Abstract: A harmonic suppression device includes a power converter that generates a harmonic suppression current that is an electric current for suppressing a harmonic current flowing in a power line and outputs the generated harmonic suppression current to the power line, a communication unit that exchanges signals with other harmonic suppression devices, and a controller that controls the power converter based on a signal received by the communication unit.

Abstract: A motor driving device and an air conditioner are capable of increasing the efficiency in a low speed region in which a motor performs low speed rotation. The motor driving device that is a motor driving device for driving a motor including stator windings, includes: a connection switching unit that switches connection condition of the stator windings to either of first connection condition and second connection condition different from the first connection condition; and an inverter that converts a DC voltage into AC drive voltages and supplies the AC drive voltages to the stator windings. The inverter includes MOS transistors as switching elements.

Abstract: A motor driving device is a device for driving a motor including stator windings, includes: a connection switching unit that is connected to the stator windings, includes circuits including semiconductor switches, and switches connection condition of the stator windings to either of first connection condition and second connection condition different from the first connection condition by setting the semiconductor switches to ON or OFF; and an inverter that supplies AC drive voltages to the stator windings.

Abstract: A motor driving device that is a device for driving a motor including stator windings, includes: a connection switching unit that includes relays as mechanical switches connected to the stator windings and excitation coils opening or closing the relays by being energized or non-energized with excitation current and switches connection condition of the stator windings to either of first connection condition (star connection) and second connection condition (delta connection) different from the first connection condition by opening or closing the relays; and an inverter that supplies AC drive voltages to the stator windings.

Abstract: 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.

Abstract: 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.

Abstract: An electric-motor driving apparatus is used to drive an electric motor including a plurality of winding groups constituting a three-phase winding. The electric-motor driving apparatus includes a switch that switches connection of windings of a first winding group and a second winding group, an inverter that drives an electric motor, and a controller that controls the inverter and the switch.

Abstract: A backflow preventing device includes a backflow preventing element that is connected between a power supply and a load and that prevents electric current from flowing backward from the load side toward the power supply side, and a commutating device that performs a commutation operation for causing the electric current to flow to a commutation path connected in parallel with the backflow preventing element. A plurality of elements including at least one or more of elements constituting the commutating device are configured as a module, so that, for example, the device can be reduced in size. Moreover, a simplified heat-dissipation design and a simplified air-duct design can be achieved.

Abstract: A power converter is configured to convert, into an AC voltage, a first power supply voltage between the first power supply wiring and the first ground wiring. A control device is connected between a second power supply wiring and a second ground wiring. The second power supply wiring is configured to supply a second power supply voltage lower than the first power supply voltage. The control device is configured to control the power converter. A separation device is configured to separate the first ground wiring and the second ground wiring from each other. The first ground wiring and the second ground wiring are electrically connected to each other at a single node.

Abstract: 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.

Abstract: Provided is a motor driving apparatus used for driving a motor including a first winding group and a second winding group to which three-phase alternating-current voltages are applied. The motor driving apparatus includes a first inverter and a second inverter; the first inverter applies an alternating-current voltage to the first winding group; and the second inverter applies an alternating-current voltage to the second winding group. A first induced voltage detector, a second induced voltage detector, and a third induced voltage detector are provided as voltage detectors for detecting induced voltages induced either in the first winding group or in the second winding group.

Abstract: An electric-motor driving apparatus according to the present invention is the electric-motor driving apparatus that drives an electric motor having a winding structure in which a first multi-phase winding and a second multi-phase winding are wound and includes a first DC/AC converter connected to the first multi-phase winding and applying a multi-phase alternating-current voltage to the electric motor, a second DC/AC converter connected to the second multi-phase winding and applying a multi-phase alternating-current voltage to the electric motor, a first three-phase switching unit to perform connecting and disconnecting between phases of the first multi-phase winding, a second three-phase switching unit to perform connecting and disconnecting between phases of the second multi-phase winding, and a winding switching unit to perform connecting and disconnecting between the first multi-phase winding and the second multi-phase winding.

