Brushless DC Permanent Magnet Motors State of the Art

The paper presents a study of the permanent magnet brushless DC machine, from two perspectives - from authors’ own experience in designing and manufacturing such motors, as well as from actual published research. Various constructive topologies and how they influence BLDC operation, windings used with emphasis on slot, concentrated windings, are also presented. The following part describes current techniques used for enhancing BLDC limited maximum speed, such as phase advance and dwell control, somewhat similar to flux weakening in AC permanent magnet brushless motors. The paper concludes with presentation of several methods used for sensing BLDC rotor position. Overall, the authors’ intention publishing this paper was to provide an insight regarding current BLDC development, as well as to assist in making documented choices when using BLDC in specific applications.

A Simple Brushless Motor and Propeller Test Stand for Experiment from Home

A brushless motor and propeller test stand is used to test brushless motors and propellers. This testing instrument is still only available in research laboratories. Students and researchers are unable to use laboratory facilities because of the Covid-19 epidemic, thus students must be able to do tests independently from home. Purchasing this testing instrument would be too expensive for students. It is essential to construct a brushless motor and propeller testing instrument at home using simple components that are easy to get on the marketplace. The design concept reads force data using a loadcell sensor and an HX711 driver, and current and voltage data with an INA 219 sensor. The brushless motor’s rotational speed is controlled by a potentiometer. Force, current, voltage, and power are all examples of test results data. A 16×2 LCD is used to show data immediately. Data is also transmitted via a USB connection to a computer device for storage or additional analysis. This study proposes a simple brushless motor and propeller test stand that can measure forces from 0 gf to 1000 gf with an error rate of 0.72 %. The power that can be read ranges from 0 mW to 18960 mW, with a 0.59 % error rate.

Experimental studies of single rotors noise of small scale

The work experimentally investigated the characteristics of the noise of large-scale isolated rotors on small-scale models. The experimental rotor model was based on the F7 / A7 design developed by General Electric. The small diameter rotors were 3D printed and powered by brushless DC motors. The studies were implemented at a speed of up to 8500 rpm. Far-field acoustic measurements were performed in a noise-damped anechoic chamber. The noise characteristics of the brushless motors used in the experiments were investigated separately. For brushless motors, the main component is mechanical noise at the speeds of the motor shaft and its harmonics. For a uniaxial electric motor, the mechanical noise at the shaft speed increases with an increase in the rotational speed, while the noise at its higher harmonics decreases. The study of the coaxial electric motor showed an increase in mechanical noise at the higher harmonics of rotation. In experiments with insulated rotors, the tonal and broadband noise content was recorded. The study showed that with an increase in the rotational speed of a single rotor, the noise level rises from 65 to 80 dB. In this case, the maximum sound pressure shifts towards higher frequencies.

Directional Camera Control on High Altitude Balloons

The research reported in this paper examined the design and control of a gimbal for solar eclipse tracking and video recording. The gimbal design required 3 axes of rotation to allow for a full range of motion. Utilizing individual brushless motors for each of the axes ensures minimum rotational requirements on each axes. In controlling the gimbal, both a mathematical and visual method was utilized. The mathematical method is a modeled version of what is currently used for solar array pointing. The visual method looks at where the position of the sun is within the image and determines what angle changes are required. Utilizing a combination of these methods helps to eliminate error that accumulates within the onboard gyros due to the erratic behavior of balloon motion during flight. Elimination of this error ensures accurate video recording of the solar eclipse.

Characterization of small Brushless motors for unmanned aerial vehicles/ Caracterização de motores Brushless de pequeno porte para veículos aéreos não tripulados

Brushless motors are increasingly present in our lives and to get the best out of them it is important to know their performance. The objective of this work is to create a methodology of experimental characterization of this type of motor. As a methodology, research was done on similar works, it was built a test bench and an acquisition system to obtain the data. The variables measured were: rotation, torque, temperature, current and voltage. In addition to possessing a servo motor that acts like brake prony type to vary the load applied to the system. The results obtained allowed the analysis of the motor performance. It was also possible to design a mathematical model that represents the system, using the information obtained and the equations present in the literature. It was possible to conclude that the bench and the methodology used were valid, and that the ESC (electronic speed controller) is a great efficiency limiter of the motors.

Performance Analysis of Brushless Motors with Segmented Cores considering Manufacturing Constraints

Brushless servomotors are widely used in industry and in all domains that require precise and easy position/speed/torque control. To further improve the performance of these motors, the segmentation of the stator core is taken into account. This approach to core construction provides a high slot fill factor, compact design, and efficient use of materials. This paper aims to present that the manufacturing constraints and tolerances of this particular core construction can increase unwanted effects in brushless motors, like cogging torque, torque ripple and their influence regarding the back-EMF. Two models for a 12slots-10 pole configuration, one with segmented core and one with standard laminated core are compared and analysed using the FEA (Finite Element Analysis) method. The influence of the additional air gaps that occur in such constructions is investigated to provide an overview for the design of segmented motors. Various lengths for air gaps between the segments of the core are taken into consideration and non-uniform distribution of such gaps. The paper also provides further steps that must be taken in order to verify/validate the studied model’s impact on motor design.

Experimental study and thermal analysis of cooling systems for brushless motors with double stator and axial gap

The results of experimental research and thermal analysis of several types of cooling of brushless electric motors with nominal power 10-12kW (PMAC), suitable for ?light? EV/HEV vehicles are presented in the research paper. The studied motors have permanent magnets, a double stator and an axial magnetic flux with air or liquid cooling. The Motor-CAD software performed the presented thermal analysis. The experimental study was made on the basis of precision results, obtained from the measurement of process temperatures during operation in a real-world environment. For this purpose, the electric motors were equipped with a number of thermocouples with which the temperatures are measured. The precise measurement and recording of the heat flux temperatures is performed using LabVIEW software. The calculations from the thermal analysis coincide with the experimental results and can be used to predict the heat fluxes in different designs and types of cooling systems. The possibilities for improving the cooling and power of standard PMAC electric motors with double stators have been studied and analyzed.

A controller for brushless direct current electric motors. Part 2. Software

A universal controller for brushless direct current (BLDC) motors was designed in the presented article. The system is controlled from the user console where operating parameters are set by the user. Signals are transmitted by cables to microcontrollers which control and monitor electric motors. Microprocessors communicate via a data bus. The controller contains the user console module and the motor control module. The user console module generates commands, and motors are controlled and monitored by the control module. Motor control modules operate independently, and each brushless motor has a dedicated control module. Brushless motors can be controlled in bipolar or unipolar mode. The control method is selected by the operator. The user console and motor controllers communicate via the I²C bus.