Abstract: An electric vehicle control device controls an induction motor with a VVVF inverter. A first calculation means calculates a rotor-resistance correction value of the induction motor based on a torque current instruction value for vector control of the induction motor and an actual torque current value. A second calculation means calculates a corrected rotor-resistance value based on the rotor-resistance correction value and a reference rotor-resistance value. A third calculation means calculates an estimated rotor temperature of the induction motor based on the corrected rotor-resistance value, the reference rotor-resistance value, and a temperature coefficient determined by a material of a rotor. The thermal condition of the induction motor is thus monitored in real time without installing a temperature sensor on the induction motor.

Abstract: While an electric vehicle is traveling in a DC section, a ripple component detecting unit detects a ripple component appearing on a filter capacitor voltage and adds the ripple component onto an inverter frequency reference in such manner as to cancel an influence in a motor current caused by the ripple component. On the other hand, while in an AC section, a damping control component detecting unit detects a magnitude of fluctuation of a DC power supplied from a DC power line as a damping control component and adds the component, like the ripple component in the AC section, onto the inverter frequency reference in such manner as to cancel an influence in the motor current caused by the damping control component. Consequently, an output current from the inverter which is to be supplied to the induction drive motor becomes very steady of ripple-free and it improves comfort for passengers on the electric vehicle.

Abstract: An electric power supply system used in electric trains or electric buses is equipped with a device for removing ripples of low frequencies which cause flickering in a lighting system on the train or bus. The system includes an inverter for inverting DC power to AC power, a low pass filter for passing components of the AC power having low frequencies, amplitude detecting means for detecting an amplitude of an output of the filter, error detecting means for detecting any deviation of the amplitude from a reference signal, and a control system for detecting and removing flickering components from an error signal generated by the error detecting means. The control system includes a flickering component passing device for passing only flickering components contained in an output of the filter, a phase compensating device for compensating a phase lag of the flickering components, and a gain compensating device for compensating a gain of the flickering components.