Permanent Magnet Synchronous In-wheel Motor Research Articles

Fixed-time anti-disturbance constraint fuzzy synchronization control for PMSM based four-wheel-independent-drive EVs

A fixed-time anti-disturbance constraint fuzzy synchronization control method is proposed, for the sake of solving the problem of fast recovery of synchronization between in-wheel permanent magnet synchronous motors (PMSMs) in four-wheel-independent drive electric vehicles. The system model of in-wheel PMSM is presented in the beginning, and fuzzy logic systems are used for approximating the uncertainty parts of the PMSM model. Based on the PMSM model, a fixed-time disturbance-observer is designed to account for fast estimation of fluctuating load torque. Then, the neighborhood synchronization error is constructed based on a directed-graph, and a performance function is designed to guarantee the neighborhood synchronization error evolves strictly within the prescribed bound. Besides, the fixed-time bound of all signals is proved. Finally, the hardware-in-the-loop platform is built, and the electronic differential and the nonlinear vehicle model are employed to validate the advanced performance of the design control method.

In Search of the Proper Dimensions of the Optimum In-Wheel Permanent Magnet Synchronous Motor Design

In this paper, a new approach to the optimized design of outer rotor Permanent Magnet Synchronous Motors (PMSMs) for in-wheel light electric vehicle (LEV) applications is presented. The optimized design study is based on various dimensions such as back iron depth, permanent magnet depth and air gap length. The novel method is developed to reveal the quality factor of design (QFD), which implies the maximum possible performance results, and determine the best possible design for in-wheel PMSMs for direct-drive LEV applications. Therefore, the thickness of the back iron, permanent magnet and air gap dimensions are altered accordingly to obtain an optimized design. This design study is conducted for an in-wheel PMSM that has rated values of 2.5 kW, 150 V, 900 min−1, and 24-slot/20-pole configuration intended for LEV propulsion. These designs are simulated in order to obtain the maximized combination of efficiency, shaft power, shaft torque and a minimized combination of total weight, iron losses, copper losses, input current and cogging torque. The measure of the optimized parameters is named QFD, which indicates the goodness of the design through the use of radar charts. The values of the essential coefficients of QFD may vary for different applications, e.g., the design of PMSMs used in traction applications has some certain criteria that imply high-performance operation. Additionally, the QFD can guide motor manufacturers as a starting point for a design study.

Multi-objective optimization design of electric vehicle in-wheel motor based on Taguchi method

In order to solve the problem of motor performance degradation caused by torque ripple and large cogging torque of in-wheel permanent magnet synchronous motor for electric vehicles, Taguchi is used to optimize the magnetic pole of built-in Permanent magnet synchronous motor, and the orthogonal optimization matrix of magnetic pole parameters is established. Through the parameter optimization matrix, the workload of pole optimization is reduced and the optimization speed is improved. The optimization results show that the orthogonal matrix optimization can not only improve the output torque of permanent magnet synchronous motor, but also further control its torque ripple and cogging. The orthogonal matrix optimization method used in this paper for V-I type built-in permanent magnet synchronous motor has a certain positive significance, and provides a certain reference value for the subsequent motor performance optimization.

Dynamic Testing of In-Wheel Motor Based Electric Vehicle in Longitudinal Direction

This paper presents an investigation into the performance of in-wheel motor (IWM) based electric vehicles (IWM-EV) in the longitudinal direction. The design of IWM-EV is an innovation of the conventional go-kart vehicle with slightly modifications in steering, suspension, and braking system, which then makes use three-phase permanent magnet synchronous in-wheel motor (PMSM-IWM) at both of the rear axle wheels. An extension of that is a simulation of IWM-EV vehicle using a 5-degree-of-freedom vehicle longitudinal model that has been developed by incorporating PMSM-IWM as a drive wheel located at the rear axles. Using the simulation, vehicle dynamic control in the longitudinal direction-based Proportional-Integral-Derivative (PID) controller has also been strategized. As the intention to confirm the capability of the IWM-EV, experimental studies-based real IWM-EV hardware have been conducted. Three dynamic tests that generalized from SAE standard SAE J866-199908, namely acceleration performance at the level pavement (include acceleration tests and acceleration then braking tests) and road gradient tests at constant speeds of 10, 15 and 20 km/h, were used as the testing method. The performance areas evaluated were vehicle body speed, wheel speed, distance travel experienced by the vehicle, IWMs current, drive torque as well as the battery voltage capacity used by the vehicle. The finding indicate that the simulation results and experimental data are similar with less than 5 % error. The outcomes from this study will be considered in the design optimization of a torque vectoring control in the next research study.

