Abstract: A main circuit of a three-level active neutral point clamped voltage source converter having a pair of additional main switches provides two paths between an output node and a neutral point in which one of the paths involves only switches of an inner pair of switches that are operated at a high frequency. An auxiliary circuit operating at a high frequency for only a brief period during each high frequency switching cycle selects the path involving only the inner switches and provides operation with zero voltage switching and avoids reverse recovery of diodes connected antiparallel with the main and additional main switches. Accordingly, turn-on switching losses in the main switches is avoided and the voltage source converter can be operated at increased frequency to allow reduction in size of magnetic components and full potential power transfer to be achieved.

Abstract: A control section which repeats inverter control in units of an inverter control period having a predetermined length is provided. In the control section, a phase current detection period in which a phase current is detected is provided between predetermined two inverter control periods, each of switching states of switching elements of a inverter circuit is controlled so that a voltage pulse having a larger width than a width of a voltage pulse in the inverter control period is output from a shunt resistor in the phase current detection period.

Abstract: To make it possible to avoid an unstable state with a simple configuration even one of the phases of the motor fails. A motor drive system in accordance with the present invention includes a motor to which a plurality of phase coils of five phases or more are connected in a star connection, an inverter connected to one end of each of the phase coils, the inverter being configured to convert a DC power into an AC power and supply the AC power to each phase of the motor, a power relay disposed at another end of each of the phase coils, the power relay being configured so as to be able to cut off a supply power to at least one phase coil among the plurality of phase coils of the motor by using a plurality of contact points interposed between the star-connected coils, and a control unit that generates a control signal for the inverter and thereby controls driving of the motor.

Abstract: The present invention is generally directed to an efficient voltage transforming and regulating device based on a High Frequency (HF) transformer and a HF Electromagnetic Voltage Regulator (HFEVR) serially connected to the transformer's coil(s). The transforming and regulating device of the invention efficiently transforms and stabilizes an input power source without requiring filtering stages. The regulation of a voltage signal according to the present invention is carried out by utilizing one or more HFEVRs of the invention which comprise a coil magnetically coupled to an electromagnet, wherein said HFEVRs are connected to the primary and/or secondary coil(s) of a voltage transformer via their coils, and wherein the voltage over the primary and/or secondary coil(s) of said transformer is regulated by adjusting the value of the reactive resistance of said coils of said HFEVRs by suitable control signal provided to the their electromagnets.

Abstract: A synchronous rectification and voltage stabilization circuit includes a saturable inductance coil (L1), a synchronous rectifier switch (33), a driving coil (L2) for turning on the synchronous rectifier switch, a discharging coil (L3) which co-operates with a controllable switching component (Q1) to turn off the synchronous rectifier switch, a filter circuit (40) and a voltage stabilization circuit (50). The saturable inductance coil, the synchronous rectifier switch and the filter circuit are connected in serial between an input terminal (10) and an output terminal (20). The saturable inductance coil is coiled together with the driving coil and the discharging coil on one core. The voltage stabilization circuit is connected between the output terminal and the saturable inductance coil, and is used for regulating a regulable saturation point of the saturable inductance coil according to an output voltage of the output terminal and a target value of the output voltage.

Abstract: A control apparatus for controlling a three- or single-phase semiconductor power converter employing fixed-pulse switching patterns superposes a DC component on an AC output voltage, to suppress asymmetrical magnetization of a transformer connected to the power converter. The three-phase semiconductor power converter 1 provides an AC output. The voltage of the AC output is changed by the transformer 12.

Abstract: A magnetic phase shifter utilizing the principle of magnetic amplifier is used as a phase shifter for applying a firing signal to a main thyristor. In order to amplify and sharpen the rise of the output pulse of the magnetic phase shifter, an auxiliary thyristor is fired by the output pulse of the magnetic phase shifter. The gate-cathode circuit of the main thyristor is connected to the auxiliary thyristor as a load thereof. Power for the auxiliary thyristor is obtained from an AC power supply which is in phase with the main thyristor through a transformer, while power for the magnetic phase shifter is introduced from an intermediate tap of the secondary winding of the transformer, thus making the magnetic phase shifter compact as well as low in cost.