Yasuhiro Komatsu

A control method for the active power filter in unsymmetrical voltage systems

In this paper, the authors propose a calculation method for the compensating current reference of the active power filter, where a nonlinear load exists in a three-phase, three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current-controlled intelligent power module inverter for both methods. The results of the experiments proved that in the unsymmetrical voltage system the source current was distorted in the case of the pq method, but undistorted in the case of the extension pq method.

Characteristics of three phase active power filter using extension pq theory

In this paper, the authors propose a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in a three-phase three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current controlled IPM inverter for both methods. The results of the experiments proved that, in the unsymmetrical voltage system, the source current was distorted in case of the pq method, but undistorted in case of the extension pq method.

A control method of active power filter in unsymmetrical and distorted voltage system

In this paper, the authors propose a calculation method for the compensating current reference of an active power filter, where a nonlinear load exists in the three-phase three-wire unsymmetrical voltage system. This new method has been named the extension pq method. The authors have experimented with the extension pq method and the pq method, using the same current controlled IPM inverter for both methods. The results of the experiments proved that, in an unsymmetrical voltage system, the source current was distorted in the case of the pq method, but undistorted in the case of the extension pq methods. Finally, the authors propose calculation methods for the compensating current reference in an unsymmetrical and distorted line voltage system. Experimental results show that the active power filter based on this method gives satisfactory operation.

Design and Implementation of a Linear Motor for Multicar Elevators

The multicar elevator system is a revolutionary new technology for high-rise buildings, promising outstanding economic benefits, but also requiring new technology for propulsion, safety, and control. In this paper, we report on experimental results with new components for linear-motor-driven multicar elevators. We show that linear synchronous motors with optimized design and with our new safety and control system can be considered as core components of a new generation of elevator systems. The main new results concern the development of a safety system integrated into the propulsion system, the design methodology of a linear motor optimized for the multicar elevator task, and the motion control system that is expected to be usable for extra high-rise buildings.

Application of the extension pq theory to a mains-coupled photovoltaic system

A mains-coupled photovoltaic system is economical because of having no storage battery. In the coupled photovoltaic system, the currents flowing from or into the power system must have no distortion. This system,must have the function supplying the appropriate reactive power at the coupling point. In other words, a coupled photovoltaic system must have the function of an active power filter. Even if the three phase voltage is unsymmetrical, these two functions must be given to the coupled photovoltaic system. In that case, the extension pq theory which the authors had previously published for the active power filter control may be used. In this paper, the authors develop the effectiveness of applying the extension pq theory to the coupled photovoltaic system.

Highly effective brushless DC motor in which the unidirectional current flows

In the small brushless DC motor, the system in which the unidirectional current flows can be adopted. However, recently, the brushless DC motor, in which the bidirectional current flows, is being mainly studied. The unidirectional motor system is easy to control the direction of the torque by all armature windings. Considering the above fact, we developed the highly effective brushless DC motor, in which the unidirectional current flows.

New induction machine rotor constants

The control of the induction motor using such methods as vector control are carried out on the basis of state space equations. In the case of the squirrel-cage induction machine, the measurement of constants used in the equation of states are difficult because the equivalent rotor winding cannot be opened. Therefore, the authors define two new rotor winding constants K and M, for the induction machine and clarify their measurement method. Next, the conventional equation of states are transformed into equations having measurable constants K and M. The simulation results obtained by the use of the measured values of K and M agree approximately with the experimental results. Thus, it is made clear that even in the absence of any knowledge of the induction machine winding resistances and inductances, by using the newly defined constants K and M, simulation of the induction machine is possible.

The study of unidirectional energized BLDC motor for E-type iron core

A unidirectional energized Brushless DC (BLDC) motor can be adopted for a small motor system. The Minato motor is one such unidirectional energized BLDC motor. Recently, bi-directional energized BLDC motors are being studied. Since controlling the torque direction by each armature winding for unidirectional motor system is easy, we developed a high efficient unidirectional energized BLDC motor. The authors have been simplifying the operation principal of the unidirectional energized BLDC motor as well as its motor drive circuit. To increase the output power and motor efficiency, the authors proposed comb-type winding. The result decreased copper loss and reduced the motors size.

Small copper loss unidirectional energized BLDC motor and the motor system

Unidirectional energized Brushless DC (BLDC) motor can be adopted in a small motor system. Minato motor is one of the unidirectional energized BLDC motors. Recently, bidirectional energized BLDC motor is being mainly studied. However, controlling the direction of the torque by each armature winding for unidirectional motor system is easier. Therefore, the authors developed a high efficient unidirectional energized BLDC motor. Asymmetric H-bridge circuit is used as a driver circuit for the proposed motor. This circuit is hard to break down, compared to the inverter used in bidirectional energized BLDC motor. During high speed rotation, undesirable armature current, which has deceleration characteristic, is generated. This current lowers the efficiency of motor. In this paper, the authors proposed measures for this solution in the proposed motors. The authors show the proof through the equations of copper loss ratio for Minato motor and proposed motors. The “3rd motor” which has the highest efficiency was discovered during examination of the equations.