Jun Oyama

New control strategy for matrix converter

The authors propose a control strategy for the matrix converter which allows output voltage of 0.866 times the supply voltage to be generated. They discuss how to eliminate voltage and current spikes in the commutation. The system operation is examined and confirmed by experiments using a matrix converter with anti-parallel-connected SITs (static induction thyristors).<<ETX>>

The fundamental characteristics of novel switched reluctance motor with segment core embedded in aluminum rotor block

We proposed a novel segment type switched reluctance motor (SRM) 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. This paper explains the operation principle and the drive system and shows the experimental results in comparison with the VR type SRM.

A trial production of small size ultra-high speed drive system

Developments of power electronics technology, low-loss iron core materials and highly efficient permanent magnets, etc. have made it possible to realize a small size, high or ultra-high speed, and high performance electrical drive system. Such a drive is expected for various kinds of applications such as co-generation system, electrical vehicle and compressor, in which small size, light weight and high efficiency are required. For these applications, we designed and built a trial ultra-high speed drive system of 2 poles, 5 kW, 240000 rpm. In this paper we describe our prototype system and show some experimental results. The computer simulation was used to evaluate the fundamental motor characteristics at the first design stage and total systematic approach to enhance the total drive system.

The Development of Small Size Ultra-High Speed Drive System

We designed and built a trial small size and ultra-high speed motor of 2 poles, 5kW and 240,000rpm as the target. And we had described our prototype ultra-high speed drive system and some experimental results in previous papers. But the evaluation of this kind of motor drive system is difficult only by the experiments. Then we also had described the electric and magnetic coupled analysis which was used not only the motor model from FEM but also the drive and control system models in the circuit simulation. This paper explains the ultra-high speed drive system including improved control method and presents experimental results using redesigned motor, and we illustrate the confirming availability of the total drive system model created by using VHDL-AMS and C-language as well.

Effect of PWM pulse number on matrix converter characteristics

In the previous paper, we proposed a new control method and a new VVVF on-line gate circuit for a matrix converter, which ensured sinusoidal input currents and sinusoidal output voltages even in the case of sudden change in input voltage or frequency. This paper discusses the effects of PWM pulse number on the characteristics of a matrix converter, especially on input and output distortion characteristics, under the new control method. Odd triangular pulse number in 60 degrees of the supply voltage is suggested in this paper because of its better distortion factor and less commutation losses.

Hybrid type novel switched reluctance motor

A new hybrid type of switched reluctance motor (SRM) and its control method are proposed in this paper. The new type of SRM consists of the usual salient pole type or a cylindrical type stator and one rotor in which two permanent magnets are installed symmetrically between the iron poles of the rotor. With the exciting current supplied to the stator windings, the magnets can generate additional torque and improve the overall motor performance. The motor performance characteristics have been estimated using the finite element method.

Model following servo control of CSI-IM vector control system

An application of model-following servo (MFS) control to the current source inverter (CSI)-fed induction motor (IM) vector control system is studied. The MFS control is a kind of two degree-of-freedom control, and the controller is designed systematically by using optimal regulator theory. For the speed control of IM, a comparison between the MFS control, conventional PI (proportional plus integral) control, and PI control with a load torque observer is made under the assumption of ideal vector control. A linear model in which a PI current controller and the change of rotor resistance are considered is presented. The robustness of the MFS control is discussed by examining the trajectories of poles and zeros and the transient responses.<<ETX>>

Stability analysis of a CSI-fed inductor motor with digital vector controller

A linear sampled-data model for a current source inverter (CSI)-fed induction-motor vector control system which is controlled digitally by a microprocessor is derived. The system stability is discussed from the viewpoints of sampling period, microprocessor computation time, and feedback parameters by examining the loci of dominant eigenvalues of the state transition matrix and the transient responses. A comparison between the sampled-data model and a continuous system model is given.<<ETX>>

Active power filter with optimal servo controller

This paper presents a reduction method of higher harmonic currents using an active filter at the AC side of a condenser input-type three-phase diode bridge rectifier. As an active filter, a three-phase PWM inverter is connected in parallel to rectifier. The principle of the active filter is to cancel higher harmonic currents contained in load current by injecting reversed phase harmonic currents into the power source side. In this system, an optimal digital servo controller with dead time compensation is used to reduce the higher harmonics at the current controller. The root locus method and the simulation are used to obtain optimal weighting factor of a performance criterion and to select the control method. Finally, power spectra of a load side current and a source side one are shown. Experimental results are shown to verify the usefulness of this system.

Application of linear motor on artificial satellite fuel pump system

The authors propose a new type of fuel pump system with linear motor propulsion, in which two pumps are equipped on both sides of the linear motor and a resonant system with springs is organized to decrease the rated thrust. A pump where the discharge pressure is 21.0 kgf/cm/sup 2/ and the discharge flow rate is 21.25 cm/sup 3//s is assumed. A prototype linear pulse motor was designed, built, and tested. The thrust characteristics are estimated using an equivalent magnetic circuit, and it is confirmed that the calculated results agree well with the experimental results.<<ETX>>