Permanent Magnet In-wheel Motor Research Articles

Sliding mode control strategy based on disturbance observer for permanent magnet in-wheel motor

A novel sliding mode control(NSMC) strategy combined with a fast terminal sliding mode observer(FTSMO) is suggested in this paper to solve the parameter variation issue of permanent magnet in-wheel motor(PMIWM) installed in the distributed drive electrical vehicle (DDEV). First, a novel sliding mode power converging law is employed to enhance the response speed of the PMIWM controller. Second, an FTSMO is suggested to compensate for the parameter variation of the PMIWM system to strengthen the robustness of the control object. Finally, a fuzzy controller is designed to adjust the control parameters of the NSMC to optimize the control performance. Several simulations and experiments demonstrate that the proposed FTSMO-NSMC scheme can precisely compensate for parameter variation of the control object and improve control accuracy effectively.

Evolutionary Characteristics of Magnetic Field for the Permanent Magnet In-Wheel Motor Under Time-Dependent Demagnetization

Evolutionary Characteristics of Magnetic Field for the Permanent Magnet In-Wheel Motor Under Time-Dependent Demagnetization

High Torque Density and Lightweight Design of Permanent Magnet In-Wheel Motor Based on Magnetic Field Modulation Effect

High Torque Density and Lightweight Design of Permanent Magnet In-Wheel Motor Based on Magnetic Field Modulation Effect

Investigation of Fault-Tolerant Performance and Inductance in a Modular Permanent Magnet In-Wheel Motor

Investigation of Fault-Tolerant Performance and Inductance in a Modular Permanent Magnet In-Wheel Motor

Design of a Modular In-Wheel Motor With High Fault-Tolerant Performance and Low MMF Space Harmonic

In-wheel motors, as the core power component of electric vehicles, not only require high power density, but also high reliability and fault-tolerant (FT) capability. This paper proposes a modular permanent magnet (PM) in-wheel motor, and design to receive the high FT performance and low MMF space harmonic. First, according to the working mechanism and main faulty types of the modular FT motor, the corresponding FT control strategies are given, and the slot-pole combination with high FT performance for the modular motor is developed. Second, the electromagnetic characteristics of the modular in-wheel motor are investigated. The relationship between the FT performance and the inductance parameters is linked through the magnetic coupling coefficient. The design requirement for the inductance of this kind of motors is proposed. Third, the torque performance of the motor is studied, and the factors affecting torque performance during fault and FT operations are revealed. Finally, a prototype with slot-pole combination of 24S16P and four modules is produced, and the electromagnetic characteristics of the motor under FT operations are verified by experiments.

New design and optimization of an in-wheel permanent magnet motor with tangentially magnetized magnets and unequal stator teeth

Abstract Permanent magnet synchronous machines (PMSM) are competitive motors for in-wheel traction systems of electric vehicles. A new tangentially magnetized permanent magnets machine with outer rotor and unequal stator teeth for in-wheel motor application is proposed in this paper. The analytical calculations of the proposed topology are presented by determining the magnetic flux densities and the iron losses in all parts of the machine. The machine design is optimized using three state-of-the-art multiobjective algorithms which are AbYSS, MOCell and NMOPSO algorithms. Moreover, the optimization procedure is carried out according to three objectives: the maximization of the machine efficiency and the minimization of the mass and ripple torque. The optimization results showed that all the algorithms can find a set of optimal solutions and that the NMPSO algorithm outperforms the other two techniques. The finite element method (FEM) is used to investigate the optimization results. It is observed some magnetic saturation in the rotor yoke and the magnet’s extremes. The value of the induction in these machine regions is about 1.9 T. The comparison between the FEM and optimization results proved the rationality of the proposed optimization procedure.

Temperature Field Analysis and Cooling Structure Optimization for Integrated Permanent Magnet In-Wheel Motor Based on Electromagnetic-Thermal Coupling

Aiming at the impact of heat generation and temperature rise on the driving performance of a permanent magnet (PM) motor, taking the PM in-wheel motor (IWM) for electric vehicles as an object, research is conducted into the temperature distribution of the electromagnetic–thermal effect and cooling structure optimization. Firstly, the electromagnetic–thermal coupling model considering electromagnetic harmonics is established using the subdomain model and Bertotti’s iron loss separation theory. Combined with the finite element (FE) simulation model established by Ansoft Maxwell software platform, the winding copper loss, stator core loss and PM eddy current loss under the action of complex magnetic flux are analyzed, and the transient temperature distribution of each component is obtained through coupling. Secondarily, the influence of the waterway structure parameters on the heat dissipation effect of the PM-IWM is analyzed by the thermal-fluid coupled relationship. On the basis, the optimization design of waterway structure parameters is carried out to improve the heat dissipation effect of the cooling system based on the proposed chaotic mapping ant colony algorithm with metropolis criterion. The comparison before and after optimization shows that the temperature of key components is significantly improved, the average convection heat transfer coefficient (CHTC) is increased by 23.57%, the peak temperature of stator is reduced from 95.47 °C to 82.73 °C, and the peak temperature of PM is decreased by 14.26%, thus the demagnetization risk in the PM is improved comprehensively. The research results can provide some theoretical and technical support for the structural optimization of water-cooled dissipation in the PM motor.

