Carrier Japan Corporation

Toshiba Carrier Corporation

Masayuki Yoshimura

Masaya Nogi

Ken Miura

Keiichi Ishida

Nariya Komazaki

Akihiro Ishigaya

According to one embodiment, a motor drive unit includes a motor including a plurality of phase windings in a mutually unconnected state, a first inverter which controls application of electric power to one ends of the phase windings, a second inverter which controls application of electric power to the other ends of the phase windings, relays each of which includes a make break contact connected between the other ends of the phase windings, and a controller which switches, according to a value of a current flowing through the motor, between an open-windings mode and a star-connection mode.

Motor drive unit and refrigeration cycle apparatus

According to one embodiment, a motor drive apparatus includes a first inverter, a second inverter, and a controller. This controller rotationally moves, at the time of startup of a motor, a rotor of the motor to an initial position by DC excitation of supplying DC exciting currents from the first and second inverters to the phase windings of the motor and, after this rotational movement, PWM-controls switching of the first and second inverters in such a manner that a rotational speed of the rotor becomes a target rotational speed. Then, the controller carries out the DC excitation fey which a zero-axis current in each of the phase windings becomes approximately zero.

Motor drive apparatus

According to one embodiment, when an effective value of an input current flowing into a booster circuit rises to a value greater than or equal to a second set value, boosting of the booster circuit is started and, after the start, when the effective value lowers to a value lower than a first set value lower than the second set value, boosting of the booster circuit is stopped. Then, if the three-phase AC source is in an unbalanced state, the first set value is set to a value lower than usual.

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Fuji, Japan

Masayuki Yoshimura