scholarly journals Design of a magnetic encoder using Hall effect

2019 ◽  
Vol 13 (2) ◽  
pp. 254-261
Author(s):  
William Alejandro López-Contreras ◽  
José Danilo Rairán-Antolines
Keyword(s):  
Hall Effect ◽  
Relative Motion ◽  
Direct Current ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Linearization Method ◽  
Acquisition Process ◽  
Voltage Variation ◽  
Hall Sensors

We present the design of a magnetic encoder to measure angular position. The proposed encoder includes two Hall sensors in quadrature in a fixed platform. In addition, and over the sensors, there are two permanent magnets in a shaft. The relative motion between the fixed and the movable components generate a voltage variation in the sensors, which serve to generate the approximation of the angular position. We detail the acquisition process and the linearization method, because we consider that these are the most important contributions of this work. Lastly, we show the application of the encoder in the position control of a direct current motor to show the performance of the encoder estimating fast and slow angular position changes.

scholarly journals Cogging Torque Reduction in Brushless Motors by a Nonlinear Control Technique

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2224 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Permanent Magnet ◽  
Electric Drive ◽  
Feedback Linearization ◽  
Permanent Magnets ◽  
Position Control ◽  
Angular Position ◽  
Control Technique ◽  
Electrical Machine ◽  
Brushless Motors ◽  
Cogging Torque

This work addresses the problem of mitigating the effects of the cogging torque in permanent magnet synchronous motors, particularly brushless motors, which is a main issue in precision electric drive applications. In this work, a method for mitigating the effects of the cogging torque is proposed, based on the use of a nonlinear automatic control technique known as feedback linearization that is ideal for underactuated dynamic systems. The aim of this work is to present an alternative to classic solutions based on the physical modification of the electrical machine to try to suppress the natural interaction between the permanent magnets and the teeth of the stator slots. Such modifications of electric machines are often expensive because they require customized procedures, while the proposed method does not require any modification of the electric drive. With respect to other algorithmic-based solutions for cogging torque reduction, the proposed control technique is scalable to different motor parameters, deterministic, and robust, and hence easy to use and verify for safety-critical applications. As an application case example, the work reports the reduction of the oscillations for the angular position control of a permanent magnet synchronous motor vs. classic PI (proportional-integrative) cascaded control. Moreover, the proposed algorithm is suitable to be implemented in low-cost embedded control units.

scholarly journals Design of an Observer-Based Architecture and Non-Linear Control Algorithm for Cogging Torque Reduction in Synchronous Motors

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2077 ◽  
Author(s):  
Pierpaolo Dini ◽  
Sergio Saponara
Keyword(s):  
Control Algorithm ◽  
Permanent Magnets ◽  
Position Control ◽  
Deterministic Model ◽  
Initial Conditions ◽  
Angular Position ◽  
Observer Design ◽  
Control Technique ◽  
Servo Drive ◽  
Cogging Torque

The problem of cogging torque is due to a magnetic behavior, intrinsic to synchronous machines and due to the presence of permanent magnets themselves. Cogging torque is a significant problem when the servo drive is used for applications where high precision in terms of position control is required. In this paper we present a method of cogging torque reduction by means of a control technique based on mathematical modeling of the cogging phenomenon itself in order to exploit this knowledge directly in the controller design. The mathematical model is inserted in the dynamic model of the synchronous machine in order to exploit the feedback linearization, providing an expression of the control law in which the contribution of the deterministic knowledge of the phenomenon is directly present. The cogging phenomenon physically depends on the angular position of the rotor, as well as the deterministic model we use to define the control vector. This makes it interesting and innovative to determine whether the control algorithm can be inserted within a sensor-less architecture, where rotor position and angular velocity measurements are not available. For this purpose, we present the use of an extended Kalman filter (EKF) in the continuous-time domain, discussing the advantages of an observer design based on a dynamic motor model in three-phase and direct-square axes. Results are presented through very accurate simulation for a trajectory-tracking problem, completing with variational analysis in terms of variation of initial conditions between EKF and motor dynamics, and in terms of parametric variation to verify the robustness of the proposed algorithm. Moreover, a computational analysis based on Simulink Profiler is proposed, which provides some indication for possible implementation on an embedded platform.

scholarly journals A Nonlinear Magnetic Stabilization Control Design for an Externally Manipulated DC Motor: An Academic Low-Cost Experimental Platform

Machines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 101
Author(s):  
Leonardo Acho
Keyword(s):  
Hall Effect ◽  
Position Control ◽  
Low Cost ◽  
Time Derivative ◽  
Control Design ◽  
Dc Motor ◽  
Flexible Beam ◽  
Experimental Platform ◽  
Hall Effect Sensor ◽  
Vibrational Control

The main objective of this paper is to present a position control design to a DC-motor, where the set-point is externally supplied. The controller is conceived by using vibrational control theory and implemented by just processing the time derivative of a Hall-effect sensor signal. Vibrational control is robust against model uncertainties. Hence, for control design, a simple mathematical model of a DC-Motor is invoked. Then, this controller is realized by utilizing analog electronics via operational amplifiers. In the experimental set-up, one extreme of a flexible beam attached to the motor shaft, and with a permanent magnet fixed on the other end, is constructed. Therefore, the control action consists of externally manipulating the flexible beam rotational position by driving a moveable Hall-effect sensor that is located facing the magnet. The experimental platform results in a low-priced device and is useful for teaching control and electronic topics. Experimental results are evidenced to support the main paper contribution.

scholarly journals A Feasibility Study of a Noncontact Torque Sensor with Multiple Hall Sensors

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Kyungshik Lee ◽  
Chongdu Cho
Keyword(s):  
Magnetic Field ◽  
Permanent Magnets ◽  
Power Transmission ◽  
Magnetic Sensors ◽  
Torque Sensor ◽  
Torque Measurement ◽  
Test Range ◽  
Variable Power ◽  
Hall Sensors ◽  
The Magnetic Field

The feasibility of a noncontact sensor is investigated. This type of sensor can potentially be used for torque measurement in a speed-variable power transmission system. Torque can be read by examining the phase difference between two induction signals from respective magnetic sensors that detect the magnetic field intensity of permanent magnets mounted on the surface of a shaft in rotation. A real-time measuring algorithm that includes filtering and calibration is adopted to measure the torque magnitude. It is shown that this new torque sensor can perform well under rotation speeds ranging from 300 rpm to 500 rpm. As an interim report rather than a complete development, this work demonstrates the feasibility of noncontact torque measurement by monitoring a magnetic field. The result shows an error of less than 2% within the full test range, which is a sufficient competitive performance for commercial sensors. The price is very low compared to competitors in the marketplace, and the device does not require special handling of the shaft of the surface.

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