Wataru Kitagawa

Design for cogging torque reduction in two-degree-of-freedom cylindrical actuator

Recently, the drive mechanism is complex configurations as the electronic component mounting apparatus and the machine tool are high performance. The head portion of those is the drive mechanism with two-degree-of-freedom of rotary and linear motion. Conventional two-degree-of-freedom drive is composed of 2 motors and mechanical elements[1]. However, it is huge, heavy and in need of maintenance by abrasion. Thus, authors have developed the two-degree-of-freedom cylindrical actuator (2DoFCA) designed as 8 poles 6 slots Permanent magnet synchronous motor (PMSM) in rotary direction and 7 poles 6 slots Permanent magnet linear synchronous motor (PMLSM)[2][3]. The proposal actuator is expected to apply a electronic component mounter. This paper proposes the cogging torque is reduced by changing the shape of stator and mover salient pole. As a result, it was confirmed that the cogging torque was reduced by 79.6%.

Input power factor control of bi-directional AC/DC converter

This paper describes the method for the control of the input power factor for a variable voltage AC/DC converter under different output voltage conditions. The proposed PWM strategy also suppresses the output voltage ripple with a reduced number of commutations. The proposed control method is verified by the experimental results.

Soft-switching three-phase AC to DC converter isolated by high-frequency transformer

This paper presents a soft-switching three-phase AC to DC converter isolated by high-frequency transformer. The-soft switching conditions are indicated and the soft-switching control method are derived. The effectiveness of the proposed circuit and control method are verified by experiments using a 1 kW prototype.

MPPT method for PV modules using current control-based partial shading detection

Partial shading conditions are the serious problems in solar modules making them to work under low efficiency when compared with steady state conditions. The required power from the Photovoltaics (PV) is achieved by combining the PV modules in the combination of series and parallel arrangements depending upon the specifications of the converter. Generally single-stage conversion is realized by connecting modules in series to built a high voltage greater than the line voltage of the grid. But highly parallel connected modules shows better performance in the output power when compared with the highly series connected modules during rapid change in partial shading conditions. A Maximum Power Point Tracking (MPPT) method with an ability of detecting the partial shading occurrence on PV array, and employs a current control method for tracking the global maximum between the local maximums.

PWM strategy of bi-directional buck AC/DC converter for reducing output voltage ripple

This paper presents a PWM strategy for a variable-voltage buck AC/DC converter for suppressing output voltage ripple. The authors propose a PWM strategy of output voltage ripple suppression via a reduction in the number of commutations. The effectiveness of the proposed PWM strategy is verified by experiments.

New PWM technique for grid-tie isolated bidirectional DC-AC inverter based high frequency transformer

This paper presents a new PWM switching technique for controlling a bidirectional isolated DC-AC-AC inverter along with its soft-switching technique. The proposed PWM technique has the ability to control the input DC current and to inject a sinusoidal three-phase current to the grid at unity power factor. In the first stage, an H-bridge converter is used to convert the DC voltage to a high-frequency square-wave single-phase voltage. In the second stage, a matrix converter is used to convert the high-frequency voltage waveform to conventional three-phase voltage synchronized with the grid. Therefore, a high-frequency transformer is used to link the H-bridge output voltage to the matrix converter input voltage. The proposed soft-switching technique is achieved by connecting shunt capacitors across the DC-AC-AC converter switches. The mathematical model and the circuit operation for soft-switching are presented along with the voltage controllable limits. The effectiveness of the proposed technique has been verified experimentally using a laboratory prototype.

Characteristic analysis of two-degree-of- freedom cylindrical actuator

This paper presents the characteristic analysis of the two-degree-of-freedom cylindrical actuator that can move in rotary and linear direction. The actuator uses the permanent magnet that is magnetized in axial direction so that the polarity in rotary and linear direction is generated alternately. When the rotary coil or the linear coil is excited, the mover moves by the principles of PMSM or PMLSM, respectively. As a result, the torque and the thrust are almost out of interference. It was confirmed that the actuator can move in rotary and linear motion independently. Moreover, the iron loss of the mover is smaller than that of the stator in rotary and linear motion, and the hysteresis loss is much larger than the eddy current loss.

Design and analysis of two-degree-of-freedom actuator using PMSM and LSM

This paper presents the design and analysis of two-degree-of-freedom actuator that can move in rotary and linear direction. The proposed actuator is moved in principles of permanent magnet synchronous motor and linear synchronous motor. The structure of the actuator is robust to use the ring magnets that magnetized in axial direction. Moreover, the stator of the actuator has the salient pole in axial direction for improvement of thrust density. Characteristics of the actuator are analyzed by three-dimensional finite element method. As a result, the actuator is obtained characteristics that the average torque is 61.8 mNm in rotary motion and the average thrust is 9.00 N in linear motion.

Discharge operation of single-stage buck bi-directional AC/DC converter

This paper presents a control method for a single-stage bi-directional AC/DC converter under discharge mode. The effectiveness of a PWM strategy for output voltage ripple suppression with reduced number of commutations during charging mode has already been verified by experiment. The control method can be applied to the control of the bi-directional AC/DC converter during discharge mode. The effectiveness of a control method of bi-directional AC/DC converter during discharge mode has been verified by experiments with prototype system.

Optimal design for electromagnetic machinery by using 3D finite element method with parallel GA

Purpose – The purpose of this paper is to automate the pre‐process that is the modeling and mesh generation of the 3‐dimensional finite element method; and genetic algorithm (GA) is embedded to this program by using Shell script.Design/methodology/approach – It is operated by Bash (Bourne‐again shell) to implement the GA. In order to adopt the analysis of 3‐D FEM as evaluation in the GA, the pre‐processes such as moving nodes, 3‐D modeling, and mesh generation must be automated. In the “Evaluation”, these pre‐processes are connected and automated by using shell script. The “Evaluation check” is to prevent re‐evaluation. In the population, there are some individuals that are already evaluated in the previous generations because of elitist strategy or result of genetic operations. In order to shorten computing time for the main process, these individuals are skipped in the “Evaluation”.Findings – It was confirmed that the cogging torque of SPMSM has been decreased by 30 per cent and the improvement about 2....