Low-resolution Hall Sensors Research Articles

Fault Tolerance Method of Low-Resolution Hall Sensor in Permanent Magnet Synchronous Machine

The estimation of the motor rotor positions with high-precision based on low-resolution Hall sensors becomes an important trend to realize the vector control in low-cost permanent magnet synchronous machine (PMSM) based control systems. Most existing studies focus on the methods to improving the estimating precision of rotor positions, while the estimating precision of failed Hall sensors and the corresponding control strategies for fault tolerance is rarely explored. This paper proposes a method that can online estimate the position of a PMSM rotor with fault detection and fault tolerance. Such a method is able to achieve both stable and precise estimations on rotor position even when one or two Hall sensors fail. Meanwhile, it can meet the needs of vector control under variable speed and load on the PMSM. Finally, a dSPACE-based semi-physical simulation platform is established, which is used to validate the effectiveness of the proposed method with multiple experiments.

Balanced parallel instantaneous position control of PMDC motors with low-cost position sensors

This paper presents an advanced parallel position control scheme for dual permanent DC (PMDC) motors based on a low-cost and low-resolution Hall sensor, which decreases the control performance and accuracy due to the insufficient resolution and slow response in the low-speed range. To balance and improve the position control performance of both PMDC motors, an instantaneous position compensation based on operating time and a current model speed observer with an adaptive sliding mode observer based on the back electromotive force (EMF) constant are presented in this paper. The insufficient resolution and low dynamic response of the Hall sensor can be improved by the advanced current model reference adaptive observer using the back EMF bias calculation and the sliding mode observer of the back EMF constant. From the proposed sensor–sensorless combined estimation method, precise continuous speed and position information can be estimated at every sampling period. To compensate for speed and position estimation errors, the back EMF constant can be adjusted with the average speed error between the speed observer and the actual speed obtained from the Hall sensor. For the balance control of parallel PMDC motors, instantaneous position and speed reference control based on the operating time is presented. In the proposed control method, the speed reference is determined by the time-based speed reference, the instantaneous position error and the position error between two motors. Smooth balancing can be achieved from the compensation term of the balanced position error. The control performance of the proposed scheme for a dual PMDC motor system is verified by comparative simulations and experiments. In both simulations and experiments, the proposed method shows a significant improvement in the position control when compared to that of the conventional control method.

Combined Sensor–Sensorless Control of PMDC Motor for HD Camera of Unmanned Monitoring System

This paper presents a position control scheme for a high-definition serial digital interface (HD-SDI) camera of an unmanned monitoring system. A combination of both sensor and sensorless algorithms of a permanent magnet (PM) DC motor is proposed to create smooth camera movements, stop it at desired positions, and obtain high-quality images without shaking. The back EMF of the motor can be estimated and its actual speed can be calculated accurately by using a model reference adaptive sensorless (MRAS) method. A low-resolution hall sensor is used to approximate the speed instead of measuring the actual value. The moving position can be estimated from the speed approximation and it can be used together with a sliding mode observer to modify the back EMF constant. In the advanced position control of the camera, both instantaneous speed and moving position references are determined by the acceleration and deceleration speed patterns to satisfy the dynamic response during operation. Furthermore, the instantaneous position error can be compensated by incorporating a speed reference. The effectiveness of the proposed control scheme was verified through experiments.

Optimal Design Strategy for Improved Operation of IPM BLDC Motors With Low-Resolution Hall Sensors

This study proposes an interior permanent magnet (IPM) brushless dc (BLDC) motor design strategy that utilizes BLDC control based on Hall sensor signals. The magnetic flux of IPM motors varies according to the rotor position and abnormal Hall sensor problems are related to magnetic flux. To find the cause of the abnormality in the Hall sensors, an analysis of the magnetic flux density at the Hall sensor position by finite element analysis is conducted. In addition, an IPM model with a notch structure is proposed to solve abnormal Hall sensor problems and its magnetic equivalent circuit (MEC) model is derived. Based on the MEC model, an optimal rotor design method is proposed and the final model is derived. However, the Hall sensor signal achieved from the optimal rotor is not perfect. To improve the accuracy of the BLDC motor control, a rotor position estimation method is proposed. Finally, experiments are performed to evaluate the performance of the proposed IPM-type BLDC motor and the Hall sensor compensation method.

