Automotive Motors Research Articles

Optimized design and magneto-thermal coupling simulation analysis of automotive permanent magnet synchronous motor

Abstract This paper presents an optimized design for automotive permanent magnet synchronous motors (PMSM) focusing on expanding their operational speed range and improving efficiency. The issues of high losses and low efficiency in standard built-in fractional-slot PMSMs, which impact the stable operation of vehicle motors, are identified and addressed., Three innovative rotor magnetic circuit structures are proposed utilizing electromagnetic theory and finite element analysis. These designs are simulated and analyzed to reduce overall motor losses to 59% of the original levels and to ensure thermal characteristics meet the demands of wide-speed automotive motors. The study establishes a three-dimensional transient temperature field simulation model to predict temperature rise and distribution across motor components. The optimized rotor structures enhance performance and serve as a reference for future thermal design in PMSMs.

Multi-physics simulation method for automotive motors with variable working conditions based on multi-software combination

Multi-physics simulation method for automotive motors with variable working conditions based on multi-software combination

Determination of Hotspot Temperature Margin for Rectangular Wire Windings Considering Insulation Thermal Degradation and Partial Discharge

Increasing current density is a common way to improve the power density of electrical machines (EMs) which also boosts the winding temperature. Higher winding temperature accelerates the thermal degradation of insulation and also increases the risk of partial discharge (PD). Commonly, the winding hotspot temperature constraint is decided based on an over-engineering approach (i.e., the winding hotspot temperature is 30°C below the wire thermal class) constraining the EM’s performance. In this paper, the margin of winding hotspot temperature is precisely determined focusing mainly on the insulation degradation issues through experimental investigation. The partial discharge inception voltage and partial discharge extinction voltage have been measured under different temperature conditions for samples with different thermal aging statuses. Rectangular wires which find application in automotive motors are selected as test samples. The results link the temperature with the PD risk and the thermal lifetime of the insulation, and the winding hotspot temperature margin is accordingly determined. An automotive case study is presented to prove the applicability of the investigation outcomes.

Hybrid-Strand Winding Topology With Improved Power Density in Automotive Electric Machines

The rectangular profile conductor with a large cross section requires less slot space and has better heat dissipation ability than the traditional round profile one. But its application in automotive propulsion electric machines is thwarted by high ac winding losses and temperature rise under high-speed operations. This article proposes a novel stator winding topology with hybrid strands based on the ac losses' distribution characteristics and the theoretical relationship between the eddy current suppressing ability and the geometric parameters. The new winding can effectively reduce the ac loss and the peak temperature in the winding at high-speed operation. Meanwhile, it can maintain a high filling rate. Therefore, the machine's maximum rotating speed and power density can be effectively improved. In experimental validation, a winding sample with this new topology is manufactured and compared with the conventional one formed by rectangular wires. It shows the proposed method can reduce the winding ac loss by up to 12% and the temperature rise by 10–21%. It is validated to have considerable industrial potential in the future development of automotive motors.

High-spatial-resolution measurement of magnetization distribution using polarized neutron imaging

The evaluation of the magnetization distribution inside a bulk magnet is important for ensuring the performance of automotive motors because it strongly depends on the quality of magnetization inside the permanent magnet. In the conventional destructive method, it is difficult to accurately measure the magnetization with a high spatial resolution. The polarized neutron imaging technique can be used to visualize the distribution of the magnetic flux density inside a magnet nondestructively. In this study, we demonstrated the imaging of the magnetization distribution using polarized neutrons in an anisotropic ferrite magnet sample. The 2D distribution of the magnetization was experimentally obtained by polarized neutron imaging with a high spatial resolution of less than 1 mm. Furthermore, the validity of the results was confirmed by comparing them with those obtained using the conventional destructive method.

Pure copper layer formation on pure copper substrate using multi-beam laser cladding system with blue diode lasers

In electrical and mechanical industries, forming a pure copper layer on various substrates would improve the performance of automotive motors, batteries, etc. However, the formation of a pure copper layer has yet to be reported on a pure copper substrate. Here, a pure copper layer is formed on a pure copper substrate (C10200) using a multi-beam laser cladding system with blue diode lasers. The powder mass efficiency increases with the laser intensity. These results are used to construct a powder temperature model. At a laser intensity of $$6.5 \times 10^{4} {\text{ W}}/{\text{cm}}^{2}$$ , 9.65% of the powder forms a copper layer. In the supplied powder, approximately 5% of the powder is melted on the fly. In addition, about 5% of the powder is melted after trapping on the substrate. Hence, melting powder on the fly and melting the trapped powder on the substrate form the copper layer.

