Hitachi Industrial Equipment Systems Co., Ltd.

Yusaku Onuma

Hiroshi Watanabe

Satoru Kaneko

Takuya Sugimoto

Kazuaki Tobari

Yoshitaka Iwaji

Agnes Hadinata

Yusuke Arao

Hiroyuki Tomita

Shigehisa Aoyagi

Atsuhiko Nakamura

Yoshiyuki Taguchi

Masahiro Hiraga

Ryoichi Takahata

Daigo Kaneko

Midori Takaoka

Kazushige Hotta

Yoichiro Arakawa

Mutsuo Tokashiki

Masato Ohya

Yuuta Iwase

Masataka Sasaki

Hironori Oohashi

The present invention achieves highly accurate control characteristics by estimating an induced voltage coefficient of a magnet motor without rotary auto-tuning. A first power Pc is calculated on the basis of the output voltage and output current of the magnet motor, and a second power P{circumflex over ( )} is calculated on the basis of the electric circuit constant, current command, output frequency, and induced voltage coefficient of the magnet motor. The induced voltage coefficient is estimated so that the calculated first power follows the second power, and the driving of the magnet motor is controlled in accordance with the induced voltage coefficient.

Power conversion device

The purpose of the present invention is to provide a power conversion device capable of suppressing an increase in current flowing through a motor even if a voltage command exceeds the amplitude of a carrier wave. To achieve the above purpose, a power conversion device, which controls the drive of a three-phase motor by converting a DC voltage into a voltage command-based voltage through the operation of a switching circuit, comprises: a DC voltage detector which detects a DC voltage; a norm generator which generates a voltage command norm from the voltage command; a modulated wave generator which generates a first modulated wave from the detected DC voltage and the voltage command norm; and a control signal generator which generates a control signal for controlling the operation of the switching circuit from the first modulated wave and the carrier wave, wherein the modulated wave generator generates, for one phase at the timing of the maximum or minimum value of the voltage command, a first modulated wave having a magnitude of ½ of the detected DC voltage, and generates, for the remaining two phases, a first modulated wave having a magnitude based on the detected DC voltage and voltage command norm.

Power conversion device and control method thereof

An object of the present invention is to provide a power conversion device capable of suppressing an increase in a current flowing through a motor even if a voltage command exceeds the amplitude of a carrier wave. In order to achieve the above object, the power conversion device controls the driving of a motor by converting a DC voltage into a voltage based on a voltage command by an operation of a switching circuit and includes: a modulated wave generator that generates a first modulated wave from the voltage command; and a control signal generator that generates a control signal for controlling the operation of the switching circuit from the first modulated wave and a carrier wave. The modulated wave generator generates a square wave based on a voltage command norm as the first modulated wave.

Power conversion device and method for controlling same

The purpose of the present invention is to provide a speed detection method for maintaining a fine time axis resolution and a power conversion device that uses the method. This power conversion device comprises an inverter for converting DC voltage into AC voltage and supplying the same to a motor, a motor speed calculation unit for calculating the speed of the motor from output pulses obtained from an encoder connected to the motor, and a control unit for receiving the motor speed from the motor speed calculation unit and controlling the inverter. In the power conversion device, the motor speed calculation unit measures the duty cycle of the output pulses, calculates the speed using the half cycles of the output pulses if the duty cycle is within a prescribed range from 50%, and calculates the speed using the full cycles of the output pulses if the duty ratio is outside of the prescribed range from 50%.

Speed calculation device and 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.

A power conversion apparatus controls a load apparatus by position sensorless vector control. The power conversion apparatus includes: a current detection unit configured to detect a current passing through the load apparatus; a current detection arithmetic unit configured to calculate a harmonic current component on a dc-axis as a control axis and a harmonic current component on a qc-axis, based on the detected current; a saliency ratio estimation unit configured to output a saliency ratio estimated value based on the harmonic current component on the dc-axis and the harmonic current component on the qc-axis; and a saliency ratio control unit configured to output a current component that increases or decreases a current command value on a d-axis of a rotor coordinate system, based on a deviation between the saliency ratio estimated value and a predetermined saliency ratio.

Power conversion apparatus

Provided is an AC electric motor control device capable of detecting, in an AC electric motor drive device, abnormal operation of an AC electric motor or abnormal operation due to, for example, a sudden change of a load without an erroneous operation regardless of the operational state of the AC electric motor. When driving a three-phase AC electric motor by an inverter, inside a controller, an electric motor constant is calculated using at least one of the current, voltage, and rotational speed of the electric motor and the variation of the constant value is analyzed, thereby detecting abnormal operation of the electric motor or abnormal operation of a load device connected to the electric motor. In order to analyze the constant, a variation to be determined to be abnormal is preset or an abnormal value is calculated in comparison with the accumulated values of past constant changes. Alternatively, only the variation of the constant calculated in the controller is extracted to detect abnormality.

AC electric motor control device

According to the present invention, in position sensorless control for switching between a 120-degree energization scheme for a low-speed region and a 180-degree energization scheme for a mid-to-high-speed region, stable and highly accurate speed control characteristics are provided by suppressing speed deviation &#x394;&#x3c9;r in the low-speed region, and by preventing current jump-up caused by a discontinuous rotational speed occurring during switching to the mid-to-high-speed region. In the case of driving in the 120-degree energization scheme, a voltage command value is corrected such that an estimated speed value or a detected speed value follows a speed command.

Synchronous motor control apparatus

An electric power converting apparatus includes a switching circuit, a PWM controller, conducting PWM all phase shut-off and zero-vector outputting, a unit configured to detect or estimate current flowing through a motor, a unit configured to conduct a DC braking, and a current comparator configured to compare between a DC braking time maximum current setup value, and a current value obtained by the unit configured to detect or estimate current. The PWM all phase shut-off and zero-vector outputting are conducted, repetitively, by the PWM controller, if the current comparator determines that a current value, which is obtained by the unit configured to detect or estimate current, exceeds the DC braking time maximum current setup value, when conducting the DC braking to obtain a braking power by running current through the motor.

Power converter device

A power converter device for achieving a stable braking operation, preventing excessive current to flow therein, when conducting DC braking on a permanent synchronous motor, comprises: a switching circuit for converting DC to AC; a PWM controller means, for controlling ON or OFF of said switching circuit; a means for detecting or estimating current flowing through a permanent magnet synchronous motor; and a means for executing DC braking of said permanent magnet synchronous motor, wherein there are provided a DC braking maximum current setup value, which is determined from an outside or is determined in advance within an inside, and a PWM all-phases cutoff function and a zero vector output function within said PWM controller means, within said PWM controller means, whereby the PWM all-phases cutoff and the zero vector output are repeated within said PWM controller means, if a current value, which is obtained by said means for detecting or estimating the current, exceeds said DC braking maximum current setup value, when running DC current to the permanent magnet synchronous motor, so as to execute DC braking for obtaining a braking power.

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Tokyo, Japan

Yusaku Onuma