Abstract: A heat pump apparatus includes an outdoor heat exchanger, a fan configured to introduce outdoor air into the outdoor heat exchanger, and a control device configured to control a defrosting operation of the outdoor heat exchanger. The fan rotates at a first rotational speed within a first period, after the defrosting operation is finished and the fan starts rotating. The fan rotates at the first rotational speed within a second period, after a non-defrosting operation is finished and the fan starts rotating. The first period is shorter than the second period.

Abstract: A speed estimation apparatus for an AC motor includes a model deviation calculation unit, first and second angular velocity estimation units, and an adder. The deviation calculation unit calculates a model deviation based on a voltage, a current, and an estimated angular velocity of the motor. The first angular velocity estimation unit calculates a first estimated angular velocity as a low-frequency component including a DC component of a real angular velocity based on the model deviation. The second angular velocity estimation unit calculates a second estimated angular velocity as a high-frequency component of a real angular velocity based on a specific high-frequency component of the model deviation. The adder adds the first and second estimated angular velocities together. An addition value of the first and second estimated angular velocities is fed back as the estimated angular velocity to the deviation calculation unit.

Abstract: A motor system according to the present invention includes: a motor including a first winding portion and a second winding portion, the second winding portion having a larger number of turns than the first winding portion; a first inverter connected to the first winding portion; and a second inverter connected to the second winding portion.

Abstract: The invention includes an inverter to convert a direct-current voltage from a direct-current power supply into an alternating-current voltage and apply the alternating-current voltage to a motor that, a direct-current-voltage detecting unit to detect a voltage in the direct-current power supply, a current detecting unit to detect an electric current flowing to the inverter, and an inverter control unit to generate PWM signals for driving switching elements of the inverter based on the detected voltage the detected electric current, to set a specific phase difference between a phase of a carrier signal used for generation of the PWM signals and a phase of the alternating-current voltage, and to control the inverter such that a frequency of the PWM signals are synchronized with a frequency of the alternating-current voltage, the frequency of the PWM signals being an integer multiple of three times the frequency of the alternating-current voltage.

Abstract: In a power converter, modules are electrically interconnected by a busbar and joint members. Each joint member has a connecting portion formed on one side and a connecting portion formed on the other side, with respect to a bisector bisecting the width. The busbar has a connecting portion on one side with respect to a bisector bisecting the width. For a 200 V power supply specification, one end of each of two busbars is fixed to one joint member. For a 400 V power supply specification, one end of one busbar is fixed to one joint member.

Abstract: A motor control device includes a position sensor that detects a position of a motor, an AD converter that converts an analog signal, which is a detection value of a motor current, into a digital signal, and a control circuit that drives an inverter using an output signal of the AD converter. The control circuit starts the AD converter during a permission period, and performs processing for the analog-digital converter during an electrical half cycle including a permission period. The length of a prohibition period obtained by excluding a permission period from an electrical half cycle decreases as the rotating speed of the motor increases.

Abstract: A leak-current detecting unit detects a zero-phase current flowing from an electric-motor driving device, which drives an electric motor with electric power from an alternating-current power supply, or the electric motor to a ground, a leak-current control unit that, on the basis of the zero-phase current detected by the leak-current detecting unit, generates a control signal having cyclicity synchronized with the alternating-current power supply, and an anti-phase generating unit that generates an anti-phase current that is in anti-phase to the zero-phase current on the basis of the control signal from the leak-current control unit, and outputs the anti-phase current.

Abstract: A motor control device includes a position sensor that detects a position of a motor, an AD converter that converts an analog signal, which is a detection value of a motor current, into a digital signal, and a control circuit that drives an inverter using an output signal of the AD converter. The control circuit starts the AD converter during a permission period, and performs processing for the analog-digital converter during an electrical half cycle including a permission period. The length of a prohibition period obtained by excluding a permission period from an electrical half cycle decreases as the rotating speed of the motor increases.