Satoshi Ibori

Tripless control method for general-purpose inverters

The control method described prevents general-purpose inverters without current regulators from tripping easily, i.e. to be tripless no matter how their load is varied, and enables motors to rotate stably at high frequencies. It uses only current sensors and is a combination of pulse-width-modulated (PWM) control and torque control. The PWM control changes an asynchronized mode to a synchronized mode when the modulation ratio becomes more than one, enabling the carrier wave frequency to be continuously varied with the inverter frequency so that motors can rotate stably over a wide frequency range. The torque control uses a real and reactive component detector, magnetic flux compensator, slip compensator, and current limit controller. Experiments prove that this tripless control can be satisfactorily applied to general-purpose inverters. >

Controllability of switching speed and loss for SiC JFET/Si MOSFET cascode with external gate resistor

The SiC JFET/Si MOSFET cascode is an attractive alternative to conventional Si MOSFETs or IGBTs due to its low on-resistance and good switching performance. However, dv/dt control without increased switching loss is difficult when using a conventional gate resistor or capacitor for the MOSFET. In this paper, a dv/dt and switching loss control method that ensures a good switching performance for the cascode with an external gate resistor for JFET, as well as for MOSFET, is presented.