Emmanuel Hoang

A new structure of a switching flux synchronous polyphased machine with hybrid excitation

The aim of this paper is to present the structure of a new flux switching synchronous machine with hybrid excitation. This machine uses the flux switching principle where all the active parts are located on the stator. The rotor is only a salient passive rotor and can be robust and made with a low cost technology. This new machine can be supplied with electricity by means of a traditional three phase voltage converter or can be associated with a diode rectifier. The hybrid excitation is an association of permanent magnets and a wound exciter.

Hybrid Excitation Synchronous Machines: Energy-Efficient Solution for Vehicles Propulsion

In this paper, the suitability of a class of electric machines for vehicle traction applications is discussed. These machines, which are known as hybrid excitation synchronous machines, combine permanent-magnet (PM) excitation with wound field excitation. The goal behind the principle of hybrid excitation is to combine the advantages of PM excited machines and wound field synchronous machines. It is shown that these machines have good flux weakening capability compared with PM machines, and that they constitute an energy-efficient solution for vehicle propulsion.

A Hybrid-Excited Flux-Switching Machine for High-Speed DC-Alternator Applications

This paper presents a new topology of hybrid-excited flux-switching machine with excitation coils located in stator slots (or inner dc windings). After describing the three-phase structure to be investigated, the working principle is discussed, and the main electromagnetic performances are simulated by finite-element (FE) analysis. It is demonstrated that the air-gap field can be easily controlled, which is interesting for variable-speed applications. Finally, a prototype having 12 stator poles and different rotor tooth numbers (10 or 14) was built. Experiments were performed, validating the FE simulations and the operation principle. Finally, the thermal behavior of the prototype machine is investigated through experiments. It is shown that, up to 12 000 r/min, the thermal stabilization is achieved, making this topology an excellent candidate for high-speed applications.

Influence of magnetic losses on maximum power limits of synchronous permanent magnet drives in flux-weakening mode

The aim of this paper is to present the structure of a new synchronous machine with stator ferrite permanent magnets and a salient passive rotor (a robust and low-cost technology) which, when supplied with current by a three-phase bridge converter, produces continuous torque. This feature serves to place our machine on a par with the best synchronous machines available (e.g. high-energy rotor magnets with flux concentration). Furthermore, the electrical characteristics of this machine make it possible to apply the well-known flux weakening technique, which enhances the performance of the entire energy-conversion system. In theory, an operating area at constant power with unlimited speed can be obtained merely by taking into account the ohmic tension drops in the coils. Experimental results demonstrate that taking both magnetic losses and windage losses into account is necessary in order to identify the maximum mechanical output power characteristics.

Hybrid Excitation Synchronous Machines: Energy Efficient Solution for Vehicle Propulsion

In this paper the suitability of a class of electric machines for vehicle traction application is discussed. These machines, known as hybrid excitation synchronous machines, combine a permanent magnet excitation with wound field excitation. The goal behind the principle of hybrid excitation is to combine advantages of PM excited machines and wound field synchronous machines. It is shown that these machines have good flux weakening capability compared to PM machines, and that they constitute an energy efficient solution for vehicles propulsion

Comparative Studies Between Classical and Mutually Coupled Switched Reluctance Motors Using Thermal-Electromagnetic Analysis for Driving Cycles

This paper presents copper and iron loss models of a classical switched reluctance motor (SRM) and a mutually coupled switched reluctance motor (MCSRM). The iron losses in different parts of machines are then detailed. Based on the power losses model, a lumped parameter (LP) transient thermal model during driving cycles is performed, the analytical results are validated by the finite-element (FE) transient thermal model. Special attention has been paid to model the salient rotor and a method to transform the salient rotor into a nonsalient one has been proposed. A comparison between the maximum temperatures obtained by using different heat source (average power losses or instantaneous power losses during driving cycles) is given. The experimental tests are also realized to verify the analytical and numerical results.

Thermal Model With Winding Homogenization and FIT Discretization for Stator Slot

The aim of the method detailed in this paper is to get an equivalent thermal model of a stator slot, in order to simplify the calculation of desired temperatures in an electrical machine winding. This study is divided in two steps: First, the equivalent thermal conductivity is deduced from a homogenization of the winding, and next, a discretization is achieved using the finite integration technique considering transient analysis. In order to evaluate the method, results from the equivalent model are compared with finite element simulations considering two slot geometries.

Modification in Rotor Pole Geometry of Mutually Coupled Switched Reluctance Machine for Torque Ripple Mitigating

This paper presents a new method to minimize the torque ripple of a 3-phase, 6-slot, and 4-pole mutually coupled switched reluctance motor (MCSRM 6/4). The difference between a MCSRM and a classical SRM is their winding configuration. In a MCSRM, the mutual inductances are no longer neglectable when compared to self inductance. On the contrary, due to mutual inductances, the MCSRM can produce higher average torque than a classical SRM. A literature review is firstly performed to identify the source of high torque ripple level of a MCSRM. Then, the method using punching holes in rotor poles to modify the waveforms of flux as well as derivatives of inductances with respect to rotor position (dL/d and dM/d ) is proposed. Using the 2-D finite-element method (FEM), the influence of dimensions of punching hole on the electromagnetic performances (average torque and torque ripple) is analyzed. The two MCSRM are supplied by three-phase sine wave currents, and comparisons in terms of average torque and torque ripple versus RMS current density are also carried out. In order to make sure that the presence of punching holes does not cause mechanical problems, some mechanical studies are performed. Finally, experimental tests are also realized to validate numerical results obtained by 2-D FEM.

Thermal–Electromagnetic Analysis for Driving Cycles of Embedded Flux-Switching Permanent-Magnet Motors

This paper presents a fast and precise electromagnetic-thermal model of a redundant dual-star flux-switching permanent-magnet (FSPM) motor for embedded applications with driving cycles, e.g., hybrid electrical vehicle (HEV) and aerospace. This model is based on a prior steady characterization by finite-element method (FEM) 2-D of the FSPM motor via calculating the instantaneous torque and the normal and tangential components of the magnetic flux density (Br and Bθ) of each element of the stator and the rotor for different root-mean-square (RMS) current densities and different rotor positions. These results are then used in the analytical copper and iron loss models for calculating the instantaneous copper and rotor and stator iron losses during one driving cycle. The lumped-parameter (LP) and finite-element 2-D transient thermal models are then carried out, in which the previously obtained instantaneous power losses are used as heat sources for calculating the temperatures of different motor parts during driving cycles. In the thermal studies, a transformation of an irregular slot structure into a regular (rectangular) one is applied to simplify the calculation of the winding thermal resistance. The thermal-electromagnetic analysis method in this paper can also be extended for all the other applications with driving cycles. The experimental tests are carried out to validate the analytical and numerical results.

Performance Synthesis of Permanent-Magnet Synchronous Machines During the Driving Cycle of a Hybrid Electric Vehicle

This paper presents a comparative study of two surface-mounted permanent-magnet synchronous machines (PMSMs): the first with integral slot windings and the other with fractional slot windings. These machines have the same winding distribution on the stator and the same magnet volume on the rotor but different rotor pole numbers. The objective is to give the advantages of PMSMs with fractional slot windings. This paper also presents a computation method of average copper losses, including the flux weakening and that of average iron losses during the driving cycle for a hybrid electric vehicle (HEV). In this paper, in the electrical motorization of a truck, the specification characteristics give a maximum torque of 500 Nm and a maximum speed of 3000 returns per minute (rpm). Finally, a comparative study in terms of average losses during the driving cycle of the HEV has been presented. The energetic efficiency of the electric motor in the vehicle is shown.