717 publications from this institution
This paper describes a high-speed circuit to protect IGBTs against short-circuit faults. The reverse transfer capacitance depends on a collector-emitter voltage and it produces a significant effect on a switching behavior under short-circuit fault conditions as well as under normal conditions. A gate charge characteristic under short-circuit fault conditions differs from that under normal turn-on conditions. Hence, hard-switching fault (HSF) can be detected by monitoring both a gate-emitter voltage and an amount of gate charge. IGBTs can be rapidly protected from destruction because the protection circuit based on a gate charge characteristic does not require any blanking time. Fault under load can be also detected by almost the same circuit configuration. Simulation and experiment verify the validity of the novel protection circuit based on a gate charge characteristic.
This paper makes discussions on a battery energy storage system based on a multilevel cascade pulsewidth-modulated (PWM) converter for its practical use. Briefly discussed are several considerations including state-of-charge (SOC) balancing of multiple battery units, and fault tolerance of the system. An active-power control of individual converter cells is presented to make the multiple battery units charged or discharged at different power levels, producing a three-phase balanced line-to-line voltage. Experimental results obtained from a 200-V, 10-kW, 3.6-kWh battery energy storage system verify its effectiveness.
