Mitsubishi Electric Corporation

Shinya Toyodome

Koichi Arisawa

Takashi Yamakawa

Kenji Takahashi

Kazunori Hatakeyama

Keisuke Uemura

Kenji Iwazaki

Mitsuo Kashima

Tomohiro Kutsuki

Shigeo Umehara

Atsushi Tsuchiya

Yosuke Shinomoto

Koyo Shimizu

Yuriko Takeda

Yasuaki Emura

A motor drive device includes: an inverter unit that supplies alternating current to a motor including a plurality of stator windings; a connection switching unit that is disposed between the inverter unit and the motor and switches a connection state of the stator windings; a rotor flux estimation unit that calculates an estimated rotor flux that is an estimated value of a rotor flux of the motor on the basis of current information that is a result of detection of a current value of the alternating current; and a determination processing unit that determines the connection state on the basis of the estimated rotor flux. The motor drive device determines an anomaly of the connection state while the motor is in operation.

Motor drive device

An electric motor drive device includes a booster circuit, an inverter, a connection switching device, and first and second control devices. The booster circuit boosts a voltage value of a bus voltage to be applied to a DC bus. The bus voltage is applied to the inverter, and the inverter applies an AC voltage having a variable frequency and a variable voltage value to an electric motor. The connection switching device switches a connection state of windings of the electric motor. The second control device performs zero current control to control the inverter such that a current flowing through the electric motor or the connection switching device is zero. When operating the connection switching device to switch the connection state, the second control device performs the zero current control after a boosting operation of the booster circuit is stopped by the first control device.

Electric motor drive device and refrigeration cycle application device

An air conditioner includes a compressor to compress a refrigerant used in a refrigeration cycle, a converter to generate a DC voltage, an inverter to generate three-phase AC voltages from the DC voltage, a motor to produce a driving force for driving the compressor with a plurality of coils, the three-phase AC voltages being applied to the coils, a connection switching unit to switch connection states of the coils between a first connection state and a second connection state, and a controller to detect an abnormality of the connection switching unit.

Air conditioner and driving device

A motor drive apparatus includes: a dq-axis current controller converting phase current flowing through a synchronous motor into d-axis current and q-axis current, and controlling the phase current by determining a voltage command based on the d-axis current and a d-axis current command as well as the q-axis current and a q-axis current command; a voltage amplitude calculating unit obtaining voltage amplitude; a speed controller controlling rotational speed of the motor by determining the q-axis current command based on a speed command, the rotational speed, and a speed droop amount that reduces the speed command; a flux weakening controller performing flux control to limit amplitude of voltage output to the motor by determining the d-axis current command based on the voltage amplitude and a first voltage limit value; and a speed droop controller controlling the speed droop amount based on the voltage amplitude and a second voltage limit value.

Motor drive apparatus

An inverter for driving a motor that has a switchable connection of windings and drives a load element having a periodically varying load torque is provided. The inverter is controlled so that an output torque of the motor follows the periodic variation of the load torque. The inverter is controlled so that a current flowing through the motor is zero during a period including a minimum torque phase at which the load torque is at or near a minimum value. The connection is switched while the current flowing through the motor is zero. It is possible to switch the connection of the windings while the motor is rotating, and avoid an increase in apparatus size.

Motor driving apparatus and refrigeration cycle equipment

An estimation device includes a phase current determination unit, a time difference calculation unit, and an estimation unit. The phase current determination unit performs a determination process for determining values of phase currents based on the value of the bus current detected by a bus current detection unit and states of gate pulse signals. The time difference calculation unit calculates a difference between a detection time of the bus current used in a previous determination process and a detection time of the bus current used in a present determination process. The estimation unit estimates at least one of a position and a speed of an AC motor based on the values of the phase currents determined by the phase current determination unit and the difference calculated by the time difference calculation unit.

Estimation device and AC motor drive device

A motor drive device: a power conversion unit; a current detection unit that detects a phase current of the alternating-current motor; a position/speed specifying unit that specifies a magnetic pole position and a rotational speed of the alternating-current motor; a d-axis current pulsation generating unit that generates a d-axis current pulsation command based on q-axis current pulsation or a q-axis current pulsation command, which being in synchronization with the q-axis current pulsation or the q-axis current pulsation command and preventing or reducing an increase or decrease in amplitude of the voltage command; and a dq-axis current control unit that generates the voltage command for controlling the phase current on the dq rotating coordinates, which rotate in synchronization with the magnetic pole position, by using the magnetic pole position, the rotational speed, the phase current, the q-axis current pulsation or the q-axis current pulsation command, and the d-axis current pulsation command.