Investigation of Open-Circuit Fault-Tolerant Strategy in a Modular Permanent Magnet Synchronous In-Wheel Motor Based on Electromagnetic–Thermal Analysis

This article investigates the asymmetric temperature distribution of a modular permanent magnet (PM) synchronous in-wheel motor under fault conditions, and based on this, proposes a fault-tolerant (FT) strategy named minimum temperature difference strategy (MTDS) to avoid the high temperature appearing at local winding. First, the modular motor system and the FT principle are introduced, and the reconfiguring fundamental magneto motive force (MMF) under open-circuit of one phase in one module is deduced. Second, the loss and temperature distributions of the motor with normal operation are analyzed by the coupled electromagnetic–thermal method. And the mutual verification between simulation and experiment is adopted to separate the copper losses, iron losses, and PM losses from total losses. Furthermore, the asymmetric temperature distributions of the motor operating with part of modules are analyzed in detail. Finally, the influence of the faulty windings on the temperature of healthy windings is investigated, and the FT strategy of MTDS is proposed. The asymmetric temperature distributions of the motor under various FT strategies are compared. The result shows that the MTDS can significantly reduce the maximum temperature of the windings and makes the winding temperature distribution more uniform.

An Improved Deadbeat Predictive Stator Flux Control With Reduced-Order Disturbance Observer for In-Wheel PMSMs

In this article, an improved deadbeat predictive stator flux control (DPSFC) based on disturbance observer is proposed to address the problems of the steady-state tracking error and robustness decrease due to the detrimental parameter mismatch and disturbance. First, the sensitivity of conventional deadbeat predictive current control to the parameter variation, including flux linkage, stator inductance, and resistance, is analyzed. Then, a reduced-order observer based on additional disturbance state variables in discrete time is designed to predict the future stator flux and observe the system disturbance caused by parameter mismatch. The proposed DPSFC method is able to enhance the robustness of the drive performance effectively via applying the estimated disturbance as the feed-forward compensations of one-step delay and stator voltage. Additionally, the theoretical proof is given. Finally, the superiority of the proposed control method is validated by simulations and experiments on a prototype of an in-wheel permanent magnet synchronous motor drive.

Water Jacket and Slot Optimization of a Water-Cooling Permanent Magnet Synchronous In-Wheel Motor

This article investigates the water jacket and slot optimization of a water-cooling permanent magnet synchronous in-wheel motor. The optimization consists of the improvements of the water jacket heat dissipation and slot heat dissipation. In order to reduce the temperature difference between the water and water jacket wall, the impact of the water jacket configuration parameters and shapes are theoretically studied. According to the researches, the method for the water jacket optimization is proposed. A slot thermal model is established to optimize the thermal behavior in slots. The variations of the thermal performances with impregnation materials and slot configuration parameters are analyzed. On the basis of the analysis, this article presents a method for the thermal optimization. The validity of the method is supported by the finite element analysis, computational fluid dynamics and experiments.

Robust Control for Active Suspension of Hub-Driven Electric Vehicles Subject to in-Wheel Motor Magnetic Force Oscillation

In this paper, after investigating the coupling effect in a permanent magnet synchronous in-wheel motor, a robust control method for active suspension of hub-driven electric vehicles (EVs) to enhance the performance of the in-wheel motor and the vehicle is proposed. Based on the electric vehicle model addressing the coupling effect between the electromagnetic excitation of the permanent magnet synchronous motor (PMSM) and the transient dynamics in EVs, the influence of the coupling effect on the motor and the vehicle performance is analyzed. The results reflect that the coupling effect in in-wheel motors intensifies the magnetic force oscillation, aggravates the eccentricity of the rotor, deteriorates the motor operation performance, and worsens the ride comfort. To suppress the magnetic force oscillation in motor and enhance the vehicle comfort, the active suspension system considering five aspects of suspension performance is introduced. Simultaneously, on the basis of Lyapunov stability theory, a reliable robust Hꝏ controller considering model uncertainties, actuator failure and electromagnetic force interference is designed. The simulation results reflect that the robust Hꝏ feedback controller can not only achieve better ride comfort, but also restrain the coupling effect in the motor. Meanwhile the other requirements such as the road holding capability, the actuator limitation, and the suspension deflection are also maintained. The proposed robust control method demonstrates a potential application in the practice of EV control.

