Single-phase Brushless DC Motor Research Articles

An Initial States Recognition (ISR) Method for Start-Up of 1Ф BLDC Motor in Hall-Sensor-Less Fan Applications

The initial state is very important for a single-phase brushless DC (BLDC) fan motor when starting, especially in fan application with a nonstatic motor. The direction of self-rotation caused by the external thrust needs to be considered to avoid the starting fail or wrong running direction. This article proposes an initial states recognition (ISR) method to smartize the starting procedure. However, the self-rotation direction identification of single-phase BLDC motors is a challenge, which is even more difficult in some applications without rotor position sensors. The unequal air gap, which is designed by the geometric variation on the pole shoe to form the asymmetric stator, is generally the necessary design for the single-phase BLDC motor to dodge the null torque position (dead point) and determine the operation direction; and it will further form the asymmetrical waveform of the back electromotive force (EMF) voltage. The asymmetric distribution of back EMF waveform will be opposite in half cycle (positive or negative half cycle) with the rotation direction. The proposed ISR method utilizes this trait to achieve the self-rotation direction recognition before starting a dynamic single-phase BLDC fan motor. Finally, under the architecture of Hall-sensor-less control, the experimental results prove that the proposed method is reliable and feasible.

Investigation of Systematic Efficiency in a High-Speed Single-Phase Brushless DC Motor Using Multi-Physics Analysis for a Vacuum Cleaner

This paper discusses systematic efficiency considering the efficiency of both a motor and airflow in an inverter-driven single-phase brushless direct-current (BLDC) motor with two different lamination designs for a cordless vacuum cleaner. In other words, multi-physical lamination design has to be conducted, and hence, the shape and placement of a whole electromagnetic structure are investigated in terms of a tradeoff between the electrical and mechanical efficiencies. In this paper, a single-phase BLDC motor for cordless vacuum cleaners is designed to satisfy starting and continuous torques by means of asymmetric air gap, and fluid analysis is performed to determine which shape of a single-phase BLDC motor has better system efficiency. The prototype of a single-phase BLDC motor has been tested, and the speed of the operation is ranged from 84468 r/min up to the rated speed of 100020 r/min. The motor efficiency of 94.7% has been measured to verify a good match with the estimated efficiency of 94.5%.

Torque Ripple Minimization Control Technique of High-Speed Single-Phase Brushless DC Motor for Electric Turbocharger

The electrification of a forced induction system (FIS) has emerged as a feasible solution for low greenhouse gas emission and high fuel economy in passenger cars and light-duty trucks. A high-speed electric motor in conjunction with the conventional FIS has numerous benefits including better transient response and higher engine output power. A single-phase brushless dc (BLDC) motor possesses a number of attractive features for this application including high efficiency, low cost, robustness, and high-speed operation capability. However, it generates higher torque ripple than that of three-phase BLDC motor due to the lack of alternate phases and phase current distortion. This paper proposes a new torque ripple minimization control technique, which has a linearly decreasing reference voltage to regulate phase current. The analytical estimation and experimental results verify that the new control technique reduces the motor vibration while improving the maximum speed and the efficiency of the motor drive.

Comparative Performance Analysis of Reference Voltage-Controlled Pulse Width Modulation for High-Speed Single-Phase Brushless DC Motor Drive

The recent advancements in power switching device material and manufacturing technology have enabled the design of highly efficient and compact high-speed motor direct drives. The use of high-switching frequency pulse width modulation in these drives provides speed and torque control capabilities and it can also serve as an effective phase current shaping method for torque ripple minimization. This paper builds upon the previous paper introducing a torque ripple minimization technique for gallium nitride high-electron mobility transistor-based high-speed single-phase brushless dc motor drive. It presents an in-depth performance analysis in comparison with the conventional high-speed control techniques. Four different high-speed control techniques are implemented and tested to quantify the maximum speed, efficiency, torque ripple, and vibration. The vibration of the motor drive is measured using a microelectromechanical systems accelerometer with a ferroelectric random access memory for high-speed data acquisition with the maximum bandwidth of 1 kHz.

Cogging Torque Reduction of Single-Phase Brushless DC Motor With a Tapered Air-Gap Using Optimizing Notch Size and Position

This paper reports a stator shape optimization design for reducing the cogging torque of single-phase brushless dc (BLDC) motors by adopting an asymmetric air-gap to make them self-starting. A time step 2-D finite-element analysis (FEA) was carried out to analyze the characteristics of the single-phase BLDC motor. The Kriging model combined with Latin hypercube sampling and a genetic algorithm were used to reduce the cogging torque and maintain the efficiency and torque. As an optimal design result, the cogging torque of the optimal model was reduced. Finally, the analysis and optimal design results were confirmed by FEA as well as by experimental results.

