IL126195A - Room temperature control apparatus - Google Patents

Room temperature control apparatus

Info

Publication number
IL126195A
IL126195A IL12619598A IL12619598A IL126195A IL 126195 A IL126195 A IL 126195A IL 12619598 A IL12619598 A IL 12619598A IL 12619598 A IL12619598 A IL 12619598A IL 126195 A IL126195 A IL 126195A
Authority
IL
Israel
Prior art keywords
air
room
temperature
flow rate
set point
Prior art date
Application number
IL12619598A
Other languages
English (en)
Other versions
IL126195A0 (en
Original Assignee
Siemens Building Tech Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Building Tech Ag filed Critical Siemens Building Tech Ag
Publication of IL126195A0 publication Critical patent/IL126195A0/xx
Publication of IL126195A publication Critical patent/IL126195A/en

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/62Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
    • F24F11/63Electronic processing
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/30Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/62Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/70Control systems characterised by their outputs; Constructional details thereof
    • F24F11/80Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
    • F24F11/83Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers
    • F24F11/84Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air by controlling the supply of heat-exchange fluids to heat-exchangers using valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/89Arrangement or mounting of control or safety devices
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/08Air-flow control members, e.g. louvres, grilles, flaps or guide plates
    • F24F13/10Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B11/00Automatic controllers
    • G05B11/01Automatic controllers electric
    • G05B11/36Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
    • G05B11/42Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/048Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators using a predictor
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B17/00Systems involving the use of models or simulators of said systems
    • G05B17/02Systems involving the use of models or simulators of said systems electric
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D23/00Control of temperature
    • G05D23/19Control of temperature characterised by the use of electric means
    • G05D23/1919Control of temperature characterised by the use of electric means characterised by the type of controller
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/0001Control or safety arrangements for ventilation
    • F24F2011/0002Control or safety arrangements for ventilation for admittance of outside air
    • F24F2011/0005Control or safety arrangements for ventilation for admittance of outside air to create underpressure in a room, keeping contamination inside

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • General Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • Signal Processing (AREA)
  • Medical Informatics (AREA)
  • Software Systems (AREA)
  • Health & Medical Sciences (AREA)
  • Evolutionary Computation (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
  • Artificial Intelligence (AREA)
  • Air Conditioning Control Device (AREA)
  • Control Of Temperature (AREA)
  • Feedback Control In General (AREA)
IL12619598A 1997-11-07 1998-09-14 Room temperature control apparatus IL126195A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US08/965,961 US6095426A (en) 1997-11-07 1997-11-07 Room temperature control apparatus having feedforward and feedback control and method

Publications (2)

Publication Number Publication Date
IL126195A0 IL126195A0 (en) 1999-05-09
IL126195A true IL126195A (en) 2001-12-23

Family

ID=25510736

Family Applications (1)

Application Number Title Priority Date Filing Date
IL12619598A IL126195A (en) 1997-11-07 1998-09-14 Room temperature control apparatus

Country Status (10)

Country Link
US (1) US6095426A (zh)
EP (1) EP0915301A3 (zh)
JP (1) JPH11224128A (zh)
KR (1) KR19990045075A (zh)
CN (1) CN1111684C (zh)
AU (1) AU742722B2 (zh)
CA (1) CA2237277C (zh)
IL (1) IL126195A (zh)
NZ (1) NZ331833A (zh)
TW (1) TW367400B (zh)