Coupling effects in hub motor and optimization for active suspension system to improve the vehicle and the motor performance

For electric vehicles (EVs) driven by in-wheel motor (IWM), the motor is directly integrated into the wheel. The coupling effects caused by the magnet gap deformation (MMG) in the motor and further enhanced by the unbalanced electromagnetic force (UEF) and the road excitation deteriorate the performance of EVs. However, few researchers have explored the coupling effects based on permanent magnet synchronous in-wheel motor and methods to suppress them. In this paper, the integrated model addressing the mechanical–electrical–magnetic coupling effects between the electromagnetic excitation in the permanent magnet synchronous motor (PMSM) and the transient dynamics in EVs is developed. The function mechanism of UEF-MMG deformation coupling circle is investigated and its influences on the performance of EV are explored. Moreover, using particle swarm optimization (PSO) algorithm, a multi-objective optimization method for active suspension system is proposed to solve the negative coupling effects. The simulation results indicate that the optimized active suspension system which considers the multi-field coupling effects of the IWM can effectively reduce the UEF caused by the eccentricity in the motor. Furthermore, it can attenuate the multi-field coupling effects and remarkably improve the ride comfort of EVs. The proposed multi-objective optimization method demonstrates a potential application in engineering practice.

Lightweight design of the in-wheel motor considering the coupled electromagnetic-thermal effect

The lightweight problem of in-wheel motor is one of the key problems to be solved in the development of in-wheel motor driving electric vehicles. However, in-wheel motor involves the cross-coupling effect of multi-physical fields, such as the structure field, electromagnetic field and thermal field. The lightweight design for the in-wheel motor means the change in the structure, which will lead to the change in other physical field characteristics. Aiming at this problem, a lightweight design method is proposed in this paper. A 15Kw embedded permanent magnet synchronous in-wheel motor is taken as the research object, the minimum volume is set as the optimization objective, and the topology optimization design method is adopted to reduce the weight of the motor. And in the optimization design process, the bilateral coupling constraint of the electromagnetic field and thermal field is taken into account simultaneously. This study aims to find the optimal topology distribution considering the cross-coupling effect of structure-electromagnetic-thermal fields, and obtain the optimal structure of the in-wheel motor that meets the design requirements. Furthermore, the validity of the lightweight design method is verified by comparing and analyzing the characteristics of each physical field of the in-wheel motor before and after optimization.

Calculation of the Iron losses in a Spoke-Type Permanent Magnet Synchronous In-Wheel Motor for Electric Vehicles by Utilizing the Bertotti Model

This paper presents an analytical method for the calculation of the iron losses in a spoke-type permanent magnet synchronous in-wheel motor. According to the magnetic field distribution, the iron cores are divided into tooth, yoke, bridge, and shoe. Based on the boundary conditions of the subdomain model, the bridge is equivalent to the fan-shaped region with constant permeability. Then, the no-load and on-load magnetic fields in the air gap, tooth, yoke, bridge, and shoe are analytically calculated. The impacts of slotting and bridge saturation are considered. On the basis of the analytical expression of the magnetic fields, the iron losses of the tooth, yoke, bridge, and shoe are obtained by the Bertotti model. The analytical results in the no-load and on-load conditions are compared with that of the finite-element analysis. The validity is verified by the finite-element analysis.

Analytical Model of a Spoke-Type Permanent Magnet Synchronous In-Wheel Motor With Trapezoid Magnet Accounting for Tooth Saturation

This paper presents an analytical model for the prediction of the performance in a spoke-type permanent magnet synchronous in-wheel motor with a trapezoid magnet accounting for tooth saturation. The impact of magnet shape on modeling is considered. To match the standard boundary conditions, the trapezoid magnet is simplified to sector magnets. According to the invariance principle of the magnetic field created by the magnet, the dimension of the sector magnet is calculated with a lumped magnetic circuit model. Then, the motor is divided into six subdomains, i.e., shaft, inner sector magnet, outer sector magnet, rotor slot, air-gap, and stator slot. Based on the boundary conditions, the magnetic field, back electromotive force, and torque are obtained by solving Poisson's and Laplace's equations. The effect of tooth saturation is considered. The finite-element method and experiments are employed to validate the accuracy of the analytical model. In addition, the proposed method can also be used to evaluate the performance of the spoke-type motor with any irregular magnet.

