End Windings Research Articles

Acoustic Noise Mitigation in Slip Angle Controlled DTC of Open-End Winding Induction Motor Drive Using Dual Randomized AISPWM for EV Application

Low vibration and acoustical noise as well as effective DC link usage are the demands of industries and Electric Vehicles (EV). Direct Torque Control (DTC) of Induction Motors (IMs) meet the EV and other modern industry requirements. Still, flux as well as torque swings lead to higher acoustical noise. Consequently, EVs as well as working place noise have become major concerns, affecting the health of individuals. Efficiency of dc link use is improved by Space Vector Pulse Width Modulation (SVPWM). Yet, SVPWM is not efficient in lowering acoustical noise. Different RPWM techniques can lower acoustic noise. Still, the lower degree of randomisation makes the noise reduction difficult. This work presents a Hybrid Dual Random PWMs (HDRPWMs) based Alternate Inverter Switching (AIS) strategy for Slip-Angle Controlled Direct Torque Control of an Open End Winding IM Drive (OEWIMD). This technique is aimed to lower the acoustical noise for EVs. The intended PWMs seek to show how well HDRRPWMs distribute the acoustical noise spectra in contrast to conventional techniques.

3D CFD modelling and experimental validation of conjugate heat transfer in wheel hub motors in micro-mobility vehicles

An experimental and 3D CFD (computational fluid dynamics) based numerical investigation of the in-wheel hub internal permanent magnet synchronous machine (IPMSM) has been carried out to understand the thermal dynamics associated with the power loss within the motor. This study can serve as a clear case baseline for the future development of thermal management systems in micro-powertrain systems. Experimental results show that the maximum winding temperature of 65.9 °C has been observed on the end-windings (EW) for an operating condition of 500 rpm (base speed), 4.5 Nm. Stretching beyond this operating point would increase the winding temperature beyond 65.9 °C, potentially damaging the winding insulation’s capabilities and magnetic properties of the permanent magnets (PMs) and adversely affecting the performance of the wheel motors. The hysteresis and eddy current loss coefficients for the stator core have been identified as 14.5×10-2 and 1.6×10-4 respectively. The experimentally identified losses have been distributed among the motor components for the development of the numerical thermal model in commercial CFD software Star-CCM+™. The CHT (conjugate heat transfer) thermal paths show that 68.4 % and 31.4 % of the total power loss from the stator components undergo convection and conduction, respectively. This indicates that convection heat transfer dominates on the in-wheel hub IPMSM motor topology. Almost 34.5 % of the heat loss is transferred radially through the air gap to the Permanent Magnets. When the air gap size decreased by 80 %, the amount of convection heat transfer through the air gap increased by a factor of 2 (69 %) and reduced the winding temperature by 13 % (57.3 °C).

Research on Temperature-Rise Characteristics of Motor Based on Simplified Lumped-Parameter Thermal Network Model

The thermal management of a driving motor is related to the performance and economy of the vehicle. The lumped-parameter thermal network (LPTN) method can provide a model basis for motor temperature-rise control and effectively shorten the development cycle of motor thermal performance design. In this study, an 80 kw water-cooled permanent magnet synchronous motor was used and the accurate thermal model of a motor was built using the LPTN. On the basis of the accurate thermal model, the simplified thermal model of a motor was obtained by reducing the complexity of the model. The temperature-rise test of the end winding and magnetic steel of the motor was carried out under some working conditions. The test conditions were selected according to continuous external characteristics and operating characteristics of the motor. Compared with the experimental results, the temperature-rise error of the two thermal models was less than 5%. The temperature-rise error of the simplified thermal model was less than 3% compared with the accurate thermal model. Therefore, the simplified thermal model can be used to quickly predict the temperature rise of the motor.

Fatigue Propagation Characteristics of Insulation Crack Failure in Stator End Winding for Large Traction Motor Based on Magnetic–Thermal–Mechanical Coupling Model

Fatigue Propagation Characteristics of Insulation Crack Failure in Stator End Winding for Large Traction Motor Based on Magnetic–Thermal–Mechanical Coupling Model

Deformed Zero-Sequence Flux Model of Open End Winding IPMSM

Deformed Zero-Sequence Flux Model of Open End Winding IPMSM

Mechanical properties and insulation damage of PMSG stator end windings with eccentricity considerations

The mechanical properties and insulation damage of stator end windings in permanent magnet synchronous generator (PMSG) are investigated by theoretical analysis, finite element analysis (FEA) and experiment verification. First, a theoretical model of the winding electromagnetic force (EF) and vibration response before and after eccentricity faults are established. Then, the stress/strain distribution of the end windings under different working conditions is analyzed. Finally, the insulation damage behavior of end windings with initial cracks is studied and characterized using the stress intensity factor (SIF). The results indicate that the winding EF and vibration responses vary under different faults. The stress/strain at the joint of the winding is the largest, and the insulation layer has the maximum stress/strain under the same section. Additionally, the SIF amplitude of the crack at the winding joint is the largest. And the SIF amplitude of the crack will increase with the increase of fault degree/crack depth/crack length. The contribution of this paper lies in the comprehensive analysis of the winding EF distribution, vibration response, stress and strain, and insulation damage before and after eccentricity. This analysis can provide valuable reference for the health monitoring of PMSG eccentricity faults and the prevention of winding insulation damage.

