Cooling of Rotating Electrical Machines: Fundamentals, modelling, testing and design

Description

Thermal management is an issue with all electrical machines, including electric vehicle drives and wind turbine generators. Excessively high temperatures lead to loss of performance, degradation and deformation of components, and ultimately loss of the system. Cooling of Rotating Electrical Machines: Fundamentals, modelling, testing and design provides a foundation of heat transfer and ventilation for the design of machines. It offers a range of practical approaches to the thermal design, as well as design data and case studies. Chapters cover fundamentals of heat transfer, fluid flow, thermal modelling of electrical machines, computational methods for modelling ventilation and heat transfer such as finite element methods and computational fluid dynamics, thermal test methods, and application of design methods. Intended for engineers and researchers working in either academia or machine design companies, this book provides sound insights into the phenomena of heat transfer and fluid flow, giving readers an understanding of how to approach the thermal design of any machine. Cover Contents List of figures List of tables About the Authors Nomenclature 1 Introduction 2 Fundamentals of heat transfer 2.1 Conduction heat transfer 2.1.1 Fourier’s law 2.1.2 Thermal conductivity 2.1.3 Thermal conduction in one dimension at steady state 2.1.4 General conduction equation 2.1.5 Thermal contact resistance 2.1.6 Boundary conditions 2.1.7 Solution of steady-state heat conduction problems in two and three dimensions 2.1.8 Transient heat conduction 2.2 Convection heat transfer 2.2.1 Physical processes taking place in a convection 2.2.2 Correlations of heat transfer coefficient 2.3 Radiation heat transfer 2.3.1 Nature of thermal radiation 2.3.2 Heat transfer due to radiation 2.3.3 Combined radiation and convection (the radiation heat transfer coefficient) 2.4 Extended surfaces (fins) 2.4.1 Introduction 2.4.2 Fin efficiency 2.4.3 Fin effectiveness 2.5 Heat exchangers 2.5.1 Introduction 2.5.2 Overall heat transfer coefficient 2.5.3 Effectiveness-NTU approach 2.6 Convective heat transfer enhancement 2.7 Heat transfer with a phase change (heat pipes) 2.8 Heat transfer in an annular gap 2.8.1 Annular gap with no axial flow 2.8.2 Effect of slotted surfaces in the annular gap 2.9 Heat transfer in rotating ducts References 3 Fundamentals of fluid flow 3.1 Basic principles of fluid flow 3.1.1 Viscosity and boundary layer 3.1.2 Navier–Stokes equations 3.1.3 Dimensional analysis and dimensionless parameters 3.2 Flow in ducts 3.2.1 Pressure loss 3.2.2 Flow separation pressure loss 3.3 Fans and rotor driven pressure gains 3.3.1 Euler’s turbomachinery equation 3.3.2 Fan’s laws 3.4 Flow in the air gap 3.4.1 Rotational pressure losses in the air gap 3.4.2 Frictional pressure loss 3.4.3 Entrance pressure loss 3.5 Flow in rotating ducts 3.5.1 Frictional pressure loss 3.5.2 Entrance pressure loss 3.5.3 Flow exits from rotating ducts 3.6 Flow over rotating discs References 4 Thermal modelling of electrical machines 4.1 Modelling technique – lumped parameter thermal network 4.1.1 Coil’s anisotropic thermal conductivity 4.1.2 Winding heat transfer 4.1.3 End-space cooling 4.1.4 Bearing losses and heat transfer 4.1.5 Lamination stack heat transfer 4.1.6 Interfaces 4.1.7 Machine losses 4.2 TENV cooling 4.3 TEFC cooling 4.4 Open ventilated cooling 4.5 Close circuit cooling with heat exchanger 4.6 Housing water jacket cooling 4.7 Sleeve with flooded stator cooling 4.8 Oil spray cooling References 5 Advanced computational methods for modelling ventilation and heat transfer 5.1 Finite-element methods 5.1.1 Stranded random wound winding 5.1.2 Bobbin stranded wound winding 5.1.3 Hairpin winding 5.1.4 Pre-formed wound winding 5.1.5 Litz wires 5.2 CFD 5.2.1 Introduction to CFD 5.2.2 Using CFD 5.2.3 Specific issues concerning the application of CFD to electrical machines 5.2.4 Examples of application of CFD References 6 Thermal test methods 6.1 Measurement methods 6.1.1 Temperature measurement 6.1.2 Heat flux measurement 6.1.3 Air flow measurement 6.1.4 Liquid flow measurement 6.2 Winding insulation system thermal conductivity 6.3 Motor losses 6.3.1 Measurement of windage losses 6.3.2 Calorimetry for measurement of total loss 6.4 Thermal model calibration 6.5 Thermal model calibration using a short transient test References 7 Application of design methods (case studies) 7.1 Thermal management of electrical insulation system 7.1.1 Slot liner 7.1.2 Impregnation resin 7.2 Totally Enclosed Non-Ventilated cooling 7.3 Totally Enclosed Fan-Cooling 7.4 Open ventilated cooling 7.5 Close circuit cooling with a heat exchanger 7.6 Housing water jacket cooling 7.7 Sleeve with flooded stator cooling 7.8 Oil spray cooling 7.9 High-Performance machine with multiple cooling methods References Index Back Cover