Hitachi Industrial Equipment Systems Co., Ltd.

Hitachi, Ltd.

Koganei Corporation

Yoshiyuki Taguchi

Kazuaki Tobari

Hiroshi Watanabe

Yoshitaka Iwaji

Takayuki Nakano

Yusaku Onuma

Atsuhiko Nakamura

Takuya Sugimoto

Tomofumi Okubo

Agnes Hadinata

Masahito Kato

Tsunehiro Endo

Hideharu Tanaka

Kiyoshi Sakamoto

Hidefumi Shirahama

Norinaga Suzuki

Masakazu Hase

Daigo Kaneko

Hajime Uematsu

Toshifumi Sakai

Yuta Iwase

A power conversion device comprising, a power converter that outputs signal to the motor to vary the motor's output frequency, output voltage and output current and control unit that controls the power converter, the control unit is, calculating the first power from the output voltage and output current, calculating the second power from the output current, electrical circuit parameters and frequency estimates, calculating the first phase error estimate so that the first power follows the second power in the first frequency domain, calculating the second phase error estimate different from the first frequency domain in a second frequency domain, controlling the frequency estimates so that the first phase error estimate or the second phase error estimate follows the command value of the phase error estimate.

Power conversion device

This power conversion device comprises: a power converter including a switching element; and a control unit which controls the power converter. The control unit calculates a torque electric current detection value and an excitation electric current detection value from an electric current flowing to an external device, and when an absolute value of the torque electric current detection value is greater than or equal to the excitation electric current detection value, performs control such that the excitation electric current detection value follows the torque electric current detection value.

A power conversion device includes a harmonic voltage generation unit that superimposes dc-axis and qc-axis harmonic voltages on dc-axis and qc-axis voltage commands in accordance with a switching signal; and an inductance estimation unit that estimates dc-axis inductance and qc-axis inductance on a basis of dc-axis and qc-axis harmonic currents, amplitude values of the harmonic voltages, and the switching signal.

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

When applying a high frequency voltage which alternates on positive and negative sides to a permanent magnet synchronous motor, a driving system of synchronous motor switches the applied voltage phase by 120 degrees successively and applies resultant voltages to three phases. A pulsating current generated by applying a high frequency voltage is detected at timing of elapse of a predetermined time &#x394;t since an output voltage of at least one phase has changed from a state in which all output voltages of the three phases of a power converter are positive or negative. Current detection is conducted by using a DC resistor or a phase current sensor provided on a DC bus. A magnetic pole estimation unit calculates the rotor magnetic pole position of the permanent magnet synchronous motor on the basis of differences between positive side and negative side change quantities in three-phase currents obtained from detected current values.

Driving system of permanent magnet synchronous motor

The object of the invention is to provide a method for cleaning circulation water, which reduces the cost of operation and maintenance as much as possible, without a cumbersome cleaning operation such as by detaching electrode plates from an electrolysis cleaning tank and removing scale from inside the tank, and to provide a device used in this method. Accordingly, the present invention provides a method for cleaning circulation water, comprising the steps of flowing circulation water to be cleaned between electrode plates placed in a face-to-face manner between one another; and applying DC voltage between the electrode plates, allowing one or more metal ions contained in the circulation water to be precipitated onto the negative electrode plates by electrolysis, to clean the circulation water, wherein the electrode plates used are made of titanium plates, and wherein a desired amount of current flows, while an anodized oxide coating formed on the surface of the positive electrode plates is compulsively subject to dielectric breakdown by increasing the voltage applied to the anodized oxide coating. FIG.is a representative drawing.

Method and device for cleaning circulation water

The object of the invention is to inhibit the axial displacement caused by the insufficiency of a control response angular frequency of a frequency arithmetic unit of a synchronous motor and realize high-precision torque control also in acceleration/deceleration. To achieve the object, the axial displacement of the synchronous motor caused by the insufficiency of the control response angular frequency of the frequency arithmetic unit is estimated in consideration of the control response angular frequency and input &#x394;&#x3b8;c(=&#x394;&#x3b8;c+&#x394;&#x3b8;c) including an estimated value &#x394;&#x3b8;cin addition to an axial displacement operated value &#x394;&#x3b8;cto the frequency arithmetic unit is acquired. Hereby, even if the frequency arithmetic unit has an insufficient control response angular frequency, the quantity of axial displacement which will be caused by the insufficiency is estimated as a second axial displacement signal &#x394;&#x3b8;c, is added and input. Therefore, actual axial displacement &#x394;&#x3b8;cof the synchronous motor is stable at a value substantially close to zero.

Control method and control device of permanent-magnet type synchronous motor

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Funabashi, Japan

Yoshiyuki Taguchi