Study on flow field of oil‐cooling permanent magnet synchronous motor with hairpin winding using porous medium model

AbstractThe oil cooling method has been widely used in the permanent magnet synchronous motor with hairpin winding. Because of the irregular shape of the hairpin end winding, there are complex oil circuits in the fluid domain, resulting in a large number of grids and a high computational cost. It is still a challenge to calculate the oil‐cooling performance of the hairpin end winding. Therefore, the porous medium model (PMM) is first proposed to replace the real hairpin end winding to analyse the oil‐cooling performance. By comparing oil volume fraction and velocity at different oil‐supplied conditions using three methods: experiments, real model (the non‐equivalent fluid domain model based on the real hairpin end winding) and PMM, the feasibility of using the PMM to calculate the oil‐cooling performance on the end winding is verified. The oil distribution of three methods is the same. The use of the PMM saves 80% of the number of grids, which improves the simulation efficiency. Relationships between the porosity, permeability and resistance coefficient and the geometry parameters of windings are determined. The results show that the flow field changes greatly with changes in porosity, permeability and resistance coefficient.

Cooling Improvement for High-Power-Density Shell-Mounted Underwater Propulsion Motors with Heat Bridges

Subject to an autonomous underwater vehicle (AUV) with rigorously limited space and weight, the high-power-density propulsion motor urgently needs an efficient cooling method to improve reliability and stability. In this paper, a cooling improvement method based on heat bridges (HBs) is proposed for the shell-mounted propulsion motor (SmPM) of the AUVs. First, the electromagnetic and thermal characteristics of a 150 kW SmPM are analyzed using a numerical method. Then, a prototype was developed and tested to verify the accuracy of the numerical calculation. Subsequently, in order to further improve the cooling performance of the motor with minimal weight increment, this paper proposes HBs mounted on the end winding. The maximum winding temperature of the motor containing the proposed HBs is decreased by 20 K at the rated operation state. Based on the validated numerical method, the effects of topologies, materials, and geometric parameters on the cooling effect are investigated. Furthermore, according to the required operating time, the SmPM is optimized based on the cooling performance improvement provided by the proposed HBs. The results show that in addition to the benefit of the cooling improvement contributed by the proposed HB, the weight of the propulsion motor is reduced by 7.14%.

Calculation of Equivalent Thermal Conductivity of Motor Winding Based on Conductor Distribution

Abstract To improve the calculation accuracy of motor thermal field, this paper proposes a method for calculating the equivalent thermal conductivity of winding based on conductor distribution, and a 24-slot 26-pole outer-rotor permanent magnet synchronous motor is taken as an example to verify the method. First, the equivalent thermal conductivity of winding is calculated by traditional equivalent methods, namely the equivalent insulation layer method and the area weighting method. Second, the equivalent thermal conductivity of the slot winding and end winding in the three-dimensional (3D) direction is derived using the conductor distribution method. Third, the 3D finite element models corresponding to three equivalent methods are established, and the temperature of the motor under different operating conditions is simulated and compared. Finally, an experimental platform is built to verify the accuracy of the proposed conductor distribution method.

Transient Thermal Exchange Analysis of an External Rotor Hub Motor for Electrified Defense Vehicles Applications Based on FVM and TNM

This paper investigates the transient temperature distribution law of a 75kW external rotor hub motor for electrified defense vehicles (EDV) using the finite volume method (FVM) and the thermal network method (TNM). Based on thermal exchange and fluid flow theories, both a transient fluid-solid coupled thermal exchange model and a lumped parameter thermal network model (LPTNM) with transient thermal capacity parameters are established. An iterative algorithm for the heat transfer coefficient is proposed to improve the accuracy of LPTNM. Compared with existing methods, this algorithm exhibits higher accuracy and stronger practicality. In addition, an experimental platform of the hub motor temperature rise is built for measuring the end winding temperature. The calculated results are in good agreement with the experimental results, verifying the rationality of the 3D transient fluid-solid coupled thermal exchange model and the LPTNM. The axial parallel water channel structure was adopted to improve the cooling performance of the end winding, taking into account the structural characteristics and assembly mode of the hub motor. This paper provides theoretical references for the transient thermal analysis and cooling structure design of the EDV hub motor.

