Electric Machine Simulation T Electric Machine Simulation Technology - PowerPoint PPT Presentation

Electric Machine Simulation T Electric Machine Simulation Technology chnology St Steve Har e Hartridge ridge Direct Director or, Electric & , Electric & Hybrid V Hybrid Vehicles hicles

Agenda Ag Intro/Session description Intr o/Session description Toda days demands/Mo ys demands/Motiv ivations ations EMA EMAG and and Thermal Thermal modeling modeling Combined w Combined workflo rkflow Exam Examples ples

Motivation f Motiv tion for Analysis r Analysis Over the last decade it Ov er the last decade it is is no noticeable that there is ticeable that there is a a gr growing need f ing need for electric r electric machines with machines with High torque High t ue or or • High power density along with a High po r density along with a • High efficiency High ef ciency demand demand or/and or/and • Reduction in duction in size, w size, weight, cost ight, cost • Leading to Leading t high gher er t temperat mperature gr ure grad adients with a ients with a higher higher • demand demand on the mat on the materials rials in in general, general, but esp. but esp. on the insulation mat on the insulation materia rials Source ce g graphics: aphics: N NREL shor shorter r lif lifetime time expectation pectation due t due to a higher a higher • risk of thermal damages (esp. in risk of thermal damag s (esp. in the the insulation materials). insulation mat rials). A higher risk igher risk of dema of demagne gnetizatio ion n of the of the • magnets magne

Motiv Motivation f tion for Analysis r Analysis Component lifetime estimates [1]: – 22% of failures due to thermal damages in insulation – 17% further thermal damage in other components Lif Lifetime d time depends on pends on t temperature hist erature histor ory; y; Temperature d erature depend pends on s on losses an losses and cooling d cooling Insulation lifetime L can be modeled by the Arrhenius chemical equation [2]: � L � A · � � � ⋅ � � Montsinger’s rule taken from transformer oil and solid insulation materials shows that the lifetime L decreases by 50% with increase of temperature T by 10 K [3]: L �T � 10K� � 0.5 · L�T� So insulation breakdown is likely to be the problem associated with high temperatures. This problem may be tackled by – either improving the insulation material and allowing the temperatures to rise or – improving the cooling performance of the windings and limiting the maximum temperature. Source: [1] Bruetsch, R., Tari, M. Froehlich, K. Weiers, T. and Vogesang, R., 2008. Insulation Failure Mechanisms of Power Generators IEEE, Electrical Insulation Magazine, 24(4) [2] Dakin, T.W., 1948, Electrical Insulation Deterioration Treated as a Chemical Rate Phenomena, AIEE Trans., Part 1, 67 [3] Binder, A., TU Darmstadt, EW, 2008, Script Large Generators & High Power Drives

Motivation f Motiv tion for Analysis r Analysis To accomplish today’s demand the new machine designs have – to eliminate the safety factors of the over-sizing designs of the past – to finally ensure the requested high power densities. The need to have an optimized thermal design besides an optimized electro- magnetic design.

Electric Machine Simulation T Electric Machine Simulation Technology chnology Electr Electromagne omagnetic Simulation tic Simulation Thermal Simulation Thermal Simulat on Elect ectrical/mech ical/mechanical per nical performance o ormance of Under Understand tand the ef the efficiency of the cooling ciency of the cooling • • design design syst system em Design studies of differe Design studies of dif erent types of t types of Optimize Optimize a flo a flow paths f paths for a giv r a given cooling en cooling • • machine IMD machine IMD vs. BDC vs. BDC syst system em Torque and ef ue and efficiency ency r requirement quirements ar are e Predict maximum com Predict maximum component onent • • met me temperatures at giv eratures at given dif en different operating erent operating points points Build efficiency map f Build ef ciency map for machine r machine • Conside Consider • Detailed geome Detailed geometric design of ric design of • Conduction/con Conduction/c onvection/rad ion/radiation syst ation system em component onents – – 2D/3D Include t Inc ude temperat mperature dependent ure dependent • Optimize Optimize magne magnet • pr proper erties es position/shape/material position/shape/mat erial Coupled Include a Includ a sim simple le/conductio ction only n only • therma thermal mod l model Problem Machine Thermal Designer/Electrical analyst/Mechanical Engineer engineer

