Abstract: A power converter having at least a pair of voltage drive switching elements, which comprises a gate control circuit, the gate control circuit comprising a detecting section for detecting at least one of a set of device parameters and a set of electric parameters of the voltage drive switching elements, a monitoring section for monitoring at least one of states of turn-on and turn-off of the voltage drive switching elements based on the at least one of a set of device parameters and a set of electric parameters of the voltage drive switching elements detected by the detecting section, and a control section for controlling a gate of the voltage drive switching elements based on a monitoring result of the monitoring section.

Abstract: A gate drive circuit for a voltage-driven type power switching device, including a control device for generating a gate voltage for the voltage-driven type power switching device, and a correction device connected to the control device for receiving the gate voltage and for correcting an effect of a magnetic flux resulted from a main circuit current flowing in the voltage-driven type power switching device applied to the gate voltage to generate a corrected gate voltage. The corrected gate voltage is applied to a gate of the voltage-driven type power switching device.

Abstract: This inverter system is directed to an inverter system in which a plurality of inverters adapted for generating output voltages corresponding to a voltage reference and a frequency reference respectively given through voltage controllers and frequency controllers are operated in parallel. In this inverter system, a difference between an output current of a corresponding inverter and output currents of other inverters is detected. By implementing the d-q axis orthogonal coordinate transform processing to that current difference, a first correction signal relating to the frequency of an output voltage of that inverter and a second correction signal relating to the amplitude of the output voltage thereof are provided.

Abstract: An off-gate circuit for a GTO thyristor comprises a power source for supplying current to the circuit at a predetermined voltage, and a switching circuit connected to the power source for supplying off-gate current to the GTO thyristor at least two different current rates.

Abstract: A turbine helper drive apparatus has an induction motor coupled to a turbine, and a power converter for power-controlling the motor. Part of the load of the turbine is shared by the motor in accordance with preset power for power control, so that auxiliary drive to compensate for the insufficient capacity of the turbine is performed and cheaper, late-night electric power is effectively utilized.