Abstract: An inverter device includes a power supply unit and a switch controller. The power supply unit supplies AC power to an AC motor whose electric characteristics in response to a rotation speed are switchable between low speed characteristics and high speed characteristics. The switch controller switches the electric characteristics of the AC motor. The switch controller executes switching control that alternately switches the electric characteristics of the AC motor between the low speed characteristics and the high speed characteristics on the basis of the rotation speed of the AC motor.

Abstract: A current source inverter device according to an embodiment includes an inverter that supplies AC power to a number n (integer of 1 or greater) of AC motors each having a number m (integer of 2 or greater) of windings per phase; and a controller that controls the inverter and AC motor. The inverter includes a switching unit, in which a number n×m+1 of switching elements per phase are connected in series, and a number n×m of nodes among the switching elements are respectively connected with a number n×m of different windings with the same phase among the windings of the number n of the AC motors. The controller includes a mode selector that selects at least one winding as a supply target of the AC power from the number n×m of the windings based on a rotation speed of the AC motor.

Abstract: An inverter device includes a power supply unit and a switch controller. The power supply unit supplies AC power to an AC motor whose electric characteristics in response to a rotation speed are switchable between low speed characteristics and high speed characteristics. The switch controller switches the electric characteristics of the AC motor. The switch controller executes switching control that alternately switches the electric characteristics of the AC motor between the low speed characteristics and the high speed characteristics on the basis of the rotation speed of the AC motor.

Abstract: It is an object to provide a winding switching device of a three-phase AC motor having a small size at a low cost in which a time required for switching a winding is shortened and the number of semiconductor switch units is decreased as much as possible.

Abstract: It is an object to provide a winding switching device of a three-phase AC motor having a small size at a low cost in which a time required for switching a winding is shortened and the number of semiconductor switch units is decreased as much as possible.

Abstract: A noise attenuation circuit is disclosed for use in a motor drive system. The motor drive system includes a pulse width modulated inverter providing three phase power output on three phase conductors for driving a motor. The noise attenuation circuit includes a common mode transformer including a common mode choke having a core, with first, second and third choke windings on the core, each connected in series with one of the three phase conductors, and a fourth winding on the core. A three phase iron core transformer creates a neutral point representing common mode voltage. The iron core transformer has three primary windings connected in a wye configuration. A capacitor circuit is connected between the iron core transformer and the three phase conductors to prevent saturation of the iron core transformer during pulsed DC operating conditions. The fourth winding is connected between the neutral point and the DC bus and develops a common mode voltage that is equal and opposite to that existing in the system.

Abstract: A noise attenuation circuit is used in a motor drive system. The motor drive system includes a variable frequency drive having a pulse width modulated inverter converting DC power from a DC bus to three-phase power output on three-phase conductors for driving a motor. The noise attenuation circuit comprises a common-mode transformer including a common mode choke having a core, with first, second and third choke windings on the core, each connected in series with one of the three phase conductors, and a fourth winding on the core. A three-phase iron core transformer creates a neutral point representing common mode voltage. The iron core transformer has three primary windings connected in a "wye" configuration to the three phase conductors.

Abstract: A power converting apparatus and a power converting method for driving a high voltage AC motor at a variable speed. Conventional invertor systems cannot solve technical subjects such as energy conservation, resource conservation, miniaturization, efficiency promotion and voltage and current waveform distortion suppression for improvement in environment needed by the market, and cannot solve another technical subject of improvement in redundancy such that, upon failure, operation is performed with a normal part.

Abstract: A bridge-type power converter has, in each phase, a inductor (L.sub.1) connected between a connection point of said two switching elements (Q.sub.1, Q.sub.2) and an output terminal; capacitors (C.sub.1, C.sub.2) connected between the output terminal and a positive or negative side of a d.c. bus for changing an output voltage along a curve determined by a phenomenon of resonance with the reactor (L.sub.1) when the semiconductors switching elements (Q.sub.1, Q.sub.2) operate, causing abrupt changes of a voltage at the connection point; diodes (D.sub.3, D.sub.4) for changing a current path at a time when the resonance goes approximately one quarter of period to thereby stop the resonance; and constant voltage diodes (ZD.sub.1, ZD.sub.2) for absorbing the energy stored in the inductor (L.sub.1) during the resonance.