Heater control

摘要

A method and apparatus are provided for controlling parallel heater elements, the method including the steps of: providing a plurality of electrical heater elements; generating a plurality of temperature signals associated with a plurality of the heater elements; generating a control signal based on one or more temperature signals; providing an alternating current power supply connected to the electrical heater elements through a power transmission system; generating a signal when the voltage of the alternating current power supply passes through ground potential; blocking electrical power to a heater element starting when a zero detection signal is detected an ending when another zero detection signal is detected, for a fraction of the alternating current cycles in a time period, the fraction being a function of the control signal; and transmitting temperature control signals through the power transmission system.