Claw Pole Research Articles

Analysis on Noise Source of Claw Pole Machine in Duplex Three-Phase and Belt-Driven System

The acoustic noise, which is generated in a belt-driven integrated starter and generator (BSG) system, is the recent issue. By many studies, it has been known that the noise can be caused by both radial and tangential components of electro-magnetic force. A duplex three-phase claw pole type machine is widely used in the BSG system. In this case, due to its structural feature and difficulty in control, additional noises at unexpected frequency can be generated. In this paper, a method to analyze noise sources was proposed and applied to a prototype that is the duplex three-phase and claw pole type machine designed for BSG system. First, the electro-magnetic force was calculated by a finite-element analysis considering the unbalanced current measured by the experiment. The obtained force was decomposed according to the frequency and then analyzed. Through the force harmonics, additional noises according to the frequency, which are generated by the unbalanced claw shape in the axial direction and current imbalance between phases, were deduced. Finally, the predicted noise sources were compared with the noise measured through the experiment.

Design and Analysis of a Dual‐Direction Hybrid Excitation Generator

With the wide use of new energy vehicles, the research and development of high‐performance generators become more important. The claw pole machine is very suitable to be used as an automobile generator because of its unique characteristics. However, its development is limited by the disadvantage of abundant harmonic content, especially when used with fractional slot concentrated winding layout. A novel dual‐direction hybrid excitation generator (DDHEG) is proposed in this paper. It has dual 3‐phase winding layout to reduce spatial subharmonic magnet motive force (MMF). Also, it uses dual 3‐phase rectifier bridge circuit to reduce armature current, so as to reduce copper loss. It uses rotor sleeve to reduce the eddy current loss in the rotor and permanent magnets (PMs) caused by higher order harmonics. It has hybrid excitation from both directions to improve the efficiency and terminal voltage. The basic characteristics of DDHEG are analyzed by finite element analysis (FEA) method. The highlights of the proposed DDHEG are illustrated. The simulation results and experimental results reveal that the proposed DDHEG can effectively adjust the terminal voltage at different loads and reduce the harmonics and loss to a satisfied degree. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Optimization Design and Performance Evaluation of a Hybrid Excitation Claw Pole Machine

Claw pole machines (CPMs) have the advantages of a simple structure and low cost; therefore, they are commonly used in electric vehicles (EV). However, the methods to improve reliability and efficiency should be studied. So, a new type of hybrid excitation claw pole machine (HE-CPM) for EV is proposed. The permanent magnet (PM) is inserted in the rotor, and the field winding is placed on the front and back ending cover. Because the hybrid flux path of the proposed machine is three-dimensional (3D) and 3D finite element analysis (FEA) is time-consuming, a 3D magnet equivalent circuit (MEC) method considering rotor position is proposed and results between 3D MEC and FEA are compared. Particle swarm optimization (PSO) and 3D MEC are combined in the optimization design of HE-CPM. The optimized results prove the effectiveness of the optimization method. Finally, the flux density distribution, electromagnetic characteristics of HE-CPM are evaluated. The thermal analysis and mechanical stress analysis are carried out. The HE-CPM prototype was manufactured. The direct current (DC) bus voltages under different excitation currents and load currents are measured and compared with those of FEA. When the armature current and the excitation current are 7 A and 4 A, respectively, the rated power and rated speed of HE-CPM are 10.28 kW and 3000 rpm, respectively. The maximum efficiency is 89%. FEA results are basically consistent with the experimental results. Accurate results and time savings can be achieved by combining PSO and 3D MEC.

A Laboratory Platform for Plotting Speed-Torque Characteristics of a Vector Controlled Induction Motor

This paper presents a platform for illustrating the speed- torque characteristics of a vector controlled three-phase induction motor. The methodology is based on acquiring the estimated torque and actual speed of a three-phase induction motor and plotting the speed-torque characteristic in real time. The platform contains a graphic interface to drive the motor and acquire the data, an induction motor, an AC drive, a communication protocol between the computer and the AC drive, and a loading system for the motor based on the claw pole alternator. LabVIEW has been used for designing the control interface. This control interface includes speed adjustment, stop command, direction of rotation, and drawing the speed-torque characteristic in real time to make the student able to notice the performance of the induction motor in the vector control mode.

