In order to solve the problem of nonuniformity of material drying caused by difference of heating plate and disturbance of air flow in vacuum pulse drying, a hardware circuit for controlling radiation intensity of heating plate based on zerocrossing trigger control was designed. The control circuit was designed as daisychaining connection mode to facilitate installation and expansion. Combining the theory of PID control with outlier detection method in data mining technology, an integral separation PID control strategy for temperature outlier optimization of heating plate was proposed. The control effect of the control system was validated by using the uniform moisture content of the patches as the test material and the uniformity of drying as the evaluation index. The experimental results show that the control system can effectively reduce the difference of radiation intensity between different heating plates. The average temperature control accuracy was ±0.8℃ and the initial transient time was 120s. The surface temperature of heating plate can recover quickly after disturbed by air flow disturbance. In terms of drying uniformity, the outlier optimization integral separation PID control was superior to the heating plate independent PID control and the heating plates whole PID control. It can reduce the influence of air disturbance on drying uniformity and improve the drying uniformity of the patches from 90% to more than 95%.
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薛令阳,王书茂,MUJUMDAR A S,王军,于贤龙,高振江.基于干燥均匀性的真空脉动干燥加热控制技术[J].农业机械学报,2019,50(4):317-325.