| The vortex flowmeter has been widely applied in the liquid, gas and steam flow measurement because of high measuring accuracy and small pressure loss. Recently the research for vortex flowmeter demonstrated that if the signal's frequency is higher, the intensity is larger and noise is less, but the noise disturbance is very serious of the low frequency band's signal, so the analysis of the low frequency band's signal is important. As the flowmeter works chronically under the non-power condition, the size of power is an important parameter. This paper introduced a design of low-power intelligent vortex flowmeter in above two aspects.In software algorithm, the sampling points for FFT calculation could be changed. Because FFT caculation of MCU is time-consuming, different points FFT operation was made regard to different frequency's signal. This algorithm make the flowmeter reached the requirements of the precision and the real-time. So for the characteristic of the vortex signal, the FFT calculated with selected sampling points within the measured frequency ranges, then determined the next sampling points on the result. The arithmetic is feasible by the error analyzing and data validating. And this technique imprvoe the flowmeter's capability of noise suppress and match real-time request. Thereby it is a high cost-performance.The size of power is an important parameter. 16 bit MCU MSP430F149 producted by TI was used as main-controller in this design. The MCU had carried on the sampling, analysis, culculation to the signals of various sensors, then made compensation for them. Low-power design was applied in hardware parts. EEPROM and real-time chip was choosed in this design, which combined with the flow of liquid,and this design will make inquiring the flow data conveniently. The results of caculation is stored in EEPROM, and it also can be outputted through serial port and display on the LCD if necessary.
|
PDF Full Text Request