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户用超声波水表的研究与设计

发布时间:2019-01-09 14:51
【摘要】:随着阶梯水价政策的实施,一个以水表计量性能提升、无线网络接入和融入互联网应用为标志的“互联网+智能水表2.0”时代已经到来。超声波水表无机械运动部件、压力损失小、始动流量低、误差特性曲线可修正,而且可实现数据远传,具备下一代智能水表的基本特征和功能。研究超声波水表,不仅可以推动阶梯水价制度的建立,而且可以实现智能水表的转型升级,对我国水表产业的发展具有重要意义。针对时差法接收到超声波信号的时刻难以精确捕获,小流速的流量计量精度低等问题,本文设计了一种相差法超声波水表,可以实现家庭用水的精确计量。根据超声波在水中的传播速度和温度的对应关系实现水温的检测。然后针对相差法测得的流量值随温度呈非线性变化的问题,提出了基于最小二乘曲面拟合的温度补偿算法。主要研究内容如下:1.在分析和比较几种常用的超声波流量检测方法的基础上,采用相差法检测流量。通过对相位比较结果累加积分,不仅可以实现微小流量的检测,还可以减小干扰信号的影响。针对流速检测过程中采集到的数据波动大的问题,采用限幅滤波、算术平均值滤波和滑动平均值滤波相结合的复合滤波算法来对采集的数据进行处理,改善了流速检测结果的稳定性。2.针对流量值随温度呈非线性变化这一问题,进一步研究对检测流量进行温度补偿的方法。采用检测超声波在水中的传播速度推算出温度、而非常规的温度传感器检测温度的方法。实验表明,温度检测检测误差在±2℃以内,并且降低了仪表的成本。3.提出了基于最小二乘曲面拟合的温度补偿算法,根据温度和流量拟合得到的曲面对流量进行预测和补偿。在实现温度补偿后,针对超声波水表自身计量特性的差异,进一步提出多温度点流量计量误差二次补偿算法,根据相邻温度点的流量计量误差和权值计算当前温度和瞬时流量下的流量计量误差,然后对误差进行补偿,可以实现流量检测的全局优化。实验表明,流量计量误差在±2.0%以内。经过实验验证,本文设计的超声波水表可以实现家庭用水的流量精确检测,达到高精度、低功耗、低成本的目的。
[Abstract]:With the implementation of ladder water price policy, an era of "Internet Intelligent Water Meter 2.0", marked by the improvement of metering performance, wireless network access and integration into Internet applications, has arrived. Ultrasonic water meter has no mechanical moving parts, small pressure loss, low starting flow rate, correction of error characteristic curve, and can realize remote data transmission. It has the basic characteristics and functions of the next generation intelligent water meter. The study of ultrasonic water meter can not only promote the establishment of stepped water price system, but also realize the transformation and upgrading of intelligent water meter, which is of great significance to the development of water meter industry in China. In order to solve the problem that the time of receiving ultrasonic signal by moveout method is difficult to capture accurately and the measurement accuracy of flow rate of small velocity is low, a ultrasonic water meter with phase difference method is designed in this paper, which can be used to measure household water accurately. The detection of water temperature is realized according to the relationship between the velocity and temperature of ultrasonic wave propagation in water. Then a temperature compensation algorithm based on least square surface fitting is proposed to solve the problem that the flow rate measured by phase difference method is nonlinear with temperature. The main contents are as follows: 1. Based on the analysis and comparison of several ultrasonic flow detection methods, the phase difference method is used to detect the flow. By summing up the results of phase comparison, not only the detection of micro flow can be realized, but also the influence of interference signal can be reduced. Aiming at the problem of large fluctuation of data collected in the process of velocity detection, a composite filtering algorithm, which combines amplitude limiting filter, arithmetic average filter and sliding average filter, is used to process the collected data. Improved the stability of velocity detection results. 2. In order to solve the problem that the flow rate is nonlinear with the temperature, the method of temperature compensation for the detection flow rate is further studied. The temperature is calculated by measuring the velocity of ultrasonic wave in water, but not by conventional temperature sensor. The experimental results show that the temperature measurement error is within 卤2 鈩,

本文编号:2405769

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