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A design approach is presented for achieving optimal flux weakening operation in surface PM synchronous machines by properly designing the machine's stator windings using concentrated, fractional-slot stator windings. This technique makes it possible to significantly increase the machine inductance in order to achieve the critical condition for pro...
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Context 1
... maximum allowable current density value varies based on the type of cooling that is available to the machine, the ma- chine size, and type of enclosure. Hence, this analysis here will focus on the relative values of the current densities in the two stator windings rather than their absolute values. Fig. 6 shows one slot pitch of the machine. To simplify the analysis, it will be assumed that both the tooth and the slot have uniform widths. Although this is only an approximation due to slot tapering, the fundamental result is not affected since this tapering applies equally to both ...
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Citations
... Among them, permanent magnet synchronous motors are widely used due to their high efficiency and power density [292][293][294], depicted in Figure 32. There are several types of permanent magnet (PM) machines that can be utilized as traction motors they are surface-mounted permanent magnet synchronous machines (SM-PMSM) [295], brushless direct current machines (BLDCM) [296,297], interior permanent magnet synchronous machines (IPMSM) [298][299][300] for both axial and radial flux magnetic configurations [297]. However, PMSM traction motors are highly temperature sensitive. ...
Emerging electric vehicle (EV) technology requires high-voltage energy storage systems,efficient electric motors, electrified power trains, and power converters. If we consider forecasts for EV demand and driving applications, this article comprehensively reviewed power converter topologies, control schemes, output power, reliability, losses, switching frequency, operations, charging systems, advantages, and disadvantages. This article is intended to help engineers and researchers forecast typical recharging/discharging durations, the lifetime of energy storage with the help of control systems and machine learning, and the performance probability of using AlGaN/GaN heterojunction based high-electron-mobility transistors (HEMTs) in EV systems. The analysis of this extensive review paper suggests that the Vienna rectifier provides significant performance among all AC–DC rectifier converters. Moreover, the multi-device interleaved DC–DC boost converter is best suited for the DC–DC conversion stage. Among DC–AC converters, the third harmonic injected seven-level inverter is found to be one of the best in EV driving. Furthermore, the utilization of multi-level inverters can terminate the requirement of the intermediate DC–DC converter. In addition, the current status, opportunities, challenges, and applications of wireless power transfer in hybrid and all-electric vehicles were also discussed in this paper. Moreover, the adoption of wide bandgap semiconductors was considered. Because of their higher power density, breakdown voltage, and switching frequency characteristics, a light yet efficient power converter design can be achieved for EVs. Finally, the article’s intent was to provide a reference for engineers and researchers in the automobile industry for forecasting calculations.
... , ΨPM and Iq are pole pairs number, flux-linkage of the PM and quadrature-axis current. However, under flux weakening region the torque of SPMM is(2). ...
span>Permanent-magnet excitation machines (SPMMs) having mounted magnet on the outer surface of their rotor are preferred for high speed applications such as turbochargers, mechanical turbo-compounding systems, racing engines and fuel pumps, over other types of machines including induction and switched-reluctance machines, since the SPMMs integrate the features of high torque density, compact rotor structure, high reliability and simple structure. However, in the SPMMs, due to the need for a retaining sleeve for the rotor, a large magnetic airgap results and consequently a large magnet thickness is required, hence the magnetic end-effect is relatively high. On the other hand, the use of an overlapping distributed winding leads to a significantly large end-winding length. Hence, the end-effect and the end-winding influences on the performances of a high-speed SPMM is considered in this paper. With a view to get the impact of the end-effect, a comparison between three-dimensional (3D-FEA) results and counterparts two-dimensional finite element analyses (2D-FEA) have been conducted. Results show that, higher efficiency at low torque and low speed due to the low electromagnetic losses and at high speeds due to the high flux-weakening capability are seen when the influences of end-effect as well as end-winding are taken into account.</span
... Flux weakening becomes inevitable in this case to further increase the speed of these machines. The flux weakening capability of PM machines, on the other hand, is dependent upon the d-axis inductance [1][2][3]. Generally, machine designers have to design a PM machine with a large d-axis inductance to increase its flux weakening capability. However, non-salient PM machines exhibit low inductance characteristics due to their low permeability surface-mounted PMs. ...
This paper presents a novel concept of phase swapping to associate multiple flux weakening ranges to a non-salient PM machine without altering any hardware of the machine. The proposed concept enables a dual three-phase machine to be operated with different displacement angles between the two three-phase windings. Hence, different flux weakening ranges using winding switching can be accomplished by applying this concept. It was also demonstrated that the proposed concept can be utilized for the discrete step as well as continuous operation of the machines. Any application requiring a wide speed range operation of up to thirteen times the base speed can benefit from this proposed concept. Analytical, simulation, and experimental results are provided to validate the effectiveness of the proposed concept.
