Hybrid Electric Vehicle Motor Research Articles

Performance Analysis of Magnetically Geared Permanent Magnet Brushless Motor for Hybrid Electric Vehicles

The magnetic field modulated variable speed permanent magnet (PM) brushless motor (MFMVS-PMBM) is a new type of power shunting device for hybrid electric vehicles (HEVs), which is composed of a magnetic gear (MG) and a PM brushless motor (PMBM). Compared with the conventional double rotor motor, the MFMVS-PMBM shows a more complex electromechanical energy conversion relationship due to its special magnetic field modulation principle. In order to obtain better electromagnetic characteristics of the motor, the key parameters of MG and PMBM are optimized in this study. The effects of gear ratio, the number of blocks per pole of the Halbach array, and the angle of connecting bridge and magnetic isolation bridge on the torque of MG are analyzed. The electromagnetic characteristics of the motor, such as pole slot matching, PM thickness, and slot opening width of PMBM, are also analyzed. Finally, the prototype is made, and the experimental platform is built. The results show that MFMVS-PMBM has a good sinusoidal back electromotive force (EMF), high transmission efficiency, and power factor.

Bidirectional DC-DC Converter for Electric Vehicle

The present work aims at designing and modelling of a bidirectional DC DC converter for driving a Permanent Magnet DC (PMDC) motor for Hybrid Electric Vehicle (HEV) and Electric Bikes (EV) application. Permanent Magnet Brushed DC (PMBDC) motors and Permanent Magnet Brushless DC (PMBLDC) motors are the most popular options that are used for the integration of an electric bicycle and bikes. But despite of the simple controllers and low cost of the PMDC motor its lower efficiency sets it back in choice in the present scenario as compared to the BLDC motors. The present design aims at improving the efficiency of the PMDC motor traction drive system by the incorporation of the bidirectional DC DC converter between the electrical source and the traction motor which in addition to its primary function of providing the traction energy, also facilitates the energy regeneration during braking (in the case of HEV and EV) and during the motion along down the slope(in case of a pedalled electric bicycle).

Research on Kinetic Characteristics of Permanent Magnet Toroidal Motor for Hybrid Electric Vehicles

In this paper, a novel permanent magnet toroidal motor (PMTM) for hybrid electric vehicles (HEVs) is proposed. According to the structural features and working principle of PMTM, the characteristics of function integration are analyzed from two turning direction combinations of permanent magnetic teeth and windings respectively. The opposite turning direction combination is selected to ensure the uniform rotation of planets. The output speed of planet carrier rotor is deduced, and the influences of worm inner rotor permanent magnetic tooth number and stator pole-pair number on output speed are investigated. Based on the equivalent magnetic charge method, the output torque of PMTM is derived in two driving modes, and the effect of rise angle of worm inner rotor permanent magnetic tooth and toroidal stator winding on output torque are discussed. The research results indicate that the output torque is better with the rise angle α <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> = 50° and α <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> ' = 52°.

Design Method for Flux-Concentrating Permanent-Magnet Traction Machine Based on Voltage-Parameter Map

A voltage-parameter map (VP-Map) is proposed for predicting the performance of electric vehicles (EVs) and hybrid EVs (HEVs), which varies with respect to the parameters in a variable load and flux-weakening range, and determining the design parameters. Through this, the maximum torque that can be generated at the maximum speed, the input current for generation of the rated torque, and whether the vehicle is operable with a light load are predicted, and the design parameters suitable for the 120-kW class interior permanent-magnet (PM) synchronous motor for HEVs, which is the target electric motor of this study, are determined. A flux-concentrating PM synchronous motor (FCPMSM) is proposed that can be designed using the desired design parameters depending on the degree of the flux concentration. The validity of the VP-Map was verified by analyzing the characteristics of three types of FCPMSMs with different parameter combinations, and a PM synchronous motor for an EV having a high output, high efficiency, and high-power factor was designed. Lastly, the requirements were checked, and the analysis was validated by testing the designed motor.