Novel Rotor Design of Wound Field Synchronous Motor for Torque Ripple Reduction in ISG System

This paper describes a method to reduce the torque ripple for the Wound Field Synchronous Motor, which does not use a permanent magnet. When a WFSM is used in an Integrated Starter Generator system, it must have a higher power density than other automotive motors in order to satisfy the size constraints and required power. An increase in the power density creates a magnetic flux saturation in the rotor, and this soon becomes the cause of an increase in the torque ripple of motor. An increase in the torque ripple can degrade the Noise Vibration Harshness characteristics of automotive by creating vibration and noise in the engine start-up mode, in which the maximum torque is generated in an ISG system. This paper proposes a method of reducing the torque ripple via a design that uses a flux barrier model in the WFSM’s rotor. The Response Surface Method is used to optimize the flux barrier model, and Finite Element Method is used to to verify the torque ripple reduction.

DyフリーNd-Fe-B系異方性ボンド磁石の開発と小型モータへの応用

The authors have successfully developed a low-cost anisotropic Nd-Fe-B magnet powder with a high coercivity value of 1591 kAm−1 without any dysprosium additives by diffusion processing of Nd-Cu-Al element into anisotropic magnet powder produced by the d-HDDR (dynamic-hydrogenation, disproportionation, desorption and recombination) method. This enhancement mechanism is to isolate the magnetic coupling between the grains of Nd2Fe14B phase by a Nd rich grain boundary phase with Cu. By surface coating this anisotropic magnet powder, the long-term aging loss behavior under air at 150℃ is less than 5% after 1000 h. By using this new anisotropic bonded magnet (New-MAGFINE), small automotive motors with excellent thermal stability and low cost characteristics have become possible.

Extension of the Temperature Range of Automotive Electric Motors by Using the Permanent Magnet Excitation Component

The article presents a technique that extends the temperature range of automotive DC motors through the use of magnets in a composite system excitation by an equivalent circuit made up for the application package IRIS-PC.

Characteristic Measurement System for Automotive Class Switched Reluctance Machines

Flux-linkage characteristics and torque characteristics (versus current and rotor position) of switched reluctance machines (SRM) can be regarded as the fingerprint of SRMs because they are indispensable fundamental data to model machine behavior for both simulation and control proposes. In contrast to other types of electrical machines, e.g. induction machines and synchronous machines, SRMs are basically characterized by a strongly nonlinear behavior due to typical operation in the magnetic saturation region. Hence, no analytical functions can be applied to describe the characteristics of SRMs precisely. An accurate SRM model inevitably needs the complete machine characteristics in form of data-intensive look-up tables to represent the machine behavior. Basically, the SRM characteristics can be calculated by Finite Element (FE) simulation. However, real SRM characteristics can be different from the simulation model due to secondary effects, e.g. non-uniform material and manufacturing tolerances, which are normally not considered in the FE-simulation model. Therefore, the experimental measurement is preferred. Measuring and preparing the SRM characteristics is a complicated and time-consuming task. The time-expense as well as possible human errors in determining the SRM characteristics can be greatly minimized, if the measurement procedures are automated.This paper presents an automated characteristic measurement system for determining SRM characteristics experimentally. The measurement system was designed for automotive class SRMs, e.g. starter-generators, hybrid or main propulsion motors. The applied measurement methods, the system design and construction are described in the paper. Furthermore, constraints and discussions concerning the measurement accuracy are treated.

Excimer laser surface treatment of a spheroidal graphite cast iron: possible application for running-in parts of automotive motors

After the final machining on spheroidal graphite cast iron, a thin layer of the matrix material covers the graphite spherulites. This layer has been selectively removed from the graphite nodules using a KrF excimer laser. The plasma created on the surface generates shock waves, which harden the bulk material to a depth of nearly 10 μm and which by reflecting on the spherulites, pushing away the molten metal, form craters. The molten layer resulting from the treatment has an extremely fine microstructure and is harder than the matrix, with a roughness slightly higher than that of the initial surface. Preliminary wear tests show that the friction coefficient appears to be lower than that of the untreated material, because of the improvement in surface properties and because of the opened spherulites which are acting like oil reservoirs. A mathematical model is presented in order to calculate the roughness of the treated surfaces. It is in rather good accordance with experimental measurements, taking into account the laser processing parameters.