Permanent Magnet Brushless Motor Research Articles

Design of Novel Shaftless Pump-Jet Propulsor for Multi-Purpose Long-Range and High-Speed Autonomous Underwater Vehicle

Owning to its extremely long endurance, small size, cost-effective employment, easy, and fast transported properties, the merits of autonomous underwater vehicles (AUVs) exceed those of manned underwater vehicles. Therefore, it has become an indispensable member in navies throughout the world, as well as with oceanographic research, commercial resource explorations, and especially the underwater search and rescue (SAR) sectors. Up to date, the tragic MH370 and QZ8501 flight incidents have dramatically increasing the awareness of high-performance SAR equipment, which in turn will stimulate the states party to the incident to urgently upgrade their shallow- and deep-sea SAR equipment. To extend the range (endurance) and shorter the searching period for the next generation SAR AUV, a sea water cooled high-power density magnetically slotless permanent magnet brushless motor is proposed and integrated with pump-jet’s impeller to achieve designated shaftless pump-jet propulsor. In this paper, the developed shaftless pump-jet propulsion system is applied in Naval University of Engineering series multi-purpose long-range and high-speed deep-sea AUV, which could provide excellent performance as a SAR platform.

Improved Fault-Tolerant Control for Brushless Permanent Magnet Motor Drives With Defective Hall Sensors

Brushless permanent magnet motor drives based on Hall sensors have received significant attention in recent years. In this area, the faults of Hall sensors become a new concern and several fault-tolerant control (FTC) methods have been proposed. However, most of the state-of-the-art FTC methods require some time to reconstruct the correct Hall sensor signals, which results in significant transient currents and speed dip during fault diagnostic process (FDP). In this paper, a new and improved FTC scheme based on FDP and vector-tracking observer is proposed. A method to identify the duration of FDP is proposed based on the analysis of acceleration estimation and the fault diagnosis results. During FDP, the method defaults to an open-loop observer control, which removes the undesirable current/torque transient. After that, the close-loop observer is re-enabled and the motor operation is restored. The proposed FTC is demonstrated in detailed simulations and experimentally on 120° brushless dc motor drives and sinusoidal PM motor drives. For both types of drives, a significant improvement is achieved in steady state and transient operation with faults of up to two Hall sensors, which has not been possible with available alternative FTC approaches (unless a sensorless control is used).

General formulation of winding factor for fractional‐slot concentrated winding design

Fractional-slot winding configurations have attracted much attention due to the availability of concentrated windings and low cogging torque in permanent magnet brushless motors. For the design of the winding configurations, many design parameters must be determined. The winding factor provides a useful index for the optimal design. However, no general expressions of the winding factor have been derived for all the winding configurations. This study performs the general formulation of the winding factor for the fractional-slot concentrated windings. The winding factor is redefined for stator windings without any information of the numbers of poles. For given stator windings, the optimal numbers of poles are determined from the obtained winding factors. The design strategy for the winding configurations is validated through a finite element method analysis.

Fault Diagnosis and Signal Reconstruction of Hall Sensors in Brushless Permanent Magnet Motor Drives

Brushless permanent magnet (BLPM) motor drives based on Hall sensors have received extensive attention in the literature and are widely used in many applications. However, most of the available and published controllers assume that the Hall signals are always available, which is not true if any of the sensors are faulted. In this paper, several fault-tolerant control schemes for BLPM motor drives are proposed. The methodology is based on fault diagnosis and its classification, and subsequent signal reconstruction. Simulation and experimental results demonstrate the effectiveness and advantages of the proposed fault-tolerant schemes in restoring the motor operation when failures occur in up to two Hall sensors. The proposed fault-tolerant schemes can be easily and flexibly realized for conventional drive systems, either by adding the code in the existing driver or by adding a simple auxiliary circuit between the Hall sensors and the driver.