Investigation on the Torque Ripple Reduction Method of a Hybrid Electric Vehicle Motor

Owing to the development of electric vehicles (EVs), research and development are underway to minimize torque ripple in relation to vibration and noise in EV motors. Although there are various ways to reduce torque ripple, this study analyzes the torque ripple, cogging torque, total harmonic distortion (THD), and magnetic flux density distribution for the three rotor shapes of interior permanent magnet synchronous motors, which are widely employed in EVs. To reduce the torque ripple while retaining the required average torque, the barrier shape is optimized, and wedge skew is applied. First, regarding the rotor barrier shape, torque ripple is primarily reduced by designing the rotor barrier shape with the response surface method, which is an experimental design method. Additionally, the wedge skew shape considering the bidirectional rotation and fabrication was applied to the stator shoe as a step and analyzed using three-dimensional finite element analysis. When designing the wedge skew, the layer subdivision according to the axial length, wedge skew diameter, and wedge skew position was analyzed and improved. The torque ripple reduction method in this paper can be applied not only to motors for EVs or Hybrid EVs (HEVs) but also all types of permanent magnet synchronous motors.

Study on the Harmonic Loss of Permanent Magnet Toroidal Space Motor for Hybrid Electric Vehicles

Based on magnetic gear transmission principle, permanent magnet toroidal space motor for hybrid electric vehicles with dual-rotor drive is proposed in this paper, harmonic loss caused by toroidal space relative motion of two rotors is conducted in hybrid drive mode. According to the structural principle of toroidal space motor, the speed of permanent magnet teeth of planet and worm inner rotor are decomposed to the revolution and rotation planes respectively. On the two planes, the frequency of alternating magnetic field at toroidal stator, planet and worm inner rotor are derived. At iron core and permanent magnetic teeth of stator and rotor, the magnetic field of revolution and rotation components are simulated. Combining with the speed relationship of toroidal space motor, the harmonic losses of revolution component and rotation component are analyzed in hybrid drive mode. The influence of speed matching of two rotors and toroidal stator material on harmonic loss are discussed. The results indicate that harmonic loss of permanent magnet toroidal space motor for hybrid electric vehicles can be reduced effectively by reducing relative speed of two rotors and adopting amorphous alloy for toroidal stator.

Development of a digital control system for a belt-driven starter generator segmented switched reluctance motor for hybrid electric vehicles

A novel four-phase 16/10 belt-driven starter generator segmented switched reluctance motor has been proposed in a previous work to reduce torque ripple and increase the fault tolerance ability. Based on the previous research, the segmented switched reluctance motor digital control system is designed and presented. The digital control system including a power converter, detection circuits, and protection circuits is introduced in detail. For detection circuits, the half-detection method is employed to decrease the cost of the system. In addition, based on MicroAutoBox DS1401, a rapid control prototype platform is established. With this software system, it is easy to transfer control models and realize real-time control directly. Then, the speed closed closed-loop control for the segmented switched reluctance motor is applied to verify the proposed system. It contains current chopper control at a low speed and angle position control at a high speed. The simulation results are given, including the flux, current, torque, and efficiency range over the entire speed range of the segmented switched reluctance motor. Finally, the experimental results are presented to verify the simulation results and the effectiveness of the system. It can be found that the simulation and experimental results are consistent and acceptable, which means that the proposed digital system can operate naturally and accurately under speed closed loop control. Hence, the proposed digital system has high compatibility and practicability.

Segment design of the complementary magnetic-geared dual-rotor motor for hybrid electric vehicles

Magnetic-geared dual-rotor motor (MGDRM) has been considered as a promising candidate of the power split device in the hybrid electric vehicles. Essentially, the MGDRM is a pure electrical component without the brush, slip ring and mechanical gears, so its reliability and lifetime can perform well. However, the design principle of the MGDRM has not been fully transferred to a practical technology. The asymmetrical back-EMF of this motor is an issue, which is a sake of the torque ripple produced by the MGDRM. The complementary structure has been proposed to improve the back-EMF, but some detailed problems of this solution have not been addressed. This paper gives the analysis and discussion on the segment design of the complementary MGDRM. Two prototype machines are also fabricated for the experimental validation of the research results.

