Ikuya Sato

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.

An Improvement Method of Matrix Converter Drives Under Input Voltage Disturbances

While the matrix converter has many advantages that include bidirectional power flow, a size reduction, a long lifetime, and sinusoidal input currents, it is vulnerable to the input voltage disturbances, because it directly exchanges the input voltage to the output voltage. The instantaneous effective power control (IEPC) method has been proposed to compensate the input voltage disturbances, in which the instantaneous effective power is kept constant by controlling input current. However, to date, no method has been proposed to maintain the stability of the system with the IEPC. The purpose of this paper is to propose a method to control the stability of the system with IEPC. First, this paper explains the IEPC theoretically. Next, a model of the system with the IEPC is developed, and stability analyses are conducted. Then, based on the results of the analyses, a stability control method for the system with the IEPC is proposed. Furthermore, the validities of the proposed method are demonstrated by simulation and experiments. Finally, a restart performance of the system after momentary power interruption is discussed. Because the IEPC does not need phase-locked-loop to detect the phase angle of the input voltage, fast restart is expected

Analysis of loss and junction temperature in power semiconductors of the matrix converter using simple simulation methods

In this paper, simple simulation methods to calculate power semiconductor loss and instantaneous junction - case temperature difference in a power module of a matrix converter are proposed. The validity of the proposed simulation method for loss calculation is confirmed through experiment using a 22 kW test set-up of the matrix converter. By using the simulation method for temperature calculating, the influence of the output frequency on the junction - case temperature difference is investigated. Moreover, the effect of using a novel IGBT (RB-IGBT) that has reverse blocking capability is discussed. It is shown that the efficiency of a matrix converter using the RB-IGBT is higher by 1.3 points than that of a conventional PWM rectifier and inverter system.

A Novel Control Strategy for Matrix Converters in Over-modulation Range.

This paper proposes a control strategy for matrix converters to reduce the torque ripple in the over-modulation range. In the over-modulation range, motor drive performance of matrix converters is deteriorated because of the output voltage saturation. Especially, the torque ripple which has lower frequency components than the input voltage frequency is remarkable. In this paper, the theoretical analysis about the causes of the torque ripple and the effect of the proposed control strategy are shown. Experimental results verify the validity of the theoretical analysis and confirm the effectiveness of the proposed control strategy. Furthermore, the harmonic distortion of the output current is also reduced compared with another control strategy.