Families Citing this family (74)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19654955C2 (de) * 1996-12-27 2000-11-16 Albert Bauer Klimatisierungsvorrichtung
JP2000111176A (ja) * 1998-10-05 2000-04-18 Toyota Autom Loom Works Ltd 空調装置
EP1013488A1 (de) * 1998-12-24 2000-06-28 DaimlerChrysler AG Verfahren zur Regelungen einer Heiz- und/oder Klimaanlage
DE59913911D1 (de) * 1999-08-02 2006-11-23 Siemens Schweiz Ag Prädikative Einrichtung zum Regeln oder Steuern von Versorgungsgrössen
WO2002089385A2 (en) * 2001-04-30 2002-11-07 Emerson Retail Services Inc. Building system performance analysis
US7117045B2 (en) * 2001-09-08 2006-10-03 Colorado State University Research Foundation Combined proportional plus integral (PI) and neural network (nN) controller
US20030171851A1 (en) * 2002-03-08 2003-09-11 Peter J. Brickfield Automatic energy management and energy consumption reduction, especially in commercial and multi-building systems
US8463441B2 (en) 2002-12-09 2013-06-11 Hudson Technologies, Inc. Method and apparatus for optimizing refrigeration systems
US6851620B2 (en) * 2003-04-30 2005-02-08 Invensys Building Systems, Inc. Floating actuator control system and method
US6988671B2 (en) * 2003-05-05 2006-01-24 Lux Products Corporation Programmable thermostat incorporating air quality protection
US7243004B2 (en) * 2004-01-07 2007-07-10 Carrier Corporation Self-configuring controls for heating, ventilating and air conditioning systems
US7036743B2 (en) * 2004-01-20 2006-05-02 Carrier Corporation Continuous fan control in a multi-zone HVAC system
US7502768B2 (en) * 2004-02-27 2009-03-10 Siemens Building Technologies, Inc. System and method for predicting building thermal loads
FR2866945B1 (fr) * 2004-03-01 2006-05-19 Florence Tantot Systeme et procede de commande d'equipements de conditionnement d'ambiance dans une enceinte
LU91175B1 (fr) * 2005-06-13 2006-12-14 Airflowcontrol S A Procédé et système d'économie d'énergie dans un bâtiment avec ascenseur
US7894943B2 (en) 2005-06-30 2011-02-22 Sloup Charles J Real-time global optimization of building setpoints and sequence of operation
EP1984679B1 (en) * 2006-01-20 2014-04-16 Carrier Corporation Electronic indoor air quality board for air conditioner controller
US7685802B2 (en) * 2006-12-19 2010-03-30 General Electric Company Methods and apparatus to facilitate gas turbine fuel control
KR20080072400A (ko) * 2007-02-02 2008-08-06 삼성전자주식회사 공기조화기 시스템 및 그 프로그램 갱신방법
US20080277486A1 (en) * 2007-05-09 2008-11-13 Johnson Controls Technology Company HVAC control system and method
US20090065596A1 (en) * 2007-05-09 2009-03-12 Johnson Controls Technology Company Systems and methods for increasing building space comfort using wireless devices
US20090045939A1 (en) * 2007-07-31 2009-02-19 Johnson Controls Technology Company Locating devices using wireless communications
US8543244B2 (en) * 2008-12-19 2013-09-24 Oliver Joe Keeling Heating and cooling control methods and systems
US8880227B2 (en) * 2010-05-27 2014-11-04 Applied Materials, Inc. Component temperature control by coolant flow control and heater duty cycle control
JP5629189B2 (ja) * 2010-11-16 2014-11-19 アズビル株式会社 制御装置および方法
JP5695492B2 (ja) * 2011-05-11 2015-04-08 アズビル株式会社 空調制御装置および方法
CN102853500A (zh) * 2011-06-29 2013-01-02 科汇工业有限公司 一种多区域恒温控制器及冷暖气通风系统
JP5903731B2 (ja) * 2011-10-27 2016-04-13 株式会社インティ 建物用空調熱源システム
WO2013151646A2 (en) * 2012-04-05 2013-10-10 Carrier Corporation Hvac system relay autotuning and verification
US9002532B2 (en) 2012-06-26 2015-04-07 Johnson Controls Technology Company Systems and methods for controlling a chiller plant for a building
US9534795B2 (en) * 2012-10-05 2017-01-03 Schneider Electric Buildings, Llc Advanced valve actuator with remote location flow reset
JP6022335B2 (ja) * 2012-12-13 2016-11-09 株式会社日立製作所 海洋深層水利用空調システム
US10653044B2 (en) * 2013-01-10 2020-05-12 International Business Machines Corporation Energy efficiency based control for a cooling system
WO2014137968A2 (en) 2013-03-04 2014-09-12 Johnson Controls Technology Company A modular liquid based heating and cooling system
US9797619B2 (en) * 2013-03-15 2017-10-24 Honeywell International Inc. Temperature compensation system for an electronic device
DE102013207449A1 (de) * 2013-04-24 2014-10-30 Dürr Systems GmbH Verfahren zum Konditionieren von Luft und Konditionieranlage