Electromagnetic-thermal coupling analysis of a permanent-magnet in-wheel motor with cooling channels in the deepened stator slots

Heat generated inside a permanent-magnet (PM) in-wheel motor is usually not well dissipated due to the narrow space inside wheel hub, causing degrading performance and even safety risk. To improve the cooling performance of PM in-wheel motor, we propose a cooling structure in which cooling channels are moved into deepened stator slots. The cooling performance and electromagnetic influence are evaluated through electromagnetic-thermal coupling analysis. The results show that when the output power is kept unchanged, cooling channels at the bottom of deepened stator slots shortens the heat flow path from windings to coolant, lowering the maximum motor temperature from 153.7 to 144.4 °C compared with the scenario of cooling channels in housing. Meanwhile, the motor efficiency is slightly reduced by 0.02% due to the increase of stator teeth height. Moving cooling channels from the bottom to the middle of deepened stator slots increases the contact area between windings and cooling channels, which further lowers the maximum temperature to 129.5 °C. The motor efficiency is further reduced by 0.15% because of the change of winding position. The analysis shows that moving cooling channels into deepened stator slots can significantly lower the motor temperature and yet exerts little influence on the motor efficiency.

Design and Optimization Analysis of Coreless Stator Axial-Flux Permanent Magnet In-Wheel Motor for Unmanned Ground Vehicle

In this article, a coreless stator axial-flux permanent magnet (CSAFPM) indirect drive (ID) in-wheel motor is proposed and researched taking into consideration the multiphysics constraints, including electromagnetic performance and mechanical strength for unmanned ground vehicles (UGVs). At first, two 12-slot-14-pole CSAFPM motors with different rotor structures are designed to meet the vehicle rim space and driving system demand. In addition, the rotor parameters are optimized to obtain higher torque density based on the response surface method (RSM) and finite element model (FEM). Meanwhile, the electromagnetic performance of optimized motors with different rotors is compared, including back electromotive force (EMF), output torque capability, and efficiency characteristics. The results indicate that the Halbach-array PM rotor has higher torque and efficiency than the spoke-type PM rotor. On that basis, the thermal stress and deformation of the stator support are analyzed and optimized, considering material property and temperature distribution. In addition, the stress of PM rotor, annular gear, and gear reducer are analyzed and optimized to achieve higher torque density. Finally, a 35-kW prototype is manufactured and tested to verify the performance of the design.

Analytical Modeling of High-Torque-Density Spoke-Type Permanent Magnet In-Wheel Motor Accounting for Rotor Slot and Eccentric Magnetic Pole

In this article, a hybrid analytical model combining the subdomain method and the lumped-parameter magnetic circuit method (LMCM) is presented for the analysis of a high-torque-density spoke-type permanent magnet in-wheel motor considering rotor slot and eccentric magnetic pole. In the proposed model, the air-gap field distribution is derived using the subdomain method, while the saturation and the axial flux leakage of the iron core are considered by LMCM. The rectangular-shaped spoke magnets, eccentric magnetic poles, and rotor slots are approximated by multiple layers of arc-shaped subdomains. The magnetic equivalent circuit (MEC) of the stator and rotor is established, and the nonlinearity of the iron core is taken into account. Based on the developed hybrid analytical model, electromagnetic performance, such as cogging torque, electromagnetic torque, flux linkage, and back electromotive force, are obtained. The analytical results are verified by the finite-element method, and its application in the optimization process is investigated. Finally, a 1800-Nm high-torque prototype machine is manufactured and tested, and the results validate the accuracy and efficiency of the analytical method.

Optimization and finite element analysis of an in-wheel permanent magnet motor

Nowadays, artificial intelligence techniques have become widely used in electrical machines optimization and design. In this attempt, different methods have been proposed. The present work is devoted to the electromagnetic analysis and design of an in-wheel radial flux outer rotor surface mounted permanent magnet motor (SMPM) for electric vehicle application. Two based-Swarm Particle Optimization (PSO) techniques, namely, the improved PSO multi-Objective optimization and the Speed-constrained Multi-objective PSO Optimization, are applied. The main idea of the current optimization procedure is to determine the optimal machine sizing parameters providing the maximum of efficiency with the minimum of weight. To reach this goal, two objective functions are employed the efficiency maximization and the weight minimization. A preliminary analytical model describing the magnetic and electrical machine features was presented. In order to find the optimum design, the optimization results are discussed and analyzed. In addition, the electromagnetic performances of the found optimum design were studied by means of finite element analysis (FEA) and compared with those obtained by the optimization procedure.

