Mitsubishi Electric Corporation

Disco Corporation

Mitsubishi Power, Ltd.

Yuichi Shimizu

Kazunori Hatakeyama

Keisuke Uemura

Atsushi Tsuchiya

Yasuhiko Wada

Kenji Takahashi

Kenji Sato

Akihiro Tsumura

Yuji Takayama

Yuki Taniyama

Ryuichi Matsubara

Yuji Nitta

Junji Morimoto

Tatsuya Furukawa

A power converter including: a non-boost rectifier circuit that converts a first alternating-current voltage into a direct-current voltage; a reactor connected to the rectifier circuit; a capacitor that smooths a direct-current voltage; an inverter that is connected in parallel to the capacitor, converts the smoothed direct-current voltage into a second alternating-current voltage having desired voltage and frequency, and outputs the second alternating-current voltage to a motor; and a controller that controls an operation of the inverter. Capacitances of the reactor and the capacitor are set such that a resonance frequency of a filter circuit including the reactor and the capacitor is smaller than a first electrical angular frequency based on a voltage command when the controller controls an operation of the inverter such that the second alternating-current voltage is maximized in a range not causing overmodulation.

Power converter and air conditioner

A drive device includes a power converter, a first magnetic pole position identification unit, a second magnetic pole position identification unit, a subtractor, and a current control unit. The power converter supplies power to a main-side synchronous motor and a sub-side synchronous motor connected in parallel. The subtractor obtains an angular difference using the magnetic pole position of the rotor of the main-side synchronous motor identified by the first magnetic pole position identification unit and the magnetic pole position of the rotor of the sub-side synchronous motor identified by the second magnetic pole position identification unit. A magnetic flux current command compensation unit adjusts the absolute value of a magnetic flux current command based on the angular difference. The current control unit controls the power converter using a torque current command and the magnetic flux current command with the absolute value adjusted by the magnetic flux current command compensation unit.

Drive device, fluid utilization device, and air conditioner

Included are a rectifier circuit that rectifies a first alternating-current voltage; a reactor connected to the rectifier circuit; a capacitor connected to an output end of the rectifier circuit; an inverter that is connected to the capacitor, generates a second alternating-current voltage through operations of a plurality of switching elements, and applies the second alternating-current voltage to a motor including a stator and a rotor; and a control unit that performs operation controls on the plurality of switching elements. The control unit causes the inverter to apply, to the motor, the second alternating-current voltage having a higher frequency than when the motor is in compression operation so as not to rotate the rotor. The application of the high-frequency second alternating-current voltage from the inverter to the motor generates a regenerative current and a current flows to the capacitor due to the regenerative current without impairing the capacitor.

Power conversion apparatus and air conditioner

A heat pump apparatus includes: a compressor including a motor; an inverter that applies a desired voltage to the motor; a current detector that detects current flowing to the motor; a drive-signal generation unit that generates a drive signal for the inverter; a magnetic-pole position estimation unit that changes a voltage phase of a voltage command value for a high-frequency voltage, and estimates a maximum-heat-amount acquisition magnetic-pole position when the generation unit applies the high-frequency voltage to the motor to heat the compressor; a steady heating control unit that determines an amplitude and voltage phase of the voltage command value from the maximum-heat-amount acquisition magnetic-pole position and a defined necessary amount of heat when the generation unit applies the high-frequency voltage to the motor to heat the compressor; and a control switching determination unit that causes one of the estimation unit and the heating control unit to operate.

Heat pump apparatus with compressor heating control

A motor drive device that drives motors with one inverter includes a step-out control unit that detects step-out in which the operating frequency of at least one of the motors does not match the inverter output frequency, or the operating frequency of at least one of the motors does not match the operating frequency of another one of the motors, and stops the motors by switching an energization state of the inverter when at least one of the motors is out of step.

Motor drive device and air conditioner

In a motor driving apparatus having an inverter which can drive n (n being an integer not smaller than 2) motors each having a permanent magnet in its rotor, and a connection switching device for switching the connection state of the n motors, the connection switching device is operated to change the number of the motors connected to the inverter thereby to change the impedance as seen from the inverter towards the motors. When i (i being any of 2 to n) motors among the n motors are concurrently driven by the inverter, the voltage outputted by the inverter may be controlled such that the inductance values of the i motors are identical. It is possible to prevent hunting and step-out due to the phase difference between the motors driven by the inverter.