Mesh-Based 3D MEC Modeling of a Novel Hybrid Claw Pole Generator

A brushless parallel hybrid excitation claw pole generator (HECPG) is proposed for electric vehicle (EV) application. Permanent magnet (PM) excitation method can reduce the volume of the machine and improve the power density and efficiency. Moreover, the voltage regulation can be ensured by field excitation. The flux path of the proposed HECPG is complex, and it will take a long time for 3D finite element analysis (FEA) to process it. To reduce simulation time, the mathematical model of the generator is given by a mesh-based 3D magnet equivalent circuit (MEC) network method considering radial and axial flux, magnetic saturation, and magnetic flux leakage. The performance of the generator is analyzed by FEA and prototype experiment. Finally, the results of 3D MEC, FEA, and experiment are compared. There is little difference between the three results, so 3D MEC can ensure the accuracy and significantly reduce the simulation time. The efficiency of the proposed HECPG is 90%, and the DC-Bus voltage can be modulated by changing the amplitude of field current.

Analysis and Cogging Torque Minimization of a Novel Flux Reversal Claw Pole Machine with Soft Magnetic Composite Cores

The performances of a novel flux reversal claw pole machine (FRCPM) using soft magnetic composite (SMC) cores is analyzed in detail. The developed FRCPM uses both a flux reversal permanent magnet machine (FRPMM) and claw pole machine (CPM). In this paper, the main dimensions are optimized to ensure that the FRCPM can achieve maximum torque. In addition, the rotor skewing technology applied in the paper leads to a reduction in cogging torque and torque ripple of the machine. The main electromagnetic parameters and performance are obtained using the 3D finite element method.

3D Rotor Position-Dependant MEC Modeling of Different Claw Pole Machine Topologies

The paper is aimed at a 3D magnetic equivalent circuit (MEC)-based modelling of claw pole synchronous machine topologies. Beyond the magnetic saturation and the armature magnetic reaction, the proposed modelling approach takes into consideration the rotor position variation, yielding the so-called: rotor position-dependant MEC. Accounting for the complexity of the magnetic circuit of claw pole topologies, specific assumptions are adopted prior a general analytical derivation of their MEC models. The developed analytical approach focuses on the air gap reluctance under variable rotor position considering a simplified geometry of the claw. A dedicated numerical procedure based on the Newton-Raphson algorithm is proposed for the resolution of the designed rotor position-dependant MEC. The proposed approach is applied to three claw pole topologies. The two first ones are equipped with a single source of excitation achieved by a field. Their analytically-predicted features are validated by experiments. The third topology has a dual excitation achieved by a field and permanent magnets (PMs) in the rotor. Its analytically-predicted features are validated by 3D finite element analysis (FEA). It is found that both experimental and FEA results are in quite good agreement with the analytical predictions yielded by the proposed rotor position-dependant MEC.

Improved Deadbeat Predictive Current Control to Enhance the Performance of the Drive System of Permanent Magnet Synchronous Motors

Thanks to the features of fast dynamic response, excellent static tracking performance, and less computation efforts, the deadbeat predictive current control (DPCC) has been widely applied for permanent magnet synchronous motors (PMSMs) in various applications like electric vehicles, where high speed operation is often adopted for achieving high power density of the drive system. However, the DPCC is a model-parameter-sensitive control method, so inaccuracy of the PMSM model or model parameter mismatch will cause significant deviation in predicting the further behavior of the control variables. To address this issue, an improved DPCC with a novel predictive model of PMSM is proposed in this paper. The novel predictive model considers the core loss of the PMSM, which may be a significant part of the electromagnetic loss but neglected in the traditional DPCC. As a case study, the proposed DPCC is used to analyze the characteristics of a claw pole PMSM drive system. To validate the merits of the improved DPCC, the analysis results are compared with those of the traditional DPCC.