Permanent magnet brushless motor control based on ADRC

Permanent magnet brushless motor is a nonlinear system with multiple variables, the mathematical model of Permanent magnet brushless motor is difficult to establish, and since that the classic PID control is hard to precisely control the motor. Active disturbance rejection control (ADRC) technique is a new nonlinear controller which does not depend on the system model. It is starting from the classic PID control, and establishing the loop control system by error negative feedback, the ESO(extended state observer) observing system which comes from the observer theory of modern control theory to observe internal and external perturbations. ADRC inherits the advantages of PID with little overshoot, high convergence speed, high accuracy, strong anti-interference ability and other characteristics, and it has a strong disturbance adaptability and robustness as for the uncertainty perturbation and their internal disturbance of control objects. Therefore, This paper attempts to use Active disturbance rejection control(ADRC), in order to improve the control of permanent magnet brushless motor. In this design of control system, the simulation of the system is realized based on MATLAB, and then the discrete control algorithm is transplanted to the embedded system to control the permanent magnet brushless DC motor (PMBLDCM). The control system is implemented on the DSP-F28335 digital signal processor, and the DSP also provides the functions like voltage and current AD sampling, PWM driver generation, speed and rotor position calculation, etc. The simulation and experiment results indicate that, the system has good dynamic performance and anti-disturbance performance.

Sensorless Sine-Wave Controller IC for PM Brushless Motor Employing Automatic Lead-Angle Compensation

This paper presents an advanced sensorless permanent magnet (PM) brushless motor controller integrated circuit (IC) employing an automatic lead -angle compensator. The proposed IC is composed of not only a sensorless sinewave motor controller but also an isolated gate -driver and current self-sensing circuit . The fabricated IC operates in sensorless mode using a position estimator based on a sliding mode observer and an open-loop start-up. For high efficiency PM brushless motor driving, an automatic lead angle control algorithm is employed, which improves the efficiency of a PM brushless motor system by tracking the minimum copper loss under various load and speed conditions. The fabricated IC was evaluated experimentally using a commercial 200 W PM brushless motor and power switches. The proposed IC was successfully operated without any add itional sensors , and the proposed algorithm maintained the minimum current and maximum system efficiency under 0 to 0.8 N∙m load conditions. The proposed IC is a feasible sensorless speed controller for various applications with a wide range of load and spee d conditions.

Optimal current waveforms for brushless permanent magnet motors

In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.

Imbalanced Force in Permanent Magnet Brushless Motors With Magnetic and/or Electric Asymmetries

In a permanent magnet brushless (PMBL) motor, any special structural design in the stator lamination may induce asymmetry in the magnetic circuit to result in intrinsic imbalanced force. Likewise, an asymmetrical phase winding arrangement may also induce imbalanced force in the motor when the armature currents are flowing. This paper presents the analysis of the imbalanced forces of two PMBL motors in an electric coolant pump system with magnetic and/or electric asymmetries using both numerical simulation and prototyping test. The results confirm the validity of force calculation method and illustrate the contributions of magnetic and electric asymmetries to the imbalanced forces in PMBL motors.

Comparative Research of 240-Coil Permanent Magnetic Brushless Motor with or without Potting Compound

In the design and analysis of motors, the issue of heat transfer is an important subject because it is relevant to the motor’s size and life. So, this study used an experimental design with the Taguchi Method to understand performance of epoxy resin on permanent magnetic brushless motors with 240 coils. The objects used for the experiment were a permanent magnet brushless motor with a 240 coiling number and a potting compound. The experiment was conducted to explore effectiveness of potting to reduce temperature. The Taguchi Method was applied to determine the optimal sample combination to obtain maximal experimental effectiveness by minimal test frequency. The results revealed from this study were positive for potting compound to transfer heat.

Optimisation Design of a Taguchi-Based Real-Code Genetic Algorithm for Thermal Reducing of Air-Core Linear Brushless Permanent Magnet Motor

This study combined the Taguchi method with the genetic algorithm (GA) to analyse the optimal design parameters of the thermal distribution in an air-core linear brushless permanent magnet motor (ALBPMM). First, this study adopted an L18(21×37) orthogonal array to determine the significant factors, including active currents, the length of magnets, pole distance of magnets, air-gap length, and thickness and width of coils. Then, the study uses response surface methodology (RSM) to construct the predictive model. Finally, the optimal combinations of design parameters that involve using real-code GA were obtained and verified by finite element modelling. The simulation results show that the thermal distribution in the optimal design of parameters is 41% more effective than that of any models in which the parameters are not optimised. Therefore, the proposed approach can be used as the basis for designing and predicting the temperature effects of the ALBPMM..

