Takeshi Horiguchi

A fast short-circuit protection method using gate charge characteristics of SiC MOSFETs

This paper describes a fast protection circuit for silicon carbide metal-oxide semiconductor field-effect transistors (SiC MOSFETs) subjected to hard-switching faults (HSFs). In terms of reliability of power converters, the protection of power semiconductors against short-circuit failures is of great concern. The reverse transfer capacitance increases with decreasing drain-source voltage during normal turn-on transient. Under HSF conditions, on the other hand, it hardly changes because the drain-source voltage remains high. As a consequence, quite a significant difference appears in gate charge characteristics between under HSF conditions and normal turn-on operation. Hence, an HSF can be detected by monitoring both the gate- source voltage and the amount of gate charge. The proposed protection circuit has high noise tolerance because it monitors not only the gate-source voltage but also the amount of gate charge. The validity of the protection circuit is verified by experiment. The proposed protection circuit can detect the HSF within only one microsecond.

Characterization and Modeling of a 1.2-kV 30-A Silicon-Carbide MOSFET

This paper describes a novel compact model for a SiC-MOSFET. The model is useful to achieve accurate simulation of output characteristics from a linear region to a saturation region, selecting both gate-source voltage and temperature as parameters. In order to construct the model systematically, attention is paid to a physics-based modeling procedure with channel mobility as an adjustable parameter. The model also features characterization and modeling of an internal drain-gate capacitor. The model shows fairly good agreement in the output characteristics and the dynamic behavior of both gate drive circuit and main power circuits between the experimental and simulated results. This successful validation indicates that this model offers a promising circuit-based simulation tool for designing whole power conversion systems using SiC-MOSFETs.

Investigation into standard parameters of motor drive systems

This paper provides a standard motor model, parameters, and a design of controllers for simulation of motor drive systems. In the motor drives working group of Investigating R&D Committee on applied simulation for power electronics systems in IEEJ, standard models for simulation of motor drive systems have been discussed. Parameters of more than 330 motors have been gathered from among released data sheets and specifications from manufacturers, IEEE transactions, IEEJ papers, and JIPE papers. Tendency of the parameters have been also investigated. A simulation example based on the investigation of dc motors is shown and the validity is demonstrated.

Modeling of a silicon-carbide MOSFET with focus on internal stray capacitances and inductances, and its verification

This paper describes a compact model for an SiC-MOSFET, which features characterization and modeling of a novel drain-gate capacitor. In addition, the inner gate resistance and stay inductances of the package are evaluated and modeled by a newly-proposal method. The gate drive circuit is also modeled and involved in this simulation study. The model shows excellent agreements in steady and transient states between simulated and experimental waveforms. The comparison shows accurate reproducibility of both the rate of drain-source-voltage change and that of drain-current-change with an error of 10 % for turn-on behavior, and with a maximum error of 20 % for turn-off behavior. This successful validation indicates that the developed model is expected to open up the possibilities of the simulation study for evaluating detailed performance of SiC-MOSFETs.