Performance Modeling and Analysis of a Doubly Yokeless Permanent Magnet Linear Motor With Improved Thrust Force Quality

In order to improve the fault-tolerant control (FTC) ability of the current sensor of the primary permanent magnet linear motor (PPMLM) drive system, the direct thrust force control (DTFC) strategy with single DC-link current sensor is proposed. According to the principle of voltage vector equivalence, the present basic voltage vector is equivalent to two adjacent sub-basic voltage vectors to achieve the equivalence of the present candidate voltage vector. The principle of different phases based on the fact that the DC-link current is equal to or opposite to one of the phase currents is introduced. The output sequence of the two sub-basic voltage vectors is determined by the principle of different phase mode to ensure that the measured currents in the two adjacent periods are any two-phase currents in the three phases, and then the third-phase current is calculated. Finally, the effectiveness and correctness of the proposed DTFC (P-DTFC) is verified by simulation and experiment.INDEX TERMS primary permanent magnet linear motor (PPMLM), fault-tolerant control (FTC), equivalent voltage vector, direct thrust force control (DTFC), current sensor.

Section: Introductionmentioning

confidence: 99%

Direct Thrust Force Fault-Tolerant Control of Primary Permanent Magnet Linear Motor With Single DC-Link Current Sensor for Metro Application

Feng

Huang

et al. 2023

“…Permanent magnet linear motors (PMLMs) have increasingly been used in a wide variety of applications due mainly to their excellent dynamic characteristics and accurate positioning capability [1][2][3][4][5] . The most notable feature is the absence of mechanical transmission components, which makes a linear motion system simpler and more reliable, since frictional wear occurs only in linear bearings and the risk to jamming in rotary to linear transmission is greatly eliminated.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Suppression of Phase Unbalance Induced Force Ripples in Permanent Magnet Linear Motors

Wang

Yang²,

Ma³

et al. 2022

Self Cite

Low force ripples from permanent magnet linear motors (PMLMs) are typically essential requirements in a wide range of demanding control applications with high motion quality. Apart from the sources present in rotary PM machines, phase unbalance due to the end effect is another major contributor of the thrust force ripples in the PMLMs. In this paper, the phase unbalance and induced force ripples are investigated in the case of a planar PMLM typically equipped with single-layer concentrated windings and quasi-Halbach magnets. It demonstrates that although the PMLM is quite carefully deigned to minimize the end effect, the phase unbalance still exists, including both the amplitude and phase position unbalances. And the phase unbalances give rise to even order force ripple harmonics, in which the 2 nd -order force ripple is particularly significant. In order to compensate the end effect and the unbalance between the three phases, a novel PMLM topology is presented, in which the width of the two end teeth (instead of the edge teeth) is adjusted to reduce the force ripple. And the impact of the end teeth width on the ripple force magnitude is further revealed. It is shown that by proper design of the end teeth width, the 2 nd -order force ripple of the PMLM can be minimized to quite a low extent. In comparison with the original design, the 2 nd -order force ripple factor of the novel topology has been suppressed from 0.4% to less than 0.03% in the case study. Such a technique has provided a new way of force ripple minimization, and is applicable to other types of linear motors or actuators with appropriate changes.

Direct Thrust Force Control of Half-Open Winding Primary Permanent Magnet Linear Motor

Wang

Feng

et al. 2022

In this paper, a direct thrust force control (DTFC) strategy is proposed for the half-open winding primary permanent magnet linear motor (PPMLM) drive system in order to improve the dynamic response and performance of flux weakening control. The independent voltage active vector (IVAV) is selected as the candidate voltage vector to suppresses the zero sequence current in the proposed DTFC (P-DTFC). Meanwhile, a new switch table is designed to determine the control vector while the complexity of control method is greatly simplified in P-DTFC. The simulation and experimental results verify that P-DTFC maintains better steady-state and dynamic-state performance with lower complexity compared with traditional DTFC (T-DTFC).INDEX TERMS Open winding motor, direct thrust force control (DTFC), common mode voltage, zero sequence current, primary permanent magnet linear motor (PPMLM), independent voltage active vector (IVAV).