Losses in Electrical Machines Losses in Electrical Machines The heat generated inside the motor originates from two main sources: – Electrical losses include • the copper l the copper losses - sses - also o I 2 2 · R losses - losses - in n the windings the windings (heating ef (heating effect due t ct due to copper resi copper resistance), ance), • core losses and core losses and (magnetic h (magnetic hyst steresis ( eresis ( ~ B k · f ) and eddy cu ) and eddy currents ( rrents ( ~ B 2 · f 2 ) in ir ) in iron on cores) cores) • eddy current losses in eddy current losses in other par her parts of the machine being electric s of the machine being electric conductiv conductive, e.g e, e.g permanent magne ermanent magnets, end s, end shields, housing par shields, housing parts, … s, … – Mechanical losses, such as • frictional losses generat frictional losses generated b ed by the bearings as w the bearings as well as ll as • windage windage losses osses

Thermal Modeling in Electrical Machines Thermal Modeling in Electrical Machines Br Brushless g ushless gener nerator Conjugate Heat Transfer Analysis of Integrated Brushless Generators for More Electric Engines Marco Tosetti, Paolo Maggiore, Andrea Cavagnino, Senior Member IEEE , and Silvio Vaschetto, Member IEEE Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino – Italy

Thermal Modeling in Electrical Machines Thermal Modeling in Electrical Machines Br Brushless g ushless gener nerator Winding Temperature Stator Core Temperature Conjugate Heat Transfer Analysis of Integrated Brushless Generators for More Electric Engines Marco Tosetti, Paolo Maggiore, Andrea Cavagnino, Senior Member IEEE , and Silvio Vaschetto, Member IEEE Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino – Italy

Achie hieving ing Coupled Models Coupled Models Electr Electromagne omagnetic Simulation tic Simulation Thermal Simulat Thermal Simulation on Coupled Manual T Manual Transf ansfer of er of losses losses Templat mplate b based de d design ign c codes des • • Problem Rotor, Stator, Windings Simple circuit models • • Homogeneous application • Mapping of distributed losses • Finite Volume flow/thermal codes • Segmented by parts • Homogeneous losses on bodies • Maintain distribution of losses • Rotor • Typically from Finite element codes • Stator • Codes often use a temperature • Windings • Heterogeneous losses • Map between grids •

Losses in Electric Machines Losses in Electric Machines Brushless DC mo Brushless DC motor, 1 10KW 0KW max po max power Homogeneous application of losses per component – Copper losses = 43 W – Iron losses stator = 345 W – Magnet losses = 0.74 W Heterogeneous application of losses – See image Comparison of Solution Heterogeneous Homogeneous

Losses in Electric Machines Losses in Electric Machines Comparison of maximum temperature Heterogeneous Homogeneous Heterogeneous “mapped” losses lead to higher maximum temperatures

Data Transf Data T ansfer t er to S STAR-CCM+ - AR-CCM+ - Losses osses The B-field v The B-f eld variation allo riation allows ir ws iron on loss loss estimation estimation – GoFER of 72 rotor positions /elec. revolution – Modified Steinmetz method in SPEED applies also to non sinusoidal currents Front par ont part of the t of the tooth sees str oth sees strong nger f er fiel eld d variations which is riations which is reflect reflected in ed in the higher the higher ir iron loss density on loss density The iron The ir on loss density can loss density can be visualized be visualized SPEED SPEED – Select the “Plot” Tab 13 13

Data T Data Transf ansfer t er to S STAR-CCM+ - AR-CCM+ - Geome eometr try SPEED geome SPEED geometry f for: stat r: stator or, slo , slot windings, windings, ro roto tor, ro roto tor b bars. CAD CAD geome geometry f for: end-windings, end- r: end-windings, end- rings, all rings, all non-activ non-active com e components (f onents (fan, an, housing, e housing, etc…) c…)

SPEED > S SPEED > STAR-CCM+ Industrial Exam AR-CCM+ Industrial Example ple Induction machine, o Induction machine, overblo erblown with f n with fan n on on the shaf the shaft – SPEED Model > loss distribution – STAR-CCM+ > Temperature profiles