A novel flux switching claw pole machine with soft magnetic composite cores

This paper proposes a novel flux switching claw pole machine (FSCPM) with soft magnetic composite (SMC) cores. The proposed FSCPM holds advantages of the conventional flux switching permanent magnet machine (FSPMM) and claw pole machine (CPM) with SMC cores. As permanent magnets are installed between the stator claw pole teeth, FSCPM has good flux concentrating ability, and the air gap flux density can be significantly improved. The torque coefficient of FSCPM is relatively high due to the applied claw pole teeth and global winding. FSCPM is mechanically robust because there are no windings or PMs on its rotor. Moreover, the core loss of FSCPM is relatively low for the SMC material has lower core loss at high frequency compared with silicon steels. The topology and operational principle of FSCPM are explained first. Several main dimensions of the machine are optimized to achieve better performance, based on 3D finite element method (FEM). Furthermore, the rotor skewing technology is adopted to reduce the cogging torque and torque ripple.

Suitable claw shape design for improving the magnetic properties of forged claw pole parts in generator

High power-generation efficiency can be achieved by optimising the shape of the claw pole used as automobile generators. The working process of the stator and rotor in the claw pole generator was simulated using the finite-element method. First, one of the eight typical claw pole types commonly used in industry was selected. Then, orthogonal optimisation was performed based on the simulation results, yielding an optimal claw shape design. To examine the adaptability of the designed claw pole to shape change, the non-destructive test for evaluating the magnetic properties of claw pole (NDTEM) was employed. Finally, a claw pole with an optimal shape was forged, and its magnetic induction intensity was assessed using the NDTEM. The results indicated that compared with the unoptimised claw pole, the magnetic induction intensity of the optimised claw pole increased by a maximum of 8.11% and its weight reduced by 4.86%. This optimisation effectively improved the efficiency of power generation and achieved the lightweight of the claw pole.

SIMULATION AND EXPERIMENTAL RESEARCH OF CLAW POLE MACHINE WITH A HYBRID EXCITATION AND LAMINATED ROTOR CORE

This paper presents the design and research results of a claw pole machine with hybrid excitation. This machine is excited by permanent magnets and an electromagnetic coil. Both excitation sources are located in the rotor of the machine. Additionally, the rotor is made of a laminated core. This approach facilitates the process of its construction and enables the implementation of even very complicated structure of the rotor, which would be difficult in case of making the rotor from a one piece of material. This paper presents the construction as well as the results of simulation and experimental tests of the machine prototype. The tests showed that the proposed machine has the ability to adjust the voltage in a wide range. Such as a feature could be used, for example, to increase the speed of motor operation in case of an electric vehicle application, but also to regulate the voltage in wind turbines which generators operate at varying rotor speeds resulting from changing wind speed.

Analysis of Claw Pole Transverse Flux Inductor Motor by Means of Magnetic Equivalent Circuit.(Dept.E)

In a preliminary design stage of claw pole fransverse flux inductor motor with E-core, an accurate magnetic calculations are very complicated due to the field arrangement. A special heavy burden is the estimation of leakage flux in the non-useful paths. Extra iron will be needed to carry this flux if saturation is to be avoided in the useful paths. This paper presents a simple equivalent circuit method by which the performance of various magnetic paths are estimated analytically. The method is based on the assumption that the flux paths are made up of straight and circular segments. It can be simply and quickly applied to examine the effects of varying the major dimensions of the motor. Experimental measurements are carried out on a simple static model to verify the proposed method. The comparison between the analytical results obtained from an ideal motor and the experimental results shows that they are in better agreement.

Design of a Novel Claw Pole Transverse Flux Permanent Magnet Motor Based on Hybrid Stator Core

Transverse flux permanent magnet motor (TFPM) benefits from the high power density and design freedom but traditional TFPM exhibits some disadvantages-high flux leakage, cogging torque, and low-power factor-which restrict its development. In order to overcome these disadvantages, claw pole TFPM (CTFPM) is developed, but it also be plagued by the demerits of soft magnetic composite (SMC) material. In this article, a novel CTFPM based on hybrid stator core (Hybrid-CTFPM) is proposed to improve the performance of CTFPM. The parameters of claw pole are investigated in this article and are optimized using a new optimization strategy eventually. This article provides a valuable reference for the design and optimization of CTFPM.

