Design And Implementation Of Resistance-Capacitance Decoupling Soft-sensing System

Resistance and capacitance are common used electrical parameters, the study of resistance measurement and capacitance measurement is of important practical significances. But resistance and capacitance are often coupled together and interact with each other, which makes them difficult to be measured directly. By analyzing traditional methods of resistance and capacitance measurement, soft sensing is applied to decouple resistance-capacitance network in this paper. In resistance-capacitance decoupling soft-sensing system, sine source is used. By establishing the model between excitation signal, response signal and resistance parameter, capacitance parameter, frequency selection soft sensing technique is used to realize the decoupling of resistance and capacitance.The system is based on TMS320F2812 of TI (Texas Instruments). With 18k SARAM, 128k Flash, abundant I/O and peripheral resources, TMS320F2812 can be used to realize complex computing and data processing. Onboard sine excitation source is realized using MAX038 plus some peripheral circuits. Sine signal of different frequency is generated with corresponding external capacitance. The 2 channels, +5V power supply, 24 bits ADC CS5360 samples signal and generates serial data sent to CPU. The system also has 2 asynchronous serial communication interfaces based on RS485 to communicate with PC.On the design of software, modular design is adopted to enhance the scalability of software. By using PIE, the analog to digital conversion is realized in the ISR. Therefore, the system can rapidly perform signal sampling and data processing. To make sure that the input data for the soft sensing algorithm is reliable, frequency selection is introduced, auto range circuit and digital filtering are also used. Error correcting is also applied to the system to improve the stability and the anti-interfere performance.The experiment proves that the error is below 1%. Resistance-capacitance decoupling soft-sensing method solves the measurement of resistance and capacitance when they are coupled together and achieves good measurement accuracy.