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Generally, brushless dc (BLDC) motor control uses a 120° conduction method that utilizes a low-cost Hall sensor as a position sensor. However, because of the mounting position error of the Hall sensor and the uneven magnetic flux density of the rotor, an erroneous position signal may be output, which will adversely affect the BLDC motor control. Therefore, this paper analyzes the abnormal electric current section that occurs due to the position error of the Hall sensor and the uneven magnetic flux density. Subsequently, the error is derived from the analyzed phenomenon as a formula. The compensation control algorithm to overcome the control problem due to this error is studied, and a method to maintain an accurate energization interval is suggested. Further, it is shown through experiments that the quantitative analysis of the error using the proposed compensation control algorithm is valid.

The spoke-type permanent magnet synchronous motor (PMSM) is a motor built using nonrare earth elements, which feature low flux density. It has a flux concentrated structure of permanent magnet arrangement to improve power density. Further, the torque in the spoke-type PMSM is composed of a magnetic torque component from the permanent magnets and a reluctance torque arising from the inductance difference between the d - and q -axis. This paper analyzed the d - and q -axes inductances that affect the reluctance torque depending on the magnitude of the applied current and the current phase angle of the spoke-type PMSM at base speed. We also derived the variation of the d - and q - axis inductances, which is shown at the operation speed region. Accordingly, the variation of the current phase angle for generating the maximum output power is analyzed. Based on the above results, we predicted the variation in the driving mode of the spoke-type PMSM, and subsequently verified the prediction experimentally.

This paper proposes the optimization of the shape and size of a ferrite magnet and the arrangements necessary to reduce torque ripple and maximize back electromotive force (B-EMF) in a permanent-magnet-assisted synchronous reluctance motor. First, four different models of general magnet arrangements were selected, and analysis using the finite-element method was performed under open circuit and load operations for each of the four models. Next, the relationship between the cogging torque and the torque ripple was analyzed, considering the segment saturation phenomenon. Then, based on the initial model, the design was optimized for maximum B-EMF and minimum torque ripple, and the total harmonic distortion was measured. Finally, the validity and superiority of the optimized design were confirmed by manufacturing a prototype motor and performing the experiment.

This paper is a study of the eddy current brake designed to replace the air brake of railway application. The eddy current brake has the advantage of being able to take a high current density compared to the other application because this brake is used for applying brakes to the rolling stock for a shorter amount of time. Also, this braking system has the merit of being able to take a high current density at low speed rather than at high speed, because the heat generated by the low speed operation is less than that of the high speed operation. This paper also presents a method of improving the output torque of the eddy current brake at low speed operation through a change of the winding as well as the basic design.

Pantograph must be correctly attached to catenary to continuously supply stable power to railway vehicle, and the device used here is Auxiliary Air Compressor (ACM). The existing ACM used the DC motor that included commutator and brush. Since maintenance and repair by mechanical friction are essential for the DC motor, BLDC motor studies have been conducted to improve this. A three-phase BLDC motor does 120° two-phase commutation through hall sensors in general. However, since hall sensor is vulnerable to heat and can run only when all three sensors work normally, sensorless control method has been studied to solve this. Using back EMF Zero Crossing Point (ZCP) detection method, this paper will introduce a stable switching sensing method that has a noncommutation area in a low speed zone.

This paper proposed a new real-time parameter tracking algorithm. Unlike the convenience algorithms, the proposed real-time parameter tracking algorithm can estimate parameters through three-phase voltage and electric current without coordination transformation, and does not need information on magnetic flux. Therefore, it can estimate parameters regardless of the change according to operation point and cross-saturation effect. In addition, as the quasi-real-time parameter tracking technique can estimate parameters through the four fundamental arithmetic operations instead of complicated algorithms such as numerical value analysis technique and observer design, it can be applied to low-performance DSP. In this paper, a new real-time parameter tracking algorithm is derived from three phase equation. The validity and usefulness of the proposed inductance estimation technique is verified by simulation and experimental results.

This paper deals with the effects of welding, which is done to fix the stator stack, on a motor in case of fabricating a prototype motor that is manufactured in a small quantity. In the case of a small motor, the stator is designed and fabricated with the segmented core as a way to raise the fill factor of winding wire to the utmost within a limited size. In case of fabrication by welding both inside and outside of the stator in order to fix the segmented-core stator, the effects of stack are ignored, and the eddy current loss occurs. This paper performed the no-load test on an IPM-type BLDC motor for driving the suction fan of a vacuum cleaner, which was manufactured by using a segmented-core stator. As a result of the test, it was found that input power more than expected was supplied. To analyze the effects of welding by using the finite element analysis method and verify them experimentally, a stator was re-manufactured by bonding, and input power supplied during the no-load test was compared.