A comparative 3-D transient electromagnetic, thermal and powertrain study of single rotor BLPMSM and dual rotor machine for electric propelled vehicle

This article addresses the benefits of novel dual rotor machine for automobile sector. In case of traditional electric vehicle technology, the vehicle has a single rotor electric machine that can able to perform motoring or regenerative operation and can be possible according to the energy available in the battery. To overcome the above-mentioned problem, novel electric machine design topology with dual operation of motor and generator at same instances of time is proposed with improved electromagnetic, thermal and mechanical transmission losses. The design can be possible by adopting 7.2 kW claw pole alternator and 15 kW brushless permanent magnet synchronous machine as a dual rotor machine considering in-wheel concept. The performance analysis of the machine is done by using finite element analysis technique. The electromagnetic compatibility of machine is performed by three-dimensional transient solver in MagNet software. The electromagnetic analysis of machine is improved by introducing notches in the stator and permanent magnets in the rotor. Based on the electromagnetic results, thermal analysis of machine is calculated by coupling transient analysis using ThermNet software. The simulation results of machine are validated by using electric vehicle Powertrain blocks. The real-time performance of the machine is tested with real-world drive cycle using simulation software. The result substantiates the novelty of this design for improving the driving range of the vehicle for electric vehicle applications.

Magnetic ageing investigation of bulk low-carbon silicon steel

In this paper, the magnetic ageing of a bulk forged non-annealed magnetic core, used in claw pole synchronous machine, is investigated. The study is carried out by characterizing the material properties of two groups of samples subjected to a thermal ageing at 180 °C that corresponds to the maximum operating temperature of the claw pole rotor. The investigated characteristics are the electrical conductivity, the magnetic properties, the material microstructure and the Vickers hardness. They were characterized along with the ageing time. The results show that, during the thermal ageing, the hysteresis losses and the Vickers hardness have been affected by the magnetic ageing, whereas the electric conductivity and the normal B-H curve have not been modified. The microstructure analyses showed that carbides precipitates were the main cause behind the magnetic ageing. Moreover, the comparison between the results of two groups of samples revealed the possibility that the magnetic ageing of the material could have started during the manufacturing process of the magnetic core.

Design and Analysis of a New Permanent Magnet Claw Pole Machine With S-Shape Winding

With the continuous improvement of magnetic and mechanical properties of soft magnetic composite (SMC) material, there is a trend to develop novel electrical machines with SMC cores for some special applications. Among these electrical machines, permanent magnet claw pole machine (CPM) has been extensively studied over the past few decades. As linear global winding has been used in this machine, it can be regarded as a linear winding CPM (LWCPM). To improve the performance of LWCPM, a new S-shape winding CPM (SWCPM) is proposed in this article. The main stator structures of the LWCPM and SWCPM are optimized to achieve maximum torque ability. Compared with LWCPM, SWCPM provides higher average torque, power factor, and higher efficiency. The main disadvantage of the proposed SWCPM is its lower flux weakening ability. 3-D finite element model is used to evaluate the performance of the proposed LWCPM and SWCPM. The accuracy of the 3-D finite element model is verified by using a previous prototype.

Optimizing the aerodynamic noise of an automobile claw pole alternator using a numerical method

