Abstract: A cooking appliance includes a heating system which is preferably capable of combining radiant, convection, microwave and conduction heating techniques to perform a cooking operation. The cooking appliance includes a convection fan and at least one heating element. A controller is provided to regulate a triac to maintain a desired heater intensity through phase angle firing. Essentially, an AC waveform provided to the heater resistor travels through the triac which is turned on by the controller at predetermined points in the AC waveform, with the delay from a zero point waveform crossing functioning to regulate the amount of power sent to the heater resistor. When the signal from the controller is removed, the triac advantageously turns off at the next zero crossing of the AC waveform such that an operationally and economically effective control system is provided.

Abstract: A cooking appliance includes a heating system which is preferably capable of combining radiant, convection, microwave and conduction heating techniques to perform a cooking operation. The cooking appliance includes a convection fan and at least one heating device. A controller is provided to regulate a triac to create a variable fan speed and variable heater intensity through phase angle firing. Essentially, an AC waveform provided to the fan motor and/or the heater resistor travels through the triac which is turned on by the controller at predetermined points in the AC waveform, with the delay from a zero point waveform crossing functioning to reduce the amount of power sent to the heater resistor and fan motor. When the signal from the controller is removed, the triac advantageously turns off at the next zero crossing of the AC waveform such that an operationally and economically effective control system is provided.