Hitachi Astemo Ltd.

Hitachi, Ltd.

Hitachi Industrial Equipment Systems Co., Ltd.

Hitachi-johnson Controls Air Conditioning, Inc.

Hitachi Appliances, Inc

Wataru Hatsuse

Masaki Koyama

Takahiro Suzuki

Shuhei Nagata

Tsutomu Ito

Kenji Tamura

Kazuaki Tobari

Shigehisa Aoyagi

Yasuo Notohara

Yoshinori Kawai

Kaito Hotta

Dongsheng Li

Kentaro Oi

Eri Maruyama

Yoji Ogura

Ryouichi Takahata

Kazuhiro Ueta

Yuuji Funayama

A highly reliable and highly efficient air suspension system for a vehicle is provided by improving the trackability of stroke control with respect to pressure fluctuations applied to a linear compressor, suppressing stroke increase due to pressure drop, preventing piston collision, and increasing a flow rate by reducing dead volume. To realize this, the air suspension system includes an air suspension that supplies and discharges compressed air to adjust a length, a compressor body in which a piston reciprocates in a cylinder to compress air, a linear motor that reciprocates the piston, a tank that is connected to the air suspension or the compressor body and stores compressed air, a solenoid valve that opens and closes the air suspension or the tank, and an inverter that changes power supplied to the linear motor according to an open and closed state of the solenoid valve to perform position control of the piston.

Air suspension system and camera cleaning system

Controllability of a linear motor or a compressor is improved in a linear motor system that includes: an armature having magnetic poles and winding wires; a mover having a permanent magnet; and a power conversion unit that outputs AC power to the winding wires, in which the mover and the armature are relatively movable, and the mover or the armature is connected to an elastic body. The linear motor system further includes: a position detection unit that detects and outputs the position of the mover with respect to the armature, a position estimation, or a current detection unit that outputs the value of current flowing through the winding wires; and a control unit that controls the output of the power conversion unit on the basis of the output of the position detection unit, the output of the position estimation unit, or the output of the current detection unit.

Linear motor system and compressor

Provided are a linear compressor and a linear compressor control system that do not require a sensor for detecting a position of a mover, and can compute a mover position with high accuracy, in consideration of position dependency of an induced voltage constant. A linear compressorincludes a field elementhaving a first end connected to elastic bodies (and) and including a permanent magnet, an armaturehaving a windingwound around a magnetic pole, and a linear motorthat causes the field elementand the armatureto reciprocate relatively in an axial direction. A stroke of a piston is controlled so that a portion where a gradient of an induced voltage when the induced voltage computed on the basis of a voltage command value output to the linear motorand a value of a current flowing through the windingis at a predetermined value is within a predetermined range corresponds to a top dead center and/or a bottom dead center of a stroke of a pistonconnected to a second end of the field element

Linear compressor and linear compressor control system

Provided is a linear motor control apparatus capable of improving estimation accuracy of a resonance frequency immediately after start, and a compressor equipped with the linear motor control apparatus. A linear motor control apparatus includes a winding to which an AC voltage is applied and a mover which is connected to an elastic body, in which the linear motor control apparatus includes an operation mode (1) which monotonously increases amplitude of the AC voltage while keeping a frequency of the AC voltage substantially constant, and an operation mode (2) which changes the frequency of the AC voltage while keeping the amplitude of the AC voltage substantially constant, and executes the operation mode (1) and the operation mode (2) in this order.

Linear motor control apparatus and compressor equipped with the same

Provided are a power conversion device and a system using the same, which can reduce loss of each semiconductor element in a power conversion circuit and enable high efficiency of a device controlled by the power conversion device. The power conversion device includes a direct current (DC) power source; and a full-bridge circuit having first upper and lower arms having an upper element and a lower element and second upper and lower arms having an upper element and a lower element, in which the first upper and lower arms and the second upper and lower arms are electrically connectable to a device, and ON resistances of the upper element of the first upper and lower arms and the lower element of the second upper and lower arms are smaller than ON resistances of the lower element of the first upper and lower arms and the upper element of the second upper and lower arms.

Power conversion device and system using the same

Controllability of a linear motor or a compressor is improved. There is provided a linear motor system that includes: an armature having magnetic poles and winding wires; a mover having a permanent magnet; and a power conversion unit that outputs AC power to the winding wires, in which the mover and the armature are relatively movable, and the mover or the armature is connected to an elastic body. The linear motor system further includes: a position detection unit that detects and outputs the position of the mover with respect to the armature, a position estimation, or a current detection unit that outputs the value of current flowing through the winding wires; and a control unit that controls the output of the power conversion unit on the basis of the output of the position detection unit, the output of the position estimation unit, or the output of the current detection unit. In the case where a signal having a frequency substantially the same as the frequency of the AC power is applied to the output of the position detection unit, to the output of the position estimation unit, or to the output of the current detection unit, the control unit changes the frequency of the AC power, and in the case where a signal having a frequency substantially larger than the frequency of the AC power is applied, the control unit keeps the frequency of the AC power substantially the same.

A boosting operation of a converter and the intermittent energization operation of an inverter are optimally performed in accordant with input or output. The power converter includes the converter capable of boosting a DC voltage outputted by switching operation alternately performing shorting and rectification; the inverter; an inverter capable of performing intermittent energization in which switching around zero cross of a motor current is turned off upon converting the DC voltage outputted by the converter into three-phase AC power; and a controller that controls the converter to perform boosting operation and the inverter to perform the boosting operation of the converter and the intermittent energization operation of the inverter linkingly.

Power converter and refrigeration air conditioner

A permanent magnet synchronous motor includes at least two series-connected windings for each phase, and is configured to be driven by selecting the windings using a multi-inverter driving device configured to switch between an inverter for low-speed drive and an inverter for high-speed drive. A ratio of an induced voltage constant of at least one group of windings constituting the windings for the high-speed drive and a d-axis inductance is larger than a ratio of an induced voltage constant of all the series-connected windings to the d-axis inductance.

Permanent magnet synchronous motor and winding-switching motor driving device, and refrigeration air conditioner and electric vehicle using same

The invention relates to a speed control method of a magnetic motor and is capable of providing a speed controller of the magnetic motor realizing highly stable, highly efficient and highly responsive control characteristics even around critical torque of the motor. When an excessive torque command value (or a q-axis commanded current value) greater than a torque maximum value (or a q-axis current) that can be outputted by the motor is required, an input of speed control is limited so that the q-axis commanded current value does not increase up to a limit value.

Growing community of inventors

Tokyo, Japan

Wataru Hatsuse