Motor driving apparatus and refrigeration cycle equipment

An outdoor unit includes at least one heat exchanger, a first motor including a first fan, a second motor including a second fan, an inverter that applies voltage to the first motor and the second for respectively, a connection switching unit that switches the voltage applied to the second motor between on and off, and a control unit that controls the inverter and the connection switching unit. The inverter is disposed closer to the first motor than to the second motor.

Outdoor unit for a refrigeration cycle apparatus and refrigerating cycle device

A motor control device includes: an inverter circuit configured to convert a direct-current voltage into an alternating-current voltage, and to supply the alternating-current voltage to a plurality of motors connected in parallel; current detectors configured to detect motor currents flowing through the respective motors; a relay provided between at least one of the plurality of motors and the inverter circuit; and a controller configured to change the number of motors to be driven. When one of two or more motors under driving is stopped, the controller lowers a current instruction value to the two or more motors under driving. When a monitor current that is the motor current detected by the current detector of the motor connected to the relay is decreased, the controller switches the relay from an on state to an off state.

Motor control device and air-conditioning device

Prior to starting of first and second synchronous motors, direct-current excitation is performed to pull in rotors of the synchronous motors to a designated position. In the direct-current excitation, a difference between a value of a direct current flowing through the first synchronous motor and a value of a direct current flowing through the second synchronous motor is reduced. For example, d-axis currents and q-axis currents corresponding to three-phase currents flowing through the motors are determined; a d-axis voltage command value for making one of the d-axis currents larger in absolute value equal to a d-axis current command value is determined, and a q-axis voltage command value for making one of the q-axis currents larger in absolute value equal to a q-axis current command value is determined; an inverter is driven using the determined d-axis voltage command value and q-axis voltage command value.

Motor driving apparatus and air conditioner

There are provided at least two disconnection contactors each of which switches between connection and disconnection of each of at least two of three second power lines for supplying a three-phase alternating-current voltage generated by an inverter to a second PM motor, at least two short-circuit contactors each of which switches between connection and disconnection between the two second power lines of each of at least two of the pairs of the three second power lines, and a calculator to control the disconnection contactors and short-circuit contactors.

Motor driving device and air conditioner

In a motor driving apparatus including an inverter connectable to n motors (n being an integer not less than 2) each including a rotor having a permanent magnet, braking operation is performed on i (i being an integer from 1 to n&#x2212;1) of the n motors, and then braking operation is performed on j (j being an integer from 1 to n&#x2212;i) of the n motors other than the i motors. It is possible to reduce the risks of failure of the inverter and demagnetization of the motors due to overcurrent by reducing current flowing through the inverter and the motors when the braking operation is performed.

A motor driving device includes an inverter to supply an alternating current, a switch unit that switches the number of at least one permanent magnet synchronous motor to which the alternating current is supplied from the inverter, a detector to detect a detection value corresponding to the alternating current supplied to the at least one permanent magnet synchronous motor, and a control device to control the inverter and the switch unit. The control device sets an overcurrent interruption threshold value at a value based on the number. When the detection value is greater than or equal to the overcurrent interruption threshold value, the control device makes the inverter stop the supplying of the alternating current to the at least one permanent magnet synchronous motor.

Motor driving device, circuitry for controlling motor driving device, control method of motor driving device, and air conditioner

A dehydrogenation processing method for a turbine blade of a steam turbine. The method includes a step of heating the turbine blade by suppling heating steam into a casing of the steam turbine after a steam turbine plant is stopped. The heating steam supplied to the casing has a temperature that is higher than steam passing through the turbine blade during operation of the steam turbine plant. The method further includes repeating the process of supplying the heating steam into the casing a multiple of times.

Dehydrogenation processing method for turbine blades

The invention provides a cutting method and a cutting apparatus that cuts without chipping a composite material consisting of laminated layers of crystal material and amorphous material, in which the amorphous material is cut with an ultrasonically vibrated cutting blade and the crystal material is cut with a cutting blade that does not ultrasonically vibrate. With such a method and apparatus, the crystal material portion and the amorphous material portion of the composite material can be cut cleanly without chipping.

Growing community of inventors

Tokyo, Japan

Yuichi Shimizu