Ruiwu Cao

A New Double-Sided HTS Flux-Switching Linear Motor With Series Magnet Circuit

A new double-sided high-temperature superconducting (HTS) linear flux-switching motor for transportation system is proposed in this paper, in which the yokeless iron, armature, and HTS field windings are located in its mover, whereas its double-sided long stator only consist of segmented and low-cost iron. Thus, this type of linear motors exhibit robust and low-cost stator, high efficiency, and high-force capability. First, the general design rule of this kind of motor is proposed. Then, based on the proposed design rule, two double-sided HTS flux-switching linear motors with series and parallel magnetic circuits are investigated and calculated based on the finite-element method. The research results show that the series magnetic circuit motor has the advantages of a more sinusoidal back EMF, high thrust-force density, and high-load capacity.

A new modular and complementary double-sided linear flux-switching permanent magnet motor with yokeless secondary

In this paper, a new modular and complementary double-sided linear flux-switching permanent magnet (LFSPM) motor with yokeless secondary is proposed and investigated, in which both the magnets and armature windings are placed in the short double sided primary mover, while the long stator consists of yokeless iron core only. Comparing with the single sided and conventional double sided LFSPM motors, the proposed motor has the advantages of simple and low cost of secondary, high power density, smaller friction force, and higher efficiency, especially suitable for the long stator application such as urban rail transit and elevator for higher building. The structure and operation principle are introduced and the static characteristics are evaluated based on finite element analysis (FEA).

Design and comparison of two kinds of primary wound field flux-switching linear motors

Purpose The purpose of this paper is to propose the complementary design rules, give a quantitative comparison, and analysis the force production mechanism of the two kinds of primary wound field flux-switching linear motors. Design/methodology/approach Primary wound field flux-switching linear (PWFFSL) motors have the merits of no rare-earth magnet, low cost and a wide operation range, in which the armature windings and the field windings are all located at the short primary mover while the secondary is very robust. Hence, the PWFFSL motor is ideal for rail transportation systems which need a long stator and a wide speed range. In order to overcome the disadvantages of the existing PWFFSL motors, the new complementary design rules will be proposed. Also, to offer a better PWFFSL motor for the rail transportation systems, it is necessary to investigate different structures of the PWFFSL motors and give a comprehensive comparison. In order to predict the force performance of the two kinds of PWFFSL motors with different secondary types, their flux density analysis and force production mechanism will be presented and compared. Findings The comparison result shows that the PWFFSL motor with toothed secondary can offer larger thrust force, higher force density and higher efficiency, while the PWFFSL motor with segmented secondary has the merits of lower force ripple, less use of stator iron, higher power factor and less critical saturation. Research limitations/implications Much more PWFFSL motors with different primary/secondary pole pitches based on the proposed design principle are not considered in this paper. Originality/value This paper has presented the air-gap flux analysis, proposed the complementary design rules for the two kinds of primary wound field flux-switching linear motors with different secondary types and compared the electromagnetic performance of the two motors.

Closed-loop position control of complementary and modular linear flux-switching permanent magnet motor

A high-precision, high-performance motion control system is significant in transportation systems and industrial applications. At present, a new series of complementary and modular linear flux-switching permanent magnet (CMLFSPM) motors with different mover/stator pole pitch ratio have attracted much attention. However, the research about the high-precision position control of these LFSPM motors is absent in literature. Therefore, the closed-loop position control performance of the CMLFPM motor based on mover flux-oriented control is investigated in this paper. The simulation and experiment results validate the effectiveness of the proposed control strategies of the CMLFSPM motor.