... The PM brushless machine applied in EVs needs to provide extended constant power speed range which is always 3–4 times the base speed, where a relatively large inductance is preferred to provide a better flux-weakening capability and lower energy consumption [23,24]. In order to maximize the constant power speed range, the corresponding optimization model is defined as follows: ...
In this paper, by considering and establishing the relationship between the maximum operating speed and d-axis inductance, a new design and optimization method is proposed. Thus, a more extended constant power speed range, as well as reduced losses and increased efficiency, especially in the high-speed region, can be obtained, which is essential for electric vehicles (EVs). In the first step, the initial permanent magnet (PM) brushless machine is designed based on the consideration of the maximum speed and performance specifications in the entire operation region. Then, on the basis of increasing d-axis inductance, and meanwhile maintaining constant permanent magnet flux linkage, the PM brushless machine is optimized. The corresponding performance of the initial and optimal PM brushless machines are analyzed and compared by the finite-element method (FEM). Several tests are carried out in an EV simulation model based on the urban dynamometer driving schedule (UDDS) for evaluation. Both theoretical analysis and simulation results verify the validity of the proposed design and optimization method.
... To satisfy different requirements, such as constant-voltage power generation for wind generations or wide-speed range constant power operation in EVs, the air-gap magnetic flux needs to be regulated readily. For traditional permanent magnet (PM) machines, flux weakening can be indirectly achieved by applying a large negative d-axis current [6]; however, this method not only needs a complex control strategy, but also reduces the machine efficiency caused by the high excitation currents. In addition, the rotor position also needs to be predicted accurately when the PMs are located on the rotor [7]. ...
Electric machines play an important role in modern energy conversion systems. This paper presents a novel brushless fault-tolerant flux-modulated memory (FTFM) machine, which incorporates the merits of a flux-modulated permanent magnet machine and multi-phase memory machine and is very suitable for applications that require wide speed ranges of constant-power operation. Due to the magnetic modulation effect, the FTFM machine can produce a large torque at relatively low speeds. Due to the usage of aluminum-nickel-cobalt (AlNiCo) magnets, this machine can readily achieve a flexible air-gap flux controllability with temporary DC current pulses. Consequently, the constant-power region is effectively expanded, and the machine's efficiency during constant-power operation is increased. Due to the multi-phase armature winding design, the FTFM machine enables lower torque ripple, increased fault tolerance ability and a higher possibility of splitting the machine power through a higher number of phases, thus the per-phase converter rating can be reduced. The design methodology and working principle of this kind of machine are discussed. The electromagnetic performances of the proposed machine are analyzed using the time-stepping finite element method (TS-FEM).
... The use of concentrated stator windings (i.e. windings encircling a single stator tooth, thus eliminating end-winding overlap among phase windings) offer several advantages compared to distributed windings, including a reduction of the copper volume of the end windings, which is especially significant when the axial length of motor is small, thus minimizing copper losses and improving the motor efficiency [7], [19] compared to stator windings with integer number of slots per pole and per phase. They also allow reducing the total length of the machine and manufacturing costs since concentrated windings are easier to realize. ...
... They also allow reducing the total length of the machine and manufacturing costs since concentrated windings are easier to realize. Finally, an important advantage is that compared to distributed windings, concentrated windings tend to provide higher inductance when the magnetic flux linkage is the same, which allows extending the flux-weakening region [19]. Since in this particular design the fault-tolerance is a must, a concentrated non-overlapping fractional-slot singlelayer winding has been selected, as shown in Fig. 2, since it provides enough magnetic and electric insulation to avoid a major propagation of a short circuit in the event of a short circuit fault. ...
... Therefore, to achieve an optimal design of the AFPM it seems reasonable to apply a multi-objective approach based on a genetic algorithm (GA) since GAs are mathematical methods well-suited for solving constrained and unconstrained single-or multi-objective optimization problems. These algorithms have been successfully applied in problems dealing with highly nonlinear, nondifferentiable or stochastic objective functions [19] and specifically in the achines [29][30][31]. ...
Electric motors used for traction purposes in electric vehicles (EVs) must meet several requirements, including high efficiency,
high power density and fault-tolerance. Among them, permanent magnet synchronous motors (PMSMs) highlight. Especially, five-phase
axial flux permanent magnet (AFPM) synchronous motors are particularly suitable for in-wheel applications with enhanced fault-tolerant
capabilities. This paper is devoted to optimally design an AFPM for in-wheel applications. The main geometric, electric and mechanical
parameters of the designed AFPM are calculated by applying an iterative method based on a set of analytical equations, which is assisted
by means of a reduced number of three-dimensional finite element method (3D-FEM) simulations to limit the computational burden. To optimally
design the AFPM, a constrained multi-objective optimization process based on a genetic algorithm is applied, in which two objective functions
are considered, i.e. the power density and the efficiency. Several fault-tolerance constraints are settled during the optimization process
to ensure enhanced fault-tolerance in the resulting motor design. The accuracy of the best solution attained is validated by means of 3D-FEM simulations.
