【作者】 应雪正；

【导师】 王剑平；

【作者基本信息】 浙江大学 ， 农业电气化与自动化， 2006， 硕士

【摘要】 近年来,随着人们对方便、营养和保健食品提出越来越高的要求,许多传统的食品加工方法受到了新兴技术强有力的挑战。就灭菌领域而言,传统的灭菌方法为热灭菌。众所周知,热处理对食品的营养、风味和色泽等外观品质方面有较大损害,还会造成加工过程中的一些问题。因此,寻求低温高效实用的灭菌方法成为广大相关企业的共同心声。因而非热处理正得到人们越来越广泛的关注,非热处理包括添加防腐剂抑制微生物、离心分离去除微生物、辐射处理杀灭微生物等。高压脉冲电场杀菌是一种全新的非热处理杀菌方法,它是利用高强度脉冲电场对食品中的微生物进行杀灭的一种技术,有杀菌时间短、效率高、能耗少等特点。 基于高压脉冲电场的广泛应用前景,本课题研制了一套基于计算机控制的完整的高压脉冲发生器,用来产生脉冲宽度、脉冲个数、脉冲电压强度均可调节的高压脉冲电场,攻克了产生高压脉冲电场的关键技术难题。 本课题的主要研究内容和研究结果如下: 1、综述了国内外利用高压脉冲电场进行灭菌技术的研究进展,并指出了国内外研究所存在的问题。 2、本课题研制的高压脉冲发生器系统由主电路与控制电路二部分所组成。在主电路中,采用全桥式逆变电路能很好地满足基于计算机控制的高压脉冲发生器的设计。同时在逆变电路中采用绝缘门极双极晶体管(IGBT)作为功率器件,其开关速度高,开关和通态时功耗小,饱和压降低,安全工作区宽,无二次击穿现象,高压脉冲形成级采用定压大电流,快前沿、低抖动、长寿命快速IGBT,在设计上留有较大余量,确保运行可靠。 3、在高压脉冲发生器的控制电路中,采用单片机技术,结合液晶屏等友好人机界面设计了电路。同时,采用专用芯片SG3525来产生脉宽调制电路,由IR2110组成的驱动电路来驱动绝缘门极双极晶体管(IGBT)。 4、采用C51语言对下位机进行模块化结构编程,采用Visual C++语言对高压脉冲发器系统的上位机(PC机软件)编程,并实现了与下位机的即时通信功能。更多还原

【Abstract】 With the increasing requirements of convient, nutritious and healthy food, many traditional food processing methods are strongly challenged by new techniques.As far as in the field of sterilization, the traditional method is thermal processing. As we all known, the thermal processing brings great damages to the appearance and quality of food, such as nutrition, favor and color, as well as other processing problems. Therefore, low-temperature, high-effective method is needed. Under this background, non-themal sterilization becomes more widely used, including the adoption of aseptics, deliminating microorganisms by centrifuge and radiate processing. High pulsed electric field is a newly-developed non-themal sterilization method, which utilize high pulsed electric field to sterilize bacterium, with the characteristic of short time, high effective and low energy consume.Owing to the promising application of the HPEF, an integrative high voltage pulsed generator is developed, which provides changeable pulsed width and voltage pulsed intensity, and the key problems of generating high pulsed electric fields are settled as a result.Main contents and results of this thesis are as follows: 1 、 The history of food processing by high pulsed electric field development is reviewed, as well as thecurrent problems. 2、 The high pulse generator system constitutes the main circuit and the control circuit. In the maincircuit, an H-bridge inverter circuit is applied to suffice the design of the high pulse generator.Meanwhile, in the inverter circuit IGBT is adopted as its switch component. Its advantages, such asfast switching and low energy consume, assure the high current and low dithering of high pulsegenerator in the high pulse grade.3 、 In the control system of the high pulse generator, microcomputer alongs with LCD screen are usedto design the friendly man-machine interface. Special chips, such as SG3525 and IR2110 are also used to generate PWM and to drive the IGBT.4、 With C51 language, the system realized the modularization programme, including main program,keysboard scan program, LCD display program, and communication of serials. With the use of Visual C++ language to the high voltage system, the software of PC actualized the communication between PC and the whole system.更多还原