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International audience; To eliminate the disadvantages of both the uncontrollability in the magnetic field of a permanent magnet excitation system and the high energy consumption of an electric excitation system in a traditional magnetically rotating arc plasma generator, a novel topology of a hybrid permanent magnet and electrically excited coil system is proposed. The proposed system will generate a large enough magnetic field to drive the arc rotation with a minimum consumption of materials and electric energy in the normal operation duty, and will guarantee a nearly zero magnetic field in the arc triggering stage. To optimize the hybrid excitation system, a comprehensive analysis and an optimization methodology; by combining finite element analysis, the moving the least squares approximation and an adaptive weighted particle swarm optimization, are proposed. Finally, a prototype hybrid excitation system is optimized with promising results in views of both saving a huge amount of electric power consumptions and ensuring a nearly zero magnetic field in the arc triggering.

Aiming to design a generator with high reliability, high efficiency, and especially a constant output voltage over a wide speed range for hybrid electric vehicles (HEVs), this paper proposes a novel topology of a hybrid excitation doubly salient generator with separate windings (HEDSGSW). The topology herein utilizes a hybrid excitation type of PMs and DC windings to generate parallel magnetic circuits. In addition, PMs are embedded in the magnetic bridge to insulate the excitation windings with armature windings. This design can achieve compactness, efficiency, and especially constant output capability over a wide speed range. The geometry and flux regulation principles, including magnetic flux circuits, are elaborated. After comparing three power generation modes, the most suitable mode, namely, the doubly salient generation 2 (DSG2) mode, is confirmed to ensure a stable voltage output performance. Then, considering the non-uniformity effect of the stator and rotor slots, the no-load back electromotive force (EMF) expressions are derived based on the EMF to air-gap relative permeance method. Furthermore, a 1 kW HEDSGSW FEA model, with an output voltage of 42 V and a rated speed of 6000 rpm, is built to demonstrate the effectiveness of the proposed method. Finally, the operating properties of the HEDSGSW, such as no-load characteristics and adjustment characteristics, are analyzed to further verify the rationality of its magnetic flux circuit and the flexibility of the excitation regulation capability.

This paper deals with the analysis and the comparison among some hybrid excited permanent magnet (HEPM) machines and interior permanent magnet (IPM) machines for electric vehicle (EV) applications. Torque, efficiency, flux weakening capability, losses are computed and compared in detail by 2D finite-element analysis method.

The main objective of aerospace industry is to produce all electric aircraft (AEA) equipped by electrical devices in coming developments. Electrical machines that provide higher torque densities are gaining more interest for researchers to obtain sustainable direct-drive electrical propulsion system for aircraft applications. In addition to lesser weight and higher torque density, a machine should be “fault tolerant” to applied in aerospace applications. A novel machine for high starting torque, identified as flux switching machine (FSM) was established over the last decade. FSMs comprise all effective sources on stator including robust rotor structure. These machines exhibited higher “torque-to-weight ratios” and reliability. Nonetheless, the challenge of developing a machine suitable for aircraft applications goes far beyond electromagnetic design and much deeper into the field of mechanical systems than traditional ones. Thus, a new double stator (DS) hybrid excitation (HE) FSM design employing segmented rotor is proposed and analyzed in this research work. The suggested design for DS HE-FSM comprises of six field excitation coils (FECs) and six permanent magnets (PMs) as their excitation sources. In this research, investigation of DS HE-FSM is accomplished with respect to flux linkage, back EMF, cogging torque and torque analysis based on 2D FEA.

Electric vehicle (EV) generators have characteristics of small volume and high power density, which leads to high temperature rise. The temperature rise will directly influence the service life and reliability of the generator, so thermal analysis of EV generators is necessary in machine design. This paper carries out thermal analysis of a dual-axis-direction hybrid excitation generator (DHEG) used in EVs. The lumped parameter thermal network (LPTN) method is used to build the three-dimensional thermal model of DHEG. Compared with finite element analysis, LPTN can significantly reduce the simulation time while ensuring a good accuracy. Then, the influence of heat dissipation rib on DHEG temperature rise is studied. The results prove that adding heat dissipation rib on the enclosure surface can effectively reduce the maximum temperature of DHEG.

Variable speed, permanent magnet synchronous machines with hybrid excitation have attracted much attention due to their flux-control potential. In this paper, a design of permanent magnet axial flux machines with iron poles in the rotor and an additional electrically controlled source of excitation fixed on the stator is presented. This paper shows results pertaining to air-gap flux control, electromagnetic losses, electromagnetic torque, back emf and efficiency maps obtained through field-strengthening and weakening operations and investigated by 3D finite element analysis. Moreover, the temperature distribution of the machine was analyzed according to the fluid–thermal coupling method. The presented machine was prototyped and experimentally tested to validate the effectiveness of numerical models and achieved results.

