Kinjiro Yoshida

Eddy-current loss analysis in PM of surface-mounted-PM SM for electric vehicles

Recently the rare-earth magnet NdFeB has been applied to electric vehicles. The rise of temperature due to eddy current loss in the permanent magnet (PM) leads to serious deterioration of the PM, especially in high speed operation. This paper describes an original analysis of the eddy current loss in the PM of a surface-mounted-PM SM for electric vehicles. The finite element analysis makes clear the effect of eddy current loss in the PM of the PM synchronous motor (SM) in the high speed range of operation including field weakening.

Mass reduction and propulsion control for a permanent-magnet linear synchronous motor vehicle

This paper deals with fundamental research on a new container transport system utilizing a permanent-magnet (PM) linear synchronous motor (LSM), and proposes a concept of mass reduction and propulsion control for container transfer operation. By applying the repulsive lift force in the PM LSM, a large percent of vehicle weight is compensated for, and it needs less thrust force to propel the vehicle. An experiment which involved propelling the test vehicle by reducing its weight by about 85% was conducted successfully.

3-D FEM field analysis in controlled-PM LSM for Maglev vehicle

The magnetic fields in the controlled-PM LSM for Maglev vehicle, of which the width is not only finite with lateral edges, but also an effective electric-airgap is very large, are accurately analyzed by using 3-D FEM. The lateral airgap-flux due to lateral edges of the machine is made clear and its effects on thrust and lift forces are evaluated quantitatively from the comparison with 2-D FEA. The accuracy of 3-D FEA is verified by comparing the calculated results with the measured values.

Sensorless DTC propulsion control of PM LSM vehicle

This paper presents a sensorless direct torque control (DTC) propulsion method of a 1/2-scale controlled-PM linear synchronous motor (LSM) Maglev model vehicle which is not levitated and used as a PM LSM vehicle supported by the wheel. This is the first experiment for DTC to be applied to linear propulsion without position and speed sensors, which is one of the most important problem to be solved in practical applications. DTC can control directly thrust force and the stator flux linkage by the switching commands of the six inverter-arms with a switching table. The DC voltage and three phase current are adapted instead of position and speed sensors. A 3-m-propelling-motion experiment with a constant speed of 0.4 m/s shows that the demanded position and speed can be traced accurately even though there is a strong detent force.

Propulsion and guidance simulation of a high-temperature superconducting bulk ropeless linear elevator

It is possible that a high-temperature superconducting (HTS) bulk linear synchronous motor (LSM) can be propelled contactlessly with no guidance and levitation control. Its design and dynamics simulation are based on very complicated analysis of HTS bulk. This paper proposes HTS bulk LSM applied to ropeless linear elevator analyzed numerically taking into account the electric field-current density (E-J) characteristic in finite-element methods. The LSM can be propelled following command motion pattern with proportional-integral-derivative control and producing stable guidance force without its control.

Mass-reduction and propulsion control of PM LSM test vehicle for container transportation

This paper proposes a new concept of mass-reduction and propulsion control for container transportation, which is based on the theory of combined levitation-and-propulsion control. The permanent magnet linear synchronous motor (PM LSM) test vehicle is propelled simultaneously, together with controlling successfully the equivalent vehicle-weight reduced by about 85%.

Decoupled-control method of normal and thrust forces in linear induction motor for Maglev vehicle Marine-Express ME01

This paper proposes a decoupled-control method of normal and thrust forces in linear induction motors (LIM). By using this method, the normal force can be used to levitate and the thrust force to propel a vehicle without the force-couple of LIM, allowing the realization of a compact combined levitation-and-propulsion system with LIM only.

Control of New PM LSM Maglev Vehicle Based on Analysis of Pitching Torque and Propulsion Force

The one of the authors Dr. K. Yoshida has been proposed a new controlled-repulsive Maglev vehicle, which can levitate, propel and guide simultaneously from a standstill, independently of the vehicle speeds. A combined levitation-propulsion-guidance control experiment using LSM only in the PM LSM controlled-repulsive Maglev model vehicle has been succeeded. But the pitching motion could not be restrained sufficiently in the conventional control method. In this paper, a new control method which is based on the analysis of the pitching torque taking into account the mechanical load-angle is proposed. The validity of the new control method is verified by running control experiments.

Pitching Stability Analysis and Control for Underwater Maglev Linear Motor Vehicle ME02

Marine express (ME) is amphibious superconducting magnetic levitation train that can run both underwater and on-land using the same guideway. The underwater experimental Maglev model vehicle ME02 in our laboratory is driven by the long-stator permanent magnet linear synchronous motor (PM LSM). Having the two motions freedom establishes the possibility for the undesired rotational pitching motion in the plan of these two motions. As a direct result of the different forces affecting the ME02, several torques are developed around the vehicle center of gravity. In the current paper, two air-cored electromagnets (AEM) are implemented to maintain the pitching stability or in other words to damp the pitching motion. The coils current controller gains are optimally tuned using the genetic algorithm (GA). The pitching motion and its control are simulated for the ME02 while performing a trip between four stations with different loading conditions. Through the study, electromagnetic forces produced by the PM LSM and AEM are found from the analytical solution of the multilayer boundary field problem. Hydrodynamic forces are estimated from the finite surface element method. Furthermore, the mass proprieties of the vehicle are estimated from 3D finite volume element method. The results show clearly the effectiveness of controller gains optimization using GA. In addition, the estimation of vehicles mass properties is a valuable guide for the future ME design

Sensorless DTC propulsion of a 1/2-scale controlled-PM LSM vehicle with minimum energy-loss attractive-levitation

This paper presents a sensorless direct torque control (DTC) propulsion control method for a 1/2-scale controlled permanent magnet (PM) linear synchronous motor (LSM) Maglev vehicle with minimum energy-loss attractive-levitation. To solve the practical problem of sensorless propulsion, DTC method is selected to control sensorlessly the thrust force and stator flux linkage of LSM, combining a voltage prediction control to decrease the variation of flux. To verify the controlled-PM Maglev propulsion theory, the vehicle is propelled by sensorless DTC method at standstill-levitation status with minimum energy-loss method. Experimental results show that, even under an extremely unbalance condition that coercive fore of one the four PMs installed on board is reduced strongly by 25%, the 256 kg-heavy-vehicle could be levitated very well with minimum energy-loss method. At levitation status, the vehicle also has been propelled sensorlessly following the demand position and speed above a low speed of 0.2 m/sec, even in acceleration and deceleration as well as constant speed phases, though there is a strong detent fore due to the large semi-closed slots which give a strong influence to the propulsion operating of DTC.