Design of a six-speed transmission hub with an integrated brushless permanent-magnet motor used for electric bicycles

Purpose – The electric motor and multi-speed transmission hub are essential components for an electric bicycle. Traditionally, these two devices have been designed and manufactured independently. The purpose of this study is to propose a novel electromechanical device that artfully integrates an exterior-rotor brushless permanent-magnet (BLPM) motor into a transmission hub to become a compact structural assembly. Design/methodology/approach – A novel design that integrates a three-phase, 20-pole/18-slot exterior-rotor BLPM motor with a multi-speed transmission hub composed of a six-link, two-degrees-of-freedom (2-DOF) compound planetary gear train (PGT) is presented in this study to overcome inherent drawbacks of existing designs. An analytical approach, based on fundamental circuits, is developed to synthesize the clutching sequences and numbers of teeth of all gears of the PGT. Findings – The integrated device provides six forward speeds, including two underdrives, two direct drives, and two overdrives, as well as two drive modes: the motor-drive mode and the human-drive mode, for electric bicycles. The main feature of the proposed design is the spur gear teeth merged with the pole shoes of the stator to dramatically minimize the detent torque, which is an oscillatory torque that always induces vibration and acoustic noise of the BLPM motor. Originality/value – The gear teeth on the pole shoes of the stator provide functions not only for transmission, but also act as dummy slots for adjusting the magnetostatic field of the BLPM motor to effectively reduce the detent torque. The peak value of the detent torque of the integrated design is only 9 percent of the original BLPM motor with identical magnet properties and motor dimensions. Such a feature is contributive in suppressing the vibration and acoustic noise of the electric bicycle's BLPM motor. A BLPM motor rated at 310 W and 250 r/min for the integrated device is presented and analyzed by using the commercial finite-element package Ansoft/Maxwell 2D Field Simulator.

Simulation of Brushless DC Motor Speed Control Using Phase Locked Loop Based on Noise Analysis

Based on analyzing the brushless dc motor (BDCM) mathematical model, the BDCM block is built. The speed of the motor is calculated through torque equation. And the back electromotive force (EMF) is obtained by using the piecewise linear method. The permanent magnet brushless motor speed control system is established using phase locked loop (PLL) technology on the basis of the BDCM model in SIMULINK. Two typical noise which will cause speed fluctuations: random load interference and power line interference in motor running is simulated in the control loop. Simulation results clearly show that the PLL control scheme acquires speed accuracy reaching about 1%, which outperforms ordinary speed-current proportional-integral (P-I) regulator control system. It also illustrates that proposed PLL solution has good rejection ratio to noise as the PLL having good linear filtering characteristics of interferences.

Rigorous Design and Optimization of Brushless PM Motor Using Response Surface Methodology with Quantum-Behaved PSO Operator

In this paper, a rigorous design of a brushless permanent-magnet (PM) motor with both lower cogging torque and higher efficiency, using response surface methodology (RSM) with a quantum-behaved PSO (QPSO) operator for a portable electric power drill application, has been presented. To decrease noise and vibration of a slotted PM motor, cogging torque must be reduced. Some skew techniques have obvious advantages of reducing cogging torque. In particular, the stepped equivalent model with its cost-effectiveness can be employed to design a high-performance PM motor for portable electric power drills in this paper. To find the most suitable combination of the geometric parameters of a brushless PM motor with skewed magnets to achieve the design goal, the RSM with a QPSO operator is employed. The 3-D finite element method (FEM) is employed as the tool for analyzing the cogging torque and performance of the proposed PM motor. The experimental results show that the proposed method can obtain the best combination of the geometric parameters for reducing the cogging torque and enhancing the operating efficiency.

Improved Angular Displacement Estimation Based on Hall-Effect Sensors for Driving a Brushless Permanent-Magnet Motor

We propose an improved method for angular displacement estimation based on Hall-effect sensors for driving a brushless permanent-magnet (PM) motor. The control current with an angle that leads the back electromotive force is then determined to extend the speed range of the motor. Traditionally, Hall-effect signals are measured by both the capture interrupt and periodic timer interrupt functions before the angular displacement is precisely estimated with a digital signal processor. Unfortunately, the capture interrupt function is highly sensitive to external noise. The proposed method retains the periodic timer interrupt function and simplifies the estimation operation, so that the controller is robust to external disturbances. We used the improved method to adjust the phase lead angle for driving both a surface-mounted-PM motor and an interior-PM synchronous motor. Experimental results show that the improved angular displacement estimation effectively rejects noise and is 2.9 times faster than the traditional approach.

