Mimpei Morishita

A new MAGLEV system for magnetically levitated carrier system

A power-saving electromagnetic suspension system has been developed in which electromagnets with permanent magnets are used to suspend the vehicle. The electromagnets are controlled to maintain air gap length so that the attractive force by the permanent magnet always balances the total weight of the vehicle and its loads, based on modern control theory. This technology realizes a significantly power-saving system in which the electromagnetic coil current required to keep a vehicle levitating was extremely small, ideally zero. The 8-kg weight test vehicle with 4-kg load could be levitated continuously over 8 h, without recharging the on-board 1300-mAh batteries. This technology realized a completely contact-free material transportation system when combined with a contact-free driving system using linear motors. The attractive force characteristics of a permanent magnet with control electromagnets and the newly developed electromagnet control system that can eliminate power collecting devices from the electromagnetic suspension system are described. >

A linear induction motor control system for magnetically levitated carrier system

An electromagnetic suspension system has been developed that cuts off electric power-collecting devices from a magnetically levitated vehicle. This system makes it possible to transport materials with no mechanical contact at all between the vehicle and ground facilities. A control system for linear induction motors used in the magnetically levitated carrier system is described. The system was developed to transport materials in an environment which must be kept free from even microscopic dust motes and trivial noise. The linear induction motor control method used for positioning a vehicle at the station is described along with several kinds of switches without any mechanical motion in the ground facilities. A supervisory control system for the magnetically levitated carrier system is also discussed. >

A novel use of superconducting oxides in a non-contact carrier for VLSI plants

Abstract A high-Tc superconductor has outstanding intergrain superconductivity and troublesome intergrain electrical conductivity at the same time. But once we consider to utilize the intergrain characteristic only, neglecting the intergrain conductivity, a new world of applied superconductivity is open before us. An yttrium-family class superconductor by the processing technique by which proper sizes and delicate distribution of precipitates are introduced in the material1). The fishing effect showing the stable floating of superconducting oxide materials has its origin in this strong pinning force. Now in a advanced Japanese VLSI plant a magnetically supported non-contact wafer-carrier is used in order to avoid the production of even traces of fine dust made by the friction of the wheels2–3). In this system the controlled attractive force between conventional electro-magnets and an iron guideway is used. The outstanding fishing effect of a strong pinned yttrium-family superconducting oxide processed by the QMG method can be expected to replace electro-magnets. We testfabricated a magnetically suspended non-contact carrier in the same dimension as a VLSI wafer-carrier currently used, with four QMG processed yttrium-family bulk pellets4). The carrier runs at any controlled speed with a load of under 3 kg, with very high stability in the vertical and lateral positions. It was driven by a linear induction motor. The outline of this system and its carrier will be reported as well as the superconducting levitation performance of the carrier.

An Adaptive-controlled Self-gap-detecting Electromagnetic Suspension System

There are few self-gap-detecting electromagnetic suspension (EMS) systems robust enough against variation of coil resistance. The authors succeeded in providing much robustness against the variation of coil resistance with a self-gap-detecting EMS system. An adaptive control for coil resistance and an exciting voltage compensator for differences between the coil resistances were applied to the self-gap-detecting EMS system. This paper proposes this new self-gap-detecting technique. The adaptive controller and the exciting voltage compensator is explained. The experimental result shows that the proposed controller can keep stability of the EMS system from variations of not only coil resistance but also levitation mass

Robust controller design for Maglev transport vehicles with a guide-effective electromagnetic suspension system

The author proposes a robust controller design using a pole location method. This design succeeds in giving some robustness to the guide-effective electromagnetic suspension (EMS) systems whose dynamics change widely according to the load weight. The guide-effective EMS system is made by combining a levitating mode with a guiding mode. The controller stabilizes not only the levitating mode but also the guiding mode using only levitation magnets and detectors. This controller design algorithm is suitable to apply PID or I-PD control to plants with some unstable poles, even if there is an order reduction as occurs in the EMS system.