Research and development of linear motors in three-dimensional analysis of rail vehicles Pang Shaohuang, Yu Ming (Guangzhou Metro Corporation, Guangzhou 510380, Guangdong, China) has brought about significant changes in design concepts. Through the analysis of the actual performance of the current linear motor vehicles in the world, the viewpoint that the vehicle quality can be reduced is proposed.
The vehicle project manager of the Construction Headquarters of the Guangzhou Metro Corporation, engaged in the introduction of new Guangzhou Metro Line vehicles and technology and project management.
A linear motor is a motor that converts electrical energy directly into linear motion without passing through any intermediate switching mechanism. The advantages of using linear motor transmission in urban rail transit systems have been recognized by more and more people. At present, seven cities in the world have successively built urban rail transit systems using linear motor vehicles.
The advantages of linear motor vehicles over ordinary rotary motor vehicles are apparent. The advantages of linear motors As described in all current books, the traction of a train no longer depends on the adhesion of the wheel-rail, but is directly generated by the interaction of the bogie (usually acting as a stator) and the line (generally acting as a rotor). The small radius can reduce the radius of the support wheel, thereby reducing the cross-sectional area of ​​the subway tunnel, reducing the subway construction cost, etc., but these are only derived from the one-dimensional concept of the traction direction of the linear motor, I believe that we must also pay attention to the straight line The use of other two-dimensional concepts of motors in linear motor vehicle design.
The following will analyze the difference between a linear motor and a rotary motor on a wheeled vehicle from a three-dimensional direction (see below), and then discuss the impact on the linear motor vehicle design and on the sleeper.
1W direction (ie, traction direction) For squirrel-cage asynchronous motors, the electromagnetic torque can be expressed by the following formula: Sub-folded resistance; r1 A certain stator resistance X1 - Stator leakage reactance X2Y - Rotor-folded leakage reactance S1 = (n1-n) /, where n1 is the synchronous speed and n is the rotor speed "f" stator winding frequency.
Corresponding vehicle braking is regenerative braking, resistance braking and the empty axle weight of the vehicle matching with the rotating motor is.) If the linear motor neglects the longitudinal end effect, the steady state equation can be used to calculate the electromagnetic thrust: Resistance and leakage inductance; T-pole distance; S2 = (vs-V)/vs, where vs is synchronous speed, 4 is actual speed; f2 - secondary frequency; "1 - primary corner frequency; Ci! 1+LS/Lm, where L' is the primary leakage inductance and Lm is the excitation inductance.
The motor can be used in 3 stages. There is now a technology that inserts a phase-shifting brake (electromagnetic brake state) between regenerative braking and mechanical braking and consumes kinetic energy on the sensing plate (when Si, S2>1) due to the movement of the vehicle. This kind of thermal energy can be left on the induction plate on the track instead of the resistance braking, while the ordinary rotating motor can not withstand such undissolved heat.
The concept of the traction direction has been discussed in some books, and the advantages and disadvantages of the well-known linear motor are analyzed. The author does not discuss it further. Only the other two-dimensional concept (there is currently no book discussed in the actual use of wheeled vehicles) is discussed below.
2y direction in the ordinary rotating electrical machine due to electromagnetic attraction to the symmetry of the rotor, mutual balance, electromagnetic attraction force is only the internal force of the rotor, in addition to the external appearance of the motor in terms of gravity, the force of the electromagnetic force is zero. The linear motor is very different, and the three-dimensional electromagnetic force is now outside. The electromagnetic attraction of the primary to the secondary is quite large (see Table 1). But how to use this kind of electromagnetic attraction, this is what the author focuses on.
In order to ensure the derailment coefficient, it seems that as long as the ordinary rotary motor vehicle is replaced with a linear motor, but from the y direction, the use of ordinary rotary table 1 three-dimensional force measurement data (kN (x axial traction force) Y-axis electromagnetic attraction j-axis transverse shear force A company B company C company As the urban rail transit travels in the prosperous urban area, the station spacing is generally short, about 1km, so the station operating time must be short to achieve other The advantage that can not be realized by ground vehicles: The initial acceleration is generally a plus 1.0m/s2, but a is used in braking.Therefore, after the train is basically accelerated to the maximum speed, the uniform speed is transferred to the brake immediately. In addition, the stator coils of the linear motor always have a large current through, that is to say the attraction of the y-direction runs through the entire running of the train.
F-sucking is the electromagnetic attraction of the primary to the secondary. The F-sucking m+ is even greater than the traction of the linear motor. In other words, the F suction ma+ of two linear motors (160~180kW/set) per vehicle is up to 10t, accounting for ordinary One-fourth of the weight of an empty car on a rotary electric vehicle. Therefore, the electromagnetic attraction gives a two-flute problem. If only the thinking design of an old ordinary rotating electric vehicle is used, the wheel diameter must not be reduced because the wheel diameter is Axis weight has a direct relationship. According to statistical data (see), with the axle weight unchanged, the incidence of peeling of the wheel tread increases with the pressure at the wheel tread.
In other words, it loses the advantage of reducing the height of the vehicle and reducing the tunnel excavation area. On the other hand, it is completely different. First, start with the analysis of derailment coefficient to analyze the differences between these two types of motors.
0.6 (linear motor vehicle) F suction provides an important basis for the weight loss of linear motor vehicles, and the work performed by F suction can be expressed by the following formula, since F suction is perpendicular to the straight track. In the direction of movement of the vehicle, usually F0 is therefore a force that does not require power consumption, but is a force that draws the bogie toward the sensing plate. If this new concept can be used in the design of a linear motor vehicle, it is possible to reduce the quality of the vehicle as much as possible while ensuring that the derailment coefficient is less than 0.6, in order to reduce operational energy consumption, reduce noise, and reduce wheel diameters. As a result, the quality of the bogie under a single series of springs is reduced and the structure is compact, so that the vehicle quality is ultimately reduced, the design height of the vehicle is reduced, the tunnel section size is reduced, and the purpose of construction investment is saved. So in the interface with the track, the sleeper is different (see). Therefore, for a linear motor vehicle, it is not possible to consider only the vehicle mass P. As a supplementary evidence for the analysis in the 3-way direction, it can be seen from the performance announced by each linear motor vehicle manufacturing company that almost the same size and power are produced for different companies. In the linear motor vehicle, the maximum empty car quality is nearly 10t/car. The author supposes that according to a car with a capacity of 180 passengers and an average weight of 60 kg per person, the load quality is 00:200:10800 kg, which is 10.8 5 weights. It can be seen that if the linear motor 3 direction attractive force is taken into consideration in the vehicle design, it will reduce 101 cars per empty car and then add 180 manpower loads, which is almost equal to that of every empty car that originally did not consider the attraction. Equal quality.
In the direction of the 3z direction, the author proposes a new concept of "magnetization guide" for the bogie, which is another advantage brought by the linear motor. As the vehicle is designed, the mechanical centerline coincides with the magnetic centerline when it is parked stationary in a flat track; and in the state of motion, the electromagnetic field makes the mechanical centerline of the linear motor stator (primary) have magnetic attraction automatically. The role of the middle induction board (secondary) mechanical centerline (see).
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