Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Hitachi Device Eng. Co., Ltd.

Hitachi Nisshin Electronics Co., Ltd.

Ikuo Yamato

Norikazu Tokunaga

Yasuo Matsuda

Hidefumi Shirahama

Hisao Amano

Hiromi Inaba

Yoshimi Sakurai

Hideki Miyazaki

Tsunehiro Endo

Kenichi Onda

Yutaka Suzuki

Akira Kobayashi

Yasuo Notohara

Atsuya Fujino

Tadashi Fukushima

Kouki Yamamoto

Keizo Shimada

Daigo Kaneko

Yuzo Morita

Teruaki Odaka

Hideki Ayano

Yorito Jifuku

Naoto Ohnuma

Shoichi Noguchi

Mitsufumi Iwanaka

Takeshi Nagano

Tomoaki Mino

Akihiro Tanba

Youuji Ishida

Satoru Inukai

In order to control the position of a mobile body without using a position detector, a magnetic pole position of a rotor of a synchronous motor is estimated based on electrical quantities in relation to electric power supplied to the synchronous motor and then the mobile body position is estimated based on the estimated magnetic pole position.

Apparatus, method or system for controlling mobile body

There is provided a vehicle operating system constituted of a vehicle and at least a charging apparatus, the system comprising means for enabling high-precision unmanned positioning, despite primarily vertical displacements of the vehicle due to changes in tire pressure or weight of a passenger or passengers, and hence enabling efficient, stable power feeding. The charging apparatus includes a power feeding unit, and a vehicle includes a power receiving unit for feeding power in a noncontact manner, which makes possible recharging without manual assistance. A C-shaped transformer and an I-shaped transformer are used for the power feeding unit and the power receiving unit, respectively, so that a magnetic flux induced therebetween can develop substantially in the horizontal direction, thereby feeding power stably despite changes in tire pressure and the like. Tire guides for guiding the vehicle to a power feeding position and a car stop are so used that when the vehicle comes in contact with the car stop, the power feeding unit and the power receiving unit will face each other in a correct position, thus enabling high-precision positioning at power feeding time.

Vehicle operating system

A circuit for controlling the outdoor unit of an air conditioner comprises a microcomputer which controls two brushless motors and a microcomputer which controls the whole outdoor unit. In accordance with the present invention, separation of a function for controlling the brushless motors from a function for controlling the whole outdoor unit can simplify software for said microcomputers.

Air conditioner and brushless motor control unit

In a uninterruptible power supply in which a plurality of inverters are operated in parallel, a current control loop is provided which responds to the magnitude of an output current of each inverter brought into parallel running to change a command value for a voltage waveform control circuit associated with each inverter, and the gain of the current control loop is made to be variable, whereby currents shared by the inverters can be set desirably to effectively suppress a cross current flowing between the inverters upon establishment of parallel running.

Inverter apparatus and uinterruptible power supply using the same

A power supply control system including a variable power converter for converting electric power from a power supply to a load into that of a specification required by the load in response to a power specification information source provided on the load side. With a change in the load, the information source also changes, thereby providing a flexible power supply control system capable of meeting different loads. For applications to a high power supply, the system comprises a plurality of variable power converters adapted to operate selectively in accordance with requisite power information sources provided in or on the side of a plurality of loads, thereby providing a system realizing a flexible power supply. For application to a low power supply, the system comprises a plug having a power specification information source and a socket having a variable power converter.

Power supply control system

A three-phase a.c. uninterruptible power supply includes a transformer providing isolation between an input and an output, a single-phase inverter, and a cycloconverter. The uninterruptible power supply operates to convert a d.c. voltage into a high-frequency a.c. voltage in the single-phase inverter, transmit the output voltage of the single-phase inverter in an isolated state, and convert the output of the transformer into a three-phase voltage having a lower frequency, such as 50 or 60 Hz, than the frequency of the output voltage of the single-phase inverter. This enables the transformer providing isolation to operate at a high frequency, thereby enabling the size of the transformer to be reduced.

Power conversion system, method for controlling the same, and

A structure is disclosed in which instantaneous phase and voltage difference values between the output voltage waveform from an inverter and the output voltage waveform from another AC power source are detected to correct the phase and the level of the output voltage waveform from the inverter so that the phase difference and the voltage difference can be controlled at high speed. As a result, excess current, which occurs if the inverter is operated at high frequencies, can be effectively controlled so that a stable parallel operation of the inverter with another AC power source is possible to perform.

Parallel inverter control apparatus

A mathematical model for simulating a dynamic characteristic of an electric power supply apparatus, a model control function for controlling an output from the mathematical model in a closed loop fashion and an electric power supply apparatus control function for approximating a control variable for the electric power supply apparatus to a reference value are provided in a control circuit, wherein an output from the mathematical model is output as a pulse width reference signal, and the pulse width reference signal is corrected by an on-delay portion due to switching elements by means of a gain revision circuit, thereby promptly and stably controlling the electric power supply apparatus.

Circuit for controlling an electric power supply apparatus, a method

In a power conversion system, a DC voltage of a DC power supply is converted into a predetermined high-frequency voltage by an inverter, and a high-frequency low voltage generated from the inverter is converted into a high-frequency high voltage by a transformer. A high-frequency high voltage generated from a secondary winding of the transformer is converted into a predetermined low-frequency voltage by a frequency changing circuit. The commutating operation of the frequency changing circuit is performed by a control circuit in response to the output current of the frequency changing circuit and in synchronism with the starting time of the short-circuiting prevention period of the inverter. As a result, the converted output of the power conversion system is prevented from decreasing.

Pulse width modulated inverter with high-to-low frequency output

A power conversion apparatus comprises an inverter for converting a voltage of a DC power source into AC power having a frequency higher than the commercial frequency, a transformer, fed by the inverter, for outputting AC power, which is adjusted at a desired voltage, a frequency converter, formed by two pairs of two gate turn-off thyristors (GTOs) connected in reverse-parallel, for converting the frequency of the AC power supplied from the transformer into the commercial frequency, and an energy regenerating device having capacitors for absorbing the energy of a spike voltage occurring due to a circuit inductance upon interruption of a current of each GTO of the frequency converter and a bridge circuit, formed by GTOs and diodes connected in reverse-paralel therewith, for switching over the direction of connecting the capacitors with a secondary winding of the transformer in accordance with the polarity of a voltage of the secondary winding in such a manner that the energy stored in the capacitors is regenerated to the transformer.

Current and frequency converter having means to reduce switching losses

A switching power supply, in which a series circuit consisting of a primary winding of a transformer and a controllable switch is connected with a DC power source and a secondary winding of the transformer is connected with a first voltage source outputting the voltage developed across the secondary winding during the on-period of the controllable switch and a second voltage source storing the exciting energy of the transformer during the off-period of the controllable switch by using the exciting inductance of the transformer as a current source, a series circuit consisting of the first and the second voltage sources being connected with a load. Owing to this construction, even if voltage-current characteristic of a load having constant voltage characteristic, such as a magnetron, vary due to variations in the temperature, etc., the output voltage is automatically compensated and a stable electric power can be supplied to the load.

Switching power supply

Growing community of inventors

Hitachi, Japan

Ikuo Yamato