A Novel Resistance Measurement Method Based on Double Frequency Excitation Signals Eliminating the Infection of Distributed Capacitance
Chongquan Zhong, Liang Zhao · International Journal of Control and Automation · 2017
The paper proposes a changing frequency method which is able to measure the value of the resistance.First, two AC square waves that have appropriate frequency are imposed on the partial circuit which is made up of electrode; and then, the critically rectified DC voltage from the partial circuit is measured; and next, the time constant of the partial circuit is calculated by solving the equation set; at last, the value of the resistance is obtained.The method eliminates the infection of the capacitance effectively, which will affect the metrical precision of the resistance value.The connection expression between the output DC voltage and the resistance to be measured and the capacitance is derived in the paper.And the infection of AC square wave amplitude to the metrical precision is eliminated effectively with the proportion method.The experimental results indicate that the metrical precision can arrive within 1 % in such a condition: the partial resistance is 100kΩ, the capacitance is within the range of 500pF~8 000 pF, and the resistance to be measured is between 1kΩ and 1 MΩ.The experimental results show that this variable frequency AC excitation decoupled measurement method effectively eliminates the mutual influence between resistance and capacitance measurement of measuring object.Meanwhile, the paper also proposes the use of proportional method for elimination of the impact of AC square wave amplitude on measurement results, thereby effectively improving the measurement accuracy.