The Design Of Thermostatic And Vacuum Control Module For WED X Ray Fluorescence Spectrometer

Temperature and vacuum control system is one of the hot areas on control system research, especially with the development of electronic technology and computer technology,for high-precision applications control system, its temperature or vacuum degree requirements of environmental will more stringent. The temperature and vacuum control system as an important module of the X-ray fluorescence spectrometer instrument, to provide a stable environment for instrument work performance. This module can be used not only in this instrument, but also can be easily ported to other systems, high control accuracy, good stability, easy to operate, will application prospects.As an important part of national major scientific instruments developed item " WED X-ray fluorescence Spectrometer R&D and industrialization"(item number:2012YQ050076). Further researching was made on the basis of summing up the current vacuum thermostat system. Self-adaptive fuzzy algorithm and improved PID control algorithm is the control core, combined with DSP control chip and peripheral control circuit to achieve a high-precision control. Providing an important support for the nationalization and industrialization of projects. The main tasks of this project contained:1. Designed accurate temperature signal and vacuum signal acquisition circuitry. PT1000platinum resistance as temperature signal sensor, combined with high-precision constant current source circuit to achieve the transition of temperature signal; vacuum signal using model PSG500-S standard Pirani vacuum gauge as sensor, according to the output of vacuum gauge to design rational switching circuit; designing of the signal enlarge and filter circuit, combined with high-precision ADC block of DSP for signal acquisition2. Designed a temperature and pressure execute circuit with high resolution, high stability, to improve the control precision of the system. Temperature and vacuum systems applying PWM waveform method, make the output converting to controlling voltage, then to change the system’s temperature and vacuum. Temperature system apply MOC3041optical coupler chip and BAT12-600TRIAC realize the heater power supply control vacuum system is designed a circuit to turn PWM signal to an analog voltage, to realize the output frequency control of inverter, then control the pump speed.3. Improved the traditional fuzzy control algorithm for adaptive parameter adjustment, retaining all the advantages of the original fuzzy control system, to improve the control performance; the improved PID algorithm when the system temperature difference is small, the effect of improving the static difference is very obvious.4. Set up the experimental platform, establishing a monitoring platform based on the Labview software, to test and analyze the performance of control system.