TWI551830B (zh) 2013-12-12 2016-10-01 財團法人工業技術研究院 用於暖通空調系統之控制裝置及其方法
US9777937B2 (en) * 2014-04-22 2017-10-03 Honeywell International Inc. Controller and loop performance monitoring in a heating, ventilating, and air conditioning system
US9193273B1 (en) * 2014-06-15 2015-11-24 Efficient Drivetrains, Inc. Vehicle with AC-to-DC inverter system for vehicle-to-grid power integration
CN104102139B (zh) * 2014-07-17 2017-02-15 杭州源牌科技股份有限公司 一种变风量空调控制系统的仿真平台
CN104216288B (zh) * 2014-08-28 2017-06-13 广东电网公司电力科学研究院 火电厂双入双出系统的增益自调度pid控制器
JP6405233B2 (ja) * 2014-12-26 2018-10-17 アズビル株式会社 監視装置および監視方法
US10684030B2 (en) 2015-03-05 2020-06-16 Honeywell International Inc. Wireless actuator service
US9851727B2 (en) 2015-05-28 2017-12-26 Carrier Corporation Coordinated control of HVAC system using aggregated system demand
US10839302B2 (en) 2015-11-24 2020-11-17 The Research Foundation For The State University Of New York Approximate value iteration with complex returns by bounding
EP3200041A1 (en) * 2016-01-20 2017-08-02 Danfoss A/S Commisioning flow system with flow verification procedure
US9582754B1 (en) 2016-05-17 2017-02-28 Roger Collins Adaptive feed forward method for temperature control
US9953474B2 (en) 2016-09-02 2018-04-24 Honeywell International Inc. Multi-level security mechanism for accessing a panel
CN110234933B (zh) * 2016-11-22 2021-10-26 贝利莫控股公司 液体循环系统及用于操作此液体循环系统的方法
CN106777711B (zh) * 2016-12-22 2019-09-17 石家庄国祥运输设备有限公司 建立车载变风量空调系统风量预测模型的方法
US11384951B2 (en) * 2017-06-14 2022-07-12 Joseph A. Ross Zoning system for air conditioning (HVAC) equipment
US12018851B2 (en) * 2017-07-26 2024-06-25 Belimo Holding Ag Method and system for controlling a valve in an HVAC system
CN107817681B (zh) * 2017-10-16 2020-04-24 清华大学 一种基于双侧等效模型的热网稳态运行状态估计方法
US10838441B2 (en) 2017-11-28 2020-11-17 Johnson Controls Technology Company Multistage HVAC system with modulating device demand control
US10838440B2 (en) 2017-11-28 2020-11-17 Johnson Controls Technology Company Multistage HVAC system with discrete device selection prioritization
US12078367B2 (en) * 2017-11-30 2024-09-03 Tyco Fire & Security Gmbh HVAC system with waterside and airside disturbance rejection
CN110469926B (zh) * 2018-05-11 2022-05-24 开利公司 用于空调系统的水循环系统及其控制方法
US10767887B2 (en) * 2018-05-16 2020-09-08 Mitsubishi Electric Research Laboratories, Inc. System and method for thermal comfort control
CN109255490B (zh) * 2018-09-28 2022-03-22 西安建筑科技大学 一种基于kpca-bas-grnn的埋地管道外腐蚀速率预测方法
US12007732B2 (en) 2019-07-12 2024-06-11 Johnson Controls Tyco IP Holdings LLP HVAC system with building infection control
US11960261B2 (en) 2019-07-12 2024-04-16 Johnson Controls Tyco IP Holdings LLP HVAC system with sustainability and emissions controls
US11761660B2 (en) * 2019-01-30 2023-09-19 Johnson Controls Tyco IP Holdings LLP Building control system with feedback and feedforward total energy flow compensation
US10789800B1 (en) 2019-05-24 2020-09-29 Ademco Inc. Systems and methods for authorizing transmission of commands and signals to an access control device or a control panel device
US10832509B1 (en) 2019-05-24 2020-11-10 Ademco Inc. Systems and methods of a doorbell device initiating a state change of an access control device and/or a control panel responsive to two-factor authentication
US11714393B2 (en) 2019-07-12 2023-08-01 Johnson Controls Tyco IP Holdings LLP Building control system with load curtailment optimization
US11274842B2 (en) 2019-07-12 2022-03-15 Johnson Controls Tyco IP Holdings LLP Systems and methods for optimizing ventilation, filtration, and conditioning schemes for buildings
CN110940095B (zh) * 2019-10-31 2021-08-10 箭牌家居集团股份有限公司 一种恒温控制方法及系统
CN112378111B (zh) * 2020-08-31 2021-11-02 中国科学院紫金山天文台 基于CRC-GL7制冷器的300mK吸附制冷自动降温优化控制方法
CN113091333B (zh) * 2021-03-26 2022-03-22 西安交通大学 一种塔式光热电站吸热器流量前馈-反馈控制方法
CN113760002B (zh) * 2021-09-01 2022-07-15 南京富岛信息工程有限公司 用于近红外光谱分析的重油预热装置及方法
CN113757833B (zh) * 2021-09-14 2022-04-08 北京联合大学 基于数据驱动的生产模式与值班模式切换方法及系统
CN113945001B (zh) * 2021-11-04 2023-04-07 中通服咨询设计研究院有限公司 一种大型场馆变风量空调系统节能控制方法
US20230314030A1 (en) * 2022-03-30 2023-10-05 Johnson Controls Tyco IP Holdings LLP Critical environment feedforward-feedback control system with room pressure and temperature control
CN114636212B (zh) * 2022-04-22 2024-01-30 苏州思萃融合基建技术研究所有限公司 一种基于grnn的多台冷水机组系统运行控制方法

