Abstract: A soft switching system DC-DC converter includes a switching element, a transformer or a reactor, and a controller configured to control a switching operation of the switching element; and carries out the switching operation of the switching element in a state that a voltage or a current to be applied to the switching element is zero. In a case where a required output value of the DC-DC converter is lower than the minimum output over which soft switching is established, the controller controls the operation of the switching element so that an operation period in which an output of the DC-DC converter becomes the minimum output or higher and a stop period in which the output becomes zero are alternately repeated.

Abstract: A dynamo-electric machine includes: a stator (5) having a plurality of stator coils (9); a rotor (1) surrounded by the stator (5), having a magnetically anisotropic rotor core (11), a plurality of permanent magnets (3) and at least one magnetically isotropic core element (24); a magnetic shunt (4) configured to shunt the magnetic flux of the at least one of the permanent magnets (3); and a shunt drive mechanism configured to locate the magnetic shunt (4) against the at least one magnetically isotropic core element (24).

Abstract: An electric motor (10) of the present invention includes: a stator (11); a rotor (12) axially supported to a rotational shaft (13) in such a configuration as to rotate relative to the stator (11), the rotor (12) being adapted to be cooled by a cooling medium (L); a cooling medium storing portion (60) disposed on the stator (11) side and storing therein (60) the cooling medium (L); and a cooling medium channel (22) for leading the cooling medium (L) from the cooling medium storing portion (60) to the rotor (12), wherein a discharge port (23a) for discharging the cooling medium (L) of the cooling medium channel (22) is disposed close to a rotational portion (18a) of the rotor (12), the cooling medium storing portion (60) is disposed lower than the discharge port (23a), and a negative pressure caused between the rotor (12) and the discharge port (23a) sucks the cooling medium (L) in the cooling medium storing portion (60).

Abstract: An electric motor includes a stator, at least one rotor, an output shaft engaged with the at least one rotor, and a contact area changing device configured to change an area of contact between the at least one rotor and the output shaft, wherein the area of contact between the at least one rotor and the output shaft affects a characteristic resonant frequency of the at least one rotor. A method to reduce vibrations in an electric motor includes engaging an output shaft into at least one rotor, rotating the output shaft and the at least one rotor with respect to a stator, changing an area of contact between the at least one rotor and a radial protrusion of the output shaft, and shifting the resonant frequency of the at least one rotor with the changed area of contact.

Abstract: An electric motor (10) of the present invention includes: a stator (11); a rotor (12) axially supported to a rotational shaft (13) in such a configuration as to rotate relative to the stator (11), the rotor (12) being adapted to be cooled by a cooling medium (L); a cooling medium storing portion (60) disposed on the stator (11) side and storing therein (60) the cooling medium (L); and a cooling medium channel (22) for leading the cooling medium (L) from the cooling medium storing portion (60) to the rotor (12), wherein a discharge port (23a) for discharging the cooling medium (L) of the cooling medium channel (22) is disposed close to a rotational portion (18a) of the rotor (12), the cooling medium storing portion (60) is disposed lower than the discharge port (23a), and a negative pressure caused between the rotor (12) and the discharge port (23a) sucks the cooling medium (L) in the cooling medium storing portion (60).

Abstract: An electric motor includes a stator, at least one rotor, an output shaft engaged with the at least one rotor, and a contact area changing device configured to change an area of contact between the at least one rotor and the output shaft, wherein the area of contact between the at least one rotor and the output shaft affects a characteristic resonant frequency of the at least one rotor. A method to reduce vibrations in an electric motor includes engaging an output shaft into at least one rotor, rotating the output shaft and the at least one rotor with respect to a stator, changing an area of contact between the at least one rotor and a radial protrusion of the output shaft, and shifting the resonant frequency of the at least one rotor with the changed area of contact.

Abstract: A four-wheel drive system for a hybrid vehicle includes at least two motor-generators and a single engine connected to a differential having multiple degrees of freedom. In some embodiments, by adjusting the outputs of the motor-generators, a controller allocates power from the engine, to or from each of the motor-generators, to the front wheels and to the rear wheels, each of which is connected to an element of the differential. The relationship between the elements of the differential is represented by an alignment chart of the differential.

Abstract: A four-wheel drive system for a hybrid vehicle includes at least two motor-generators and a single engine connected to a differential having multiple degrees of freedom. In some embodiments, by adjusting the outputs of the motor-generators, a controller allocates power from the engine, to or from each of the motor-generators, to the front wheels and to the rear wheels, each of which is connected to an element of the differential. The relationship between the elements of the differential is represented by an alignment chart of the differential.