MOSFET Based ADC for Accurate Positioning of Control Valves in Industry

Authors: K. Diwakar, N. Vasudevan, C. Senthilpari

Abstract:

This paper presents MOSFET based analog to digital converter which is simple in design, has high resolution, and conversion rate better than dual slope ADC. It has no DAC which will limit the performance, no error in conversion, can operate for wide range of inputs and never become unstable. One of the industrial applications, where the proposed high resolution MOSFET ADC can be used is, for the positioning of control valves in a multi channel data acquisition and control system (DACS), using stepper motors as actuators of control valves. It is observed that in a DACS having ten control valves, 0.02% of positional accuracy of control valves can be achieved with the data update period of 250ms and with stepper motors of maximum pulse rate 20 Kpulses per sec. and minimum pulse width of 2.5 μsec. The reported accuracy so far by other authors is 0.2%, with update period of 255 ms and with 8 bit DAC. The accuracy in the proposed configuration is limited by the available precision stepper motor and not by the MOSFET based ADC.

Keywords: MOSFET based ADC, Actuators, Positional accuracy, Stepper Motors.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1337075

References:

[1] Pui-Kei Leong, Chun-Hung Yang, Chi-Wai Leng and Chien-Hung Tsai "Design and Implementation of Sigma-Delta DPWM Controller for Switching Converter”, IEEE International Symposium on Circuits and Systems, pp. 3074-3077, 2009.
[2] Jiaxin, Wanrong Zhang, Haolin Du, Yanfeng Jiang and Yamin Zhang "New Architecture of Low Voltage Sigma-Delta ADC”, IEEE 8th International Conference on ASIC, pp. 203-206.
[3] Jonathan W. Kimball, Kyle Roger Eckler and Luke Watson (2010) "Sigma-Delta Modulation of Multi-Phase High Frequency Converters”, Applied Power Electronics Conference and Exposition (APEC) 2010, pp 2202-2206,2009.
[4] Nandha Kumar Thulasiraman., Haider A.F Mohamed & Yearp Soo Cheng "A Reconfigurable Wireless Stepper Motor Controller Based On FPGA Implementation”, IEEE symposium on industrial Electronic and Applications, pp.585-590, October 3-5, 2010.
[5] Daniel Carrica, Marcos A. Funes and Sergio A. Gonzalez, "Novel Stepper Motor Controller Based on FPGA Implementation”, IEEE/ASME Transactions on Mechatronics, Vol 8, No.1, March 2003.
[6] Ngoc Quy Le and Jai Wook Jeon, "An Open-loop Stepper Motor Driver Based on FPGA”, International Conference on Control, Automation and Systems, Oct. 17-20, 2007.
[7] Donald A. Neamen, Microelectronics Circuit Analysis and Design. McGraw-Hill International edition, 2007, pp 122-127.
[8] Hausila Singh, and Sudhansu Mohan Sharma, "Some Novel μP-Based Configurations for Controlling Remotely Located Stepper Motors as Actuators of Control Valves”, IEEE Transaction on Industrial Electronics, Vol.38, No.4, August 1991, pp 283-287.
[9] N.P. Mahalik and P.R. Moore, "Fieldbus Technology Based, Distributed Control in Process Industries: A Case Study with LonWorks Technology”, Integrated Manufacturing Systems, Vol. 8, No.4, 1997, pp231–243.