Direct thrust control of complementary and modular linear flux-switching permanent magnet motor

With the high power density and the simple structure, complementary and modular linear flux-switching permanent magnet (CMLFSPM) motor is especially suitable for urban rail transit application. A high dynamic performance of the system is significant in transportation system. Compared to the flux-oriented control, the Direct Thrust Control (DTC) method has fast torque response and is scarcely influenced by the variation of the motor parameters. However, the direct thrust control of linear flux-switching permanent magnet (LFSPM) is rarely reported. Therefore, a direct thrust control method for the CMLFSPM motor is investigated in this paper. The performance of the proposed control method is demonstrated by simulation results with MATLAB/Simulink software.

Speed control of double-sided linear flux-switching permanent magnet motor system for electromagnetic launch system

In this paper, a new double-sided linear flux-switching permanent magnet (DLFSPM) motor for electromagnetic launch system is proposed, in which the mover only consists of yokeless iron while the permanent magnets and armature windings are all located on the stator. Hence, this motor incorporates the merits of high thrust density of permanent magnet linear motor and high reliability of linear induction motor in high speed electromagnetic launch system. The mathematical model and field-oriented control strategy of DLFSPM is investigated. The simulation results indicate that the DLFSPM can offer a very good dynamic performance based on the selected control strategy.

Improved rotor position estimation for permanent magnet synchronous machines based on hall-effect sensors

In order to replace the traditional high-resolution position sensors in the permanent-magnet synchronous machines (PMSM), the digital Hall-effect sensors are commonly employed to estimate the rotor position and speed. However, the traditional estimated method based on the average speed results in position error due to the six discrete Hall-effect signals in one resolution at low speed, which will degrades its performance. To compensate the estimated rotor position and speed errors, the Hall-based position observer combined with a non-smooth feedback phase-locked loop (NSFP) is introduced in this paper, which can achieve continuous rotor position and speed signals at all speed range. The static and dynamic performance of the estimation algorithm is validated by experiments on one prototype.

A closed-loop I/f sensorless control based on current vector orientation for permanent magnet synchronous motors

To overcome the drawbacks of conventional I/f scalar control method, the limits of the current amplitude and torque angle have been investigated. In this paper, the closed-loop I/f sensorless control strategy based on direct current vector oriented is proposed. The key of this strategy is to integrate the torque angle loop using instantaneous power estimation into the I/f scalar strategy. Thus, the proposed strategy possesses the merits of high current utilization, enhanced reliability, low loss and simple structure. Moreover, it can be applied to both of salient and nonsalient PMSMs. Finally, experiment results are given to verify the validity.

A new double-sided primary wound field flux-switching linear motor

In this paper, a new double-sided primary wound field flux-switching linear (PWFFSL) motor is proposed, in which the yokeless iron, DC field and armature windings are all located in the short primary mover, while the long double-sided secondary stator is only made of iron. Also, this motor can offer sinusoidal and symmetrical back-EMF and smaller force ripple, because each phase includes two armature coils whose positions are mutually 180 electrical degrees apart. Hence, these kinds of linear motors incorporate the merits of simple structure and low cost of linear switched reluctance (LSR) motors and simple control due to its sinusoidal back-EMF of linear synchronous PM (LSPM) motors, which are perfectly suited for long stator applications such as elevator system. By means of finite element analysis (FEA), the proposed double-sided PWFFSL motor has been optimized and compared with a LSR motor based on the same overall dimension. The results show that the proposed motor can offer higher thrust force and lower force ripple.

Open-circuit fault diagnosis of a dual-winding fault-tolerant permanent magnet motor drive for aerospace applications

Dual-winding fault-tolerant permanent magnet (DFPM) motor offers the advantages of high power density, high efficiency and high fault-tolerance. In this paper, a new open-circuit fault diagnosis of the DFPM motor drive for aerospace applications is proposed and investigated. The proposed open-circuit fault diagnostic strategy can realize real-time detection and localization of single and multiple open-circuit faults. Furthermore, it is more robust against the issue of false alarms and it is not required to adjust alarm threshold values under different load and different speed conditions. The research results verify the reliability and effectiveness of the proposed open-circuit fault diagnostic strategy.