A new partitioned stator hybrid excitation (HE) doubly salient machine with permanent magnets (PMs) sandwiched between adjacent inner stator tooth tips and with armature and field windings housed in outer and inner stators, respectively, is proposed in this paper. In comparison of the conventional HE machines with single stator, the space utilization is significantly boosted. So more windings and PMs can be employed to obtain increased torque density and improved flux regulation capability. In order to investigate the effect of inner stator yoke, which contributes significant influence to electromagnetic performances, the equivalent magnetic circuit method is employed. Moreover, the multi-level design optimization method is adopted to optimize the key parameters efficiently. Notably, the rated operating point with excitations of PMs and field current of 1 A is defined according to its efficiency. Then, the electromagnetic performances at different operating points are analyzed and compared based on the 2-D finite-element analysis. The results reveal that the output torque is increased at new rated condition due to the flux-enhancing current, and the flux-weakening capability is also improved, so that a wider constant power speed range can be achieved because of the defined rated operating point.

The paper presents three novel rotor design concepts for a three-phase electric controlled permanent magnet synchronous machine (ECPMS-machine) with hybrid excitation. The influence of magnets and flux-barriers arrangement on the magnetic field distribution and field-weakening characteristics of the machine is examined, based on a three-dimensional finite element analysis (3D-FEA). Moreover, a prototype rotor design based on a new rotor concept with a good field-weakening capability is presented in detail. Finally, the experimental results of no-load back electromotive force (back-EMF) waveforms and field-weakening characteristics versus a control coil current of the machine are reported.

This paper presents a closed-loop flux-weakening controller for hybrid-excitation synchronous machine drives based on separate regulation of amplitude and phase angle of the armature voltage. Operating point analysis is carried out to investigate the dynamic properties of the drive and to give guidelines in the tuning of the controller. Finally, experimental tests validating the theoretical derivations are performed on a prototype hybrid-excitation drive.

For power generation purposes, wound-field synchronous generators are often preferred to permanent magnet machines, due to the need of controlling the field winding voltage and current for guaranteeing a constant voltage at the generator's armature terminals. In a traditional generating set, this function is accomplished by a relatively complex feedback control system which typically comprises an excitation system and an automatic voltage regulator. Due to their excellent and proven performance capability, such classical generating sets have seen only strictly incremental improvements in the last 60 years or so. However, today, there is an interest in revamping their design and development, partly due to the even increasing efficiency and reliability requirements and partly due to advances in material and manufacturing techniques. This work investigates the feasibility of a hybrid permanent magnet - field winding excitation for synchronous generators' exciters. This design solution aims at reducing the losses of the exciter and thus of the whole generating system, while also increasing its reliability.

Potentials and limits of the Hybrid-Excitation Permanent-Magnet (HEPM) synchronous machine are dealt with in this paper. A six-pole machine is taken into consideration, and both parallel and series configurations are analysed and compared. Taking advantage of the rotor excitation coils, the permanent magnet (PM) rotor flux can be adjusted according to the operating speed to improve its performance parameters. The electro-magnetic force is analysed in its first harmonic and in the complete shape. Moreover, a comparison between analytical and numerical formulation has been done for the rotor current control. In particular, the speed range is extended, and electro-mechanical torque and power are increased, as well as the efficiency. It will be shown that the rotor flux reduction by using the excitation winding yields an improvement of the motor performance. The main advantage will be obtained during the flux-weakening operations. In this paper, different rotor topologies will be analysed to highlight the advantages and drawbacks of each of them, and how it is possible to achieve higher speed with higher torque and without high saliency ratio. A magnetic network will be introduced to explain the different contribution of the excitation winding to the rotor flux. Furthermore, a comparison of the amount of the volume of PM, copper and iron in internal permanent magnet (IPM) motor and HEPM motor will be analysed. Actually, an analysis of the harmonic content in the electro-motive force even varying the excitation current and a mechanical stress analysis of each machine will be shown. Finally, it will be verified that the excitation losses represent a minimum component of the total losses.

This contribution discusses the degrees of freedom that could be advantageously exploited in the conception of permanent magnet (PM) machines in the context of very demanding applications, such as electrical vehicle traction. The aim is to inventory degrees of freedom identified in scientific and technical literatures. Identifying these additional degrees of freedom will help positively respond to highly constrained design problems, which are appearing due to the higher usage of electrical energy in many industrial and consumer products. The goal is also to stimulate new ideas in the design of PM synchronous machines.

The paper deals with the overview of different designs of hybrid excited electrical machines, i.e., those with conventional permanent magnets excitation and additional DC-powered electromagnetic systems in the excitation circuit. The paper presents the most common topologies for this type of machines found in the literature—they were divided according to their electrical, mechanical and thermal properties. Against this background, the designs of hybrid excited machines that were the subject of scientific research of the authors are presented.

A sandwich-type multi-degree-of-freedom (MDOF) ultrasonic motor with hybrid excitation is proposed in this paper. The motor adopts pair combination of three resonance modes to drive the sphere rotations around three coordinate axes. When the sphere rotates around any axis, all piezoelectric ceramics of the proposed motor are excited for the vibration of the motor. The final structure parameters of the motor are confirmed by way of finite element method, and the elliptical motion trajectories of the driving areas are verified. At last, the prototype is fabricated and tested. The prototype achieves no-load speeds of 109.8 r/min, 107.9 r/min, and 290.8 r/min in the YOZ, XOZ, and XOY driving modes, respectively. The proposed motor employs only four pieces of lead zirconate titanate ceramics to achieve the MDOF rotations of a spherical rotor.