Thermal Analysis and Cooling Strategies of High-Efficiency Three-Phase Squirrel-Cage Induction Motors—A Review

In recent times, there has been an increased demand for electric vehicles. In this context, the energy management of the electric motor, which are an important constituent of electric vehicles, plays a pivotal role. A lot of research has been conducted on the optimization of heat flow through electric motors, thus reducing the wastage of energy via heat. Futuristic power sources may increasingly rely on cutting-edge innovations like energy harvesting and self-powered induction motors. In this context, effective thermal management techniques are discussed in this paper. Importance was given to the potential energy losses, hotspots, the influence of overheating on the motor efficiency, different cooling strategies, certain experimental approaches, and power control techniques. Two types of thermal analysis computation methods, namely the lumped-parameter circuit method (LPCM) and the finite element method (FEM), are discussed. Also, this paper reviews different cooling strategies. The experimental research showed that the efficiency was greater by 11% with the copper rotor compared to the aluminum rotor. Each rotor type was reviewed based on the temperature rise and efficiency at higher temperatures. The water-cooling method reduced the working temperatures by 39.49% at the end windings, 41.67% at the side windings, and by a huge margin of 56.95% at the yoke of the induction motor compared to the air-cooling method; hence, the water-cooling method is better. Lastly, modern cooling strategies are proposed to provide an effective thermal management solution for squirrel-cage induction motors.

Improved PWM Control with Wide Speed Range for A Double-Side Asynchronous Rotor AFPMM Series End Winding Drive

Improved PWM Control with Wide Speed Range for A Double-Side Asynchronous Rotor AFPMM Series End Winding Drive

Improvement of the uniformity of the magnetic field inside a short solenoid by the end winding system

Improving the level of homogeneity of the magnetic field in the middle of the working volume of a short solenoid makes it possible to improve devices for demagnetizing technical objects and studying the magnetic properties of materials. One of the means of increasing the level of homogeneity of the magnetic field in the middle of the solenoid is to approximate the shape of its winding to the closed surface. The use of a system of a solenoid and two end axisymmetric current windings with a common current source is proposed as such a surface. A mathematical model of the scalar potential of the magnetic field of such a system was built using spherical harmonic analysis, and functional dependences of the current density on each surface were obtained for its first harmonic, which is the dipole component of the magnetic field. Formulas for calculating the number of turns in the end windings and the geometric parameters of their arrangement and the simulated total magnetic field inside the proposed system are obtained. A comparative analysis of the homogeneity of the magnetic field created by a separate solenoid and a solenoid with end windings, depending on the geometry of the system, was conducted. The use of end windings significantly improves the uniformity of the magnetic field near the ends, especially on the axis of the solenoid. Due to this, the efficiency of the end windings significantly depends on the solenoid elongation indicator and allows you to increase the working volume by 5-20%, depending on this indicator. The proposed system makes it possible to obtain a magnetic field with a maximum deviation of 5% from uniformity for a solenoid elongation index of 2. As the elongation increases, the efficiency of the end windings decreases and for systems with an elongation of 10 or more, their use becomes impractical. The results of the analysis testify to the effectiveness of using the proposed system in devices for demagnetizing technical products that differ in a small indicator of the elongation of the working solenoid - primarily devices that create a uniform magnetic field with an amplitude decreasing over time of 240 A/m and are used in particular to remove soft residual magnetization from elements of space vehicles

Research on Thermal Calculation and End Winding Heat Conduction Optimization of Low Speed High Torque Permanent Magnet Synchronous Motor

Research on Thermal Calculation and End Winding Heat Conduction Optimization of Low Speed High Torque Permanent Magnet Synchronous Motor

Design and Analysis of Complex End Region of Pumped Storage Generator Motor Based on Novel Electromagnetic Vector Method

A very large end leakage flux is produced by the end winding of a pumped storage generator motor. It has a significant impact on the design, flux density, and temperature in the end region of the pumped storage generator motor. The high temperature makes it difficult to design pumped storage generator motors. To quickly and accurately obtain the flux density of end components, a novel electromagnetic vector method is proposed in this paper. A 300 MW pumped storage generator motor is designed. The electromagnetic vector method and finite element method are used to calculate the flux density of the end components, respectively. The obtained results are compared and analyzed. The results reveal that the novel method is more convenient and faster than the finite element method. The novel electromagnetic vector method reduces the design time and calculation time of the end flux density. The flux density and losses of the end components in the pumped storage generator motor are studied under different operating conditions. Three-dimensional fluid and thermal coupled field is calculated and analyzed. Moreover, the calculation results are verified by the experimental values.

