混合动力车用混合励磁爪极皮带式起动发电机多领域仿真分析_英文_

第 30 卷 第 36 期 中 国 电 机 工 程 学 报 Vol.30 No.36 Dec.25, 2010 2010 年 12 月 25 日 Proceedings of the CSEE ©2010 Chin.Soc.for Elec.Eng. 7 文章编号：0258-8013 (2010) 36-0007-09 中图分类号：TM 31 文献标志码：A 学科分类号：470⋅40 混合动力车用混合励磁爪极皮带式起动发电机 多领域仿真分析 李维亚，黄苏融，张琪 (上海大学机电工程与自动化学院，上海市 闸北区 200072) Multi-domain Simulation Analysis of A Hybrid Excitation Claw-pole Belt-alternator Starter Generator for Hybrid Electrical Vehicles LI Weiya, HUANG Surong, ZHANG Qi (College of Mechatronics Engineering and Automation, Shanghai University, Zhabei Distrct, Shanghai 200072, China) ABSTRACT ： The traditional claw-pole machine control air-gap flux to transmit stable output voltage to batteries by regulation excitation current, which has disadvantages such as lower output capacity and inefficiency caused by leakage flux. It doesn’t meet the current requirements of hybrid vehicle power supply. A hybrid excitation claw-pole belt-starter- generator (BSG) machine for 42 V power supply system hybrid electric vehicles (HEVs) has been created. Through permanent magnets inserted among claws, this kind of generator can reduce the leakage between the claw-poles, increase machine power density and output capacity under low speed. This paper will use magnetic circuit and three-dimension finite element methods to analyze the structure and principles of BSG. The multi-domain simulation methods include mechanism, vibration modal and thermotics to solve the analysis of high-density machine ultimate capacity and optimization. The simulation results have showed that with high starting torque in starter mode, the machine can constantly provide output voltage at wide speed range for batteries charging in generator mode. Experimental results of prototype confirm the theoretical analysis and simulation conclusion. The prototype has advantages such as low leakage, large output capacity and hard output characteristics, which has broad application prospect for hybrid electrical vehicles. KEY WORDS ： hybrid excitation; belt-alternator starter generator (BSG); hybrid electrical vehicles (HEVs); three-dimension finite element; multi-domain simulation 摘要：传统爪极电机通过调节励磁电流控制气隙磁通，用以 满足变负载运行时恒压向蓄电池供电，但由于漏磁大，导致 基金项目：863 节能与新能源汽车重大项目(2008AA11A108， 2008AA11A109)。 The Energy and New Energy Vehicles of 863 Program (2008AA11A108, 2008AA11A109). 输出能力小、效率低等缺点，满足不了目前混合动力汽车供 电要求。该文设计了一种 42 V 供电系统混合动车用混合励 磁爪极皮带式起动发电机(belt-starter-generator，BSG)，通过 在爪极间镶嵌磁钢来减小爪极间漏磁，提高电机功率密度和 低速输出能力。采用磁路法和三维有限元法分析了 BSG 电 机结构及其原理，基于机械、模态和热工多领域综合仿真分 析解决高密度电机极限能力分析与优化设计。仿真分析 得出样机在电动模式下，可以获得起动转矩起动引擎，在发 电模式下，可以在宽速度变化范围内输出恒定的电压向蓄电 池供电。实验数据和三维有限元计算结果与理论分析一致， 样机具有漏磁低、输出能力大、输出特性硬等优点，该电机 的设计在混合动力汽车中具有广泛的应用前景。 关键词：混合励磁；皮带式起动发电机；混合动力汽车；三 维有限元；多领域仿真 0 INTRODUCTION Under the growing concern on environmental protection and energy conservation, the development of hybrid electric vehicles (HEVs) has taken on an accelerated pace [1]. As one of the core parts of HEVs, the generator is required to pursue perfect performance and high efficiency. Rather than the separated starter generator in the conventional automotive electrical system, the concept of the Belt-alternator Starter Generator (BSG), namely, the functions of both the starting engine and generating electric power are fulfilled by one electrical machine in an onboard vehicle system, which has been becoming more and more popular in modern auto industry [2-4]. Valeo has developed the first generation of “Stop-Start” system with 14 V power 8 中 国 电 机 工 程 学 报 第 30 卷 supply system, which has 2.5 kW output power [5]. With the wide application of ventilation, air-conditioning, anti-lock braking system, electronic ignition device, automobile safety fault diagnosis system, information systems, entertainment products, etc., auto electric power requirement has rapidly increased to 1.5~3 kW. Due to its high space usage, compact structure, low cost and excellent regulated performance, the traditional claw-pole generator has become the mainstream product within automotive generators. Nevertheless, its further development will confront with the challenges of leakage flux, noise, inefficiency and poor output performance. So it is important to develop a hybrid excitation claw-pole generator with highdensity, highspeed and highefficiency. GM companies have proposed a hybrid excitation claw-pole generator structure for vehicles [6], and some researchers have comparatively studied on the claw-pole electrical machine with different structures such as CCPM, PMCPM [7] and outer rotor structure[8]. The permanent magnet claw-pole synchronous machine is used for direct-driven wind power applications [9]. The 3D FEA method is used in [10] to analyze superconducting claw motor, and the circuit coupled simulation method is used in [11] to research a temporary linearization claw-pole model. In order to reduce computing time, the improved equivalent magnetic circuit is used for analyzing the claw-pole machine [12]. With the development of SMC (soft magnetic composite) materials, the claw-pole external rotor PMSM has been designed to reduce eddy current loss [13]. A magnetic circuit structure of the series hybrid excitation claw-pole generator mentioned in [14] minimizes the leakage flux when p=2; while the reducing number of pole-pairs increases the claws’ weight, and makes claws enlarged, which results in rotor-stator friction in high speed. [15] gives the inductance calculation methods of the hybrid excitation claw-pole motor. The modern design concept