Method for estimating parameters of conductivity second-order resistance-capacitance coupled network

Abstract

The invention provides a method for estimating parameters of a conductivity second-order resistance-capacitance coupled network, and belongs to the technical field of soft measurement of the solution conductivity, wherein the measurement of the solution conductivity is converted into parameter estimation of a second-order equivalent resistance-capacitance coupled network; and the method specifically comprises the following steps of: for a conductance cell second-order resistance-capacitance system model taking lead distributed capacitance and electrical double-layer capacitance influences into account, orderly employing two sine excitation signals of different frequencies to excite the resistance-capacitance network; on the basis that the amplitude ratio and phase difference of sine response signals in relation to the sine excitation signals thereof are estimated, respectively, establishing an over-determined system related to the resistance and capacitance parameters to be estimated according to the relationship deduced between the amplitude ratio and the phase difference and the solution resistance, the lead distributed capacitance and the electrical double-layer capacitance; and then obtaining the estimated values of the resistance and capacitance parameters by a subspace confidence region optimization algorithm based on the nonlinear least square principle. The method provided by the invention is high in rate of convergence, high in estimation accuracy and good in anti-interference capability, and suitable for industrial online real-time application.

Description

technical field [0001] The invention belongs to the technical field of solution conductivity soft measurement, and relates to a parameter estimation method of a second-order equivalent resistance-capacitance coupling network of conductivity, in particular to a method for estimating the parameters of a second-order equivalent resistance-capacitance coupling network through a resistance-capacitance system when considering the influence of lead distributed capacitance and double-layer capacitance. The method of obtaining the estimated value of the resistance-capacitance parameter from the estimated value of the phase characteristic. Background technique [0002] Solution conductivity measurement is widely used in human production and life. With the continuous development of science and technology, the research on conductivity measurement at home and abroad is also deepening, and various new applications of conductivity measurement technology are also emerging. At present, the m...

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Problems solved by technology

The literature "Cui Pengfei, Zhang Liyong, Zhong Chongquan, Li Dan. Numerical simulation of multi-frequency square wave excitation RC decoupling soft measurement. Journal of Instrumentation, 2010, 31(1): 154-160" proposed a method using multiple A non-linear least squares estimation method for the RC parameters of the RC network excited by an AC square wave of frequency, but ignores the influence of the electric double layer capacitance

Patent document "Zhou Kaidi, Zhang Liyong, Ling Jingwei, Zhong Chongquan, Li Dan. Resistance-capacitance decoupling soft measurement method base

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