Design and analysis of different cooling schemes of a flux‐modulated permanent magnet in‐wheel motor for electric vehicle applications

The flux-modulated permanent magnet (FMPM) in-wheel motor has provided a promising solution to drive electric vehicles (EVs) because of its salient features such as tight structure, high power (torque) density, and high transmission efficiency. But it easily causes excessive temperature rise and limits the torque output due to the poor heat dissipation capacity inside the in-wheel cavity. In this regard, a 3D fluidic-thermal coupled model integrating computational fluid dynamics and numerical heat transfer is proposed and validated by experimental results on a 2.1 kW, 1800 rpm PM motor prototype. The temperature rise distribution of a 22.6 kW, 600 rpm FMPM in-wheel motor under an existing natural cooling structure is then numerically investigated. It is revealed that it is difficult to satisfy the thermal requirements of the motor using only natural cooling approach. Consequently, a self-ventilated cooling system and a non-contact lead-in (NCLI) system are used to maintain the temperature rise. In addition, to further improve the heat dissipation capacity, the NCLI structure is modified with water cooling channels separated by orifice plates to limit the excessive motor temperature rise. The motor temperature rises under different cooling schemes are analyzed to verify the effectiveness of the proposed cooling structures.

Vibration noise suppression approach based on random switching frequency control for permanent magnet motor

The vibration noise of the distributed drive autonomous ground vehicle (AGV) is mainly produced by the inverter-fed brushless DC permanent magnet in-wheel motor (PMIWM). It is necessary to reduce the vibration noise level of the PMIWM driven by pulse width modulation (PWM). A suppression approach of electromagnetic vibration noise for the PMIWM is investigated. First, the air gap magnetic field of the inverter-fed PMIWM was analyzed. The electric current harmonics and the unbalanced magnetic force (UMF) were investigated. The natural frequency and noise of the PMIWM were presented. Then, a flux-weaken approach was employed to maintain the robustness of the PMIWM when a sudden drop of DC bus voltage. The random switching frequency (RSF) PWM control method based on a two-state Markov chain is proposed to decrease the amplitude of the harmonics caused by the switching frequency and the multiple switching frequencies. The experimental results show that the RSFPWM can not only effectively reduce the vibration noise and the inverter losses, but also improve the robustness of the PMIWM control system under unpredictable uncertainties.

Electromagnetic Vibration Analysis and Slot–Pole Structural Optimization for a Novel Integrated Permanent Magnet In-Wheel Motor

This paper presents a novel integrated permanent magnet (PM) in-wheel motor (IWM) driving system for electric vehicles (EVs), in order to overcome the disadvantages of electromagnetic vibration and cogging torque in the topology scheme, on the basis of maintaining high output torque. Firstly, the transient magnetic field of the integrated PM motor is analyzed using the improved analytical subdomain model and finite element (FE) model. The harmonic component of magnetic force density (MFD) is obtained with no-load condition. Furthermore, the vertical dynamic model for the dynamic vibration absorber is established to investigate the influence of the magnetic force harmonic on the vibration response of the stator and rotor. On this basis, the multi-objective optimization design of the pole–slot structure parameters is carried out by using the adaptive weighted particle swarm optimization (AWPSO) algorithm. Finally, the optimization results are compared and verified by FE analysis. The investigation shows that the unbalanced magnetic force and cogging torque is significantly reduced by the adjustment of the pole-arc coefficient, PM thickness, stator slot width and slot opening width.

Nonsingular Terminal Sliding Mode Control Based on Sensor-Cloud System for Permanent Magnet in-Wheel Motor

A nonsingular terminal sliding mode control (NTSMC) scheme based on beetle antennae search (BAS) algorithm is employed in this paper to overcome the internal interference of permanent magnet in-wheel motor (PMIWM) applied in the hybrid electric vehicles (HEVs). Firstly, a nonsingular terminal sliding mode approaching is applied to accelerate approaching speed and improve the response speed of the PMIWM system. Secondly, aiming at the undesired chattering caused by the large switching gain during the sliding mode control, fuzzy rules and fuzzy controller are designed to adjust sliding mode approaching parameter in online to inhibit the chattering phenomenon. Finally, a BAS algorithm based on sensor-cloud system (SCS) is adopted in this paper to obtain the ideal control parameters for the NTSMC control strategy, which can effectively improve the dynamic performance of the PMIWM. Through various simulation and experiments, the results demonstrate the proposed BAS-NTSMC strategy has optimal control performance and robustness, as well as reducing the chattering phenomenon during the control process significantly.

