This paper presents the servomotor structure suitable for sensorless drives based on high-frequency injection method. The position estimation accuracy is related to the saliency ratio of the motor. Although the motor with increasing saliency ratio with the load has been reported, the mechanism of the phenomenon has not been explained.In this paper, the improvement in the saliency ratio in a conventional servomotor structure is explained with respect to the magnetic flux distribution. Moreover, the increase in the saliency ratio through further structural improvement is examined, and the effect is confirmed by experiments.

This paper presents a method for improving the position estimation accuracy for magnetic saliency based sensorless control. Conventional magnetic saliency based sensorless position estimation methods are based on the voltage equation of Interior Permanent Magnet Synchronous Motor without incorporation of the mutual inductances between the d-axis and q-axis of rotating reference frame synchronized with rotor. The mutual inductances are caused by magnetic saturation due to load current and highfrequency injection signal for position detection. Furthermore, the mutual inductances contain the harmonic components due to the motor structure. Consequently, the position estimation error is caused by the neglected mutual inductances. It is difficult to determine the actual value of mutual inductance, particularly the harmonic components that vary depending on the rotor position. Therefore, in this paper, a method for improvement of the position estimation accuracy by considering the cross-coupling factor without determining the mutual inductances is proposed. The experimental results demonstrate the validity of the proposed method.

Abstract-Sensorless control techniques that do not use a linear scale are desired for applications that require a long-stroke linear synchronous motor (LSM). This paper discusses the development of a stator-magnetless LSM (i.e., no magnet is mounted on the stator of the LSM) for sensorless control that includes a high-speed position estimation algorithm based on the magnetic hysteresis phenomenon. This paper presents a new structure of a flux-switching LSM that achieves a high saliency ratio using a cutout that results in magnetic saturation in the armature core. The effect of the sub-tooth on reducing the cogging thrust is also discussed. Furthermore, the analytical and experimental characteristics of inductance, thrust, cogging thrust, and sensorless drive control are discussed based on a prototype.

Abstract-Sensorless control techniques that do not use a linear scale are desired for applications that require a long-stroke linear synchronous motor (LSM). This paper discusses the development of a stator-magnetless LSM (i.e., no magnet is mounted on the stator of the LSM) for sensorless control that includes a high-speed position estimation algorithm based on the magnetic hysteresis phenomenon. This paper presents a new structure of a flux-switching LSM that achieves a high saliency ratio using a cutout that results in magnetic saturation in the armature core. The effect of the sub-tooth on reducing the cogging thrust is also discussed. Furthermore, the analytical and experimental characteristics of inductance, thrust, cogging thrust, and sensorless drive control are discussed based on a prototype.

Vigorous research and development o n v e h i c l e n a v i g a t i o n has b e e n underway f o r s o m e years . Essential for a navigation system is the a b i l i t y t o r e c o g n i z e t h e l o c a t i o n o f a c a r accurately . Without that ability , i t would be useless t o provide detailed road map inforniation , r o a d and traffic i n f o r m a t i o n ( traffic j a m s , c l o s e d -r o a d , traffic accidents , etc. ) , and p a r k i n g s p a c e a v a i l a b i l i t y --in d e v e l o p m e n t u n d e r a J a p a n e s e p r o j e c t of ' R o a d / A u t o m o b i l e Communication System ' _ T h e m e t h o d s t o f i n d c a r ' s l o c a t i o n c a n b e classified into two groups ' dead-reckoning and r a d i o n a v i g a t i o n . T h e d e a d -r e c k o n i n g system c a l c u l a t e s c a r ' s l o c a t i o n a c c o r d i n g to i t s direction and distance travelled .This method is advantageous in that there is no areal limitation for its o p e r a t i o n . But i t cannot be free from errors which increase a s the car accumulates the distance , making i t necessary to set the initial position . On the other hand, the radio navigation system pinpoints the location of a car in terms of absolute position through radio waves and has an a d v a n t a g e o f a l w a y s l o c a t i n g a car w i t h i n the system's accuracy range . But this system requires a v a s t n e t w o r k o f r a d i o t r a n s m i t t e r s t o b e effective , and i t can only operate in the areas covered by the system network . Dead-reckoning is basis for car locating but w i l l no purpose without some provision for automatic c o r r e c t i o n o f its e r r o r s . Radio navigation is expected to give accurate location . although i t w o u l d h a v e d i f f i c u l t y in p r o v i d i n g a c c u r a t e l o c a t i o n c o n t i n u o u s l y . I t s e e m s by c o m b i n i n g t h e s e t w o m e t h o d s t h a t a s y s t e m c a p a b l e o f accurate and continuous car location will become a reality . T h i s paper d e s c r i b e s the signpost navigation , map-matching , and satellite navigation a s methods for c o r r e c t i n g the accumulated errors of deadr e c k o n i n g , and m e t h o d s t o obtain accurate and continuous car location by combining those methods and dead-reckoning . Also discussed are the merits /demerits and feasibility of each method , 1. IMPORTANCE OF CAR LOCATING IN VEHICLE NAVIGATION SYSTEMS 1.1 Development Trend of Vehicle Navigation Systems V e h i c l e n a v i g a t i o n s y s t e m s h a v e b e e n u n d e r development for many years . I t was in 1981 that a system offering simple driving information , such a s s t r a i g h t d i s t a n c e t o t h e d e s t i n a t i o n , percentage of distance covered , and direction of t h e d e s t i n a t i o n , was f i r s t c o m m e r c i a l i z e d in Japan . In 1984 , another system was put on sale which offered a compact disc ( CD-ROM ) storing digital map data allowing the driver t o call up a map ...