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Yang S.,Hefei University of Technology | Xu K.,Hefei University of Technology | Liang L.,Hefei University of Technology | Zhang R.,Hefei University of Technology | Wang G.,Chongqing Sichuan Automation Co.
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2011

Aiming at slurry measurement, a high-frequency square-wave excitation circuit was designed, a slurry signal processing method was proposed, and a slurry-type electromagnetic flowmeter was developed with DSP-chip TMS320F2812. In the excitation control section, a constant current source is built using linear regulator and powered by high voltage supply to realize the excitation of high-frequency square-wave and ensure the stability of signal zero point. In the signal conditioning section, a differential amplifier and offset adjustment method are adopted to overcome common mode interference and polarization drift. In the signal processing section, a signal processing method combing statistical analysis and signal reconstruction is put forward to remove the slurry interference and obtain steady flow-rate output. The results of water flow calibration and paper slurry measurement experiment show that the measurement accuracy of the slurry-type electromagnetic flowmeter is better than 0.5% for water flow; and the fluctuating rate is lower than 4% and the dynamic response time is less than 4 seconds for slurry flow, which satisfies the requirements of slurry measurement in practical applications. Source


Xu K.-J.,Hefei University of Technology | Luo Q.-L.,Hefei University of Technology | Wang G.,Chongqing Sichuan Automation Co. | Liu S.-S.,Hefei University of Technology | Kang Y.-B.,Chongqing Sichuan Automation Co.
Review of Scientific Instruments | Year: 2010

Digital signal processing methods have been applied to vortex flowmeter for extracting the useful information from noisy output of the vortex flow sensor. But these approaches are unavailable when the power of the mechanical vibration noise is larger than that of the vortex flow signal. In order to solve this problem, an antistrong-disturbance signal processing method is proposed based on frequency features of the vortex flow signal and mechanical vibration noise for the vortex flowmeter with single sensor. The frequency bandwidth of the vortex flow signal is different from that of the mechanical vibration noise. The autocorrelation function can represent bandwidth features of the signal and noise. The output of the vortex flow sensor is processed by the spectrum analysis, filtered by bandpass filters, and calculated by autocorrelation function at the fixed delaying time and at τ=0 to obtain ratios. The frequency corresponding to the minimal ratio is regarded as the vortex flow frequency. With an ultralow-power microcontroller, a digital signal processing system is developed to implement the antistrong-disturbance algorithm, and at the same time to ensure low-power and two-wire mode for meeting the requirement of process instrumentation. The water flow-rate calibration and vibration test experiments are conducted, and the experimental results show that both the algorithm and system are effective. © 2010 American Institute of Physics. Source


Yang S.-L.,Hefei University of Technology | Wang G.,Chongqing Sichuan Automation Co. | Xu K.-J.,Hefei University of Technology | Shi L.,Chongqing Sichuan Automation Co. | Li J.-C.,Chongqing Sichuan Automation Co.
Jiliang Xuebao/Acta Metrologica Sinica | Year: 2011

Based on the simulation analysis of constant excitation current control, a novel method of dual-loop control for constant excitation current control is proposed in order to improve high-frequency square wave excitation performance of the electromagnetic flowmeter. This method includes an outer loop for high/low voltage power switching and an inner loop for current fine-tuning, which can ensure zero satiability of the sensor output signal and high power efficiency of the excitation system when electromagnetic flowmeter is excited by high-frequency square wave. A square wave excitation control system is designed to realize to excite the coil by high frequency precisely. The simulation results show that the higher the high voltage power, the more widely the excitation frequency can be expanded. The experimental results show that the speed of constant excitation current control is fast and the sensor output signal of the electromagnetic flowmeter has steady zero when the excitation system is excited by high-frequency square wave. Source


Wang Q.,Hefei University of Technology | Xu K.,Hefei University of Technology | Jiang P.,Hefei University of Technology | Wang G.,Chongqing Sichuan Automation Co. | Jiang H.,Chongqing Sichuan Automation Co.
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2011

The dynamic characteristic of piezoelectric valve positioner is nonlinear in its operational range. There are both over shoot and lots of PWM pulses in the valve positioning process when conventional five-step switching method is used. A five-step switching method with backward PWM is proposed in this paper. In the closed-loop control process, forward PWM or backward PWM is selected according to the speed of the actuator. In the parameter self-tuning process, different optimal forward PWM duty cycles are determined for different positions, and their calculation is implemented in real-time. A hardware and software system is developed based on low power MCU MSP430F5418A chip to realize parameter self-tuning process and control algorithm in real time. Experiments have been performed for various pneumatic regulation valves, and good control results are obtained. Source


Liang L.-P.,Hefei University of Technology | Xu K.-J.,Hefei University of Technology | Yang S.-L.,Hefei University of Technology | Zhang R.,Hefei University of Technology | And 2 more authors.
Jiliang Xuebao/Acta Metrologica Sinica | Year: 2012

To solve the problem of slurry measurement for electromagnetic flowmeter, the statistical signal models of both water flow-rate and slurry are built up by means of probability analysis method so as to reveal their statistical distribution patterns. And then a reconstruction-filter processing method is proposed for EMF to measure slurry. To verify the effectiveness of the algorithm, the slurry experiments are conducted to compare the performance indexes of our system with those of the slurry-type EMF made by Toshiba Company in Japan. The experimental results show that both the processing algorithm and system for slurry developed by us are feasible and effective. Source

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