Research Of Electronic Pressure Measurement Detector Based On The Capacitive Sensor Principle

Capacitive sensor can convert the non-electrical quantity change to capacitance change. With the progress of micro-electrical mechanical systems (MEMS) design and process, the application of capacitive sensor technology become more widespread. Chamber pressure measurement plays an important role in the development of artillery interior ballistics. According to domestic and international chamber pressure measurement technology, the capacitive sensor used in the artillery chamber pressure test is worth exploring.The electronic pressure measurement detector is designed on the basis of capacitive sensor principle, which adopts the voltage detector shell as pressure sensitive element. Firstly,the principle and characteristic of capacitive sensor are introduced. Secondly, the detector is analyzed theoretically. Thirdly, the coaxial cylindrical capacitor value is calculated. Lastly, the factors of affecting the capacitance measurement are analyzed.Two constant current sources are used to charge and discharge the capacitors. According to the transformation of the two capacitor voltage, the capacitance value of the shell can be acquired. Micro-capacitance signal detection and extraction is completed by the circuit, which is differential DC charging method detecting the shell capacitor. The micro-capacitor converter circuit, with the feature of high resolution and high sampling rate characteristics, can reduce the nonlinearity error, interference and parasitic capacitance; improve the sensitivity of the sensor.This design improves the structure of the sensor and completes the unity of the sensor and the shell; provides a new method for artillery chamber pressure test. More importantly, a kind of practical micro-capacitance signal detection circuit is proposed, the measured frequency of which is much higher than that of integrated chips. All above make the exploratory research for future high-speed measurement of micro-capacitance.