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Thermal barrier coating (TBC) is deposited onto the gas turbine blade surface in order to protect the substrate from high-temperature combustion gas. Cracks and delamination of the ceramic coating which come from high heat flux loading are serious problem in TBC. In this study, the rapid thermal cycling device utilizing laser irradiation was developed. It was then investigated how the damage progresses in the ceramic coating exposed to cyclic rapid thermal loading. As a result, a sintering layer was formed in the surface of the ceramic coating, although such phenomenon was not recognized in TBC sample tested by the conventional thermal cycling test using an electric furnace. It was also revealed from the cross-sectional observation that the vertical crack was initiated at the surface of TBC and propagated into sintering layer. Finally, mechanical factors of those damages from finite element analysis using the TBC model including sintering progress was discussed

This paper designs the width of slit-like flux barriers to improve the space harmonic distribution of the air-gap flux density in a slit stator motor. The slit stator motor has slit-like flux barriers at wound teeth of the stator. The stator design can adjust the space harmonic distribution with the slit width. Space harmonic distributions govern torque and losses in motors. For this reason,the dependence of the space harmonic distribution on the slit width should be clarified to design slit stator motors. The dependence is investigated through a theoretical calculation based on a magnetic circuit model and a finite element method analysis. These methods show that a space harmonic producing the drive torque is maximised at a slit width and other dominant detrimental space harmonics are decreased with the increase of the slit width. The improved space harmonic distribution is verified by performing an experiment with a measuring rotor., IET Electric Power Applications, 13(8), pp.1125-1130; 2019

Permanent magnet (PM) machines generally employ rare-earth PMs. The rare-earth PMs increase the manufacturing cost of PM machines due to their high material cost. To reduce the manufacturing cost of PM machines, this paper studies a consequent-pole configuration. Consequent-pole PM machines have poles with magnets and poles composed of iron-cores. The rotor design can adjust the air-gap flux density distribution. This improves the average torque and reduces the volume of PMs simultaneously. In this paper, the rotor of a consequent-pole surface-mounted PM machine is designed to reduce the volume of PMs. The characteristics are investigated for the rotor structure through a theoretical calculation and a finite-element method analysis. These results show that the consequent-pole configuration can reduce the volume of PMs in comparison with a conventional one.

This paper proposes bridged slit-stator motors to eliminate the complexity in the manufacturing process. Slit stator motors increase average torque and operational efficiency in comparison with conventional motors. However, such motors complicate the manufacturing process due to the insertion of slits. In the proposed motors, the slits are bridged to connect core parts of the stator. A magnetic circuit model is created from the current flowing through the stator. The air-gap flux density distribution is theoretically obtained. The effect of the bridges is clarified by theoretically and numerically obtaining the air-gap flux density distribution of the bridged slit-stator motors.

Objective. Kampo medicine, a traditional Japanese medicine, is widely used in Japan, especially in the field of menopause medicine. However, few studies have shown evidence-based effects. This study aimed to confirm the effects of kamishoyosan on menopausal symptoms with a randomized, placebo-controlled, double-blind clinical trial. Methods. Subjects were randomly allocated to groups that received either kamishoyosan (n = 101) or a placebo resembling kamishoyosan (n = 104). The primary outcomes were the change in the number of hot flashes, depression scores, improvements of anxiety, quality of life (QOL), and menopausal symptoms before and 4 and 8 weeks after initiation of treatment with the study drug. The secondary outcome was drug safety. Results. After 8 weeks, the number of hot flashes decreased after treatment in both groups, but there was no significant difference between the two groups. The changes in SDS scores showed the same results. Moreover, no significant differences were observed between the two groups in assessments with the STAI, SF-36, and JSOG menopausal index. No serious adverse effect was reported. Conclusions. This first placebo-controlled double-blind randomized trial with kamishoyosan demonstrated that it was safe and had some effects on climacteric symptoms, but not significant compared with placebo. Some problems, such as placebo effects, in the study of Kampo therapy for menopausal symptoms, were revealed. This trial is registered with the trial registration number. UMIN 000006042.

