1、大连交通大学 2013 届本科生毕业设计（论文）外文翻译 外文原文 The Rise Of The Permanent-magnet TractioMotor Technology offering benefits in terms of mass, size and energy consumption, the permanent-magnet synchronous machine is increasingly being adopted for traction drives, despite the need for complex control systems and pot
2、ential failure modes. In the past couple of years, many of the bids for new rolling stock placed with major international suppliers have proposed the use of permanent-magnet synchronous traction motors, which are smaller and lighter than the three-phase induction motors that have dominated the marke
3、t in recent times. Permanent-magnet motors first came to prominence with the use of two powered bogies from Alstoms AGV in the V150 trainset which broke the world speed record on April 3 2007, but they have subsequently been used in a variety of applications, ranging from the Citadis-Dualis tram-tra
4、in to SBBs Twindexx double-deck inter-city trainsets (Table I). Although railway operators are often viewed as conservative in the adoption of new technologies, the designers and manufacturers of rail traction systems tend to capitalise on the latest drive technologies, which are rapidly deployed in
5、 service if they promise significant performance improvements. This was the case for the early choppers supplying series-connected DC traction motors, separately-excited DC motors, synchronous AC motors and drives (as used on the first generations of TGVs) and for the various generations of asynchro
6、nous (squirrel-cage) three-phase drives. As technology moved forward, traction drives became more efficient and more controllable, allowing better use of available adhesion while reducing energy consumption. The permanent-magnet synchronous machine, with its associated control electronics, represent
7、s the latest such advance in traction technology. Millions of small PMSMs are already being used in the transmissions of hybrid cars, thanks to their low mass and good controllability. Larger machines offer a similar potential to enhance the overall performance of the railway traction package. The t
8、echnology is now beginning to be introduced into a variety of new rolling stock, 大连交通大学 2013 届本科生毕业设计（论文）外文翻译 but the integration of PMSMs into traction packages presents some significant technical challenges which must be overcome. Fundamental requirements Petrol and diesel engines for automotive a
9、pplications generally require complex gearboxes to allow the prime mover to operate in the optimum speed band. By contrast, electric motors for rail traction are expected to operate effectively and efficiently over the entire speed range, allowing a permanent coupling to the axles and wheels, either
10、 directly or via a single ratio gearbox. This mechanically elegant solution results in highly reliable drives which need relatively little maintenance. Thus the first requirement placed on the design of traction motors is the ability to provide torque or tractive effort over a wide speed range, such
11、 as from 0 to 320 km/h. Whilst it is essential for the traction motor to operate reliably, it is equally important from the drivers and railway operators perspective that modern traction systems control the torque accurately and smoothly throughout the speed range. Excellent torque control results i
12、n optimum use of available adhesion between wheel and rail, along with smooth acceleration and the ability to cruise at a constant speed and to brake the train electrically (dynamic braking). Tractive effort, power and speed The torque produced in a traction motor is translated into a linear force a
13、t the wheel-rail interface. This force, which causes the train to accelerate or brake dynamically, is normally referred to as the tractive effort. Fig 1 shows the TE curve of a typical drive system, together with the associated train or vehicle resistance curve. The TE curve intersects the resistanc
14、e curve at the so-called balancing speed, that is, the theoretical maximum speed. Close to this speed, there is only a very small amount of tractive effort available to accelerate the train, as indicated by the red arrow in Fig 1. Fig 2 shows the power produced by the drive and the propulsion power
15、required, which is the product of speed and tractive effort. Traction motors are generally designed to match a particular duty. The motor must produce the required full torque at zero speed and sustain this torque up to the so-called base speed, throughout region 1 of the TE curve. Above this speed,
16、 the machine operates at its maximum power output, and in region 2 the 大连交通大学 2013 届本科生毕业设计（论文）外文翻译 tractive effort is therefore inversely proportional to the speed v. In the third region, tractive effort has to reduce in inverse proportion to v because of machine limitations. Torque control At low
17、speeds, the motor can in theory provide a torque that is greater than that which can be transmitted by means of the adhesion available at the wheel-rail interface. However, this would overload the motor beyond the normally accepted level and must therefore be avoided either by driver action or an el
18、ectronic control system. Early DC traction drives were controlled by adjusting the supply voltage using series resistances and by changing the motor group configuration. Today, both DC commutator motors and classic synchronous and asynchronous AC motors are controlled electronically, by varying eith
19、er the voltage or the voltage and frequency. Modern power drives with relatively simple algorithms achieve very good control of tractive effort throughout the speed range. Power control of permanent-magnet synchronous machines can easily deliver good performance in the constant-torque region, but th
20、is needs complex algorithms to control the machine in the constant power region. AC and DC motors, as well as PMSMs, fundamentally rely on the same physics to generate accelerating and braking torques. Hence the control strategies are similar to some extent. In all types of machines, the torque is c
21、reated through the interaction between two magnetic fields. To generate a torque, there must be an appropriate electrical angle (ideally 90) between the two magnetic fields. These fields can be generated by currents flowing through windings or by permanent magnets. Although todays traction applicati
22、ons mostly use three-phase induction motors, it is important to understand the nature and behaviour of the magnetic fields in the stator and rotor of the different types of machine. In a conventional DC traction motor, the north and south poles of the stator field are always oriented in the same dir
23、ection while the rotor field is maintained at a 90 (electrical) angle by the action of the commutator. In a series-connected machine, the same current flows through the stator and rotor windings (Fig 3), while a separately-excited machine allows the armature and stator fields to be controlled independently (Fig 4).