Finite Element Modeling of Five Phase Permanent Magnet BLDC Motor for High Power Density Application

Fault-tolerant capability of electrical motor drives is an essential feature in applications such as automotive, aeronautic, and many others. A multi-phase permanent-magnet BLDC motor exhibits a high fault tolerant capability hence increasing the reliability, as it can be designed to reduce the fault occurrence as well as to operate indefinitely in the presence of fault. With multi independent phases, in the event of failure of one or more, the remaining healthy phases let the motor to operate properly. This paper presents finite element modeling and results of a five-phase permanent magnet brushless motor designed for high power density application. DOI: http://dx.doi.org/10.11591/ijpeds.v3i4.4184

Nonlinear Adaptive Lumped Parameter Magnetic Circuit Analysis for Spoke-Type Fault-Tolerant Permanent-Magnet Motors

This paper proposes a nonlinear adaptive lumped parameter magnetic circuit (LPMC) model for a new spoke-type fault-tolerant permanent-magnet (ST-FTPM) brushless motor. The LPMC method, which reduces the total computational time greatly, can be used as a finite-element method (FEM) assistant design tool. Hence, it is used to calculate the flux linkage, back-electromotive force (back-EMF), inductance, and torque performance of the ST-FTPM motor. The novelty of this paper is to predict short-circuit current based on the developed LPMC model. Meanwhile, in order to ensure the analytical accuracy, the magnetic saturation is considered in the model design. The effectiveness of the presented LPMC model is verified by FEM and the experiments.

Analytical Calculation of Slotless Permanent Magnet Motor Based on Soft Ferrite

High-speed slotless permanent magnet brushless motor based on soft ferrite adopts a large effective air gap structure. For the large effective air-gap, the air-gap flux distribution becomes uneven and the end leakage flux significantly increases. Thus, the traditional analytical method of the phase EMF is inapplicable. This paper deduces the analytical expression of the phase EMF based on the analytical calculation of the air-gap field and analyzes the distribution of the end leakage flux by 3D finite elements methods. Then the end leakage flux is considered by a correction factor of the core length. Finally the analytical calculation method is proved to be feasible by the comparison between the finite elements results and the prototype test results.

A Novel Rotor Position Detection Method for Sensorless Control of Magnetic-Geared Permanent-Magnet Brushless Motor

This paper presents a novel rotor position detection method for sensorless control of magnetic-geared permanent-magnet brushless motor. Instead of use of traditional position sensor such as encoder and resolver, two special sensor windings are installed in the stator slots to replace the position sensors. A magnetic-geared permanent-magnet brushless motor has been designed and simulated to verify the validity of the proposed method. The result shows that this novel rotor position detection method is compact, effective and it can be used for sensorless control of magnetic-geared permanent-magnet brushless motor.

Estimation of commutation instances using back emf mapping for sensorless control of brushless permanent magnet motors

This study presents a novel sensorless scheme to control brushless permanent magnet motors using back emf mapping with six-step control. All commutation instances, corresponding to 30 electrical degrees, at various speeds can precisely be calculated using a single known reference slope and a back emf point considered at the same speed. Zero crossing detection point (ZCP), phase shifters, delay managers, integration and third harmonics, hard switching techniques and/or look-up table are eliminated. This increases the signal to noise ratio and overcomes some cases where ZCP could be undetected. Simulation and experimental work on six-step controlled permanent magnet synchronous motors validate the proposed approach.

Conceptual Design of Integrated Brushless Permanent-Magnet Motors and Planetary Gear Trains

Integrated designs of brushless permanent-magnet (BLPM) motors and basic planetary gear trains (PGTs) are described in this paper. The kinematic characteristics of the basic PGT and the typical topologies of the BLPM motor are studied first. Then, design requirements are concluded to rationalize the integrated designs. Four novel integrated devices with interior and exterior topologies are synthesized subject to design requirements. The unique characteristics and application fields of the proposed designs are also indicated.