This paper proposes a design method of stator cores to modify the component ratio of space harmonics in the magnetic field due to stator windings for 12-slot 10-pole concentrated winding motors. The method inserts slit-like magnetic flux barriers in stator wound teeth. In fractional-slot concentrated winding motors, the magnetic field due to stator windings includes dominant space harmonics with a specific space harmonic that produces drive torque. These space harmonics give rise to undesirable effects that increase iron loss in cores and eddy-current loss in magnets. For 12-slot 10-pole motors with single-layer windings, the proposed method increases the driving space harmonic and decreases dominant detrimental space harmonics. This modification of the space harmonics leads to torque enhancement and efficiency improvement. The efficacy of the proposed method is determined by deriving the winding factor, estimating magnetic flux distribution and motor performance through a finite element method analysis, and demonstrating the actual motor performance of a prototype., IEEE Transactions on Industry Applications, 54(5), pp.4377-4385; 2018

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 saturation 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., IEEE Transactions on Industry Applications, 53(5), pp.4559-4568; 2017

The first piston ring application of a hydrogen-free diamond-like carbon (H-free DLC) coating to a mass-production gasoline engine reduces friction. It is found that the friction reduction effect between the cylinder bore and piston is 18%. When H-free DLC is applied to top ring, friction is over 10% reduced. The effect is larger than H-free DLC applied to oil rings. Because DLC as low friction coating is effective in a thin oil film and there are few oil at a large area near piston Top Dead Center (TDC). The friction reduction effect is enhanced when lower viscosity engine oil is used. In this study, the adhesion strength of H-free DLC coating on piston rings is also improved. It is shown that the relation between the adhesion strength and 2 coating parameters; i.e. providing substrate roughness and coating thickness. Adhesion strength is verified by test results using actual parts considered to piston ring environment by gasoline engine. Piston rings with low friction and high reliability are developed.

Due to the demands of expanding the high efficiency area and controllable torque / speed area, the new concept variable field flux motors have been researched. We also proposed a variable field flux motor with a half-wave rectified brushless self-excitation method. This motor is possible to construct a brushless self-excited by connecting a diode in series with the field winding on the rotor. And it is possible to excite and control the rotor field flux by the stator winding current. This paper describes the influence of the rotor and stator core design on the torque and efficiency characteristic for proposed motor. And the final designed model is shown with motor parameters. Further, the variable field flux characteristics of the designed motor are confirmed by electromagnetic field analysis.

Fractional-slot winding configurations have attracted much attention due to the availability of concentrated windings and low cogging torque in permanent magnet brushless motors. For the design of the winding configurations, many design parameters must be determined. The winding factor provides a useful index for the optimal design. However, no general expressions of the winding factor have been derived for all the winding configurations. This study performs the general formulation of the winding factor for the fractional-slot concentrated windings. The winding factor is redefined for stator windings without any information of the numbers of poles. For given stator windings, the optimal numbers of poles are determined from the obtained winding factors. The design strategy for the winding configurations is validated through a finite element method analysis., IET Electric Power Applications, 10(4), pp.231-239; 2016

We proposed a half-wave rectified brushless self-excitation method that generates the field flux on the rotor field winding short-circuited by a diode. And the amplitude of the rotor field flux is controlled from a zero to its maximum by the stator excitation current. This paper discusses the influence of turns ratio of stator and rotor windings on the self-excitation method by analysis results.

Fractional-slot concentrated winding motors generate several dominant space harmonics. The space harmonic distribution is closely associated with the motor performance. A slit stator motor (SSM) has been proposed to improve the space harmonic distribution. The motor decreases iron loss. However, the dependence of loss generation on each space harmonic has not attracted much attention. To clarify the dependence, iron loss of the rotor is decomposed with respect to space harmonics. The composition of the iron loss caused by each space harmonic is compared with iron loss caused by stator winding current. This result clarifies that the iron loss can be evaluated for each space harmonic in the SSM.

A segment type linear switched reluctance motor is proposed for a linear actuator or a liner generator. A flat gap motor and a cylindrical gap motor are designed and their characteristics are compared. The movers have concentrated armature windings. The stators consist of segment cores and aluminum block bodies. The characteristics are calculated using a finite element method analysis. The efficiency of the cylindrical gap motor is larger than the flat gap motor because the armature windings without end windings reduces copper loss.

