Naoya Eguchi

A novel approach to practical matrix converter motor drive system with reverse blocking IGBT

This paper proposes a novel control strategy and a protection circuit and shows the advantage of utilizing a newly developed reverse blocking insulated gate bipolar transistor (RB-IGBT), to solve several practical problems of the matrix converter. The proposed control strategy is based on a virtual indirect control method with a virtual rectifier and a virtual inverter. Pulse-width modulated (PWM) pulses for the matrix converter are obtained by combining PWM pulses for the virtual rectifier and inverter. As a result, the control part of the input current and output voltage can be clearly separated. Thus, the conventional inverter control algorithms can be applied to the virtual inverter control. The advantage of this method is confirmed by experimental results with a 22-kW induction motor drive system. Good sinusoidal waveforms are obtained for the input and output currents, and the total harmonic distortion (THD) of the input and output current are 5.1% and 1.4%, respectively. The conduction loss of the RB-IGBT is decreased to about two-thirds of the conventional ac switch with series connection diode. Thus, the converter loss is about a half to the conventional PWM rectifier-inverter system with the same capacity. Furthermore, the protection problem is solved by a dynamic clamp method without an electrolytic capacitor. This protection circuit directly dissipates reactive load energy by dynamic clamp operation of an IGBT.

A resonance dumping control for a line-current detection type active filter

The active power filters with line current detection need fewer detectors than those with individual load current detection, though the former have harmonics resonance problems. To avoid these problems, we propose a novel control system consisting of a line characteristics identifier and a 2nd-order filter. The identifier provides the line frequency characteristics observed from the point of the active power filter. The parameters of the 2nd-order filter are determined according to the identified characteristics. We obtained good results of both simulations and experiments using a prototype model.

Series power line compensator using self-commutated inverter

A novel power line compensator is proposed, which has an inverter connected to a power transmission line in series. One of the advantages of this compensator is to compensate even the voltage drop which occurs in the power supply side of the transmission line, which needs a larger capacity for the SVC. The operating principle and control systems of this compensator are described in this paper. The protective method of the compensator is also treated. The validity of this compensator and its control system are examined by experimental tests, including static and transient characteristics, harmonic effects and the protective functions.