Quantifying the commutation error of a BLDC machine using sensorless load angle estimation

BLDC motors are often used for high speed applications, for example in pumps, ventilators and refrigerators. For commutation discrete position information is necessary. This feedback is often provided by Hall sensors instead of more expensive encoders. However, even small misalignment of the Hall sensors in low cost BLDC motors can lead to unwanted torque ripples or reduced performance of BLDC motors. This misplacement leads not only to noise and vibrations caused by the torque ripples but also to lower efficiency. In this paper, a self-sensing technique to assess the misalignment is introduced. The objective is to obtain knowledge of the quality of the commutation by quantifying the misalignment. The method used in this paper is based on the fundamental components of voltage and current measurements and only needs the available current and voltage signals and electrical parameters such as resistance and inductance to estimate the misalignment

Rotor Position Identification for Brushless DC motor

Permanent magnet BLDC motors are characterized by a central magnetic core, called the rotor, and fixed electric coils (usually six) equally spaced in a ring around the core, called the stator. Motor movement is controlled by alternately energizing and de-energizing the stator coils to create a rotating magnetic field that propels the rotor. In order for this process to work correctly, BLDC motors required a technology called electronic commutation, in which the coil currents must be very carefully synchronized to rotor position to ensure that the rotating field is correctly aligned with the permanent magnetic field in the rotor. Usually rotor position is measured by external sensors such as Hall-effect sensors and optical encoders and these external sensors increase the system cost and reduces reliability. In order to control the price and make it more reliable this thesis propose to infer the rotor position from voltage and current measurement of motor. The most common approaches to sensorless control are based on the measurement of the electromotive force (back-EMF), that is induced by the rotor motion. As the back-EMF is nearly zero at very low speed and at stationary position, and can not be measured. Therefore a separate algorithm is required for start-up and control at low speed. The other method of sensorless control involves the inference of rotor position from the variation in inductance caused by rotor position. This thesis presents a prototype system for sensorless control of BLDC motors over the entire speed range of the motor, including stall (zero speed) conditions using the voltage and current signals from the motor

Design of a Printed Circuit Board for a Sensorless Three-Phase Brushless DC Motor Control System

The use of brushless motors has increased in recent years due to superior performance characteristics compared with alternatives. The operation of a brushless motor is dependent upon a separate controller which is often in the form of a printed circuit board. As such, the size and performance capability of the controller can restrict the performance of the overall motor control system so advancements of these controllers further the potential use of BLDC motors. This project outlines the design of a PCB based, sensorless motor controller for operation of a three-phase BLDC motor powered by a 24 V, high current external supply. Components used were selected to withstand an ambient temperature environment of 125 degrees C. The design for this PCB based motor control system was completed but fabrication and testing of the system was prevented by COVID-19 related restrictions that prohibited the use of necessary facilities and equipment. The detailed design including component selection, board layout, and software development is included in addition to a plan for fabrication and fundamental functional testing. Although no results are available for analysis to bring about any conclusions, a variety of design strategies and corresponding learnings hold the potential to be a source of valuable reference to the further study and development of future designs

Position Sensor-less and Adaptive Speed Design for Controlling Brush-less DC Motor Drives

This paper proposes a method for direct torque control of Brushless DC (BLDC) motors. Evaluating the trapezium of back-EMF is needed, and is done via a sliding mode observer employing just one measurement of stator current. The effect of the proposed estimation algorithm is reducing the impact of switching noise and consequently eliminating the required filter. Furthermore, to overcome the uncertainties related to BLDC motors, Recursive Least Square (RLS) is regarded as a real-time estimator of inertia and viscous damping coefficients of the BLDC motor. By substituting the estimated load torque in mechanical dynamic equations, the rotor speed can be calculated. Also, to increase the robustness and decrease the rise time of the system, Modified Model Reference Adaptive System (MMRAS) is applied in order to design a new speed controller. Simulation results confirm the validity of this recommended method

Design of a Three-Phase Brushless DC Motor Control System

In the past several decades, the Brushless DC (BLDC) motor has seen increased usage due to several distinct advantages over its brushed counterpart, including higher performance, increased reliability, and minimal maintenance requirements. However, the electronic commutation system of the BLDC motor creates the need for an accompanying electronic motor control system of increased complexity, adding to the overall cost of the BLDC motor and motor control system. As such, continued research and exploration in the area of BLDC motor control is necessary to continue to reduce the cost of BLDC motors and their corresponding motor control systems. This project focuses on the design of a motor control system for a Three-Phase Brushless DC Motor. A printed circuit board was designed for use in Three-Phase BLDC motor control and the design process was documented within this report. Due to an international IC shortage at the time of this project, fabrication was unable to be completed, however fabrication plans and cost estimation is included herein. Preliminary software modifications were tested to the extent possible with an off-the-shelf evaluation board, and future software modifications were outlined. Description of the hardware design and software development of this system is included in this report, as well as analysis of this system for future design, fabrication, and testing

Contribución en el ámbito de la tecnología sensorless para la detección de la velocidad y posición en motores dc monitorizando únicamente la corriente: mejora de la precisión, minimización del coste computacional y aplicabilidad a motores de alta potencia

Actualmente en muchas aplicaciones es necesario conocer la velocidad y posición de un motor. Esto puede ser conseguido mediante observadores convencionales como son encoders, tacómetros o resolvers, o mediante observadores sensorless. Los observadores sensorless son técnicas que miden la tensión y/o la corriente y estiman la velocidad y posición. En motores DC, los observadores sensorless se dividen en tres grupos, los basados en el modelo dinámico, los basados en la componente ripple y los basados en la combinación del modelo dinámico y la componente ripple. Este trabajo presenta tres nuevos métodos donde cada uno de ellos presenta una mejora frente a los observadores sensorless existentes que monitorizan únicamente la corriente para la estimación de la velocidad y/o posición. El primer método funciona en motores dc de baja potencia, se basa en la componente ripple e intenta minimizar el efecto del ruido. El segundo método funciona en motores DC de baja potencia, se basa en la componen ripple e intenta minimizar el coste computacional. El tercer método funciona en motores DC de alta potencia, en este caso una nueva teoría sobre las componentes espectrales de la corriente ha sido desarrollada, y en esta teoría se basa para realizar la estimación. Finalmente los tres métodos han sido testeados y medida su precisión dando como resultado que tienen una precisión aceptable.Departamento de Teoría de la Señal y Comunicaciones e Ingeniería Telemátic