Fast Terminal Sliding Mode Control of Permanent Magnet In-Wheel Motor Based on a Fuzzy Controller

A fast terminal sliding mode control is proposed in this paper for improving the dynamic performance and robustness of a permanent magnet in-wheel motor system driven by a voltage source inverter. Firstly, a fast terminal sliding mode approaching law was designed to accelerate the approaching rate of the control system. Then, a torque load observer was designed to compensate for disturbances and uncertainties. Finally, fuzzy rules were designed to suppress the chattering phenomenon. Simulation and experimental results demonstrated that the fast terminal sliding mode control strategy presented better response speed than the conventional sliding mode control strategy. It had better dynamic performance and anti-interference and effectively reduced the chattering phenomenon in the control process.

Thermal Modeling and Analysis of Active and End Windings of Enclosed Permanent-Magnet Synchronous In-Wheel Motor Based on Multi-Block Method

This paper presents an accurate modeling method to investigate the thermal performance of the windings under steady state. The model considers the heat conduction of active windings and heat convection of end windings. To verify the validity of this model, a 20/24 poles/slots permanent magnet (PM) in-wheel motor is taken as an example. Firstly, the temperature distribution of the active windings in the slot is calculated by a multi-block 2-D temperature field model, which is verified by the model built according to the reality. The numerical results of blocks model agree well with those of the real model. Secondly, a 3-D temperature field model with the end windings is built on the 2-D blocks model. Furthermore, to include the air inside the motor, computational fluid dynamics (CFD) has been utilized, and the numerical results are experimentally verified. Finally, the distribution of the heat transfer coefficient (HTC) of the end windings and the influence of rotor speed on the HTC are investigated. These HTCs acquired from CFD results and empirical formulas are compared and analyzed carefully.

A novel hybrid control approach for modular automation system: a case study of sensorless interior permanent magnet in-wheel motor

PurposeSensorless interior permanent magnet in-wheel motor (IPMIWM), as an exemplar of modular automation system, has attracted considerable interests in recent years. This paper aims to investigate a novel hybrid control approach for the sensorless IPMIWM from a cyber-physical systems (CPS) perspective.Design/methodology/approachThe control approach is presented based on the hybrid dynamical theory. In the standstill-low (S-L) speed, the rotor position/speed signal is estimated by the method of the high frequency (HF) voltage signal injection. The least square support vector machine (LS-SVM) is used to acquire the rotor position/speed signal in medium-high (M-H) speed operation. Hybrid automata model of the IPMIWM is established due to its hybrid dynamic characteristics in wide speed range. A hybrid state observer (HSO), including a discrete state observer (DSO) and a continuous state observer (CSO), is designed for rotor position/speed estimation of the IPMIWM.FindingsThe hardware-in-the-loop testing based on dSPACE is carried out on the test bench. Experimental investigations demonstrate the hybrid control approach can not only identify the rotor position/speed signal with a certain load but also be able to reject the load disturbance. The reliability and the effectiveness of the proposed hybrid control approach were verified.Originality/valueThe proposed hybrid control approach for the sensorless IPMIWM promotes the deep combination and coordination of sensorless IPMIWM drive system. It also theoretically supports and extends the development of the hybrid control of the highly integrated modular automation system.

Inductance Characteristic Analysis of Consequent-Pole Permanent Magnet In-Wheel Motor

This paper presents inductance characteristics analysis of the consequent-pole permanent magnet in-wheel motor (CPM). Considering the specialty of consequent-pole structure, this paper analyzes the change rule of the winding self-inductance via equivalent magnetic circuit method (EMCM). The corresponding equivalent resistance is directly given when the rotor is in different positions. Based on this, equivalent magnetic circuit (EMC) that reflects the inductance of the CPM is summarized in this paper. In order to analyze the difference and connection of the inductance among the CPM, two models with 36 slots 32 poles and 48 slots 40 poles are established and compared. Moreover, the Fourier analysis expression of winding self-inductance is deduced to prove the different periodicities of winding self-inductance between two motors. The experimental result is consistent with the theoretical analysis, and the conclusion effectively proves the close relationship between the inductance characteristics and its internal structure of the motor.

Decoupling control for permanent magnet in-wheel motor using internal model control based on back-propagation neural network inverse system

Decoupling control for permanent magnet in-wheel motor using internal model control based on back-propagation neural network inverse system