Design and optimisation of oil injection pipe cooling structure for permanent magnet synchronous motors in hybrid electric vehicles

AbstractIn recent years, with the continuous improvement of motor power density, oil cooling technology has been widely used in permanent magnet synchronous motors (PMSMs) for electric vehicles (EVs) as an efficient cooling method. A PMSM with a rated capacity of 53kW for hybrid electric vehicles (HEVs) is designed, and the motor is cooled by the oil injection pipe. In order to improve the heat dissipation efficiency of the end winding, the number of injection pipes and the structure of the nozzle are optimised, and a novel nozzle structure is proposed. By using the moving particle solution (MPS) method to simulate the fluid flow, the optimal cooling structure of the motor is determined. In addition, different from the equivalent winding model in the traditional temperature field simulation, a hairpin winding model that can more realistically reflect the geometry of the end winding is established. On this basis, the temperature field of the motor is simulated. It is verified that the cooling structure designed can effectively improve the thermal performance of the end winding.

Analysis of transient electromagnetic force on end windings of 300 Mvar synchronous condenser during dynamic reactive power compensation process

The uneven distribution of renewable energy supply and demand promotes the development of high-voltage direct current transmission. As the critical reactive power compensation equipment for high voltage direct current transmission, the synchronous condenser must have a strong overload capability. One of the critical factors limiting the improvement of its overload capacity is the reliability of the end winding, which depends on the magnitude of the force on end windings during dynamic large reactive power output. Therefore, this paper proposes a coupling model of transient electromagnetic force for the high voltage direct current transmission system and the end zone of the synchronous condenser. The transient response of the synchronous condenser under different fault degrees is calculated, analyzed, and verified by experiments. Based on the current response of the synchronous condenser, the transient electromagnetic force on end windings is calculated. The distribution law of the force on end windings of the synchronous condenser under different degrees of dynamic reactive power compensation process is revealed. Further, the regions on end windings with larger force during strong overload are indicated. The optimizing fixation scheme for end windings is proposed according to the distribution features of the force, which can improve the operational reliability of end windings.

Direct drive double fed wind generator

An electric machine topology characterized by single tooth winding in both stator and rotor is presented. The proposed machine is capable of operating as a direct drive double fed wind generator (DDDF, D3F), because it requires no gearbox. A wind turbine drive built around a D3F generator is cheaper to manufacture, requires less maintenance and has a higher energy yield than its conventional counterparts. The all tooth wound generator of a D3F turbine has a superb volume utilisation and lower stator I2R losses due to its extremely short end windings, efficient cooling and reduced active length. Both stator and rotor of a D3F generator can be manufactured in segments, which simplifies its assembly and transportation to the site, and makes its production cheaper.

Thermal Design and Analysis of Oil-Spray-Cooled In-Wheel Motor Using a Two-Phase Computational Fluid Dynamics Method

In-wheel motors for new energy vehicles are close to the brake, which results in a high ambient temperature. Thus, there is a high demand for cooling systems. This paper designs an oil-spray-cooled system based on the flat structural characteristics of an in-wheel motor. A computational fluid dynamics method with a two-phase volume-of-fluid model is applied to simulate the transient process of oil spraying from nozzles onto the stator carrier and then dripping to the end windings. The spatially distributed fluid interfaces with location and shape fidelity are derived. Considering the big difference of thermal inertia between the motor solid and oil fluid, the mixed timescale method is applied to calculate the temperature fields of the fluid and solid. Finally, a prototype is fabricated and tested to verify the proposed oil-cooling system and simulation method.

Circulating and Eddy Current Losses in Coreless Axial Flux PM Machine Stators With PCB Windings

Printed circuit board (PCB) stators in coreless axial flux permanent magnet (AFPM) machines have been proposed, designed, and studied for use in multiple industries due to their design flexibility and reduction of manufacturing costs, volume, and weight compared to conventional stators. This paper investigates mechanisms and methods of approximating open circuit losses in PCB stators within example wave and spiral winding topologies for a dual rotor, single stator configuration using 3D FEA, analytical hybrid techniques and experiments. The effect of rotor magnet shape, end winding, and active conductor geometry on eddy currents is studied, and some mitigation techniques are proposed. Through stator equivalent circuit analysis, circulating current losses caused by mechanical abnormalities and magnetic circuit asymmetry are assessed. Possible strategies and schemes to minimize circulating current losses are also described. The trade-off between stator loss components and some practical design considerations are outlined in detail. The open circuit power losses of a prototype coreless AFPM motor were experimentally tested using multiple example PCB stators and emulated rotor asymmetries, with the findings being comparable to the FEA and hybrid analytical methods results.