This paper suggests the new PMSM design that can reduce leakage magnetic flux. Through adapting non-magnetic frame structure, it decreases leakage magnetic flux on the rotor’s rib and web structure. And with this, it increases power density of the motor. To verify the effectiveness of the new design of rotor compared to the common type, through small sized real model’s test was conducted. To obtain final model, structural FEM analysis was also used for structural stability. Additional loss generation problem that can occur in the new frame structure was checked with the 3D FEM analysis.

The control performance of hybrid PWM inverter using a phase current measurement is presented in this paper. The hybrid PWM technique consists of space vector pulse width modulation (SVPWM) and six-step voltage control operation. The SVPWM is performed to reduce the harmonic components in the low speed region, and the six-step modulation is applied to increase the maximum speed of the IPMSM in the high speed region. Therefore, it is possible to obtain a great performance in both the low speed range and high speed range. However, the six-step modulation cannot be completely implemented, since the inverter that includes the lag-shunt sensing method has an immeasurable current region. In this paper, a quasi-six-step modulation using a modified voltage vector is proposed. The validity and usefulness of the proposed PWM technique is verified by MATLAB/Simulink and experimental results.

Recently, the permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) that can replace induction motor has been more studying because of the needs of the high efficiency motor development for minimum energy performance standard. PMa-SynRM requires the speed and position information of rotor to control motor correctly. However, sensor for rotor information has many problems such as mounting space shortage and the additional system cost. Therefore, in this paper, the speed-sensorless control based on reference model adaptive control is introduced to eliminate the sensor. And mechanical design is improved for control. The proposed method is verified by simulation.

A 3-D.O.F. spherical PM motor has 3 degrees of freedom in its motion by tilting and rotating of a shaft, which can be applied in a range of fields. The back-EMF is proportional to the field flux and angular velocity. The back-EMF constant in conventional rotating machine has a uniform value. However, in a spherical PM motor, the back-EMF constant of the coils varies according to the tilting conditions regardless of whether the angular speed is constant. Consideration of the back-EMF constant is useful for designing 3-D.O.F. spherical PM motors. In this study, the back-EMF constant of the spherical PM motor was considered carefully.

This paper presents the control method that inverter output keeps to linear to reference voltage of Synchronous Reluctance Motor (SynRM) using DC Link voltage Synthesis. This method is reduced torque ripple considering parameters with magnetic saturation. To estimate parameters of inductances for SynRM, the proposed method uses recursive least square (RLS) estimation algorithm. The estimated inductances are used for calculating torque and DC link voltage. The Inverter output voltage cannot be displayed to linear about inverter reference voltage if Real DC Link voltage is different from DC Link voltage of PWM amplitude. Also, the over-modulation is linearity broken if reference voltage is out of range. Torque ripple generates the vibration and noise of a motor. This paper proposes the control method so that the torque ripple decreases and the linearity of inverter output keeps using the DC Link voltage Synthesis. The proposed control method is verified by computer simulation and experiment.

The multi-degrees of freedom surface permanent-magnet motor (Multi-D.O.F. SPM) has several degrees of freedom operations that are defined as the “roll”, “yaw”, and “pitch”. Normally, the torque that is generated to rotate a rotor includes ripples. The analysis of the torque ripples is important for improving motor performance. In terms of the electric analysis, torque ripple occurs as a result of many factors, including the rotor and stator structures, the distribution of the air-gap flux density, and the waveform of the current in the coils. In particular, the torque ripple is an important factor in the stable operation of the Multi-D.O.F. SPM. Therefore, in this work, the torque ripple was analyzed using various types of magnetization for the permanent magnet. An improved model was proposed for the Multi-D.O.F. SPM based on this analysis.

This paper presents the design process of permanent magnets to enable a wide range of constant-power operation and reduce the torque ripple by using analytical and numerical methods in PMA-SynRM. For a wide range of constant-power operation, the minimum d-axis flux-linkage of the permanent magnet is designed to be close to zero. Moreover, the unbalanced flux density in each segment is adjusted by changing the size of each permanent magnet to reduce the torque ripple. Finally, control simulations and experiments will be conducted to prove the validity of the suggested process.

A permanent magnet spherical wheel motor, which consists of magnets on rotor and coils on spherical stator, is able to operate on 3-D space as using magnetic alignment torque generated from between coils and magnets. Especially the shaft can be tilted stably by optimized coil position on stator. Because, however, the spherical wheel motor has feature of 3-D structure as relative position between coils and magnets, stable holding torque for rotor position should be analyzed as function of the tilt degree of a shaft. The characteristic of stable holding torque can be changed nonlinearly by the alpha and beta degrees of a shaft. Therefore, when reference current is commanded at coils, the shaft cannot be tilted to the reference position exactly for the nonlinear characteristic. In this paper, for improving the nonlinear phenomenon of holding torque, the authors research and improve a current compensation function to increase stable operating range. Also, the compensation function was estimated by using torque ripple computed from torque simulation.

