Control system for non-resonant microwave dryers

Abstract

The control system monitors the input power to and the output from the dryer applicator, and varies the input power to the applicator as a function of change in applicator efficiency and input power. The control system may consist of a first and a second circuit. The first circuit receives a signal P.sub.in.sbsb.1 from a first monitor and a signal P.sub.out.sbsb.1 from a second monitor. These signals are combined into an efficiency signal .eta..sub.1 to which a reference efficiency signal -.eta..sub.o is added. An amplifier having a predetermined gain K amplifies the resulting signal to produce -K(.eta..sub.1 -.eta..sub.o). The second circuit adds the signals P.sub.in.sbsb.1 from the first monitor, -K(.eta..sub.1 -.eta..sub.o) from the first circuit and P.sub.in.sbsb.o, a signal representative of input power for a reference condition, to produce an output signal I.sub.in.sbsb.1 - [P.sub.in.sbsb.o + K(.eta..sub.1 -.eta..sub.o)] which is coupled to the microwave source to control the input power to the applicator. The reference signal P.sub.in.sbsb.o may be generated by a voltage source as a function of transport speed of the load through the applicator.

Dependencies are inferred from the claim text.