Numerical and Experimental Calculation of CHTC in an Oil-Based Shaft Cooling System for a High-Speed High-Power PMSM

Self Cite

This article addresses the rotating effect on the pressure loss and heat transfer coefficient (HTC) of a hollow‐shaft rotor cooling system for an automotive traction motor. Firstly, a numerical model based on computational fluid dynamics (CFD) was established to fully understand the mechanism of rotational flow patterns. Experiments were then performed to measure and compare heat exchange and pressure loss between rotating and stationary conditions with the assistance of an analytical thermal model. Finally, trends of pressure drop and HTC at various rotational rates were explained in detail. Based on CFD simulations and experimental prototype testing, two opposite effects: boosting or diminishing on pressure drop and heat transfer due to rotation have been identified. Moreover, the rotation can significantly improve the overall HTC and pressure loss of an axial turbulent flow. As a result, a significant drop in terms of rotor temperature is identified for an automotive traction motor when such a rotor cooling system is implemented.

Section: Computational Fluid Dynamicsmentioning

confidence: 99%

Numerical prediction and measurement of pressure drop and heat transfer in a water‐cooled hollow‐shaft rotor for a traction motor application

Gai

et al. 2021

Self Cite

“…The temperature distribution of a FMPM in-wheel motor under a natural cooling system is calculated by the fluidicthermal coupled method, and the mathematical models are illustrated as [18,19]:…”

Section: Calculation Model and Boundary Conditionsmentioning

confidence: 99%

“…The temperature distribution of a FMPM in‐wheel motor under a natural cooling system is calculated by the fluidic‐thermal coupled method, and the mathematical models are illustrated as [18,19]:

\nabla \cdot (λ \nabla T) = - q

\nabla \cdot (ρ χ u) = \nabla \cdot (ξ \nabla ϕ) + K_{ϕ}

where λ is the heat conductivity coefficient, q the heat generation rate, ρ the fluid density, ϕ the general variable, u the fluid velocity vector, ξ the general diffusion coefficient, and K ϕ the generalized source. The general variables and coefficients are listed in Table 3.…”

Section: Temperature Rise Calculation Under Natural Cooling Conditionmentioning

confidence: 99%

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

Zhu

Zhao

et al. 2021

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. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

“…Since the FSI method can couple the fluid flow and the conjugate heat transfer during modelling, it has great practical values in complex cooling problems with unpredictable convective heat transfer coefficients and ambient temperatures. Gai et al [14] analysed the fluid flow and cooling effect of the oil in a hollow shaft for electrical machines, and the calculation accuracy was validated by experiments.…”

Section: Introductionmentioning

confidence: 99%

“…Gai et al. [14] analysed the fluid flow and cooling effect of the oil in a hollow shaft for electrical machines, and the calculation accuracy was validated by experiments.…”

Section: Introductionmentioning

confidence: 99%

A full‐domain fluidic‐thermal approach for a high‐speed PMSM considering the bearing components

Zhu

Mei

et al. 2021

This paper presents a refined full-domain model for the fluidic-thermal coupled analyses of a 15-kW 30,000-rpm high-speed permanent magnet synchronous machine (HS-PMSM) considering the heat generation and dissipation of the bearing components. In order to analyse the heat dissipation capacities of the bearing components, firstly, the fluid flow conditions inside the bearings with different revolution and rotation ratios are researched, and the most serious case is taken in the full-domain calculations. Secondly, the three-dimensional (3D) full-domain model is established, and the fluidic-thermal analyses are conducted based on the basic principles of numerical heat transfer and CFD. During calculations, in order to obtain the temperature rise precisely, the angular contact ball bearings are well modelled with all the internal components including the oil films, and the frictional loss in the bearings are computed by the Palmgren model. A 15-kW 30,000-rpm HS-PMSM prototype is established and tested to verify the full domain thermal modelling methodologies and indirectly validate the bearing performance calculations. Finally, a self-ventilated structure is employed to prevent the bearing temperature rise, and the cooling effectiveness is validated by numerical calculations.