Improvement of the accuracy of absolute magnetic encoders based on automatic calibration and the fuzzy phase-locked-loop

This paper presents an approach for the improvement of the accuracy of absolute magnetic encoders (AME). The encoders comprise the following two magnets: a multipolar magnet to increase the resolution and the accuracy, and a center-located bipolar magnet for the calculation of the absolute angle. The multipolar signal processing is crucial for the increasing of the encoder accuracy; however, the multipolar signals are not ideal, i.e, dc offsets, different amplitudes, phase shifts, and random noise. The present paper proposes a calibration method that is based on the adaptive linear neural network (ADALINE) for the reduction of the effect of the nonidealities. In addition, to optimize the loop-acquisition time and to enhance the random-noise reduction, the bandwidth is adapted using the fuzzy phase-locked-loop (F-PLL). This method is simulated using Matlab software and is implemented on the ARM STM32F405R. The study results demonstrate the efficient high performance that can be achieved with the use of the proposed method.

[1]  Ambrish Chandra,et al.  Position error compensation in quadrature analog magnetic encoders through an iterative optimization algorithm , 2014, IECON 2014 - 40th Annual Conference of the IEEE Industrial Electronics Society.

[2]  Alireza Bab-Hadiashar,et al.  Calibration of Resolver Sensors in Electromechanical Braking Systems: A Modified Recursive Weighted Least-Squares Approach , 2007, IEEE Transactions on Industrial Electronics.

[3]  Qi Lin,et al.  Error Analysis and Compensation of the Orthogonal Magnetic Encoder , 2011, 2011 First International Conference on Instrumentation, Measurement, Computer, Communication and Control.

[4]  Ambrish Chandra,et al.  A Novel Algorithm Based on Polynomial Approximations for an Efficient Error Compensation of Magnetic Analog Encoders in PMSMs for EVs , 2016, IEEE Transactions on Industrial Electronics.

[5]  Hua Yuan,et al.  All DPLLs based on fuzzy PI control algorithm , 2011, 2011 Second International Conference on Mechanic Automation and Control Engineering.

[6]  P L Heydemann,et al.  Determination and correction of quadrature fringe measurement errors in interferometers. , 1981, Applied optics.

[7]  Kok Kiong Tan,et al.  New interpolation method for quadrature encoder signals , 2002, IEEE Trans. Instrum. Meas..

[8]  Stefano Bifaretti,et al.  A digital filter for speed noise reduction in drives using an electromagnetic resolver , 2006, Math. Comput. Simul..

[9]  Silvano Balemi,et al.  Automatic calibration of sinusoidal encoder signals , 2005 .

[10]  Jae Wook Jeon,et al.  An Efficient Approach to Correct the Signals and Generate High-Resolution Quadrature Pulses for Magnetic Encoders , 2011, IEEE Transactions on Industrial Electronics.