Modeling and Analysis of Loss and Temperature Field in Permanent Magnet Synchronous In-wheel Motor Based on Preisach Theory

Modeling and Analysis of Loss and Temperature Field in Permanent Magnet Synchronous In-wheel Motor Based on Preisach Theory

Transient thermal analysis of an interior permanent magnet synchronous in-wheel motor driving system

The close integration of the in-wheel motor (IWM) driving system structure makes the space closed and narrow, and heat dissipation difficult. Meanwhile, the pursuit of high power density of the IWM leads to the increase of the loss density and the temperature of the IWM. This seriously affects the safe operation of the motor and the vehicle. In this paper, an interior permanent magnet synchronous IWM driving system is taken as the research object. The electromagnetic and temperature field analysis model are developed based on the detailed structure of the IWM driving system firstly. Then the transient thermal analysis under the rated and peak condition are carried out through the magneto-thermal coupling method. The results show that, under rated condition, when the IWM reaches a steady state, the highest temperature occurs on the copper wire of the stator winding, which is 111.8°C; under peak condition, due to the big loss generated by the motor overload operation, the maximum temperature of the motor reaches 170°C during the simulation analysis of 60 s, which has exceeded the motor insulation level requirements of 155°C. Therefore, cooling design is necessary in order to ensure the normal operation of the IWM and the vehicle.

Transient thermal analysis of an interior permanent magnet synchronous in-wheel motor driving system

The close integration of the in-wheel motor (IWM) driving system structure makes the space closed and narrow, and heat dissipation difficult. Meanwhile, the pursuit of high power density of the IWM leads to the increase of the loss density and the temperature of the IWM. This seriously affects the safe operation of the motor and the vehicle. In this paper, an interior permanent magnet synchronous IWM driving system is taken as the research object. The electromagnetic and temperature field analysis model are developed based on the detailed structure of the IWM driving system firstly. Then the transient thermal analysis under the rated and peak condition are carried out through the magneto-thermal coupling method. The results show that, under rated condition, when the IWM reaches a steady state, the highest temperature occurs on the copper wire of the stator winding, which is 111.8°C; under peak condition, due to the big loss generated by the motor overload operation, the maximum temperature of the motor reaches 170°C during the simulation analysis of 60 s, which has exceeded the motor insulation level requirements of 155°C. Therefore, cooling design is necessary in order to ensure the normal operation of the IWM and the vehicle.

Design and implementation of a loss optimization control for electric vehicle in-wheel permanent-magnet synchronous motor direct drive system

As a main driving force of electric vehicles (EVs), the losses of in-wheel permanent-magnet synchronous motor (PMSM) direct drive system can seriously affect the energy consumption of EVs. This paper proposes a loss optimization control strategy for in-wheel PMSM direct drive system of EVs which optimizes the losses of both the PMSM and the inverter. The proposed method adjusts the copper losses and iron losses by identifying the optimal flux-weakening current, which results in the PMSM achieving the lower losses in the whole operational range. Moreover there are strongly nonlinear characteristics for the power devices, this paper creates a nonlinear loss model for three-phase half-bridge inverters to obtain accurate inverter losses under space vector pulse width modulation (SVPWM). Based on the inverter loss model and double Fourier integral analysis theory, the PWM frequency is optimized by the control strategy in order to maximize the inverter efficiency without affecting the operational stability of the drive. The proposed loss optimization control strategy can quickly find the optimum flux-weakening current and PWM frequency, and as a result, significantly broaden the high efficiency area of the PMSM direct drive system. The effects of the aforementioned strategy are verified by both theoretical analysis and experimental results.

