Abstract: A power conversion apparatus has a circuit configuration in which a collector voltage of an IGBT is divided. It also has a unit which protects the IGBT against overvoltages applied to the collector by outputting a potential of a voltage dividing point to a gate of the IGBT. A case of a resistor on the high-voltage side of the voltage dividing point is fixed to an emitter potential of the IGBT.

Abstract: Switching devices conjointly use snubber circuits without disposing for each switching device and is interposed between a DC neutral point N and a positive terminal plate of a DC power source. A second snubber circuit is interposed between the DC neutral point N and a negative plate terminal of a DC power source. A third snubber circuit is interposed between the DC neutral point N and an AC output terminal O. The snubber circuit suppresses the rise of the voltage when each switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device when this voltage exceeds the power source voltage during the process in which the switching device shifts from ON to OFF. The snubber circuit clamps a voltage applied to the switching device or when this voltage exceeds the power source voltage during the process.

Abstract: A power converter is disclosed, in which the sum of the length of that portion of a control signal line which is in opposite relation to an area of a main circuit wiring where a main circuit current flows and a plurality of tabular conductors are in superposed relation with each other, the length of that portion of the control signal line which is in opposite relation to an area of the main circuit wiring where the main circuit current does not flow and the length of that portion of the control signal line which is located outside an end of the main circuit wiring, is substantially equal to the total wiring length of the signal control line.

Abstract: A three level inverter apparatus for suppressing a resonance current flowing therethrough, to thus improve its conversion efficiency and operational stability. This inverter apparatus includes a converter 1 for converting AC power source power to DC power, an inverter for converting thus converted DC power to AC power, and a DC link for interconnecting these converter and inverter. This DC link has two first smoothing capacitors connected in series between a positive-polarity potential bus P and a negative-polarity potential bus N for storing DC power obtained by the converter 1 and two second smoothing capacitors connected in series between the positive-polarity potential bus P and the negative-polarity potential bus N for storing DC power to be supplied to the inverter. The positive-polarity and negative-polarity potential buses each have a resonance-suppressing reactor inserted therein and the intermediate-potential bus, a resonance-suppressing resistor inserted therein.

Abstract: In order to provide a power inverter device which can reduce surge voltages in all of the operating conditions thereof and has a simple structure, in a neutral point clamped 3 level type power inverter device formed by connecting semiconductor switching elements, diodes and smoothing use capacitors connected via plate shaped conductors, a first plate shaped conductor connects the diodes and the smoothing use capacitors and a plurality of plate shaped conductors connecting the elements are disposed over the first plate shaped conductor and separated from it by an insulating material.

Abstract: The invention provides an electric power converter system which uses a standard low-priced control processor and is suitable for improving the voltage utilization factor in the output voltage. D-axis and q-axis voltage commands and a rotation angle .theta. defining a voltage command vector on a rotating coordinate system are input to a voltage calculation circuit. The voltage command vector is transformed in a rotating coordinate transformation unit into a .alpha. axis and .beta. axis voltage commands to be defined relative to stationary coordinate system. A judgment unit determines which section contains the voltage command vector, from among three sections on the stationary coordinate system having one axis thereof (.alpha.-axis for example) coinciding with one axis of the three phases. A three phase voltage generation unit then selects a method of calculation on the basis of a result of the section determination, and calculates three phase voltage command values respectively utilizing the .alpha.

Abstract: A large capacity (1-2 MkVA) driving system for variable-speed-driving an AC motor by a power converter (inverter, converter) in which GTO (gate turn-off) thyristors are used as switching devices. In this system, high frequency GTO thyristors are connected in series, power converters are multiplexed, the AC motor is used in its plural phases, instantaneous spatial vector PWM (pulse width modulation) control is performed, vector control for the motor is performed, and a circuit for recovering snubber energy for GTO thyristors and a power factor adjusting circuit are provided. Thus, this driving system provides a torque ripple of 1% or less, speed response of 60 rad/sec or more, efficiency of 95% or more and a power factor of 98% or more.

Abstract: In a control method and device for an AC motor, when transforming output power of a converter to AC power by an inverter and controlling the AC motor with the AC power, a source current value is determined from the value of an electric variable in the input or output side of the inverter, and the converter is controlled in accordance with the source current value. This makes the source current free from an influence of ripple components. Accordingly, even when the load of the AC motor is fluctuated abruptly, the required AC power can be applied to the converter so as to follow such fluctuations.

Abstract: A control apparatus for controlling a PWM inverter, the PWM inverter receiving AC power and generating an AC output having a controlled frequency to be supplied to an AC motor, comprises a circuit for generating, on the basis of a given running command, a PWM signal controlling the inverter with a given sampling period, and a circuit for controlling the PWM signal generating circuit, whereby the AC motor generates an electromagnetic tone preselected so as to correspond to desired information when the AC motor is driven by output of the inverter controlled by the PWM signal. The above described desired information may be information representing the running state of the motor or selected music.