Hybrid excitation flux switching motor with permanent magnet placed at middle of field coil slots and high filling factor windings

Design and experimental studies on a hybrid excitation flux switching motor as a traction motor for hybrid electric vehicles drive are presented. A stator body of the motor consists of not only laminated silicon-iron electromagnetic steel and three-phase armature windings, but also both of field excitation coils and permanent magnets working together as a variable field magnetomotive force source. On the other hand, a rotor is composed of just laminated silicon-iron electromagnetic steel with salient poles like switched reluctance motor. To bring out the best in drive performances of the hybrid excitation flux switching motor as a variable flux motor for the application, each material adopted for the stator and rotor body should be designed properly in terms of motor efficiency, maximum torque and power densities and so forth. As some of them, in this paper, thinner silicon-iron electromagnetic steel sheet and permanent magnets with high remanent and low amount of Dysprosium used are applied for achieving higher motor efficiency. Moreover, all coils wound flatwise and edgewise using rectangular wires are introduced to realizing high filling factor for reduced copper losses. Experimental tests using a 60kW prototype of the motor demonstrates the designed motor has good motor efficiency under frequent operating points expected for the target vehicle drive.

Acoustic Noise Reduction of a High-Efficiency Switched Reluctance Motor for Hybrid Electric Vehicles With Novel Current Waveform

One of the major topics of switched reluctance machines (SRMs) is how to reduce the acoustic noise and vibration without decreasing the efficiency. In this paper, a few novel current profiling methods are proposed to reduce the acoustic noise by flatting the radial force sum and to reduce optimal torque ripple with best efforts to enhance the efficiency. The proposed method is adopted to the 18/12 pole SRM, which has identical outer dimensions and competitive torque, output power, efficiency, and operating region of the permanent-magnet motor used in the hybrid vehicles. It is found that the proposed method can improve not only the radial force ripple characteristic but also the iron loss minimization. The efficiency enhancement is also found to be possible in a few cases depending on the demanding criteria; thanks to the phase shift of the fundamental component of the current waveform. The proposed method is verified in the experiments.

Modelling and Control of PMSM Drive by Field Oriented Control For HEV

The Hybrid Electric Vehicles (HEVs) have the best of both worlds significant fuel saving, on demand power, lowered emission and quiet, smooth, emission-free electric motive power as well. Nowadays Permanent Magnet Synchronous Motor (PMSM) minimizes the drawbacks of the BLDC motor and it has high efficiency and their inherently high-power density they have been accepted as having great potential to compete with induction motor for HEV. Such that in this paper, The Field Oriented Control (FOC) method is implemented to control the speed and torque of the PMSM motor by using dq reference frame theory. The PI controllers are used to regulate the speed and the dq current to generate the gate pulses for switching of the inverter according to correction voltage. The whole system is simulated under the MATLAB Simulink environment. Results are carried out based on step change of speed and torque and we analyzed performance parameters such as gate pulse for the inverter, inverter output voltage and current, rotor angle, motor speed, dq current, and electromagnetic torque. Simulation results show that PMSM has a fast-dynamic response and tunable output speed and torque with minimum deviation.

Shaft Design for Electric Traction Motors

This paper presents shaft design techniques specifically for applications in electric traction motors for hybrid electric vehicles (HEVs) and electric vehicles (EVs). The typical characteristics of several shafts used in traction motors for commercial HEVs/EVs are studied. Then, the shaft design for a 24/16 switched reluctance machine (SRM) is presented. The 24/16 SRM is designed to replace an interior permanent magnet synchronous traction motor used in an HEV application. The requirements of shaft design, design procedures, circumferential positioning, bearing positioning, and design of output end and sensor end are presented and discussed in this paper.