We have proposed a claw pole type half-wave rectified variable field flux motor (CP-HVFM) with special self-excitation method. The claw pole rotor needs the 3D magnetic path core. This paper reports an analysis method with experimental BH and loss data of the iron powder core for FEM. And it shows a designed analysis model and characteristics such as torque, efficiency and loss calculation results.

A novel synchronous generator is proposed for wind power generation. The field flux is generated by the half-wave rectified excitation method. The generator does not require slip rings and brushes for field power supply, as well as permanent magnets. In this paper, the excitation method is explained, and then, the basic characteristics are calculated using the finite element method analysis. Furthermore, the generator is designed for increasing the output power and efficiency.

Hydrogen-free diamond-like carbon (DLC) coatings display markedly lower friction coefficients under a lubricated condition owing to the adsorption of oiliness agents and their decomposed components. This study examined the effect on friction properties of the sp2/sp3 bonding ratio of DLC coatings and the addition of nitrogen for improving surface wettability. Evaluations of friction properties under a lubricated condition showed that DLC coatings with a lower ratio of sp3 bonds and nitrogenated DLC coatings displayed higher friction coefficients. Results obtained by electron spin resonance revealed that adding nitrogen decreased the number of dangling bonds of DLC coatings in proportion to the sp3 bond ratio. Assuming that such dangling bonds are oiliness agent adsorption sites, it is concluded that adding nitrogen is not conducive to reducing friction coefficients.

Sensorless control technique is desired in applications of a long stroke linear synchronous motor (LSM) without using a linear scale. This paper discusses the development of a stator-magnetless LSM (no magnet mounted on the stator of LSM) for sensorless control technique that includes a high speed position estimation algorithm based on magnetic hysteresis phenomenon. This paper presents the new structure of a flux-switching LSM to achieve a high saliency ratio by designing a cutout which causes magnetic saturation in the armature core. The effect of sub-teeth to reduce cogging thrust is also presented. Furthermore, this paper also reports the analytical and experimental characteristics of inductance, thrust, cogging thrust, and sensorless control drive using a prototype.

The vehicle system is a multi-domain system that requires many branches of science and engineering. Therefore the development of the vehicle system requires the use of design methodologies that utilize simulations, which have grown increasingly sophisticated in recent years. This paper describes how VHDL-AMS was used to model the powertrain, alternator and battery system that are the basic elements of the vehicle power network system, and examines the simulation results with the aim of realizing a system simulation whose scope covers the entire vehicle., 2010 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM 2010) : Pisa, Italy, 2010.06.14-2010.06.16, SPEEDAM 2010, pp.1046-1051

We have developed a low-speed and low-capacity wind power generator. In this paper, we introduce the outline of the 5kW multi-polar synchronous generator that generates the electric power efficiently from 50rpm to 180rpm. The generator is produced by a magnetic powder core for cost reduction. We also express the outline and field test results of the low-capacity power plant constructed in Ohmura City, Nagasaki.

In the previous paper, we proposed a long-armature type novel linear synchronous motor with half-wave rectified self excitation. The field winding was short circuited with a diode and the armature winding was usual 3-phase windings. This paper presents a short-armature type novel linear synchronous motor applicable for a transport system. Compensated short pitch windings are proposed for the armature windings in order to decrease end effect., International Conference on Electrical Machines and Systems, ICEMS 2007; Seoul; 8 October 2007 through 11 October 2007, ICEMS 2007, pp.1513-1516

This paper presents the principle and basic characteristics of a novel linear synchronous motor based on “half-wave rectified self excitation principle.” The field winding is short circuited through a diode and the armature winding consists of conventional three-phase windings. If the amplitude of the balance three-phase currents is modulated by an alternating wave with bias frequency, the produced magnetomotive force pulsates at the bias frequency and moves at the synchronous velocity. This pulsating magnetomotive force induces the electromotive force with a bias frequency in the field winding. The field excitation is obtained by rectifying the electromotive force with the diode in the field winding. In this paper, the authors design and build an experimental machine and confirm its basic characteristics. They also deduce the performance equations and investigate the thrust ripple reduction. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(1): 82–90, 2008; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/eej.20684

This research aims to examine the possibility of Switched Reluctance Motor (SRM) for the application to servo system. This paper proposes a position control at the arbitrary rotor position using measured torque curves. This proposed method is able to compensate the magnetic nonlinearity and manufacturing flaw, and realizes precision torque and position control. This paper verifies our proposed method through experimental results under various loads.

