控制技术概论2.ppt

  1. 1、本文档共76页,可阅读全部内容。
  2. 2、有哪些信誉好的足球投注网站(book118)网站文档一经付费(服务费),不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
  3. 3、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。如您付费,意味着您自己接受本站规则且自行承担风险,本站不退款、不进行额外附加服务;查看《如何避免下载的几个坑》。如果您已付费下载过本站文档,您可以点击 这里二次下载
  4. 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“版权申诉”(推荐),也可以打举报电话:400-050-0827(电话支持时间:9:00-18:30)。
查看更多
THE END * 电气信息工程学院自动化教研室 Thermal Systems Modeling of thermal systems by linear differential equations is generally not as common as the other systems since thermal systems tend to be generally nonlinear. However, in order to obtain a first approximation we shall linearize the systems about an appropriate operating point. Often this results in the assumption that the physical system under consideration be characterized by one uniform temperature. The fundamental concept used for deriving the thermal system equation is that the difference of heat coming into and leaving a body is equal to the increase of the thermal energy of the system. The physical properties used are mass, specific heat, thermal capacitance, conductance, and resistance. Temperature is the driving potential and heat is the quantity which flows. Generally, thermal resistance is defined as * 电气信息工程学院自动化教研室 Where is the temperature difference and q the heat flow. Depending upon the system, R may include the contributions of thermal conduction, convection, and radiation. The thermal capacitance C is the product of mass and specific heat and Consider a mass m dropped into an oil bath at temperature .we shall assume that the temperature is uniform inside the mass at any given time and also that the oil bath temperature is constant. The heat entering the mass from the oil at any time is Thermal Systems * 电气信息工程学院自动化教研室 Where is the temperature of the mass. Here R=1/ hA where A is the surface area of mass in contact with the oil and h is the heat transfer coefficient due to convection. This heat entering the mass goes to increase the heat content (or internal energy) of the system, i.e. Equating Eq. (2-16) to Eq. (2-17) we have Defining we obtain Which is a first-order differential equation. For obtaining the transfer function we assume that the initial temperature of the mass is . Letting , Laplace

文档评论(0)

heroliuguan + 关注
实名认证
内容提供者

该用户很懒,什么也没介绍

版权声明书
用户编号:8073070133000003

1亿VIP精品文档

相关文档