Design Theoreticaland Experimental Study On Permanent Magnet Retarder For Vehicle

Auto retarder, which is a non-contact auxiliary braking device for vehicle, canreduce the driving costs. It consumes most of the vehicle kinetic energy before itbrakes, so it can effectively improve driving safety and continuous brakingperformance. Many European countries have enacted the retarder laws at themid-nineteenth century, which required the retarder as standard auto parts. Recently,retarders are applied and popularized gradually in China as the promulgation ofrelevant laws and regulations. At present, eddy current retarder (ECR) and hydraulicretarder (HR) have been used widely at home and abroad. ECR has manydisadvantages, such as the severe hot recession of braking torque, bulk density andhigh energy consumption. HR's price is so high that few heavy vehicles install it. It isdifficult to meet the requirements of the domestic heavy vehicle, so the retarderinstallation rate of heavy vehicles is less than1%. Therefore, it is great significance toresearch highly cost-effective retarder that has independent intellectual property. Itcan break the monopoly of foreign retarder, ensure the safety of heavy vehicle, andimprove the independent innovation capability of domestic cars.In the1990s, Japan developed a novel air-cooled permanent magnet retarder(PMR) for the first time, which has no power-consumption, light weight and compactstructure. However, it doesn't get large-scale promotion. In order to overcome thebraking performance thermal recession problem of PMR, a new type PMR is designusing water-cooled method in this dissertation. The systemic theory and keytechnology of water-cooled PMR are researched, and lots of bench and real vehicletests are made. Performance evaluation system of water-cooled PMR is formed, andmany important results are obtained. Main chapters of the dissertation are as follows:Chapter I introduces the role of auxiliary braking device for vehicle, thenecessary of installation, the domestic and foreign laws, the application, and researchsignificance. Retarder types, working principles, performance comparisons, andprogress in PMR design theory and structure are introduced. The developmentdirection of PMR is proposed by summing up common technical problems of theretarder. The progress of eddy current braking and multi-physics coupling theory arereviewed, and the research methods of PMR design theory are proposed.Chapter II proposes a structure and principle of water-cooled PMR. At first, thestructure of Japanese traditional PMR, the working principle, the control method, theinstallation method, the characteristics and the used effects are described in detail. Thebasic structure and working principle of water-cooled PMR are introduced. The water-cooled PMR maintains low working temperature, braking performance does notoccur thermal recession and the continuing work capacity is improved greatly.According to the vehicle installation requirements, three kinds of water-cooled PMRstructure which meet the requirement of heavy vehicles and buses are proposed. Thematching characteristics of water-cooled PMR with the electrical, cooling and brakingperformance of the vehicle are studied. The electronic control unit and vehicle coolingsystem pipes layout of PMR are designed, and the matching relationship between thebraking torque and vehicle weight are proposed.Chapter III builds a mathematical model of water-cooled PMR. The PMRbraking performance for vehicles is evaluated by the brake deceleration and brakingdistance. The PMR braking process of the separate braking and combined braking isanalyzed. The transient eddy current field of PMR is solved by armature reactiontheory and iterative methods, and the analytic formulas of the braking torque andbraking power are obtained. The change law of the transient electromagnetic field isrevealed in braking process of PMR, and the mathematical model of PMRelectromagnetic fields is established. A temperature mathematical model of PMR isestablished by the analysis of the heat transfer process, heat transmission path andboundary conditions. In order to analyze permanent magnet (PM) demagnetization onhigh-temperature in PMR, PMR mathematical model is established firstly, and theboundary conditions of finite element analysis are determined. Then eddy currentfield distribution is gained by solving eddy current demagnetization field, and PMdynamic permeance coefficient is obtained. Combined with the PM demagnetizationcurve analysis, the demagnetization properties are analyzed.Chapter IV builds a multi-physics coupling model of water-cooled PMR. Theelectric-magnetic-thermal field coupling model is established and solved numerically.The eddy current braking mechanism of PMR is visualized by electromagneticsoftware and the magnetic field and eddy current distribution are obtained. Theheat-fluid field coupling model is established and solved numerically. Thewater-cooling law in the stator is visualized by computational fluid dynamics (CFD)software. The temperature distribution of PMR is obtained. Theelectric-magnetic-thermal-fluid coupling model is established by semi-Lagrangemoving coordinate system. The tests show that the multi-field coupling calculationresults are closer to experimental values.Chapter V studies the key technology of PMR design. The approximate linearrelationship between low-speed braking torque and suction is found by eddy current brake experiment platform. The design method of static suction is proposed. Thebraking torque influence of stator material conductivity, permeability and the platinglayer is discussed by finite element method, and the relationships between brakingtorque and air gap length, stator thickness, PM shape, shielded rotor thickness areobtained. PMR structure is optimized by experimental design method and theRosenbrock method, and the integrated design platform of PMR is developed.Chapter VI studies the test methods of water-cooled PMR. The test bench andchassis dynamometer test program for water-cooled PMR are designed. The systemand method of vehicle road tests for PMR are proposed. The water-cooled PMR istested by bench, chassis dynamometer and car road. The braking performanceevaluation system of water-cooled is formed.Finally, the dissertation conclusion and future research outlook are proposed.