A Low‐Speed,High‐Torque Motor Drive Using a Modular Multilevel Cascade Converter Based on Triple‐Star Bridge Cells (MMCC‐TSBC)

This paper provides an experiment‐based discussion on a modular multilevel cascade converter based on triple‐star bridge cells (MMCC‐TSBC) for a low‐speed high‐torque motor drive. The TSBC is a direct ac‐to‐ac power converter capable of achieving bidirectional power flow as well as drawing and feeding three‐phase sinusoidal input (supply‐side) and output (motor‐side) currents with any power factor at both sides. This paper discusses active dc‐capacitor‐voltage control applied to the low‐speed, high‐torque motor drive. A specially designed downscaled system combining a 320‐V, 38‐Hz, 6‐pole, 15‐kW induction motor with a 400‐V, 15‐kW TSBC is constructed and tested to confirm the validity of the motor drive. Experimental waveforms obtained from the downscaled system confirm stable operation with the rated load torque across a range from a standstill to the rated speed, including satisfactory start‐up performance.     

Design considerations for the switched reluctance motor

Analytical design equations are developed to predict the performance and to guide the design of the switched reluctance motor (SRM). The use of these analytical equations to trade-off different SRM attributes is discussed. The various approximations and simplifications used in the development of the analytical design equations are justified using results obtained from a detailed computer model of the SRM and by using experimental results from a high power density SRM designed for an aircraft engine fuel pumping application. Comparisons of predicted and measured machine performance parameters for this 90 kW 25000 r/min machine, such as flux linkage curves, back EMF, electromechanical power converted, and inverter voltampere requirements are presented. It is also shown that there exists a fundamental maximum torque density that is attainable with the SRM and an estimate of this maximum torque density limit is given. The power factor for an SRM is defined and the machine parameters that determine its value are presented. This power factor is compared to the similarly defined power factor for an AC machine and found to be smaller     

秦皇岛燃气轮机试验站拖动电动机的研制

为满足燃气轮机试验时所需的不同扭矩和转速,研制了目前国内速度变化范围最大的异步变频电动机,其额定功率为6000kW,工作速度为0～3000r/min.本文主要介绍此种电机在研制过程中遇到的一些问题和解决办法.     

Performance comparisons of radial and axial field,permanent-magnet, brushless machines

The objective of this paper is to provide a comparison between the traditional radial field permanent-magnet brushless machine and four unique configurations of axial field permanent-magnet brushless DC machines. These consist of a single-gap slotted axial field machine, a dual-gap slotted axial field machine, a single-gap slotless axial field machine, and a dual-gap slotless axial field machine. The comparison is done at five power levels ranging from 0.25 to 10 kW. A rated speed of 2000 r/min is chosen for the 0.25-kW designs while 1000 r/min is chosen for the rest of the designs. The trends in performance and sizing for the different power outputs are obtained to get an understanding of the capability of various machine configurations. The comparison consists of required copper, steel, and magnet weights, copper and iron loss, moment of inertia, torque per unit moment of inertia, power per unit active weight, and power per unit active volume for five different power levels. For a given application, the results provide an indication of the machine best suited with respect to performance and size. The basis for the comparison is described with details on the design procedure     

最小脉宽特性对高压三电平变频器的影响

最小脉宽,即单个开关器件的最小导通和关断时间,在高压大容量变频调速系统运行过程中至关重要.本文通过仿真和基于IGCT的1.25MW/6000V三电平变频器上进行试验,对最小脉宽对大容量变频调速系统起动和稳态运行的影响进行了较为全面的评估,并在此基础上提出了相间最小脉宽的概念,既保证了单管最小脉宽,又在开关动作之间留有适当间隙.最后分析了最小脉宽与起动电流、稳态电流以及转矩脉动之间的关系,对大容量变频调速系统的安全运行有十分重要的指导意义.仿真和试验均验证了上述分析的正确性.     

抑制开关磁阻电机振动的结构设计研究

开关磁阻电机(SRM)应用于众多领域,但是本身的结构使其比其他传统电机有更大的振动和噪声,因此抑制SRM振动仍是研究的热门领域。为了抑制电机的振动,设计了一种新型的电机结构,即在转子两侧开孔,并在此基础上对定子齿顶开槽。以一台7.5 kW、1 500 r/min、12/8极SRM为例,通过有限元分析仿真,对新型电机结构进行参数化计算,并得到最优结构。在保证平均转矩基本保持不变的情况下,减小了转矩脉动以及径向力。与原始电机相比,转矩脉动系数下降了16.01%,径向力峰值下降了19.96%。因此,证明了该方法对SRM振动抑制有较好的效果,对后续SRM设计及控制具有一定的借鉴意义。     