This paper studies the dynamics of the proposed vibration energy harvester to develop the method of designs and controls for the system. The harvester converts vibrational energy into electrical energy through rotational motion of a mechanical pendulum or a so-called parametric pendulum. The rotation is maintained for periodic vibration with appropriate amplitude and frequency. However, such appropriate vibration is not always supplied from nature. For this reason, reasonable energy conversion requires system designs including the electrical circuit for output power and control methods to establish and maintain the rotation against vibrations of nature. The study on the load characteristics of the system indicates the possibility to control the behavior of the mechanical pendulum by regulating the electrical load and to improve the mechanical characteristics by designing the load.

Recently development of the new concept motor for EV or HEV becomes very active. The wider torque and speed controllable operating range and high efficiency under driving area are needed for traction motor. As a novel motor candidates, we proposed a novel Claw Pole Type Half-Wave Rectified Variable Field Flux Motor (CP-HVFM). This motor is simple and robust brushless structure and has variable field flux performance. This paper describes the influence of the rotor structure on the torque characteristic of CP-HVFM.

A novel segment type switched reluctance motor (SRM) is proposed, in which the segment core is embedded in aluminum (conductive metal) rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. The effect of design parameters on the average torque is investigated using the finite element method. Comparison with conventional VR type SRMs and segment type SRMs without conductive metal construction rotor show the proposed segment type SRM has advantages in the torque performances and the vibration and noise characteristics. The performance is also investigated by experiment.

In previous papers, we proposed the Cylindrical Rotor Type Switched Reluctance Motor (SRM), in which q-axis short-circuited windings were wound around the q-axis iron poles of the rotor and the stator windings were excited by the usual pulse current. It is confirmed experimentally that the short-circuited windings reduced the q-axis leakage flux and caused additional torque generation. In this paper we describe characteristic analysis of the new type SRM using the circuit simulation considering all the inductances coupled with the FEM analysis.

In this paper, we propose a new hybrid-type switched reluctance motor (SRM) with salient pole stator, which has a pair of permanent magnets attached symmetrically between the iron poles of the rotor. We describe experimental results not only on the basic characteristics of the hybrid SRM, but also characteristics with a current control loop under optimized advanced firing angle and cutoff angle control. Considerable improvement of machine performance, especially in the efficiency and power factor, for the hybrid SRM over the conventional VR-type SRM is confirmed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(3): 72–79, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10285

In this paper, we propose a new Hybrid type SRM with salient pole stator, which has a pair of permanent magnets attached symmetrically between the iron poles of the rotor. The paper describes experimental results of not only basic characteristics of the Hybrid SRM but also characteristics with current control loop under optimized advanced firing angle and cut-off angle. Considerable improvement of machine performance, especially efficiency and power factor, in the Hybrid SRM over conventional VR type SRM is confirmed.

The Carrier Frequency Component Voltage (CFCV) of a PWM inverter supplying an Interior Permanent Magnet (IPM) motor is used as the rotor position information source. Mathematical expressions relating the rotor position to the CFCV and the corresponding Carrier Frequency Component Current (CFCC) in the motor stator phases are developed. In the lower speed range (up to about 50% of the rated speed) the rotor position has been obtained from the measurement of the CFCC only and has been used to control an IPM motor. The motor speed has been controlled successfully starting from zero speed with excellent performance. Experimental results are presented and discussed. The method is very simple and requires only a few additional electrical components.

Permanent magnet (PM) motors, which have a simple and maintenance-free structure and high performance, have been used widely in the fields of industry applications. The PM motor, however, has some problems on the cost and weight in high power usage.In this paper, we propose a method for optimizing surface PM synchronous motors (SPMSM) using non linear optimization technique. In the formulation, the performance characteristics are estimated using space harmonic analysis. The accuracy of the formulas is investigated by experiment. The exterior point transformation method and the simplex method are applied to solve the constrained nonlinear programming problem. Eight parameters are chosen as the independent variables, such as number of poles, the stack height, the number of slots per pole per phase, the coil pitch, the ratio of slot width to slot pitch, the width of magnet, the height of magnet and the height of rotor yoke. The SPMSM design is analyzed under four objective functions; the primary weight, the cost of materials, the input KVA and the power rate.