of high-density motor is integrated with electricity, magnetism, mechanics, thermal, structure, power electronics and control strategy [16]. This paper lays emphasis on bypass magnetic path structure, and discusses the principles of bypass magnetic path, the computation of three-dimension finite element and the test of prototype, which verifies the correctness of relevant theories. Multi-domain simulations include accurate computation and design improvement in mechanical, vibration modal and thermodynamic characteristics, which keep machines safe. This concept is newly extended to the BSG and a new type of vehicle bypass hybrid excitation claw-pole BSG from the engineering perspective is designed accordingly. It not only overcomes the drawbacks of machines mentioned above, but also meets many rigorous requirements of the BSG system. 1 MECHANICAL STRUCTURE Fig.1 shows that the structure of bypass hybrid excitation claw-pole generator includes stator, rotor, shaft, bearing, permanent magnets, carbon brushes and rectifier circuit. The stator consists of armature coils (5) and stator core (6); the rotor is composed of rotor iron core (1), excitation coils (4), permanent magnet (3) and the magnets mounted between the claws; and chassis and cover are both made by non-magnetic materials. The design adopts water-cooled structure (12). 12 2 1 4 10 11 3 (a) Flat structure 7 6 5432189 (b) Simulation of three-dimensional structure 图 1 混合励磁BSG电机结构 Fig. 1 Structure of bypass hybrid excitation claw-pole BSG 第 36 期 李维亚等：混合动力车用混合励磁爪极皮带式起动发电机多领域仿真分析 9 In order to reduce product cost， the rotor is made of 08F low-carbon steel; the stator is made of 50 silicon steel; and the shaft is made of 45# steel. The leakage flux hinders the improvement of claw-pole generator, therefore, the reduction of leakage flux in a claw-pole magnetic generator is beneficial to output performance and efficiency improvement. As the claw-pole motor always operates under high temperature environment, N35SH permanent magnet with high-temperature resistance is selected. This permanent magnet owns the advantages of excellent magnetic properties, uniform magnetization, sufficient utilization ratio and anti-demagnetization. The bypass hybrid excitation claw-pole motor has similar manufacturing process with the conventional claw-pole motor, but more practical. 2 BYPASS STRUCTURE CONCEPT AND ANALYSIS Fig.2 displays the magnetic paths of bypass hybrid excitation machines. The main magnetic path consists of permanent magnetic path and excitation magnetic path, which forms the hybrid excitations bypass structure. S N N S N S (a) Permanent magnet path (b) Electrical excitation magnetic path 图 2 混合励磁磁路图 Fig. 2 Claw-pole magnetic paths analysis The voltage equation of hybrid excitation claw pole motor can be described as follows (Appendix 1): a a a a b b b b c c c c 0 0 d0 0 d 0 0 u r i u r i t u r i ψ ψ ψ ⎡ ⎤ ⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥= +⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦ ⎣ ⎦ (1) Hybrid excitation flux linkage can be expressed as: a aa ab ac a ma b ba bb bc b mb c ca cb cc c mc L L L i L L L i L L L i ψ ψ ψ ψ ψ ψ ⎡ ⎤ ⎡ ⎤ ⎡ ⎤ ⎡ ⎤⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥= +⎢ ⎥ ⎢ ⎥ ⎢ ⎥ ⎢ ⎥⎣ ⎦ ⎣ ⎦ ⎣ ⎦ ⎣ ⎦ (2) No-load hybrid excitation flux linkage is: pma f afma mb pmb f bf mc pmc f cf i L i L i L ⎡ ⎤+⎡ ⎤ ⎢ ⎥⎢ ⎥ = +⎢ ⎥⎢ ⎥ ⎢ ⎥+⎣ ⎦ ⎣ ⎦ ψψ ψ ψ ψ ψ (3) No-load back EMF in Phase A is: A ma gd / de t KN Bψ ω= = (4) In terms of the situation of single-phase power and steady state for hybrid excitation claw-pole machine, the terminal voltage U meets 1 AU K e= . Therefore, when the supply voltage is constant, there is a limit for the speed ωmax of the machine. 1 max gU KK NBω= (5) In starter mode, maxω plays inverse ratio to Bg. When the reverse excitation is applied, the motor’s air-gap flux density decreases and the maximum speed increases, which is broadening the range of motor speed. In generator mode, the output voltage is in direct ratio to the air-gap flux density. Output voltage regulation is controlled by the air-gap flux density. To research the flux regulation capability of the hybrid excitation claw-pole machine, the flux regulation formula is defined as: t f pm pmk= + =Φ Φ Φ Φ (6) tΦ is the total excitation flux linkage in the armature windings; fΦ is the excitation flux linkage generated by field windings, and pmΦ is the excitation flux linkage yielded by magnets. Considering insulation, temperature and leakage flux, the regulation factor k is between 0~3.5 in average. In the case of 0, the air-gap flux generated by magnets is totally offset by the field current. Taking the example of 2, the air-gap flux is strengthened. Due to a longer and complicated magnetic path, the amount of leakage flux between claws is comparatively more than other leakages, which can be reduced by optimizing the size of the claw-pole machine. Fig.3 (Appendix 2) shows the claw-pole machine magnetic path. Bypass structure is used to block the leakage magnet flux, where G is called diverging point of bypass flux. When Fe≥FG (the Fig.3), the machine stays in the state of increasing magnet. The main flux of permanent magnet, which goes through 10 中 国 电 机 工 程 学 报 第 30 卷 G, and flows into the stator, will convert into an effective magnet flux. Thus the leakage flux along the rotor-yoke loop can be reduced, and the machine output can be promoted. When Fe表

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