Abstract: An electric power translating device employs a converter for converting an AC source voltage into a DC voltage, a smoothing capacitor connected at the DC side of the converter, an inverter for inverting the DC from the smoothing capacitor into an AC and for supplying the AC to an AC motor and means for controlling the voltage, frequency or phase in the AC output from the inverter. The device further includes means for regulating at least one of voltage, frequency and phase in the AC output of the inverter based on a ripple frequency component contained in the AC output of the inverter and associated with the rectification by the converter. Whereby, beat phenomenon caused by rectification ripple is suppressed.

Abstract: An electric power translating device employs a converter for converting an AC source voltage into a DC voltage, a smoothing capacitor connected at the DC side of the converter, an inverter for inverting the DC from the smoothing capacitor into an AC and for supplying the AC to an AC motor and means for controlling the voltage, frequency or phase in the AC output from the inverter. The device further includes means for regulating at least one of voltage, frequency and phase in the AC output of the inverter based on a ripple frequency component contained in the AC output of the inverter and associated with the rectification by the converter. Whereby, beat phenomenon caused by rectification ripple is suppressed.

Abstract: In a control apparatus of an induction motor including an inverter for converting a direct current to an alternating current having a variable voltage and variable frequency in accordance with a pulse width modulation control, and a controller for controlling an output voltage of said inverter through a modulation rate which is requested in accordance with an exciting magnetic current component command in a primary current of the induction motor driven by said inverter and a voltage component command corresponding to said respective components which are executed in accordance with a torque current component command, the control apparatus of the induction motor operates to detect a torque current component in accordance with said primary current of the induction motor, to correct said torque current component from a deviation between said detected torque current component value and said command value, to correct an output frequency of said inverter in accordance with said corrected torque current component com

Abstract: The control system is constructed so that an inverter output frequency command is increased/decreased based on a frequency-to-time rate-of-change command, and the frequency-to-time rate-of-change command is controlled with a current control system. Further, it is also constructed so that the frequency-to-time rate-of-change command is adjusted and the current command is changed with a readhesion control system. The control system is capable of accelerating and decelerating the vehicle with a torque corresponding to an inverter output current command which is generated basically without using any rotational frequency of induction motor, and further capable of accelerating and decelerating the vehicle with a torque corresponding to a value near the limit adhesion between the wheel and the rail under a condition of occurrence of slip/skid.

Abstract: A control apparatus for controlling an electric vehicle, electric car, rolling stock and electric locomotives, which ensures that an inverter output frequency command for its inverter will not depend on the rotor frequency of the induction motor, but controls the inverter output current using a constant current control system, thus preventing an overcurrent, and is capable of accelerating or decelerating the vehicle at a torque precisely corresponding to a current command. The inverter output frequency command is incremented or decremented in accordance with a frequency-to-time rate-of-change command which has been updated by the current control system.

Abstract: In order to equalize voltage shares of DC-side voltage dividing capacitors of a three-level power converting apparatus for converting a DC voltage to a three-level AC phase voltage, there is provided an arrangement for compensating for rising and falling instances of a three-level AC voltage pulse depending on a difference voltage between the two voltage dividing capacitors and the polarity of the AC current, thereby adjusting a zero-voltage period of the AC voltage.

Abstract: An electric power converting apparatus equipped with a 3-level PWM control in which the output voltage can be continuously and smoothly controlled from zero to a maximum voltage. The electric power converting apparatus includes a multi-pulse generating unit arranged for a dipolar modulation, a unipolar modulation, and an overmodulation; a 1-pulse generating means; and a unit for controlling the transfer operation among these modulation regions.

Abstract: An electric railway vehicle control system including a converter for converting a single-phase a.c. voltage to a d.c. voltage, a PWM inverter for inverting the d.c. output of the converter to a variable voltage, variable frequency a.c. voltage, and a three-phase induction motor supplied with the a.c. output voltage of the inverter to drive electric railway vehicles. The control system further includes a unit for controlling the output voltage of the inverter in a variable voltage, variable frequency mode for changing the output voltage substantially relative to a change in the output frequency thereof and in a constant voltage, variable frequency control mode for fixing the output voltage to a substantially constant value, and a unit for detecting a rectification ripple in a frequency band including a frequency double the frequency of the single-phase a.c. voltage included in the d.c. input voltage to the inverter.

Abstract: Disclosed is an apparatus for realizing a small apparatus by making element currents uniform in the dipolar modulation mode. The zero voltage period in the dipolar modulation period is made shorter than other voltage output periods. Accordingly, currents of switching elements constituting the main circuit of an inverter can be made uniform.