Equivalent stator slot model of temperature field for high torque-density permanent magnet synchronous in-wheel motors accounting for winding type

Purpose – For high torque-density permanent magnet synchronous in-wheel motor, service life and electromagnetic performance are related directly to winding temperature. The purpose of this paper is to investigate the equivalent stator slot model to calculate the temperature of winding accurately. Design/methodology/approach – This paper analyzes the the law of heat flux transfer in slot, which points the main influence factors of equivalent stator slot model. Thermal network model is used to investigate the drawbacks of conventional equivalent model. Based on the law of heat transfer in stator slot, a new layered winding model is put forward. According to winding type and property of impregnations, detailed method and equivalent principle of the new model are presented. The accuracy of this new method has been verified experimentally. Findings – An accurate equivalent stator slot model should be built according to the low of heat transfer. According to theory analysis, the drawbacks of conventional equivalent stator slot model are pointed: it cannot reflect the temperature gradient of winding; the maximum and the average temperature of winding are much higher than actual value. For the new layered model, equivalent principle is related to winding type and property of impregnations, which makes the new model widely used. Originality/value – This paper presents a new layered model, and shows detailed method, which is more meaningful for designers. The new layered model takes winding type and property of impregnations into account, which makes the new model widely used. It is verified experimentally that layered model is applicable to not only steady-state temperature field but also transient temperature field.

Stability Enhancement of Four-in-Wheel Motor-Driven Electric Vehicles Using an Electric Differential System

This paper presents a new multi-machine robust control based on an electric differential system for electric vehicle (EV) applications which is composed of four in-wheel permanent magnet synchronous motors. It is based on a new master?slave direct torque control (DTC) algorithm, which is used for the control of bi-machine traction systems based on a speed model reference adaptive system observer. The use of an electric differential in the design of a new EV constitutes a technological breakthrough. A classical system with a multi-inverter and a multi-machine comprises a three-phase inverter for each machine to be controlled. Another approach consists of only one three-phase inverter for several permanent magnet synchronous machines. The control of multi-machine single-inverter systems is the subject of this study. Several methods have been proposed for the control of multi-machine single-inverter systems. In this study, a new master?slave based DTC strategy is developed to generate an electric differential system. The entire system is simulated by Matlab/Simulink. The simulation results show the effectiveness of the new multi-machine robust control based on an electric differential system for use in EV applications.

Optimization of In-Wheel Permanent Magnet Synchronous Motor for Electric Car

The objective of this work is to find the optimal geometric parameters for the design of permanent magnet synchronous machines (PMSM) with inversed structure (outer rotor) for electric vehicles applications. Firstly, the machine model is presented with a special attention given to the calculation of the mass and engine efficiency. A multi objective optimization based on the genetic algorithm is then implemented. It will determine the parameters values that optimize the chosen criteria while respecting the specifications: to minimizing the total mass and maximizing the machine efficiency. Finally, 2D steady-state finite element analysis is used for to verify the results given by the optimization method.

Interaction of In-wheel permanent magnet synchronous motor with tire dynamics

Drive wheel systems combined with the in-wheel permanent magnet synchronous motor (I-PMSM) and the tire are highly electromechanical-coupled. However, the deformation dynamics of this system, which may influence the system performance, is neglected in most existing literatures. For this reason, a deformable tire and a detailed I-PMSM are modeled using Matlab/Simulink. Furthermore, the influence of tire/road contact interface is accurately described by the non-linear relaxation length-based model and magic formula pragmatic model. The drive wheel model used in this paper is closer to that of a real tire in contrast to the rigid tire model which is widely used. Based on the near-precise model mentioned above, the sensitivity of the dynamic tire and I-PMSM parameters to the relative error of slip ratio estimation is analyzed. Additionally, the torsional and longitudinal vibrations of the drive wheel are presented both in time and frequency domains when a quarter vehicle is started under conditions of a specific torque curve, which includes an abrupt torque change from 30 N · m to 200 N · m. The parameters sensitivity on drive wheel vibrations is also studied, and the parameters include the mass distribution ratio of tire, the tire torsional stiffness, the tire damping coefficient, and the hysteresis band of the PMSM current control algorithm. Finally, different target torque curves are compared in the simulation, which shows that the estimation error of the slip ratio gets violent, and the longitudinal force includes more fluctuation components with the increasing change rate of the torque. This paper analyzes the influence of the drive wheel deformation on the vehicle dynamic control, and provides useful information regarding the electric vehicle traction control.