Analysis and Design of a Compound-Structure Permanent-Magnet Motor for Hybrid Electric Vehicles

On the basis of the excellent driving force demand of hybrid electric vehicles (HEVs), this paper studies the torque property of the compound-structure permanent-magnet motor (CSPM motor) used for HEVs, which is influenced by magnetic field oversaturation and variable nonlinear parameters. Firstly, the system configuration of HEVs based on CSPM motor and its working mode are introduced. Next, the state equation of CSPM motor in three-phase stationary coordinate system is proposed in order to investigate its torque performance; then, the factors affecting the output torque are gained. Finite element method (FEM)-based electromagnetic parameters analysis and design is carried out, to raise the output torque and reduce the torque ripple of CSPM motor. Besides, optimized design parameters are used to establish the FEM model, and the simulation results of electromagnetic performances for the CSPM motor before and after optimization are given to verify the rationality of optimization.

Modeling of electromagnetic torque considering saturation and magnetic field harmonics in permanent magnet synchronous motor for HEV

Electromagnetic torque ripple of permanent magnet synchronous motor (PMSM) causes electro-mechanical coupling vibration and noise in hybrid electric vehicle (HEV). However, the traditional mathematical model of PMSM cannot absolutely reflect the reason of torque ripple and variation on the different operation performance of the motor for HEV. The purpose lies in the fact that electromagnet factor originated torque ripple and variation have been taken into account in the mathematic model of PMSM. Based on the classical Park's transformation theory and the Fourier series analysis of magnetic field, a general nonlinear mathematical model of PMSM considering saturation and magnetic field spatial harmonics and time harmonics is presented in this paper. The general analytical model cannot only taking into account the variation of electromagnetic parameters caused by electric vehicle operating, but also can explain the frequency and the order of torque ripple theoretically. The model's effectiveness is tested through finite element analysis simulations and some experimental results. The analytical model presented here can be used for the characteristic analysis, the drive system dynamic precise analysis and fault diagnose of PMSM for HEV.

Cylindrical Rotor Design for Acoustic Noise and Windage Loss Reduction in Switched Reluctance Motor for HEV Applications

A switched reluctance motor (SRM) is one of the candidates of rare-earth-free motors for hybrid electric vehicles (HEVs). An SRM has been developed with same interior permanent magnet synchronous motor (IPMSM) dimensions having competitive maximum torque, operating area, and maximum efficiency. However, this SRM has a windage loss of 1.3 kW due to the salient poles of the SRM driven at the maximum rotational speed. In addition, considerable acoustic noise is caused by the salient poles. In this paper, a simple design of a cylindrical outer shape rotor is proposed, and a comparison with the conventional SRM rotor is carried out. It is found that the efficiency is improved due to the windage loss reduction. It is also found that the acoustic noise is significantly reduced in the proposed rotor design.

Research and design of doubly salient permanent magnet motor for hybrid electric vehicle based on the NdFeB permanent magnet material

The performance of hybrid electric vehicle motor directly affects its power performance and fuel economy. The high performance sintered NdFeB permanent magnet material is chosen as the core material of the hybrid vehicle motor for the design of the permanent magnet in this paper, and its size is also determined. A doubly salient permanent magnet motor is proposed here on the basis of the selected NdFeB permanent magnet material, and its structure size is designed. The finite element numerical calculation is carried out for the motor in particular rotor position angle on the basis of the field quantity to obtain the magnetic field distribution law in several typical rotor positions and the static characterise parameters of the motor are further obtained. Final, inspect the performance of the prototype objectively based on the bench experiment of the designed physical prototype, and the prototype experiment and finite element results both proved that the designed doubly salient permanent magnet motor could meet the requirements of hybrid electric vehicle, so as to achieve the purpose of the research and design of the doubly salient permanent magnet motor used in hybrid electric vehicle.