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4817864A (en) * 1986-08-28 1989-04-04 Honeywell Inc. Temperature compensation for vav system
US5541833A (en) * 1987-03-30 1996-07-30 The Foxboro Company Multivariable feedforward adaptive controller
US5090303A (en) * 1990-09-28 1992-02-25 Landis & Gyr Powers, Inc. Laboratory fume hood control apparatus having improved safety considerations
US5092227B1 (en) * 1990-09-28 1995-02-14 Landis & Gyr Powers Inc Apparatus for controlling the ventilation of laboratory fume hoods
US5385505A (en) * 1993-07-02 1995-01-31 Phoenix Controls Corporation Pressure maintenance system for substantially sealed space
US5810657A (en) * 1994-11-22 1998-09-22 Lighthouse Associates, Inc. Controller to maintain a certain set of environmental parameters in an environment
US5579993A (en) * 1995-01-06 1996-12-03 Landis & Gyr Powers, Inc. HVAC distribution system identification
US5573181A (en) * 1995-01-06 1996-11-12 Landis & Gyr Powers, Inc. Global control of HVAC distribution system

Also Published As

Publication number Publication date
AU742722B2 (en) 2002-01-10
CN1224823A (zh) 1999-08-04
JPH11224128A (ja) 1999-08-17
CA2237277C (en) 2001-07-24
US6095426A (en) 2000-08-01
CN1111684C (zh) 2003-06-18
TW367400B (en) 1999-08-21
IL126195A0 (en) 1999-05-09
CA2237277A1 (en) 1999-05-07
KR19990045075A (ko) 1999-06-25
EP0915301A3 (en) 2002-05-15
NZ331833A (en) 2000-01-28
EP0915301A2 (en) 1999-05-12
AU8932598A (en) 1999-05-27

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