The Optimal Design Of Capacitive Acceleration Sensor

Acceleration sensor, as one of the most important mechanical quantity sensor, starting from the date of birth is attracting widespread attention.Among them, the capacitive acceleration sensor is widely used in automotive electronics, aerospace and other fields with high sensitivity and accuracy of measurement, good stability, smaller temperature drift, the advantages of low power consumption.At the same time, the capacitive acceleration sensor was also because of its special structure, leading to its work frequency width, the complex signal processing circuit, parasitic capacitance and detection capacitance in the same order of magnitude of faults,therefore, in the guarantee its has the advantages of good stability at the same time, the original structure optimization design, improve the measuring linearity between output and to improve its measuring precision, and capacitive accelerometer is important research subject.Based on the principle of measurement of the capacitive acceleration sensor and the structure of differential capacitive acceleration sensor model for mathematical deduction, it is concluded that the structure of the sensor can complete one dimensional direction on two process measuring acceleration and deceleration, and be able to double precision.Then, the finite element simulation software Ansys, in two-dimension plane space, complete the one-armed beam structure of the solid modeling of capacitive acceleration sensor model, and has made the static analysis of the initial model structure, get the differential capacitance change and structure deformation caused by the function relation between the static force.According to the static electric field under the action of electric potential of the equivalent distribution, it is concluded that the structure of the initial model need to be optimized.After the flat structure is optimized, by optimizing the front and back under the action of electrostatic field such as electric potential distribution to evaluate optimization results analysis, edge effect decreased significantly;through static analysis for the optimized structure, by comparing the difference before and after optimization function relation between the capacitance and static force, after optimized model of the sensor, is measured with the linearity between output has improved significantly.Based on the results of two-dimensional planar structure analysis, still USES the Ansys finite element simulation analysis software, one-armed beam structure of the differential capacitive acceleration sensor was improved design,Design for four arm beam structure differential capacitive acceleration sensor, and completes the modeling of three-dimension model, the model structure under the action of inertial load were analyzed, and the differential capacitance and the function relationship between the inertial load, Compared with previous one-armed beam structure sensor, four arm beam structure of differential capacitance sensor has better linearity.Finally, based on the four arm beam structure of capacitive accelerometer for modal and harmonic analysis, it is concluded that the sensor in the measuring direction on the harmonic response of the resonant frequency of126.30Hz, so to determine the appropriate frequency bandwidth of the sensor work is:0-40Hz and180-180Hz.