CN203217405U

CN203217405U - High-precision automatic controller for thermostatic bath

Info

Publication number: CN203217405U
Application number: CN 201320191009
Authority: CN
Inventors: 肖兰
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-04-16
Filing date: 2013-04-16
Publication date: 2013-09-25
Anticipated expiration: 2023-04-16

Abstract

A high-precision automatic controller for a thermostatic bath comprises a temperature-sensing module, a conditioning module, a VFC module, a main control module, a power adjusting module, an electric heating wire and a user interaction module, wherein the temperature-sensing module, the conditioning module, the VFC module, the main control module, the power adjusting module, and the electric heating wire are successively connected, and the main control module is also connected with the user interaction module. First, a user sets a temperature for the thermostatic bath through the user interaction module; the temperature-sensing module, after the controller begins to work, acquires the temperature data of the thermostatic bath; the electric resistance changes of a sensor within the temperature range of 0 to 500 degrees are converted into voltage changes within the range of 0 to 5 V by the conditioning module; and at the same time the conditioning module corrects the non-linearity of the temperature-sensing module. Second, the voltage changing with the temperature is converted into the frequency changes of a TTL square wave through the VFC module; the main control module counts the TTL square wave within unit time so that a current temperature value is obtained; a PID calculation is performed according to a measured result; the duty cycle that the power adjusting module outputs is controlled according to the calculated result so that the heating power of the electric heating wire may be controlled, and the purpose of constant temperature automatic control is achieved.

Description

The high-precision thermostat bath self-actuated controller

Technical field

The utility model relates to a kind of chamber controller, especially the high-precision thermostat bath self-actuated controller.

Background technology

The control of electrical heating temperature has intensification one-way, big inertia, large time delay, time-varying Characteristics, for example its intensification one-way is because electrically heated heating and heat preservation is to rely on the resistance wire heating, cooling then is to rely on the naturally cooling, when in case temperature overshoot just is difficult to make its cooling with the refrigeration control device, thereby be difficult to set up precise analytic model and determine parameter with mathematical method, use traditional mimic channel control method and be difficult to reach ideal control effect.

Summary of the invention

In view of above reason, the utility model provides a kind of high-precision thermostat bath self-actuated controller, uses single-chip microcomputer to carry out the digital PID computing, can give full play to the dirigibility of software systems, makes it more perfect to pid algorithm correction where necessary.

The technical scheme that its technical matters that solves the utility model adopts is: a kind of high-precision thermostat bath self-actuated controller, comprise temperature sensing module, conditioning module, VFC module, main control module, user interactive module, power conditioning module, electrical heating wire, it is characterized in that, temperature sensing module, conditioning module, VFC module, main control module, power conditioning module, electrical heating wire connect successively, and the main control module also is connected with user interactive module.At first the user sets the temperature of calibration cell by user interactive module, after the controller operation, the temperature sensing module is gathered the temperature data of calibration cell, change the resistance variations of sensor in 0 ~ 500 ℃ of temperature range the change in voltage of 0 ~ 5V into through conditioning module, conditioning module is revised the non-linear of temperature sensing module simultaneously; Utilize the VFC module with the frequency change of temperature-dependent voltage transitions for the TTL square wave then, the main control module was just counted this TTL square wave in the unit interval can obtain current temperature value, carry out the PID computing according to measurement result, dutycycle according to the output of operation result control power conditioning module, realization is to the control of electrical heating wire heating power, thereby reaches the constant temperature purpose of control automatically.

The beneficial effects of the utility model are, have realized that the constant temperature fluctuation controls automatically less than 0.01 ℃ high-precision thermostat bath, have advantages of high practicability.

Description of drawings

Fig. 1 is theory diagram of the present utility model.

Embodiment

In Fig. 1, a kind of high-precision thermostat bath self-actuated controller, comprise temperature sensing module 1, conditioning module 2, VFC module 3, main control module 4, user interactive module 5, power conditioning module 6, electrical heating wire 7, it is characterized in that, temperature sensing module 1, conditioning module 2, VFC module 3, main control module 4, power conditioning module 6, electrical heating wire 7 connect successively, and main control module 4 also is connected with user interactive module 5.At first the user sets the temperature of calibration cell by user interactive module 5, after the controller operation, temperature sensing module 1 is gathered the temperature data of calibration cell, change the resistance variations of sensor in 0 ~ 500 ℃ of temperature range the change in voltage of 0 ~ 5V into through conditioning module 2, conditioning module 2 is revised the non-linear of temperature sensing module 1 simultaneously; Utilize VFC module 3 with the frequency change of temperature-dependent voltage transitions for the TTL square wave then, main control module 4 was just counted this TTL square wave in the unit interval can obtain current temperature value, carry out the PID computing according to measurement result, dutycycle according to 6 outputs of operation result control power conditioning module, realization is to the control of electrical heating wire 7 heating powers, thereby reaches the constant temperature purpose of control automatically.

Temperature sensing module 1 adopts the Pt100 platinum resistance temperature sensor, change the resistance variations of Pt100 platinum resistance temperature sensor in 0 ~ 500 ℃ of scope the change in voltage of 0 ~ 5V into by the conditioning module 2 of special use, simultaneously the non-linear of platinum resistance revised.Because controller requires temperature fluctuation less than 0.01 ℃, be that cost performance is higher, the AD654 chip of good stability so VFC module 3 adopts, the frequency of corresponding 0 ~ 200kHz after AD654 carries out the VFC conversion, the temperature resolution of this moment has reached 0.0025 ℃.51 series monolithics that main control module 4 adopts, the highest frequency that external pulse is counted is 1/ 24 of clock frequency, the highest count frequency when namely adopting the 12MHz crystal oscillator is 500kHz, count results occurred unstable when the external pulse frequency was greater than 450kHz during actual the test, select 0 ~ 500 ℃ at last, corresponding 0 ~ 5V voltage, power conditioning module is regulated P2.4 by single-chip microcomputer, P2.5, P2.6, the P2.7 pin connects the choosing of trimmer potentiometer sheet respectively, the choosing of coarse adjustment potentiometer sheet and lifting/lowering control input pin, the input clock pin, P2.6, P2.7 is that fine setting and coarse adjustment potentiometer share, and distinguishes two potentiometers according to chip selection signal.User interactive module 5 is made up of programmable I/O interface control chip 8255, charactron, keyboard and part peripheral circuit, the basic input and output controls of 8255 working mode selection (mode 0), its C mouth, B mouth are made delivery outlet, are used for controlling the charactron displays temperature; The A mouth is done the input port, is used for scanning detecting rule, and the triode array amplifies the signal of PC0-PC6.Power conditioning module 6 is made of digital regulation resistance and solid-state relay, and digital regulation resistance is selected the X9312TP of Xicor company for use.Because the standard thermostatic oil groove of temperature sensor calibrating usefulness is very high to the requirement of constant temperature fluctuation degree, has increased the fine setting digital regulation resistance, make the power adjustments resolution characteristic reach ten thousand of heater strip peak power/.Solid-state relay is selected 30A/ 220V alternating current zero crossing type for use.

Claims

1. high-precision thermostat bath self-actuated controller, comprise temperature sensing module (1), conditioning module (2), VFC module (3), main control module (4), user interactive module (5), power conditioning module (6), electrical heating wire (7), it is characterized in that, temperature sensing module (1), conditioning module (2), VFC module (3), main control module (4), power conditioning module (6), electrical heating wire (7) connect successively, and main control module (4) also is connected with user interactive module (5).