The aerodynamic noise of an alternator, which is difficult to predict due to the complex internal flow, has become an issue for vehicles in recent years. To study the acoustic characteristics of the vehicle claw pole alternator, a numerical simulation method is proposed in this paper to predict its aerodynamic noise. First, a Scale Adaptive Simulation (SAS) in the numerical calculation is used to calculate the flow field. Then, the Ffowcs-Williams and Hawkings acoustic model is applied to calculate its acoustic characteristics. Additionally, a series of experiments are performed to verify the accuracy of the simulation method. According to the experimental data, it is determined that the dominant influencing orders for the overall noise are the 8th, 16th and 24th orders. Comparing the simulation results with the experimental results, the prediction errors are −0.67 dBA, −2.9 dBA and −3.22 dBA in the acoustic power levels of the 8th, 10th and 12th orders, respectively, which are all within 4%. Finally, the Vector Composition Method (VCM), considering the mass flow rate and low noise, is applied to ameliorate the distribution of the spectral energy by optimizing the distribution angles of the rear fan. Moreover, a prototype is produced to verify the practical application of this method. After optimization, the numerical results indicate that the mass flow rate of the rear fan is reduced by 5.172%, while the front fan is increased by 5.128%. The experimental results indicate that the maximum increasing overall noise on the 6th order is 4.7 dB and the increasing values of the 10th and 14th orders are all in a limited range. Additionally, the maximum decreasing overall noise amounts of the 8th order and 12th order exceed 5.1 dB and the average decreasing amount exceeds 2.5 dB; that is to say, this method has a remarkable effect on the acoustic noise spectral structure.

Development of Brushless Claw Pole Electrical Excitation and Combined Permanent Magnet Hybrid Excitation Generator for Vehicles

Aiming at the problems of large excitation loss and low power generation efficiency of silicon rectifier generators and the unstable output voltage of permanent magnet (PM) generators, a hybrid excitation generator (HEG) with suspended brushless claw pole electrical excitation rotor (EER) and combined magnetic pole PM rotor is proposed in the present work. With only one fractional slot winding stator, the generator adopts PM field as the main magnetic field and electrical excitation field as the auxiliary magnetic field, which not only retains the advantages of high efficiency of PM generators but also effectively reduces excitation consumption. The main structure parameters and the design method were analyzed, and a simulation analysis of no-load magnetic field distribution and flux regulation ability was carried out using finite element software to verify the rationality of the hybrid excitation parallel magnetic circuit design. Moreover, the no-load, load, regulation, and voltage regulation characteristics of the designed generator were tested, and the results show that the designed generator has a wide range of voltage regulation, which can ensure stable output voltage under variable speed and load conditions.

A Novel Claw Pole Motor With Soft Magnetic Composites

The integrated starter generator used in micro hybrid electric vehicle is usually claw pole motor. The claw pole core in the motor is forged by low carbon steel, which is of complex technology and the eddy current loss of the whole conductor in the magnetic field is large. To solve these problems, a novel claw pole motor is proposed in this article, which uses iron-based soft magnetic composites to prepare claw pole core and to insert permanent magnet between claw poles. By studying the preparation process parameters of iron-based soft magnetic composites, it is found that the mechanical properties and magnetic properties of the soft magnetic composites are the best under 700 MPa pressing pressure and 500 °C annealing temperature. A prototype is designed and manufactured, and its power generation and starting performance are tested, which can meet the performance requirements of 48 V micro hybrid system.

A Study on the Novel Design to Improve Efficiency of Wound Field Synchronous Machine

This study describes the research to improve the performance of motor generator for integrated starter generator (ISG) mounted on ecofriendly vehicles. The ISG must be able to start the engine by high torque at the starting mode and generate electric power at the generating mode. In particular, the existing automotive generator is a field winding alternator of CLAW POLE structure, so wound field synchronous machine (WFSM) was used in early ISG. However, it is difficult to control the starting of WFSM with instantaneous high starting torque required at the start and high field current is applied to field windings to generate the magnetic flux. But high field current generates high heat shortening the life of the device. Therefore, consequent pole wound field synchronous machine (CPWFSM) as a novel structure is proposed in this article. It is possible to generate instantaneous high torque easily at starting because of permanent magnet (PM). In the generating mode, CPWFSM can generate power in a wide operation speed that is proposed by taking advantage of WFSM. CPWFSM consists of consequent pole and field winding in the rotor. So it generates high torque with high responsiveness at starting compared with WFSM and it has the advantage of generating output power using low field current at various speed areas because of PM. Simulation of CPWFSM and WFSM is performed by finite-element method (FEM) of ANSYS Electromagnetic Suite (EM 19.0) software, and the experimental results are compared by the dynamo experiment.