摘要:我国一直是蔬果生产大国，尤其最近几年，随着我国农业产业结构发展及调整步伐的加快，果蔬的生产规模不断扩大。但新鲜水果保质期较短，易于腐烂变质。通过对蔬果的脱水处理可以在保持蔬果原来颜色、形状、口味、营养成分的基础上脱去蔬果中大部分水分，使其便于存储，易于运输，而且能使蔬果具有升值的商业效应。

本次毕业设计对蔬果干燥技术进行了解分析，具体研究了蔬果干燥设备的工艺流程，并在设备中计入PLC控制系统。这里的控制系统主要是为了实现温度、压力、湿度、风速的数据采集，系统故障检测处理，干燥技术的手自动切换，设备的启停等等。蔬果干燥设备的温度控制系统很明显具有滞后性、不对称性以及外界环境和干燥对象的不稳定性，所以本设计既使用了PID控制，又考虑了模糊控制的情况来实现对参数进行快速精确的控制。

关键词：蔬果干燥设备；热风真空组合干燥；PLC；PID控制；模糊控制

Abstract:China has always been a major producer of fruits and vegetables, especially in recent years, with the development of China's agricultural industry and the pace of adjustment to accelerate the scale of fruit and vegetable production continues to expand. But the fresh fruit shelf life is shorter, easy to rot deterioration. Through the dehydration of fruits and vegetables can be preserved in the original color of vegetables and fruits, shape, taste, nutrition, based on the removal of most fruits and vegetables in the water, making it easy to store, easy to transport, and can make fruits and vegetables have the commercial effect of appreciation.

The graduation design of fruit and vegetable drying technology to understand the specific study of the fruits and vegetables drying process, and in the equipment included in the PLC control system. Here the control system is mainly to achieve the temperature, pressure, humidity, wind speed data acquisition, system fault detection and processing, drying technology, automatic switching, equipment, start and stop, and so on. The temperature control system of the fruit and vegetable drying equipment obviously has the hysteresis, the asymmetry and the instability of the external environment and the dry object. Therefore, the design uses the combination of PID control and fuzzy control to form the compound controller to control the parameters quickly and precisely.

Keywords: Vegetable and fruit drying equipment; hot air vacuum combination drying; PLC; PID control; fuzzy control

目录

第一章绪论 1

1.1研究背景和意义 1

1.2蔬果加工自动控制及趋势 1

1.3蔬果干燥控制的研究现状 2

1.4PID温度控制和模糊温度控制 3

1.4.1PID控制的特点 4

1.4.2模糊控制的特点 5

1.5主要研究内容和步骤 5

第二章蔬果干燥设备控制系统方案设计 7

2.1设备工艺图设计 7

2.2设备的组成 7

2.3设备的工作过程 8

2.4蔬果干燥系统控制要求 9

2.5蔬果干燥系统控制方案设计 10

2.5.1系统风速控制设计 10

2.5.2系统湿度控制设计