC line often suffer from severe crosstalk as the firing of one circuit causes jitter in the timing of another. The specification of this product requires 1% linearity, so jitter cannot be tolerated. Product Resources' engineers developed new phase control techniques using phase lock loop technology and digitally timed, optically isolated gate firing circuits to produce a rock solid system.

The 12-Channel Power Supply interfaces directly with a process control computer. Feedback includes true RMS voltage and current signals. Each output is current limited to prevent overstressing the lamp filaments during rapid increases in temperature.

The technology used in this product is suitable for any application which requires accurate control of multi-kilowatt electrical loads from a 3 phase AC line.

Technologies: phase fired SCR control, phase lock loop (PLL), photonics, RMS to DC signal conversion, high power semiconductor heatsinks, computer control interface, sheetmetal, plated copper bussbars

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