Enhancement of Coercivity of Nd-Fe-B Ultrafine Powders Comparable With Single-Domain Size by the Grain Boundary Diffusion Process

Nd-Fe-B sintered magnets are widely used in many applications. However, for the use in motors for hybrid electric vehicles (HEV), the development of Dy-free or Dy-lean Nd-Fe-B sintered magnets with high coercivity is desirable. Decreasing grain size of the Nd 2 Fe 14 B phase is an established method for increasing coercivity of Nd-Fe-B sintered magnets. We decreased the size of jet-milled powder to around 1 mm by helium (He) jet-milling in Dy-free Nd-Fe-B sintered magnets and obtained high coercivity (μ 0 H cJ ) of 2 T with (BH) max of around 400 kJm−3 [1]. We also succeeded further decrease in the size to 0.3 μm by combining hydrogenation-disproportionation-desorption-recombination (HDDR), hydrogen decrepitation (HD) and He jet-milling [2, 3]. However, the effect of annealing on magnetic properties of the ultrafine powders was not clear. On the other hand, the grain boundary diffusion (GBD) process [4-6] is well known as an effective method for the enhancement of coercivity. However, the effect for the ultrafine powders has not been investigated. Therefore, in this investigation, we investigated the effects of annealing and GBD process on coercivity of the Nd-Fe-B ultrafine jet-milled powders prepared by our developed process which combined HDDR, HD and He jet-milling.

Design of Synchronous Reluctance Motor for Hybrid Electric Vehicles

This paper deals with the design of a synchronous reluctance motor suited for hybrid electric vehicles. The focus is mainly on rotor design: the angles of the flux barrier ends are chosen with the aim of reducing the torque ripple due to the slot harmonics. A comparison among different rotor arrangements (one, two, and three flux barriers per pole) is presented. Furthermore, an improvement in terms of low ripple and high average torque is given owing to the “Machaon” configuration. The current vector control method is used to maximize the torque according to the voltage and current constraints, taking into account the saturation effects. The impact of the electrical design on the mechanical characteristics of the rotor (natural frequencies) is discussed as well. At last, the predicted mechanical characteristics of the reluctance motor are presented: torque versus speed behavior, power losses, and power factor. The efficiency map of the machine is also reported in the whole operating region.

Proposal of Improved Winding Method for VR Resolver

The variable reluctance (VR) resolver is generally used instead of an optical encoder as a position sensor on motors for hybrid electric vehicles or electric vehicles owing to its reliability, low cost, and ease of installation. The commonly used conventional winding method for the VR resolver has disadvantages, such as complicated winding and unsuitability for mass production. This paper proposes an improved winding method that leads to simpler winding and better suitability for mass production than the conventional method. In this paper, through the design and finite element analysis for two types of output winding methods, the advantages and disadvantages of each method are presented, and the validity of the proposed winding method is verified. In addition, experiments with the VR resolver using the proposed winding method have been performed to verify its performance.

Optimization of 6S-14P E-Core Hybrid Excitation Flux Switching Motor for Hybrid Electric Vehicle

Research on hybrid electric vehicle (HEV) which combined battery based electric motor and conventional internal combustion engine (ICE) have been intensively increased since the last decade due to their promising solution that can reduce global warming. Some examples of electric motors designed for HEV propulsion system at present are dc motor, induction motor (IM), interior permanent magnet synchronous motor (IPMSM) and switched reluctance motor (SRM). Although IPMSMs are considered to be one of the successful electric motor used in HEVs, several limitations such as distributed armature windings, un-control permanent magnet (PM) flux and higher rotor mechanical stress should be resolved. In this paper, design improvement of E-Core hybrid excitation flux switching motor (HEFSM) for hybrid electric vehicles (HEVs) applications are presented. With concentrated armature and field excitation coil (FEC) windings, variable flux capability and robust rotor structure, performances of initial and improved 6S-14PE-Core HEFSM are analyzed. The improved topology has achieved highest torque and power of 246.557Nm and 187.302 kW, respectively.