Position Estimator Employing Kalman Filter for PM Motors Driven with Binary-type Hall Sensors

Application of vector control scheme for consumer products is enlarging to improve control performance. For the field-oriented control, accurate position detection is essential and generally requires expensive sensors. On the other hand, cost-reduction is important in home appliances, so that binary-type Hall-effect sensors are commonly used rather than using an expensive sensor such as an encoder. The control performance is directly influenced by the accuracy of the position information, and there exist non-uniformities related to Hall sensors in electrical and mechanical aspects, which result in distorted position information. Therefore, to get high-precision position information from low-resolution Hall sensors, this paper proposes a new position estimator consisting of a Kalman filter and feedforward compensation scheme, which generates a linearly changing position signal. The efficacy of the proposed scheme is verified by simulation and experimental results carried out with a 48-pole permanent magnet motor.

Position linearisation scheme for permanent magnet synchronous motor drive of washing machine using low‐resolution hall sensors

Variable speed systems have been widely applied to home appliances. One of the applications is vector control scheme of a washing machine using low-resolution hall sensors. Vector controller with binary-type hall sensors is cost effective. However, due to electrical and mechanical non-uniformity related to hall sensors, the position obtained by hall sensors does not change linearly, and resultant bumps in the position information degrade control performance. To solve this problem, a new position observer that generates linearly changing position signal is proposed. The proposed scheme removes necessity of knowing mechanical parameters and additional calculation process by utilising a Kalman filter for speed detection. The feasibility and effectiveness of the proposed algorithm are verified through experimental results carried out with a washing machine.

IJIREEICE - Electrical, Electronics, Instrumentation and Control

2 Abstract: A novel speed estimation approach with control system based on model reference adaptive control (MRAC) is presented for low cost brushless dc motor drives with low-resolution hall sensors. The back EMF is usually used to estimate speed. But the estimation result is not accurate enough at low speeds because of the divided voltage of stator resistors and too small back EMF. Moreover, the stator resistor is always varying with the temperature. A speed estimation algorithm based on MRAC was proposed to correct the speed error estimated by using back EMF. The proposed algorithms most innovative feature is its adaptability to the entire speed range including low speeds and high speeds and temperature and different motors do not affect the accuracy of the estimation result. The effectiveness of the algorithm was verified through simulations and experiments.

Model Reference Adaptive Control-Based Speed Control of Brushless DC Motors With Low-Resolution Hall-Effect Sensors

A control system with a novel speed estimation approach based on model reference adaptive control (MRAC) is presented for low cost brushless dc motor drives with low-resolution hall sensors. The back EMF is usually used to estimate speed. But the estimation result is not accurate enough at low speeds because of the divided voltage of stator resistors and too small back EMF. Moreover, the stator resistor is always varying with the motor's temperature. A speed estimation algorithm based on MRAC was proposed to correct the speed error estimated by using back EMF. The proposed algorithm's most innovative feature is its adaptability to the entire speed range including low speeds and high speeds and temperature and different motors do not affect the accuracy of the estimation result. The effectiveness of the algorithm was verified through simulations and experiments.

Driving and braking control of PM synchronous motor based on low-resolution hall sensor for battery electric vehicle

Resolvers are normally employed for rotor positioning in motors for electric vehicles, but resolvers are expensive and vulnerable to vibrations. Hall sensors have the advantages of low cost and high reliability, but the positioning accuracy is low. Motors with Hall sensors are typically controlled by six-step commutation algorithm, which brings high torque ripple. This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor (PMSM) based on low-resolution Hall sensors. Field oriented control (FOC) based on Hall-effect sensors is developed to reduce the torque ripple. The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed. The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing. The braking control algorithms based on six-step commutation and FOC are studied. Two variants of the six-step commutation braking control, namely, half-bridge commutation and full-bridge commutation, are discussed and compared, which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces (EMF), thus can deliver higher efficiency and smaller current ripple. The FOC braking is analyzed with the phasor diagrams. At a given motor speed, the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit, which is proportional to the motor speed. Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control, compared to six-step commutation braking control. Therefore, FOC braking is selected as the braking control algorithm for electric vehicles. The proposed research ensures a good motor control performance while maintaining low cost and high reliability.