《单片机控温系统英文文献》由会员分享，可在线阅读，更多相关《单片机控温系统英文文献（4页珍藏版）》请在金锄头文库上搜索。
1、 0020-4412/02/4503-$27.00 2002 AIK “Nauka /Interperiodica”0408 Instruments and Experimental Techniques, Vol. 45, No. 3, 2002, pp. 408411. Translated from Pribory i Tekhnika Eksperimenta, No. 3, 2002, pp. 127130. Original Russian Text Copyright 2002 by Teplov, Anisimov. This work describes a thermost
2、atting system for a temperature range of 20 to +70 C with a universal control circuit based on a single-chip microcomputer. To cool and heat a heat carrier, thermoelectric modules based on the Peltier effect are used 1, 2. The described liquid thermostatting system is developed for a NMR relaxometer
3、diffusometer but can be used to control temperatures of any volume-comparable objects almost without modifi cations. As applied to the NMR setup, the block diagram of the system is shown in Fig. 1. The temperature-controlled object is an ampoule with the studied sample 1 placed into the sens or of t
4、he RF spectrometer between the poles of magnet 2 . The temperature of the ampoule is controlled by the liquid heat carrier circulating in a closed sealed contour. The sealed liquid contour of the thermostatting system con- sists of thermojacket 3 surrounding the ampoule with the sample and a thermou
5、nit (designated in Fig. 1 by a dotted frame), which contains the electric heater 4 , thermoelements based on the Peltier effect 5 , pump 6 , heat-carrier-volume variation compensator 7 , and con- necting pipes 8 . The electronic section of the system consists of a thermal converter 9 , personal comp
6、uter 10 being the part of the NMR setup and controlling the operation of its units 11 , and control and interface circuits 12 based on a single-chip microcomputer (SCM). In the process of the operation, the SCM of the unit 12 calculates the optimum power of the heater and cooler from the cur- rent t
7、emperature data obtained from the thermal con- verter 9 placed near the sample in the NMR sensor. The heater 4 together with the Peltier-effect-based thermoelements 5 heats the heat carrier, while, in the cooling mode, the electric heater automatically turns off, and the Peltier-effect-based thermoe
8、lements con- nected in the opposite polarity cool the heat carrier. The design versions of the thermounit and thermojacket are described in 3, 4. It is rather important that, due to the programmed control used in the described thermostatting system, the temperature measurement and stabilization poin
9、t and heat carrier heatingcooling place can be separated by signifi cant distances (in this case, the distance is 250 300 mm). This is sometimes necessary, for example, for LABORATORY TECHNIQUES Thermostatting System Using a Single-Chip Microcomputer and Thermoelectric Modules Based on the Peltier E
10、ffect V. Yu. Teplov* and A. V. Anisimov* * Kazan State University, ul. Kremlevskaya 18, Kazan, 420008 Russia * Kazan Institute of Biochemistry and Biophysics, Kazan Science Centre, Russian Academy of Sciences, box 30, Kazan, 420111 Russia Received May 16, 2001; in fi nal form, October 22, 2001 Abstr
11、act A fl exible temperature-controlling system matched with the liquid thermostatting circuit is based on a single-chip microcomputer. Thermoelectric modules based on the Peltier effect are used for sample cooling and heating. The accuracy of the temperature maintenance is better than 0.1 C in a ran
12、ge of 20 to +70 C. The system is designed for NMR relaxometers but can be also used to control the temperatures of any volume-com- parable objects (50 cm 3 ). 11 10 12 9 1 NS 4 5 67 8 2 3 Fig. 1. Block diagram of the thermostating system: ( 1 ) ampoule with the sample studied; ( 2 ) magnet of the NM
13、R setup; ( 3 ) thermojacket; ( 4 ) heater; ( 5 ) Peltier-effect-based thermoelements; ( 6 ) pump; ( 7 ) heat carrier volume temper- ature variation compensator; ( 8 ) connecting pipes; ( 9 ) ther- mal converter; ( 10 ) personal computer; ( 11 ) electronic units of the NMR setup; and ( 12 ) control a
14、nd interface system. INSTRUMENTS AND EXPERIMENTAL TECHNIQUES Vol. 45 No. 3 2002 THERMOSTATTING SYSTEM USING409 the elimination of electromagnetic interferences caused by heatingcooling devices near a thermostatically controlled object. The violation of the system stability due to a time delay in the
15、 liquid contour is excluded by an integral link in the thermostatting algorithm. A block diagram of the electronic control unit for the thermostatting system is shown in Fig. 2. The pro- grammable controller of the digital power regulator based on the SCM 5, 6 controls the temperature and keeps it a
16、t a constant level. The current temperature of the thermostat is mea- sured by the SCM performing the bit-by-bit balancing algorithm of the digital-to-analog converter (DAC) sig- nal and output potential of the temperature converter (TC), which are compared by the analog comparator (AC). The same DAC is used to set the power trans- ferred by the actuating amplifi er (AA) to the heater. For the DAC switching-over time to the temperature mea- surement mode, the signal d
