Hitachi Industrial Equipment Systems Co., Ltd.

Hitachi, Ltd.

Masakazu Hase

Hiroyuki Matsuda

Hideharu Tanaka

Masahiko Takano

Hajime Uematsu

Kenji Morita

Yoshitaka Iwaji

Kazuaki Tobari

Masakazu Aoki

Takashi Nakajima

Shigeyuki Yorikane

Kiyoshi Sakamoto

Norinaga Suzuki

Daigo Kaneko

Yoshiyuki Taguchi

Tomofumi Okubo

Akira Iyozumi

Yoshihiko Sagawa

Tomotake Sakaguchi

A gas compressor includes a compressor main body, an electric motor that supplies driving force to the compressor main body, a power conversion device, a plurality of air release valves disposed in a plurality of air release systems communicating with a discharge piping system to discharge the compressed gas to an atmospheric pressure environment, and a controller. The gas compressor performing an unload operation of reducing, when a discharge pressure reaches a predetermined pressure, a load on the compressor main body by opening one of the air release valves. The gas compressor including the plurality air release systems for each of which the air release value is disposed, and a plurality of pressure regulating valves provided on a downstream side of each air release valve, respectively, wherein the controller selects one of the air release valves and performs the unload operation.

Gas compressor with a plurality of air realease systems each having an air release valve and an air regulating valve

A technique is provided that can further reduce power at the time of 'unload operation control' in a gas compressor that generates a compressed gas at a set pressure by constant-speed control. The gas compressor includes a compressor main unit, a drive source, an intake throttle valve, a gas release valve, rotation speed converting means, a pressure detecting device that detects a discharge pressure, and a controller that, the relationship between an upper-limit pressure H and a lower-limit pressure L being H&#x3e;L, carries out opening the intake throttle valve and closing the gas release valve and operating the drive source at a full-load rotation speed until the discharge pressure reaches the upper-limit pressure H. The controller carries out at least one of closing the intake throttle valve and opening the gas release valve to reduce the discharge pressure to within a predetermined range when the discharge pressure reaches the upper-limit pressure H. The controller carries out switching to load operation when the discharge pressure drops to the lower-limit pressure L. In the gas compressor, the controller outputs a command of a lower rotation speed than the full-load rotation speed to the rotation speed converting means when the discharge pressure rises and reaches the upper-limit pressure H. The controller outputs a command of the full-load rotation speed to the rotation speed converting means when the discharge pressure drops and reaches the lower-limit pressure L.

Gas compressor

Disclosed is a motor control apparatus for controlling a synchronous motor, which includes a receiver section for receiving the value detected by a temperature sensor installed inside the synchronous motor. The synchronous motor is started up with the current fed into it, whose magnitude is changed in accordance with the temperature received by the receiver section at the time of starting up the synchronous motor. In this way, the stable startup of the synchronous motor can be guaranteed and the useful life of the semiconductor elements can also be prolonged.

Motor controller, air compressor, air conditioner, controller of passenger conveyor and controller of conveyor

The present invention is a compressor compressing air, an electric motor driving the compressor, and an inverter variably controlling a rotating speed of the electric motor, the compressed air manufacturing facility is provided with a pressure sensor detecting a discharge pressure of the compressor at an upstream side position of a discharge air system connected to a discharge side of the compressor, and a control apparatus computing a pressure loss of the discharge air system in correspondence to a rotating speed of the electric motor, and changing a control range of the discharge pressure of the compressor at the upstream side position of the discharge air system on the basis of the computation in such a manner that a terminal pressure at a downstream side position of the discharge air system comes to a predetermined range.

Compressed air manufacturing facility

In order to provide a compressed air manufacturing facility which can increase a stability of a supply pressure while obtaining an energy saving effect, in a compressed air manufacturing facility provided with a compressor compressing an air, an electric motor driving the compressor, and an inverter variably controlling a rotating speed of the electric motor, the compressed air manufacturing facility is provided with a pressure sensor detecting a discharge pressure of the compressor at an upstream side position of a discharge air system connected to a discharge side of the compressor, and a control apparatus computing a pressure loss of the discharge air system in correspondence to a rotating speed of the electric motor, and changing a control range of the discharge pressure of the compressor at the upstream side position of the discharge air system on the basis of the computation in such a manner that a terminal pressure at a downstream side position of the discharge air system comes to a predetermined range, and variably controlling the rotating speed of the electric motor via the inverter in such a manner that the discharge pressure of the compressor detected by the pressure sensor comes to the changed control range.

In a driving system for an inverter that uses a diode rectifying circuit to convert a single-phase or three-phase AC voltage to a desired DC voltage and drives a permanent magnet motor, a DC-voltage pulsating frequency is estimated from a pulsating frequency setting calculated from the power supply frequency of an AC voltage and the detected current values of the inverter, and the resulting estimated pulsating frequency value and detected current values are used to correct the output voltage of the inverter.

Beat-less controller for permanent magnet motor

Current command values are used instead of detected current values to estimate axis error by calculation. An axis error command value is generated according to a speed command value, and a difference between the generated axis error command value and the estimated axis error value is used to control an estimated frequency value.

Highly responsive permanent magnet motor controller

Air compressor

A compressed air production facility includes at least one variable speed compressor and a plurality of constant speed compressor, which are connected in parallel with one another. The variable speed compressor and the plurality of constant speed compressors are capacitively controlled with the use of a pressure in an air reservoir into which discharge air from these compressor are led. Both upper limit pressure at which the variable speed compressor is turned into its load operation mode into its unload operation mode and a lower limit pressure at which the variable speed compressor is turned into its unload operation mode into its load operation mode are set between an upper limit change-over pressure at which all of the plurality of constant speed compressors are turned into their load operation into their unload operation and a lower limit change-over pressure at which all of the plurality of constant speed compressors are changed over from their unload operation into their load operation. With this arrangement, it is possible to provide a power consumption characteristic which is substantially proportional to an air consumption.

Growing community of inventors

Shizuoka, Japan

Masakazu Hase