Design Constraints of Small Single-Phase Permanent Magnet Brushless DC Drives for Fan Applications

Permanent magnet brushless dc (BLDC) machines are widely used due to various advantages such as high efficiency and high torque density, and therefore compactness as well as long expected lifetime. All of these benefits are of major interest when designing a drive for a small fan application of a few watts. This paper presents the design investigations of a small single-phase BLDC motor for such an application. Notably, it discusses different constraints which arise during the design process and which may be of special relevance due to the particular given power level and application.

단상 BLDC 전동기의 코깅토크 저감을 위한 고정자 형상 최적설계

This paper proposes the optimal design of stator shape for cogging torque reduction of single-phase brushless DC (BLDC) motor with asymmetric notch. This method applied size and position of asymmetric notches to tapered teeth of stator for single-phase BLDC motor. Which affects the variation of the residual flux density of the permanent magnet. The process of optimal design included the extraction of the sampling point by using Latin Hypercube Sampling(LHS), and involved the creation of an approximation model by using kriging method. Also, the optimum point of the design variables were discovered by using the Genetic Algorithm(GA). Finite element analysis was used to calculate the characteristics analysis and cogging torque. As a result of finite element analysis, cogging torque were reduced approximately 39.2% lower than initial model. Also experimental result were approximately 38.5% lower than initial model. The period and magnitude of the cogging torque were similar to the results of FEA.

환풍기용 외전형 단상 브러시리스 직류전동기 개발

This paper is development of single-phase brushless DC motor with outer rotor for ventilation fan. Cogging torque causes the noise?vibration to greatest impact on ventilation fan. Asymmetric notches are applied to tapered-teeth for cogging torque reduction of single-phase brushless DC motor. Initial model is notchless and proposed model is applied 2 asymmetric notches. The proposed method is proved motor characteristic through finite element analysis(FEA). Also, experimental results verify that the proposed model considerably reduces cogging torque and have the good sound quality in ventilation system.

Optimal Control for Single-Phase Brushless DC Motor with Hall Sensor

This study deals with the optimization control of a single-phase brushless DC motor (BLDCM) with Hall sensor. A simple modeling method with feasible parameter identification is adopted to meet characteristics of single-phase BLDCM. With the linear Hall sensor feedback, the advantages of current-mode control scheme and soft-commutation scheme are proposed to achieve maximum efficiency over the entire speed range. This thesis also develops a low-cost and high efficiency control for single-phase BLDCM. The hardware test platform has been constructed on a single-chip Field Programmable Gate Array (FPGA) of Cyclone II Family of Altera to verify the performance and feasibility of the proposed optimization control strategies. When using the control scheme with Hall sensor, experimental results show that there are at least a 10% improvement for average value of dc-link current, a 10% improvement for RMS value of phase current and a 40% improvement for peak value of phase current.

A Single-Phase Brushless DC Motor With Improved High Efficiency for Water Cooling Pump Systems

This research deals with the optimization of a single-phase brushless DC motor (BLDCM) by substituting a commercial single-phase BLDCM for pump application in order to satisfactorily improve its efficiency regarding the required performance of a motor for pump systems (pump load 1,800 rpm, at 2 Nmm). The reliability of the results is verified between simulation and experiment using performance tests. In the sampling process, latin hypercubic sampling (LHS), the subject of many experiments, is usually used. However, this method requires a great deal of time and expense. This paper utilizes the table of orthogonal array in order to use the smallest possible number of experiments. In addition, a metamodel with second approximation polynomials is made using response surface methodology (RSM). The adjusted coefficients of multiple determinations which shows the reliability of the metamodel (multiobjective functions) is 100%. This result shows that the table of orthogonal array with the smallest number of experiments is suitable for sampling. The genetic algorithm (GA) is implemented to search for optimum solutions on the constructed metamodel which consists of two objective functions. With the optimal design set, predicted results of the GA are better than the generalized reduced gradient (GRG) algorithm. Nevertheless, verification results of the GRG are better than the GA. This result has an error within 1%.

Optimal Driving Efficiency Design for the Single-Phase Brushless DC Fan Motor

One of the methods to improve efficiency and torque performance of the single-phase brushless DC (BLDC) motor is to find out the optimum commutation angle at each different speed. We used the finite-element method (FEM) to simulate the back-EMF voltage and the coil current for the single-phase BLDC motor, and then adjust the conduction time of switches by detecting the waveform of coil current. The motor can improve its efficiency, noise, and vibration when it obtains the optimal shift angle of each speed. We used PSPICE to verify the exactness of FEM simulation results of the single-phase BLDC motor. We adopted Microchip's dsPIC30F4011 digital signal processor (DSP) to process the Hall signal and the driving signals of switches of the driving system prototype of the single-phase BLDC fan motor. Finally, we used the related experimental results to confirm the feasibility and effectiveness of the proposed driver.