Motor drive device, compressor drive system, and refrigeration cycle system

An over-current protection circuit for a motor capable of selecting one of a plurality of connection states has a plurality of decision circuits, a combining circuit, and a nullifying circuit. The combining circuit combines results of the comparisons in the plurality of decision circuits. The nullifying circuit nullifies part of the comparisons in the plurality of decision circuits. The number of outputs of the over-current protection circuit is one, so that for controlling the driving and stopping of the inverter needs just one terminal is required for receiving the output of the combining circuit. Moreover, because the over-current protection circuit is formed of hardware, the protection can be performed at a high speed.

Motor driving apparatus

A motor driving device includes: a connection switcher that has an electromagnetic contactor connected to a winding of a motor and switches connection condition of the winding by switching condition of the electromagnetic contactor; an inverter to apply an output voltage as an AC voltage to the winding via the connection switcher; a short-circuiting circuit having a rectification circuit and a switch; and a controller to control the electromagnetic contactor, the inverter and the switch, wherein a circulating circuit is formed by the short-circuiting circuit and the winding when the switch is set at ON, and the connection switcher switches the connection condition of the winding in a period in which the output voltage of the inverter is set at zero in a rotating operation of the motor and a current caused by the rotating operation circulates in the circulating circuit.

Motor driving device and air conditioner

A speed estimating device for an AC motor includes: a model deviation computing unit computing a model deviation based on a voltage, a current, and an estimated angular velocity of the AC motor; a first angular velocity estimating unit computing a first estimated angular velocity based on the model deviation; a second angular velocity estimating unit computing a second estimated angular velocity differing from the first estimated angular velocity in frequency, based on the model deviation; a compensation phase computing unit computing a compensation phase based on a disturbance frequency; and an estimated angular velocity calculator computing an estimated angular velocity of the AC motor based on the first estimated angular velocity and the second estimated angular velocity. Either one of the first estimated angular velocity and the second estimated angular velocity is computed based on the compensation phase.

Speed estimating device for AC motor, driving device for AC motor, refrigerant compressor, and refrigeration cycle apparatus

The motor driving apparatus includes a switch that is a mechanical switch for changing coil connection states of a motor; an inverter that generates alternating voltage from direct voltage and outputs the alternating voltage to the motor; and a control device that controls the switch and the inverter. The control device causes the switch to change the coil connection states while the alternating voltage output from the inverter is zero.

Motor driving apparatus, refrigeration cycle system, air conditioner, water heater, and refrigerator

In a motor driving apparatus including a DC power supply circuit of variable output voltage value, an inverter of variable frequency, and a connection switching device for selecting connection, switching of the connection switching device is performed in a state where an output voltage of the DC power supply circuit is increased, a rotational speed of a motor is increased, and a current flowing through the motor is made not greater than a predetermined threshold. For example, the switching of the connection switching device is performed in a state where the current through the motor is made zero. For example, the switching is performed in a state where the output voltage of the DC power supply circuit is set at a value corresponding to the rotational speed of the motor during the switching. It is possible to prevent increase in apparatus size and switch the connection of windings while the motor is rotating.

A power converting apparatus includes: a boost circuit including a reactor supplied with first voltage output from an alternating-current power supply, a first leg including first upper-arm and lower-arm switching elements connected in series, and a second leg connected in parallel with the first leg and including second upper-arm and lower-arm switching elements connected in series, and boosting the first voltage; a first voltage detecting unit detecting the first voltage; a smoothing capacitor smoothing voltage output from the boost circuit; and a second voltage detecting unit detecting second voltage smoothed by the smoothing capacitor. When the second voltage is larger than the first voltage and is lower than or equal to twice the first voltage, a width of a second drive pulse to turn on the first upper-arm switching element is larger than a width of a first drive pulse to turn on the first lower-arm switching element.

Power converting apparatus, motor drive control apparatus, blower, compressor, and air conditioner

In a motor driving apparatus having an inverter for driving a motor capable of switching between a star connection and a delta connection, when currents detected by winding current detecting elements detecting currents flowing through windings become excessive, the inverter is made to stop. Moreover, inverter output currents are calculated after removing a circulating current component at the time of the delta connection, from the winding currents detected by the winding current detecting elements, and the inverter is controlled using the calculated inverter output currents. Because over-current protection is performed based on the detected values of the winding currents, it is possible to prevent demagnetization taking account oSf the circulating current. Also, the inverter control is prevented from being affected by the circulating current in the delta connection. Accordingly, it is possible to reduce the number of the current detecting elements, and perform the over-current protection and control properly.

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Tokyo, Japan

Shinya Toyodome