真空干泵用爪极永磁电机设计与分析

轴向分段式爪极电机具有转矩密度高、结构简单、制造成本低以及节约材料等优点。设计了一台1.5 kW、9 000 r/min的轴向分段式爪极电机。对电机的电磁设计与温度分布进行分析，验证设计的合理性。对于爪极参数的选取，研究了爪极角与爪尖长度对电机转矩大小、转矩波动以及空载电动势的影响，给出了合适的选取范围。分析结果为新型真空干泵驱动电机产品开发提供了参考依据。     

Selection Criteria for Servo Motor Drives

The power density and acceleration characteristics of the ac servo drive are being recognized as being superior to those of the dc counterpart. The ac servo family consists of permanent-magnet synchronous, dc brushless, induction, and switched reluctance motor drives. This ac servo family is comprised of radial (also known as the sausage type) and axial (also known as the pancake type) field motors, thus enlarging the spectrum of ac servo motors to the users. Realizing that the ac servos are of recent development, it is obvious that their potentials and pitfalls have not been published, thus making it difficult for the user and application engineer to choose one servo from the family of ac servos for a particular application. In this regard, an attempt is made here to develop a set of selection criteria to differentiate the various servo drives of the ac family. The factors proposed to do that are cost, power density, acceleration rates, peak torque capability, speed range, torque per unit ampere, thermal capability, parameter sensitivity, cogging torque, ripple torque, braking, rotor position feedback device, etc. Application of these criteria would promote appreciation for the various facets of ac servos through their comparison with other drive types.     

Design and performance of field regulated reluctance machine

A unique topological configuration for rotating electromagnetic machines that can produce significantly higher force density than an induction machine is investigated. The stator is constructed using full pitch concentrated windings embedded in conventional slots. Rotor saliency is produced using poles constructed of axially oriented laminations. Operation is such that all of the conductors are actively taking part in torque production all of the time. The means for exciting the stator windings allows for independent control of torque and regulation of the rotor flux. A force density comparison is made based on operation with equal surface current density, conduction losses, and peak air-gap flux density. Construction and testing of a prototype 500 RPM, 28 kW laboratory machine, power converter, and controller are described     

Bidirectional isolated three-phase dc-dc converter using coupled inductor for dc microgrid applications

The main objective of this project is to study the analysis and design of an isolated three-phase bidirectional dc-dc converter connected to the dc microgrid system. The proposed topology achieves efficient power conversion with a wide input voltage range, continuous input current, and bidirectional operation. In forward mode operation, the topology acts as a three-phase push-pull converter to reach a step-up voltage conversion ratio (90 to 450 V ). In backward mode operation, the converter acts as an interleaved flyback converter to provide a step-down voltage conversion ratio (450 to 90 V ). Over and above that, in both operation senses, the dc voltage gain is presented. The main advantages of this topology are high-switching frequency, the three-phase transformer that provides galvanic isolation between the dc voltage link bus to the battery or ultra-capacitor storage, and input/output filters size reduction. Besides, a fewer number of power switches, the frequency of output voltage, and input current ripple are three times higher than the switching frequency. The three active switches are connected to the same reference, which simplifies the gate drive circuit. Ultimately, the theoretical analysis of the proposed topology is carefully confirmed with the experimental results of the 4 kW converter prototype.     

Development of High‐Power Density Interleaved dc/dc Converter with SiC Devices

We developed an interleaved dc/dc converter with SiC devices. We applied full‐SiC modules including MOSFETs and SBDs to the interleaved dc/dc converter to achieve a high‐power density. An SiC has a high temperature resistance, which facilitates an improvement in high‐frequency drives. We achieved a high‐power density by utilizing this high temperature resistance. We also fabricated a prototype and tested it with loads up to 65 kW.     

The design and development of an axial flux permanent magnetbrushless DC motor for wheel drive in a solar powered vehicle

This paper presents the development of a “weight-power trade-off” applicable to high-performance, power limited vehicles. The theory is then applied to the electric vehicle case to justify the pursuit of an “in the wheel” motor design. The singular benefits of axial flux geometry are discussed with reference to the particular requirements of electric motors for vehicular applications. The basic design process, construction, and test results for a motor fitted in a 26 inch wheel to drive a 260 kg all up weight vehicle are presented. At an output power of 1 kW, the attainable vehicle speed is 72 km/h, corresponding to a motor/wheel speed of 578 r/min and torque of 16.5 Nm, at an estimated motor efficiency of 94%     