In recent years, Permanent-Magnet-Type Synchronous Machine is used in many applications for industrial drive for the improved performance. Especially, for the armature winding, the fractional slot winding is known about the improved efficiency performance and torque ripple performance. In this paper, we proposed the irregular pitch winding on the fractional slot winding to improve torque ripple characteristics, used the rectangle shape magnet. At the case of the conventional regular pitch winding, we can calculate the winding factor Kw by the typical formula. But at this irregular pitch, it is too difficult to seek Kw from the formula. So, we propose the solution to seek Kw used “Slot Star Diagram” on the irregular pitch, and we seek the optimum the irregular pitch angle to decrease the harmonic component in EMF considered with the field magnet shape. For it, we explain how to derive by using “Slot Star Diagram” for the winding arrangement to be simply. And in the case of the odd and even slot, it has given the examples for each, which describes the procedure of derivation of the winding factor Kw., 2013 International Conference on Electrical Machines and Systems, ICEMS 2013; Busan; South Korea; 26 October 2013 through 29 October 2013, Electrical Machines and Systems (ICEMS), 2013 International Conference on, pp.1032-1035; 2013

A dual rotor segment type switched reluctance motor (SRM) is proposed for flat configuration. It has toroidal stator coil and has inner rotor as well as outer rotor. The performance characteristics are calculated using finite element method. On a flat type SRM, leakage flux is greatly generated at both side coil. To reduce the leakage flux we propose shield structure. Effectiveness of the shield structure is verified analytically., 2013 IEEE 10th International Conference on Power Electronics and Drive Systems, PEDS 2013; Kitakyushu; Japan; 22 April 2013 through 25 April 2013, Power Electronics and Drive Systems (PEDS), 2013 IEEE 10th International Conference on, Article number 6527174; 2013

This paper describes an approach to realize precision and quick position control for Switched Reluctance Motor (SRM). But the magnetic nonlinearity of SRM makes the torque and current control complex and unstable. However, with regard to the high torque and rapid response, SRM has the potential to achieve higher performance. The proposed position control system has the torque controller which considers the magnetic nonlinearity and manufacturing flaw. In the torque controller, the reference current is calculated using the look-up tables tabulated by measured torque characteristics. The experimental results show that the proposed method has the position control capability at arbitrary rotor position.

The authors developed a novel segment type switched reluctance motor (SRM) as a rare earth less motor. The torque was increased by 40% and radial force was decreased by 76% compared with the same size VR type SRM. In this paper we propose a new type rotor using grain-oriented electric steel for the segment core. We compare the torque and efficiency characteristics with a non-oriented electric steel type by a finite element method and show effectiveness of the new type rotor., 2011 International Conference on Electrical Machines and Systems, ICEMS 2011; Beijing; 20 August 2011 through 23 August 2011, ICEMS 2011, pp.1-4

Previously, the authors proposed a “half-wave rectified brushless synchronous motor” as a novel servomotor. The rotor winding emf of the motor is induced by the stator current mmf which rotates at synchronous speed and pulsates at bias frequency. The field excitation is produced by the field current obtained from rectifying the emf with a diode inserted into the field winding. To improve the power factor and the efficiency, they also proposed a new-type half-wave rectified brushless synchronous motor with permanent magnets. This paper analyzes the flux distribution and the torque characteristics of the new half-wave rectified brushless synchronous motor using the finite element method. The computed torque characteristics are confirmed with the experimental results. Furthermore, the steady-state characteristic equations are derived and the effect of the modulation function waveforms on the motor performance is investigated. The theory also is confirmed by the experiments.

We proposed, in the previous papers, a “half-wave rectified brushless synchronous motor” as a novel servo motor. The rotor winding emf of the motor is induced by the stator current mmf which rotates at synchronous speed and pulsates at bias frequency. The field excitation is produced by the field current obtained from rectifying the emf with a diode inserted into the field winding. In order to improve the power factor and the efficiency, we also proposed a new type half-wave rectified brushless synchronous motor with permanent magnets.In this paper, we analyze the flux distribution and the torque characteristics of the new type half-wave rectified brushless synchronous motor using the finite element method. We confirm the computed torque characteristics with the experimental results. Furthermore, We derive the steady state characteristic equations and investigate the effect of the modulation function wave forms on the motor performance. The theory is also confirmed by the experiments.

