Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Kenichi Iizuka

Hideo Uzuhashi

Minoru Kobayashi

Hideo Aoki

Fumio Tajima

Yuzo Kadomukai

Kunio Miyashita

Tsunehiro Endo

Masaaki Fujinawa

Yozo Nakamura

Hiroaki Hata

Mitsuru Nakamura

Masahiko Sugiyama

Tunehiro Endo

Koujirou Yamashita

Motokazu Uchida

Kiyoo Takeyasu

Susumu Kashiwazaki

Yoshihisa Uneyama

Ryoichi Fujimoto

Morio Kobayashi

Tooru Kitayama

Michiya Matuda

Takashi Seshita

Akihisa Hamaguchi

Noriaki Arawaka

Nobuaki Kato

Stunehiro Endo

A torque control unit rotates a motor machine having a motor element and a load element. The load element is coupled to the motor element via a rotational main shaft and driven to rotate by the motor element. Rotational acceleration at each rotation angle during one revolution of the rotational main shaft is detected and fed back. An electromagnetic torque of the motor element is controlled so that a difference between the electromagnetic torque of the motor element and a load torque of the load element may become zero at each rotation angle of the rotational main shaft.

Torque control apparatus for rotating motor machine

In speed control apparatus and method for a motor operable to drive a load whose magnitude varies over a predetermined period which use a unit for controlling voltage or current supplied to the motor such that the speed of the motor can coincide with a command speed, n pieces of data indicative of voltages or currents supplied to the motor and corresponding to n divisions of the predetermined period are independently stored in a read/write storage, at least one of the n pieces of data is corrected at the rate of each of the n divisions in accordance with a difference between the command speed and the speed of the motor, and the voltage or current supplied to the motor is controlled in accordance with at least the one of the n pieces of data, so that pulsation and noise occurring especially under low revolutions can be minimized.

Speed control apparatus and method for motors

AC power supply is converted to DC by a rectifier circuit. The DC is stepped up by a step-up chopper circuit. The output of the step-up chopper circuit is smoothed by a smoothing circuit. The output of the smoothing circuit is input to an inverter via a current detecting circuit and a voltage detecting circuit. A synchronous motor is connected to the inverter. When the speed of the synchronous motor is judged to be in a high speed region based on the output signal of the voltage detecting circuit, the first speed control apparatus operates the interrupting control of the switching element of the step-up chopper circuit in such a manner that a deviation speed between an instruction speed signal to the motor and the detected speed of the motor reaches to zero. When the duty ratio of the inverter reaches to 100%, that is, when the speed of the motor reaches to a low speed region, the first control speed apparatus controls the switching element of the step-up chopper circuit based on the output signal of the current detecting circuit, and the second control speed apparatus carries out the pulse width modulation control of the inverter in such a manner that a deviation speed signal between an speed instruction signal to the motor and the detected speed of the motor reaches to zero.

Speed control apparatus for a brushless direct current motor

A method of magnetizing a rotor of a motor including the rotor made of an integrated magnet member and a stator is provided. Predetermined magnetic fields are preliminarily applied to the rotor to form magnetic paths and thereafter, the rotor is demagnetized. Then, the rotor is assembled into the stator. The rotor and stator are positioned such that the directions of the magnetic fields which are generated from the stator winding of the stator coincide with the directions of the magnetic paths of the rotor. Subsequently, in the state in which both of the rotor and stator are positioned, a current is supplied to the stator winding and the magnetic fields are generated, thereby magnetizing the rotor by the magnetic fields.

Method of magnetizing rotor of motor

A refrigerator temperature control system is disclosed in which the compressor for compressing a refrigerant is driven selectively at either a normal lower rotation speed or a higher rotational speed and the higher rotational speed is applied only when any of the freezer compartment temperature and the fresh food compartment temperature is not reduced below a predetermined temperature level for at least a predetermined time interval.

Refrigerator temperature control system

An inverting apparatus comprises: a capacitor input type rectifying circuit consisting of a full-wave rectifier and a smoothing capacitor; a single-phase bridge inverter having four semiconductor switches; and a driving control unit for opening and closing the semiconductor switches, wherein the smoothing capacitor is provided with a switch to open and close the smoothing capacitor.

Inverting apparatus

The present invention continuously speed-controls an electric motor for driving a compressor for refrigerant compression such that the compressor is driven in its maximum rpm if the difference (temperature deviation) between a target cooling temperature and an actual temperature is greater than a first predetermined value, the compressor is stopped if the temperature deviation is less than a second predetermined value, and the compressor is speed-controlled by a digital control signal if the temperature deviation is between said first and second predetermined values.

System of controlling refrigerator temperature

A novel refrigerator control system is disclosed which comprises an inverter for driving a motor for a compressor, and a change-over device for driving the compressor directly with a commercial power supply when the compressor motor is not driven by the inverter.

Refrigerator control system

In a control system for a brushless motor comprising a power source, a plurality of driving coils and contactless switching elements for intermittently supplying voltage across the power source to the driving coils in response to rotor position signals, rotor position signals are chopped by a chopping signal in which a ratio of a high level period to a low level period can be changed, and a portion of the contactless switching elements is driven by the chopped rotor position signals, thereby controlling the rotating speed of the brushless motor.

Control system for a brushless motor

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Ashikaga, Japan

Kenichi Iizuka