The permanent magnet spindle motor for a hard disk or an optical disk drive is outer rotor type and the permanent magnet is mounted on the inner surface of the rotor. Because the motor is very small, the magnet for the motor is not a premagnetized segmented-magnet but a ring magnet which should be magnetized on the magnetization fixture. The magnetization distribution of the magnet is settled by a configuration of the fixture and magnetizing current. In many cases, the magnet is not fully magnetized on the whole regions because of the limitation of the magnetizing current. The magnetization distribution of the magnet influences the air-gap flux density distribution of the motor and the flux density distribution influences the cogging torque and the back electromotive force of the spindle motor. In this paper, the effects of configuration of the fixture on performance of the spindle motors are specified and alternative configuration for more complete magnetization is suggested.

This paper presents the optimal rotor design method in a single-phase line-start permanent magnet motor (LSPM) considering the starting torque and efficiency. To consider nonlinear characteristics, the design process is comprised of the FEM and analytical method. During this study, permanent-magnets and cage bars were designed using the magnetic equivalent circuit method and the barriers that control all magnetic flux were designed using the FEM, and the tradeoff of starting torque and efficiency is controlled by weight function in Taguchi method simulation. Finally, the performance of the optimal model is compared with those of conventional models.

This paper presents a sensorless algorithm of the synchronous reluctance motor(SynRM). Conventionally flux estimation method using phase voltage integration has problem in low speed operation. This is due to insufficient terminal voltage in that speed. However in high speed operation, it is enough to estimate rotor flux. Therefore in this paper the current model which uses phase current signal is proposed to compensate the insufficiency of terminal voltage in low speed to estimate rotor position. Computer simulations are performed to confirm the adequacy of the proposed control scheme. The experiments are also performed for verification of proposed algorithm.

This paper analyzed the characteristics of the permanent magnet (PM) type claw-pole stepping motor by using 3-D finite-element analysis (FEA). As the magnetization occurs along the z-axis of the motor, it is necessary to apply 3-D FEA for analysis of the PM type claw-pole stepping motor. Considering the computation time, however, the number of the analysis model is minimized by using the "design of experiments (DOE)". By using the DOE, efficient analysis was able to be done. To see the effects of the design factors, the 3-D FEA is applied only to the selected models. As the design factors, the teeth shape, the number of turns, and the PM overhang was selected

Vector control provides a fast torque response for motor control. In general, the vector control is used for the control of a rotary machine. In the case of the 3-degree-of-freedom (3-DOF) motor, the position of the rotor is changed on three-dimensional space by tilting and rotating the motion of the shaft. Thus, when applying the vector control to the 3-DOF motor, the 3D co-ordinate transformation algorithm is required to decouple not only the field and torque current but the positioning (or tilting) current. The reliability of the proposed control algorithm was proven via experiments.

3-DOF spherical PM motor has 3 degrees of freedom in its motion by tilting and rotating the shaft, which is applicable in various fields. In this paper, D-Q-P vector control method is proposed for motion and speed control of the shaft. Using the reference table of current is the conventional control method obtained through numerous simulation and experiments. Vector control of general rotary motor has been researched for a long time. The vector control is the main control method in rotary motor because it allows an instantaneous torque control. But in the case of 3-DOF spherical PM motor, locus of magnet rotation varies by shaft position. So general D-Q axes vector control methods can't be applied directly. This paper shows D-Q-P vector control method for 3-DOF 4 poles spherical PM motor considering shaft response factor with mathematical and experimental verification.

In this paper, the torque characteristics of multi degree of freedom surfaced permanent-magnet motor (multi-D.O.F. SPM) are introduced. The multi-D.O.F. SPM can rotate a shaft while the rotor tilts to one side [1]. To decrease the torque ripple, the locus of summed wave forms of motor driving current have to be in an ellipse. Because the axis of electro motive force is generated by many numbers of currents as considering rotor position, the currents have different phase while the rotor is tilting. Therefore the phase of each current is defined as function of rotor position as using compensated phase method in this paper. The modified current is verified by comparison of analytic simulation results to experimentation results.

In this paper, authors are proposed drive system for BLDCM using motor drivers based on LabVIEW. Most researchers generally use MATLAB/SIMULINK program as computer simulation tool for their control system design. These control system must be coded to the motor drivers using program language such as C for its verification. We developed drive system using LabVIEW, it is able to complete whole process from control system design to verification of control system without program coding. Authors also proposed power conversion stack designed for LabVIEW controller and BLDCM drive.

A pulse with modulation(PWM) that keeps a constant angle of dwell and adjusts duty ratio is a good method for speed control of SRM. And a method of one pulse control is proper to operate on range of high speed in SRM for a good energy efficiency. Because PWM method is more safety than one pulse method, conversion of those is best choice according the speed range. So, some algorithm is demanded for smooth conversion of the mode for speed control. This paper presents a factor for conversion that satisfies the conversion of control mode between PWM and one pulse method smoothly. The factor can be determined from estimation of torque. And the factor is proper at the variable range of conversion and shows the adaptive conversion characteristic than constant factor applied.