... The equivalent number of turns is calculated such that the same flux is produced. Inductances are calculated using the winding function approach [20]. The calculated inductances are the stator self inductances, and the mutual inductances between the stator windings and the virtual field winding representing the PM effect. ...
... According to winding function theory [20] , the mutual inductance between any two arbitrary windings i and j in any electric machine can be computed using: ...
The performance of fault-tolerant modular permanent magnet (PM) machines depends on the proper selection of the pole and slot numbers which result in negligible coupling between phases. The preferred slot and pole number combinations eliminate the effect of low order harmonics in the stator magneto motive force and thereby the vibration and stray loss are reduced. In this paper, three external rotor machines with identical machine dimensions are designed with different slots per phase per pole (SPP) ratios. A simulation study is carried out using finite element analysis to compare the performance of the three machines in terms of machine torque density, ripple torque, core loss, and machine efficiency. A mathematical model based on the conventional phase model approach is also used for the comparative study. The simulation study is extended to depict machine performance under fault conditions.
... For surface mounted permanent magnet (SMPM) motors, the phase current is in phase with the corresponding phase back EMF for SMPM and for internal permanent magnet (IPM) motors, the phase current is in advance with the corresponding phase back EMF. However, to reach higher speeds, the control then reduces the total phase flux by applying the optimum switching lead angle [1], [2]. The voltage control is associated with a pulse width modulation (PWM) at a relatively high frequency. ...
Industry applications involving torque brushless dc motors require high efficiency over a large speed range. In order to achieve such specifications, flux weakening is necessary, which could lead to relative high electromagnetically induced vibrations and consequently to audible noises. Furthermore, in order to decrease cogging torque and to satisfy motor manufacturing constraints, concentric windings are usually considered. Such motor configurations lead to harmonics of the electromagnetic forces being the sources of mechanical vibrations. This paper focuses on the electromagnetic forces created in surface-mounted permanent magnet and internal permanent magnet motors for two concentric windings: one and two coil sides per slot. These forces are determined using both lumped magnetic scheme and two-dimensional finite-element (FE) simulations. Then, three-dimensional FE simulations enable to predict the mechanical modes and the acoustic radiated power. Finally, the authors propose a simple method to mitigate the magnetic forces and their variations. This method deals with skewing the stator. The skewing angle is optimized differently as in the usual case of decreasing the cogging torque. This method is really interesting for industry applications, because does not require any important change in the motor construction. The acoustic measurements confirm the analysis and the proposed improvement technique (stator skewing).
... Due to short end-winding, high torque density and efficiency, the fractional-slot PM machines with non-overlapping windings are widely employed in many applications123456789101112, such as servo, spindle and traction drive systems. As another kind of machines with non-overlapping windings, flux-switching PM (FSPM) machines are being considered and under extensive investigation131415 since FSPM machines exhibit some novel features, such as PMs on the stator, simple rotor structure, bipolar and sinusoidal phase flux-linkage. ...
Purpose
– The purpose of this paper is to analyze the phase coil connections and winding factors of flux‐switching permanent magnet (FSPM) brushless AC machines with all poles and alternate poles wound, and different combinations of stator and rotor pole numbers.
Design/methodology/approach
– The coil‐emf vectors, which are widely used for analyzing the conventional fractional‐slot PM machines with non‐overlapping windings, are employed for FSPM machines.
Findings
– Although the coil‐emf vectors have been employed to obtain coil connections in the conventional fractional‐slot PM machines, they are different in FSPM machines. It is mainly due to different polarities in the stator of FSPM machines. In addition, from the coil‐emf vectors it is able to predict whether the back‐emf waveforms are symmetrical or asymmetric.
Originality/value
– This is the first time that coil‐emf vectors are used to determine the coil connections and winding factors in FSPM machines with different topologies and combination of stator and rotor pole numbers.
... The concentrated windings make it possible to significantly increase the machine inductance in order to reduce the characteristic current to the point of establishing equality with the rated current. This offers the possibility of optimal flux weakening [11], [12]. Beyond this capability, concentrated winding PM machines have been gaining an increasing interest over the last few years due to several advantages. ...
In this paper is presenting the preliminary designing and control of a synchronous machine with axial airgap single stator dual-rotor with permanent surface magnets and different pole pairs number, destined for hybrid electric vehicles (HEV) applications. For machine’s designing was used the equivalent magnetic circuits method that takes into account the saturation and dispersion of the magnetic field. The control model is developed for a single inverter that produces three phase output voltage with two frequencies components; the torque current for each rotor is controlled through the stator current that passes the two serial windings. The machine, coupled with the thermal engine (ICE), can operate as starter for short time at start-up and as generator, when the rotational speed is established by the thermal engine’s regulator. The other machine can operate as motor in wide speed range (both inferior and superior to the generator’s), but also in generator regime with power recovery at braking.