This paper deals with a parallel hybrid excitation synchronous machine (HESM). First, an expanded literature review of hybrid/double excitation machines is provided. Then, the structural topology and principles of operation of the hybrid excitation machine are examined. With the aim of validating the double excitation principle of the topology studied in this paper, the construction of a prototype is presented. In addition, both the 3D finite element method (FEM) and 3D magnetic equivalent circuit (MEC) model are used to model the machine. The flux control capability in the open-circuit condition and results of the developed models are validated by comparison with experimental measurements. The reluctance network model is created from a mesh of the studied domain. The meshing technique aims to combine advantages of finite element modeling, i.e., genericity and expert magnetic equivalent circuit models, i.e., reduced computation time. It also allows taking the non-linear characteristics of ferromagnetic materials into consideration. The machine prototype is tested to validate the predicted results. By confronting results from both modeling techniques and measurements, it is shown that the magnetic equivalent circuit model exhibits fairly accurate results when compared to the 3D finite element method with a gain in computation time.

22nd IEEE International Conference on Electrical Machines (ICEM) -- SEP 04-07, 2016 -- Lausanne, SWITZERLAND YILDIRIZ, Emin/0000-0002-6003-6780 WOS: 000390884900366 A new axial field hybrid excitation synchronous machine (AFHESM) with shunt rotor type is proposed for wind turbine applications. The architecture, material properties, operation principle of the AFHESM are introduced. Considering the directions of flux, 3D models of the AFHESM are investigated. Finite element analysis (FEA) is used to compute airgap flux density and the control performance of the flux by manipulating the MMFs. Parametric analysis is used to observe the effects of auxiliary airgap and magnet sizes on the field weakening and enforcing. The results show that the proposed AFHESM has the ability to control the magnetic flux density of airgap over a wide range when the excitation current is changed between -8 A to 8 A. Int Conf Elect Machines Assoc, Inst Engn & Technol, IEEE Ind Elect Soc, IEEE Ind Applicat Soc, IEEE

Magnetic field regulation is a difficult and long-existing issue in surface-mounted permanent magnet synchronous machines (PMSMs). To produce effective and efficient flux regulation for PMSMs, a new topology, named a dual-structure parallel hybrid excitation machine (DS-PHEM), is presented in this paper. In this machine, the rotating permanent magnet (PM) excitation and stationary DC field excitation are artificially arranged and designed at the inner and outer magnetic circuits, respectively. Therefore, a decoupling and parallel feature is obtained between two excitation sources. This machine integrates the merits of a brushless structure and theoretically infinite constant power range, as well as zero risk of demagnetization. In this paper, the machine configuration is introduced, mainly focusing on some important design criteria for electromagnetic integration, and the operating principles of flux control are also analyzed in detail. To further verify the feasibility of the proposed scheme, the overall electromagnetic performance of the proposed DS-PHEM is evaluated by using the time-stepping finite-element method.

This paper investigates methods to achieve a wide constant power speed range (CPSR) in electric drives using hybrid excitation synchronous machines; five strategies are presented and compared. These range from state-of-the-art flux weakening based on demagnetizing armature current injection, to algorithms based on wound excitation (WE) current regulation, all the way to techniques involving both armature and WE current regulation. It is shown that one of these latter strategies allows a theoretically infinite CPSR and unity power factor operation throughout. This result is also verified experimentally, and a 10:1 range is demonstrated. Finally, a discussion is presented on practical limiting issues such as harmonic flux linkage components, inductance variations, and high-speed iron losses.

Under the condition of load changing, the magnetic field of traditional permanent magnet generators (PMG) is hard to be adjusted, and the mechanical bearings are significantly worn. To overcome the drawbacks above, a novel hybrid excitation bearingless permanent magnet generator (HEBPMG) is proposed in this paper, which has integrated the merits of hybrid excitation permanent magnet generators and magnetic bearings. Firstly, the structure and winding configuration of the HEBPMG are introduced, and then the principles of radial suspension and power generation are presented. The suspension principle as well as power generation principle is analyzed in this paper. Then, the flux linkage and induced voltage equations are derived, and the accurate mathematical model of radial suspension force is built based on the Maxwell tensor method. Subsequently, by means of the finite element analysis software-ANSYS Maxwell, the corresponding electromagnetic characteristics are analyzed to verify the correctness of the mentioned models. In addition, a compensation control strategy based on flux-linkage observation is proposed to solve the problems of unstable suspension force and generating voltage under variable load condition in this paper. Meanwhile, the corresponding control system is constructed and its feasibility is validated by simulation results. Finally, an experimental prototype of a 2.2 kW HEBPMG is tested. Experimental researches show that the HEBPMG can operate steadily under variable load condition and possess good suspension performance and power generation quality.