Abstract: The invention provides a control apparatus of a power conversion system for driving an induction motor via a VVVF inverter, wherein the AC voltage generated by the inverter is increased so as to expand the high-speed side property of the induction motor, to thereby improve the performance during power running and regenerative braking. In the present system, a DC power supply source having a power storage system with a capacity capable of processing the current flowing into or out of the inverter is inserted in series to the ground side of the input of the inverter, and the output voltage thereof is controlled from zero in a continuous manner to be added to the trolley voltage, which is then applied to the inverter.

Abstract: The invention provides a control apparatus of a power conversion system for driving an induction motor via a VVVF inverter, wherein the AC voltage generated by the inverter is increased so as to expand the high-speed side property of the induction motor, to thereby improve the performance during power running and regenerative braking. In the present system, a DC power supply source having a power storage system with a capacity capable of processing the current flowing into or out of the inverter is inserted in series to the ground side of the input of the inverter, and the output voltage thereof is controlled from zero in a continuous manner to be added to the trolley voltage, which is then applied to the inverter.

Abstract: In order to detect a current with high accuracy in an electric power converting system, an inductor is connected to a main terminal of a switching element in series, and a voltage generated in both ends of the inductor during switching period is integrated using an integrating circuit to detect the current.

Abstract: A two level inverter having a switching element the switching frequency of which is higher than that of GTO, and providing a continuous control substantially over a full range of output voltages wherein the two level inverter comprises as its pulse modes an asynchronous bipolar modulation mode, a multi-pulse mode of an overmodulation mode, and a one pulse mode, and wherein advantageously the multi-pulse mode and the one pulse mode are arranged to be changed, thereby to enable a continuous control of its output voltage and reduce tone changes in the magnetic noise as well.

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: 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: In a power converter system wherein each thyristor of a three-phase full-wave bridge circuit having thyristors connected in all of bridge arms is fired for its controlling to thereby control the dc output voltage, when the dc output voltage is low, the firing angle of a group of thyristors on the negative side is fixed to a large value and the firing angle of a group of thyristors on the positive side is rendered variable within a small range so that a period may occur through which two thyristors connected in series in the full-wave bridge circuit are fired simultaneously. When the dc output voltage is high, the firing angles of groups of thyristors on both the positive and negative sides are made equal to each other and varied simultaneously. The system improves power factor and form factor over the entire controlling range of the dc output voltage.

Abstract: In a speed feedback control system wherein a speed command signal and a speed feedback signal are compared and wherein the deviation between these signals is entered into a speed control unit, the speed signal is differentiated to apply speed damping in order to suppress the oscillations of the control system. In this case, while the speed command and the actual speed make a great difference transiently, the speed command is approximate to the sum between the speed feedback signal and the damping signal even transiently. Therefore, the speed command signal is compared with the sum between the speed feedback signal and the damping signal, and the fault of the speed control system is detected upon the fact that the deviation has exceeded a predetermined value.

Abstract: A thyristor fault-detecting apparatus comprises a thyristor bridge with A.C. terminals connected to a three-phase A.C. power supply and having six thyristor arms, and an inductive load connected to D.C. terminals of the bridge. Each of the A.C. paths has a saturable reactor with an output winding so set as to be excited by the line current within the range from .pi./3 to 2.pi./3 (rad). Output voltages of the reactors are rectified and added, so that a fault in the thyristor is detected by the disappearance of the added output.