Permanent magnet linear synchronous motors have the advantages of high thrust density, high acceleration, high speed, and high efficiency, which are widely used in CNC lathes, lithography machines, rail transportation, etc. In high-speed, high-precision servo control systems, detent force fluctuation caused by end effect can easily cause problems such as speed fluctuation, mechanical vibration and electromagnetic noise, which affect the servo performance of permanent magnet linear synchronous motors. Aiming at the detent force fluctuation caused by the end effect of permanent magnet linear synchronous motor, this paper proposes a stepped double auxiliary pole method. The method has a good suppression effect on the end normal force fluctuation and the end thrust fluctuation, which improves the servo performance of the permanent magnet linear synchronous motor in the high-precision servo system. In the traditional methods of suppressing the fluctuation of end detent force, two common methods are using a magnetic isolation aluminum plate and optimizing the auxiliary pole size. The former needs a magnetic isolation aluminum plate to connect the auxiliary pole and the primary mover. Therefore, it needs to add the connection device to connect those three parts. The connection device complicates the auxiliary pole part and increases manufacturing difficulty. The latter does not change the manufacturing process, but in the early design process, the optimum size of the auxiliary needs to be considered. Compared with these two methods, the one proposed in this paper avoids the complex structure of magnetic isolation aluminum plate, the stepped double auxiliary pole is integrated with the primary mover. Moreover, it has a fixed structure with optimum size. Therefore, the method in the paper does not change the manufacturing process, improves the strength of the initial pole structure, and reduces design period. Finally, the finite element analysis by ANSYS was performed to illustrate the correctness and effectiveness of the method.

We propose and experimentally demonstrate a highly sensitive temperature sensor based on cascaded high birefringence fiber loop mirrors (HiBi-FLMs) with the Vernier effect. The two HiBi-FLMs have almost the same free spectrum range (FSR), which can be regarded as two scales of different periods of an optical Vernier-scale, and act as the fixed part and the sliding part, respectively. A Gauss fitting algorithm is introduced to fit the Vernier spectrum envelope to accurately trace the spectral shift of the envelope. The temperature sensitivity and temperature resolution of the cascaded configuration are much larger than those of the individual HiBi-FLMs due to the Vernier effect. The experimental result shows that the temperature sensitivity of the proposed sensor can be improved from − 1.723 n m / ∘ C (single HiBi-FLM) to − 43 n m / ∘ C (cascaded configuration) by employing the Vernier effect, and the temperature resolution is enhanced from ± 0.029 ∘ C to ± 0.001162 ∘ C . The amplification factors for temperature sensitivity and temperature resolution are both 24.96, which shows good agreement with the theoretical predictions. The proposed sensor with huge temperature sensitivity, high resolution, and simple configuration may be a promising candidate for some applications that need precise temperature control.

China’s railways are developing rapidly, and the charger of the auxiliary power supply system is an indispensable part of the maglev train. The existing maglev train charger usually uses the traditional PID controller to control the output of the charger which has a simple structure. To meet the requirements of the maglev train charger output performance which is getting higher and higher, it is necessary to optimize the control strategies which can achieve adaptive control of the system. In this paper, taking Qingyuan maglev train as the research object, the control principle of the charger of the maglev train is studied, and the simulation model of the charger of Qingyuan speed maglev train is built in MATLAB ®/ Simulink ®. After verifying its feasibility, the paper proposes fuzzy PID control to improve the charger control method, and uses genetic algorithm to optimize fuzzy control membership function and fuzzy rules. Finally, the paper builds a fuzzy PID controller simulation model, compares the output performance of the charger under different control methods, and verifies the superiority of the new control method.

In position sensorless control based on a high-frequency pulsating voltage injection method, filters are used to complete the extraction of high-frequency response signals for position observation. A finite impulse response (FIR) filter has the advantages of good stability and linear phase. However, the FIR filter designed by using traditional methods has a high order which will cause a large time delay. This paper proposes a low-order FIR filter design method for a high-frequency signal injection method in the permanent magnet linear synchronous motor. Based on the frequency characteristics of the current signal, the requirement that the FIR filter needs to meet were analyzed. According to the amplitude–frequency characteristic of the FIR filter, these requirements were converted into constraint equations. By solving these equations, the coefficient of the FIR filter could be obtained. The simulation and experiment results showed the effectiveness of this low-order FIR filter.

The Chinese railways are characterized by a wide range of various locomotive series. Nowadays, 80% of the locomotives driven by electricity run on the most main railroads. Most of the electric locomotives designed by AC-DC traction system till 2003 while DJ1 locomotives manufactured by AC-DC-AC traction system. Power Electronics is one of the pivotal parts of the whole locomotive equipment, playing important roles in power outputting, traction torque releasing, brake dynamic inflicting etc. This paper probes into 3 ages of the power electronics technology used in the electrical locomotives in China. The line-commutated control (thyristor and diodes) and the line-commutated control (thyristor and diodes) in traction and auxiliary system delegates the different age. Problems in system design concerning match of invert and asynchronous traction motor are discussed. Main circuit diagram, power electronics and general technical parameters are presented. At last, The paper gives a comparison of the traction characteristic for the electrical locomotive in different age.