Properties of Cogging Torque, Starting Torque, and Electrical Circuits for the Single-Phase Brushless DC Motor

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A single-phase brushless dc motor requires an asymmetric air gap to eliminate the dead point where the excitation net torque is zero. In this paper, we use the finite-element method (FEM) to analyze the properties of cogging torque, starting torque, and electrical circuits. Others have discussed the influences of various asymmetric air gaps on these properties. However, the optimum asymmetric air-gap condition is very difficult to find. Here, we describe an optimum asymmetric air-gap structure that not only produces an optimum starting torque but also reduces the cogging torque to a tolerable range. We compare simulation results with the measurement results to illustrate the accuracy of the FEM model. </para>

Drive of Single-Phase Brushless DC Motors Based on Torque Analysis

The high torque peaks commonly found in single-phase brushless dc motors can be compressed by different driving methods, which are proposed and studied based on finite-element analysis (FEA). It is concluded that one dead-zone can be added into the driving signals to improve current waveforms and torque envelope. The test results show that the noise level and performances are greatly improved when one proper dead zone is implemented

Novel topology of unequal air gap in a single-phase brushless DC motor

Most single-phase brushless DC (BLDC) motors have unequal air gaps to eliminate the dead point where the developed torque value is zero. These unequal air gaps deteriorate the motor characteristics in cogging torque. Thus in this paper a new topology of the unequal air gaps is proposed to solve this problem. As a result, it is proved by the finite element analysis and experimental results that the proposed air gap topology is very effective in reducing the cogging torque.

A new type single-phase spindle motor for HDD and DVD

The cogging torque and dynamic performance of a newly designed single phase brushless DC motor have been investigated in this paper. The single phase brushless spindle motor is usually applied for cooling fan, pump and blower before the performance is improved by the reengineering process. The stator configuration and the drive circuit have been remodeled in order to meet the requirements of the spindle motor used in the DVD and HDD applications. The cogging torque is reduced to 18 g-cm by the salient pole reshaping. An automatic phase adjuster is also introduced to improve the performance of the dynamic characteristics of a single phase spindle motor in this paper. According to the test results, the maximum speed could be increased from 6500 rpm to 12000 rpm and the efficiency from 22% to 38%. A single phase motor has been demonstrated successfully in HDD and DVD applications by reshaping for the salient pole and phase adjusted automatically with the rotation speed.

Cogging torque reduction of a single-phase brushless DC motor

In this research, the cogging torque of a newly designed single-phase brushless DC motor used in CD-ROM application is investigated. A finite element method is employed to numerically analyze the magnetic field distribution inside the motor, in which a three-dimensional mesh is constructed. The torque due to the magnetic coupling between the rotor and stator is estimated based upon the virtual work concept. It is proposed in this paper that the salient pole be divided into several regions in the azimuthal direction. By properly choosing the radii for these regions, the cogging torque can be greatly reduced.

Analysis and Modeling of a Single-Phase Brushless DC Motor Drive System

Brushless dc motors are becoming widely used in low-power applications such as blower motors, computer disk-drive spindle motors, and in copiers and laser printers. For these applications, the brushless dc motor offers the following advantages: small size, reliability, no carbon dust from brushes, precise speed control, and potentially high efficiency. The most commonly used brushless dc motors are twoor three-phase permanent-magnet ac machines driven by a dc-to-ac inverter. The three-phase machine combined with a six-pulse full-bridge inverter often represents the best trade-off of machine iron and copper utilization with the cost of the inverter. Because of the prevalence of two-and three-phase devices, they are the brushless dc motors which have been analyzed the most extensively. On the other hand, there has been little investigation into the operation of the single-phase brushless dc motor. Single-phase motors, in general, suffer from slower starting characteristics, less efficient utilization of machine iron and copper, and higher losses. Therefore, single-phase motors are limited to low-power applications where rapid response and high efficiency are not required. The primary advantage of single-phase devices is the simplified source requirements. For example, a single-phase brushless dc motor requires only one-third the number of transistors and position sensors needed by a three-phase motor and can be powered by a single dc voltage source. Thus, in applications where cost is of greater importance than performance, the single-phase motor may be a superior alternative to a two-or three-phase motor.

Analysis and modeling of a single-phase brushless DC motor drive system

A single-phase brushless DC motor drive system with a bifilar stator winding and asymmetrical stator pole faces is investigated. The form of the permanent-magnet component of the stator winding flux linkage is analyzed considering the asymmetry of the stator pole faces. Equations describing the electromechanical dynamics of the motor are then derived along with an expression for the electromagnetic torque. These equations are expressed in state-model form, and a mathematical model of the inverter is developed for use in a computer simulations. The computer simulation is used to demonstrate steady-state and dynamic operation of the motor. Comparison of simulation results with measurements of an actual motor-inverter system indicate that the computer model is reasonably accurate.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>