Abstract: A power conversion apparatus includes a converter circuit converting AC voltage output from an AC power supply into DC voltage. The converter circuit includes unit converters. The power conversion apparatus includes a low current-oriented controller the unit converters to cause current corresponding to a single phase to flow through a current detector, and a high current-oriented controller controlling operation of the unit converters based on a result of comparison between a duty command and a carrier signal, where the duty command is generated based on detection values detected by the current detector and a voltage detector. When the detection value detected by the current detector is less than or equal to a first threshold, the low current-oriented controller is activated, and when the detection value detected by the current detector is greater than the first threshold, the high current-oriented controller is activated.

Abstract: 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.

Abstract: An air-conditioning apparatus includes an indoor unit and an outdoor unit including a compressor that compresses a refrigerant and a motor drive system that drives the compressor. The motor drive system includes an inverter that converts a DC voltage into an AC voltage, and an electric motor including three stator windings with both ends open. The electric motor operates based on the AC voltage obtained by the inverter. The motor drive system further includes a connection state switching unit that has a function to change the connection state of the three stator windings included in the electric motor, and sets the connection state to a star connection at the start of operation of the air-conditioning apparatus.

Abstract: An air conditioner has a power conversion device including: a reactor having a first end and a second end, the first end being connected to an AC power supply; a rectifier circuit that is connected to the second end of the reactor and includes a diode and at least one or more switching elements, the rectifier circuit converting an AC voltage outputted from the AC power supply into a DC voltage; and a detection unit detecting a physical quantity indicating an operation state of the rectifier circuit. Switching is made between control for a current from the AC power supply to be applied to the diode or control for the current to be applied to the switching element in accordance with an operating mode of the air conditioner.

Abstract: An electric motor drive device includes: a wire connection switching unit; an inverter; a control device controlling the wire connection switching unit and the inverter; and an overcurrent protection circuit preventing current exceeding a predetermined value from continuously flowing through the electric motor. The overcurrent protection circuit includes: determination circuits each correlated one-to-one with any one of possible wire connection states of a stator winding and determining whether current flowing through the inverter is abnormal; a combining circuit combining determination results; and an invalidation circuit invalidating a determination process by one or more of the determination circuits, and causing the combining circuit to output a determination result by the determination circuit correlated with a selected wire connection state of the stator winding.

Abstract: A motor drive apparatus includes a reactor, a converter connected to an alternating current power supply via the reactor, a smoothing capacitor connected between output terminals of the converter, and an inverter that converts a direct current voltage output from the smoothing capacitor into an alternating current voltage to be applied to a motor and outputs the alternating current voltage. The motor drive apparatus includes a plurality of operation modes for controlling conduction of switching elements of the converter and causing the converter to operate in different modes of operation, and changes operation of at least one of the switching elements of the converter and the inverter according to the operation mode when a bus voltage indicates an excessive value.

Abstract: A direct current power supply device includes: a reactor; a converter connected to an alternating current power supply via the reactor; a smoothing capacitor connected between output terminals of the converter; an inrush current preventing circuit disposed on a charging path from the alternating current power supply to the smoothing capacitor; a current detection unit detecting direct current representing an operating state on an output side of the converter; a current detection unit detecting power supply current representing an operating state on an input side of the converter; and a control unit receiving the direct current and the power supply current and controlling an operation of the converter. The control unit receives a detected value of saturated current from at least one of the direct current and the power supply current when the power supply voltage recovers from a state in which the power supply voltage is reduced.

Abstract: A motor driving apparatus for driving a motor, the apparatus being connected to the motor by first, second, and third connection lines respectively corresponding to first, second, and third phases, the apparatus including: an inverter converting direct-current voltage into three-phase alternating-current voltage by using first, second, and third switching element pairs respectively connected to the first, second, and third connection lines, and outputting the three-phase alternating-current voltage to the motor; a voltage detection circuit detecting a first voltage based on a potential difference between a potential of the first connection line and a reference potential; and a control unit calculating a voltage value of the direct-current voltage based on the first voltage during a first period in which an upper-arm switching element of the first switching element pair is on, controlling operation of the inverter according to the voltage value, and changing the first period according to the voltage value.

Abstract: 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.

Abstract: A motor driving apparatus for driving a single-phase motor includes an inverter disposed between a battery and the single-phase motor, the inverter applying a first voltage to the single-phase motor at startup and applying a second voltage to the single-phase motor during a normal operation. A stop time period is present after application of the first voltage, application of the first voltage being stopped during the stop time period, and the inverter applies the second voltage after a lapse of the stop time period.

Abstract: A motor drive device includes a single-phase inverter that converts a direct-current voltage output from a power supply which is a battery, into an alternating-current voltage. The inverter outputs the alternating-current voltage as an applied voltage to be applied to a motor. The applied voltage is lower when the direct-current voltage is a second voltage lower than a first voltage than when the direct-current voltage is the first voltage. Consequently, a discharge current of the battery is reduced, and the motor drive device capable of reducing an increase in battery temperature can be obtained.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An electric blower includes a motor including a rotor having a rotation shaft, and a stator provided to surround the rotor, a moving blade mounted at one end side of the rotation shaft in the axial direction of the rotation shaft, a bearing portion provided between the moving blade and the stator in the axial direction and rotatably supporting the rotation shaft, and a frame. The frame includes a motor housing portion housing the stator, a bearing housing portion housing the bearing portion, a wall formed between the motor housing portion and the bearing housing portion and facing the moving blade, and a hole passing through the wall. The electric blower further includes a first air path outside the frame, and a second air path inside the frame. An air volume in the first air path is larger than an air volume in the second air path.

Abstract: 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?1) of the n motors, and then braking operation is performed on j (j being an integer from 1 to n?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.

Abstract: 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.

Abstract: 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.

Abstract: 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.