18kW异步电机高压直流起动发电系统设计与实现

采用异步电机的起动/发电双功能电源系统将是战机、战车和汽车等移动电源系统的一个有竞争力的发展方向。结合18kW 270V高压直流起动/发电系统的研究工作,该文介绍了异步电机与变换器控制结合的起动/发电系统综合设计方案,通过两路三相变换器的功率开关的通断实现电机起动时Δ接法、发电时Y接法的转换运行,解决了起动时低压蓄电池供电和发电时输出高压的矛盾。分别阐述了异步电机起动运行和发电运行的控制策略,对比了异步电机"Y"、"Δ"2种接法下的转矩控制技术的特点,并简要介绍了宽转速范围内提供恒压电功率技术。这些关键技术使系统大大提高了发电的动静态品质和起动性能。最后给出系统仿真及样机试验结果。     

轴向磁通永磁电机的设计与优化

本文根据一款家用乘用车的结构和运行性能需求,设计出了额定功率95kW,峰值功率190kW的轴向磁通永磁电机。电机采用内单定子外双转子结构,定子铁心采用分块式设计形式。基于永磁电机设计理论,总结归纳轴向磁通永磁电机的初始设计流程,并对其电磁性能进行初始评估。采用有限元法建立电磁分析三维模型,对采用多种转子结构电机的电磁转矩、齿槽转矩、转矩脉动及永磁体涡流损耗等进行计算和分析。文中所归纳的电动汽车驱动用轴向磁通永磁电机设计流程及降低齿槽转矩、转矩脉动和永磁体涡流措施的效果对比,为此类电机的设计及优化提供借鉴经验。     

Thick-film hybrid technology for low-output-voltage DC/DC converter

The new requirements in portable and telecommunication equipment also affect the supply systems. The current tendency to lower the output voltage (3.3, 2.7 V/sub DC/) together with the necessity of an important size reduction is modifying the strategies for dc/dc converter implementation. Low-voltage high-power-density applications present two important factors that must be analyzed: thermal problems due to high power density, and the high currents to be handled. This paper presents a 10-W dc/dc buck converter with passive integration using hybrid technology (within the frame of ESPRIT Project 23910.). As a result of the mentioned integration technique, a power density of 6.25 W/cm/sup 3/ was obtained with high efficiency (approximately 90%).     

高速工况下车载综合电力系统失稳预测

针对车载综合电力系统因离网运行、发动机动态响应慢以及工况复杂从而易失稳的问题,开展了系统失稳预测研究.通过建立各微源、负载变换器的小信号模型,得到各微源输出阻抗与负载输入阻抗.基于改进的阻抗比判据提出了车载综合电力系统小信号失稳判据.利用波特图从发动机转速、车速以及驱动电机转矩3个方面进行系统失稳预测分析.最后通过硬件...     

一种双管正激ZVT-PWM开关电源的研制

介绍了一种双管正激ZVT鄄PWM电路的软开关拓扑,详细分析了该拓扑结构实现软开关的工作原理,给出了一个开关周期中各个开关模态的关键参数计算公式,利用公式推导说明了实现软开关的策略。在理论分析和计算的基础上,采用双管正激ZVT鄄PWM主电路拓扑结构,成功开发并研制了1.5kW(26V/50A)的开关电源。该电源具有体积小、效率高、可靠性高、电磁干扰小的优点。针对实测波形和理论分析波形存在的差异,文中给出了准确的说明和分析。     

活性炭/氧化镍干凝胶超级电容器研究

以高性能活性炭作为负极材料、纳米氧化镍干凝胶作为正极材料组成超级电容器,研究了此电容器在7 mol/L KOH水溶液体系中的电化学性能,其充放电电压可以达到1.6 V,比能量和比功率分别达到45 Wh/kg和35 kW/kg(以正负极活性材料本身质量计算),是一种性能优良的超级电容器.     

Development of an Induction Machine Commutated Thyristor Inverter for Traction Drives

Several designs detailing the construction of brushless cage-rotor induction machines operating at unity or leading power factor at the 35-hp level have recently been published [1]-[3]. The experimental machine combines the torque characteristics of a conventional cage induction machine with the leading power-factor (PF) capability of an overexcited dc field synchronous condenser into one unit using a common cage rotor and a common stator core. The ability of this machine to naturally commutate a high-power current-source thyristor inverter is apparent without any need for capacitors. The preferred adjustable speed propulsion arrangement consists of a mains-fed phase-delay-rectifier (PDR), high-voltage dc link, and a current-source inverter powering a ten-pole traction motor with constant V/Hz control. The drive system provides continuously variable torque during motoring, and regenerative braking modes and specific details are given for a 150-hp cage-rotor traction motor and converter, capable of natural commutation up to 200 Hz, currently under development.