The authors proposed a high power and low vibration novel segment type switched reluctance motor (SRM), but it had a problem of large torque ripple. We also proposed the novel segment type SRM with a 2-steps slide or skew rotor to reduce the torque ripple. We produced the experimental machine and measured the characteristics. The average torque was decreased slightly in comparison with the non slide one, but the torque ripple was decreased well and the vibration was decreased too. In this paper, we apply a current control method aiming at the additional torque ripple reduction.

Recently, the use of multi domain simulation is becoming indispensable for discussing system performance of a vehicle. In this paper, the simulation technology applied to CO 2 reduction using regeneration for a conventional 12V battery system vehicle is discussed. The energy analysis results for Drive Shaft, Brake and Alternator regeneration shows the optimized Alternator performance for the fuel economy.

The authors proposed a high power and low vibration novel segment type switched reluctance motor (SRM), but it had a problem of large torque ripple. We propose in this paper a novel segment type SRM with 2-step slide or skew rotor to reduce the torque ripple. We produce the experimental machine and confirm the characteristics. The average torque decreases slightly in comparison with the non slide one, but the torque ripple is decreased well. We confirm also that the vibration is decreased too.

This paper presents a newly developed magnetic powder core for a multi-polar synchronous generator. The magnetic characteristics of the magnetic powder core are greatly improved in comparison with the previously produced one. In addition, the multi-polar synchronous generator with molded-in magnetic powder stator is modeled in order to analyze the performance characteristics with the FEM analysis. The calculated results are also compared with the experimental results. Based on this result, we manufactured the 5 kW type multipolar synchronous generator with molded-in powder type stator.

This paper proposes a stator design that consists of a combination of an alternate slot winding and dummy slots to minimize pulsating torque in surface-mounted permanent magnet synchronous motors. The alternate arrangement of winding coils is designed to eliminate a harmonic component of back electromotive force that gives rise to a harmonic component of pulsating torque. However, the non-uniform arrangement of slots decreases the frequency of the cogging torque by half and may aggravate torque pulsation. To compensate for the drawback or the decrease in the frequency of the cogging torque, dummy slots are introduced in the alternately slotted stator. A theoretical method is developed for the proposed stator combination. The proposed stator design is applied to a prototype in combination with other rotor magnet design techniques, such as magnet shifting and the adjustment of magnet width, to minimize pulsating torque. The results show that the designed motor reduces the ripple factor of the torque by approximately 30% relative to the original value. In addition, the proposed alternate slot winding is validated by comparing the design with equal slot-winding designs optimized through finite-element method analysis., IEEE Transactions on Magnetics, 51(6), 8202911; 2015

The goal of this research is to realize a complete position and speed sensorless system using a "half-wave rectified brushless synchronous motor" we proposed as a novel AC servo motor. This paper proposes an initial rotor position estimation method using the bias frequency component of a half-wave rectified brushless excitation. This technique is verified by simulations and experiments

We proposed a novel segment type switched reluctance motor (SRM) in which the segment core was embedded in aluminum (conductive metal) rotor block in order to increase the mechanical strength and easy manufacturing as well as to improve the performance characteristics and reduce the vibration and acoustic noise. This paper explains the operation principle and the drive system and shows the experimental results in comparison with the VR type SRM.

A study has been made of vector control of an AC-excited brushless synchronous motor. This novel motor has no separate exciter, and the rotor winding is only single-phase short-circuited. The stator winding is excited by a three-phase current, the amplitude of which is modulated by a trapezoidal wave. The excitation current command and the torque current command are estimated only by detecting the position of the rotor. The control method is investigated theoretically, and the experimental results for steady-state characteristics are presented. >

A carrier frequency component method (CFCM) of an interior permanent magnet (IPM) motor sensorless vector-control scheme over full-speed-range is presented. PWM-inverter switching-frequency component current, or carrier frequency component current (CFCC), has been used as the rotor position information source. Control over the whole speed range has been achieved. Experimental results have been presented and discussed.