Abstract: The power converter of the invention relates to a small-sized highly efficient power converter for generating an a.c. voltage output of multiple levels with less harmonic content. In the power converter, a d.c. voltage source is separated into plural sections by series connected voltage dividing capacitors and multiple levels of a.c. output voltage are obtained from the divided d.c. voltage by on-off control of switching devices. The power converter has plural sets of the voltage dividing capacitors disposed separately adjacent to each switching devices, and series connection point of each set of the voltage dividing capacitors are connected to division points of the corresponding switching devices of each phase. The voltage dividing capacitors are connected with each other at their series connection points. Thereby, the arrangement makes wiring length short and equal between the switching devices and the voltage dividing capacitors for each phase and reduce a loss in the snubber circuit, resulting in an a.c.

Abstract: An electric power converting apparatus equipped with a 3-level PWM control in which the output voltage can be continuously and smoothly controlled from zero to a maximum voltage. The electric power converting apparatus includes a multi-pulse generating unit arranged for a dipolar modulation, a unipolar modulation, and an overmodulation; a 1-pulse generating means; and a unit for controlling the transfer operation among these modulation regions.

Abstract: An electrical power converter having a phase converter constituted by positive side semiconductor switching elements connected in series and negative side semiconductor switching elements connected in series which converts a DC voltage to an AC output phase voltage having at least three potential levels, resulting in three possible modulation modes: dipolar, partial dipolar and unipolar. Dipolar modulation is realized by alternating positive and negative output pulses. Unipolar modulation is realized by output pulses having only the same polarity as the corresponding fundamental modulation wave. Transition is accomplished via partial dipolar modulation which is realized by alternating positive and negative output pulses in a first period of a half cycle by outputting alternating positive and negative pulses and in a second period by outputting pulses having only the same polarity as the corresponding fundamental modulation wave.

Abstract: An apparatus for a three-level DC/AC converter, in which the width of output pulse having the same polarity as the fundamental wave of the converter output phase voltage is adjusted depending upon the DC component of a differential voltage between two DC voltages in a dipolar modulation system of the converter. Whereby, the imbalance of DC components between the two DC voltages is easily and effectively suppressed.

Abstract: The present invention relates to a control apparatus of a three-level inverter and intends to provide a control apparatus of simplified construction which can suppress a fluctuation in neutral point voltage effectively. Only a third harmonic component which is particularly large in the fluctuation in neutral point voltage is suppressed, a third harmonic component for suppression has a ratio of amplitude to that of a fundamental wave and a phase which are set to be constant regardless of the inverter frequency, and this third harmonic component is applied to a command of the fundamental wave.

Abstract: In an inverter control apparatus including a pulse width modulation inverter supplied with power from a d.c. power source to generate an a.c. output, a frequency control unit controlling the output frequency of the inverter, and a voltage control unit controlling the output voltage of the inverter, a frequency adjusting unit is provided to adjust the operating frequency of the inverter so that the product of voltage and time in each positive half cycle of the output voltage of the inverter becomes equal to that in the next adjacent negative half cycle of the output voltage of the inverter.

Abstract: In a PWM inverter, a first three pulse mode, in which three voltage pulses exist within 120.degree. in the electric angle of the inverter output voltage, is changed over to a single pulse mode, in which the pulse width is equal to 120.degree., through a second three pulse mode, which is composed of two voltage pulses on both sides outside the period of 120.degree. and a center voltage pulse therebetween.The jump of the output voltage and the phase deviation therein upon changeover between the three pulse mode and the single pulse mode is prevented by controlling the pulse width of the two side pulses and the intervals between the center pulse and the side pulses.

Abstract: For controlling the rotational speed of an induction motor, an inverter is provided which converts direct current to alternating current and feeds the converted current to the motor. The output voltage and frequency of the inverter is controlled by a pulse-width modulated control device. The number of pulses contained in a half cycle of the inverter output voltage are changed every time the inverter output frequency reaches one of plural predetermined reference values. The plural predetermined reference values are adjusted in accordance with the DC supply voltage and/or with the motor current.

Abstract: A control system for an A.C. motor which is connected to the output terminals of a thyristor inverter, a capacitor is connected between the D.C. input terminals of the thyristor inverter, and the respective thyristors constituting the inverter are extinguished by self commutation due to an oscillating current produced by the capacitance of the capacitor and the reactance component of the armature coils of the A.C. motor connected to the A.C. output terminals of the thyristor inverter, and a current in the waveform of pulses produced by electric oscillation is delivered in a predetermined phase sequence to the armature coils of the A.C. motor.