Abstract: A motor drive system can detect a misconnection. A motor drive system for driving a motor including a plurality of stator windings includes: an inverter that converts a DC voltage supplied from a DC voltage source into an AC voltage and applies the AC voltage to the motor; a connection switching device that is disposed between the inverter and the motor and can switch a connection state of the stator windings; and a controller that performs abnormality determination on a connection state of the connection switching device on the basis of a current value of a current flowing in each of the stator windings.

Abstract: A refrigerating cycle device includes a compressor, a motor, and a wiring switch part. The compressor compresses a refrigerant. The motor generates power for compressing the refrigerant by rotating a rotor with voltage applied to a plurality of wirings. The motor is disposed in the compressor. The wiring switch part switches between a plurality of wiring states by changing connection between the plurality of wirings. When a rotational speed of the rotor exceeds a predetermined value, the wiring switch part switches to a first wiring state of the plurality of wiring states. The first wiring state differs from a second wiring state of the plurality of wiring state. Efficiency of the second wiring state is highest at the rotational speed.

Abstract: A load driving device includes a smoothing capacitor, an inverter, and a control unit. The inverter includes two legs, each including upper and lower arm switching elements connected in series and converts direct-current power stored in the smoothing capacitor into alternating-current power. The control unit performs voltage drop prevention control for preventing the voltage across the smoothing capacitor from becoming a negative voltage. The control unit stops power running control on the load when the capacitor voltage is higher than the sum of a first voltage and a second voltage. The first voltage is a potential difference between a second terminal and a first terminal in the upper-arm. The second voltage is a potential difference between a second terminal and a first terminal in the lower-arm in the same leg as the leg of the upper-arm.

Abstract: A motor drive device includes an inverter to apply power to a motor, and a plurality of relays to switch a connection state of the motor by each switching its state between a first state and a second state. A timing at which at least one of the plurality of relays switches from the first state to the second state is different from a timing at which the other relays switch from the first state to the second state.

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 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: A drive apparatus for an electric motor includes an inverter, an inverter substrate, a wire connection switching unit, a control unit, and an alternating-current wire electrically connected at one end to the inverter and at the other end to one end of the windings of an electric motor. The drive apparatus for an electric motor includes an alternating-current wire electrically connected at one end to the alternating-current wires and electrically connected at the other end to one end of the wire connection switching unit, and an alternating-current wire electrically connected at one end to the other end of the wire connection switching unit and electrically connected at the other end to the other end of the windings of the electric motor. The drive apparatus for an electric motor includes a noise suppression unit provided at least on the alternating-current wires to suppress noise that occurs in the alternating-current wire.

Abstract: An electric blower includes a fan, a motor to drive the fan, a first board including at least one switching element, and a second board including a microcomputer. The motor, first board, and second board are arranged in this order in a blowing direction of the fan.

Abstract: An electric blower includes a fan, and a board disposed in an airflow path of the fan and including a switching element. The board includes a lead wire projecting into the airflow path.

Abstract: A motor drive device includes a single-phase inverter which is an inverter including a plurality of switching elements. The inverter converts a direct-current voltage output from a direct-current power supply into an alternating-current voltage, by operation of the plurality of switching elements operating, and applies the alternating-current voltage to a motor. The motor drive device includes a control power supply outputting power having a voltage lower than the direct-current voltage, by using the direct-current voltage. The motor drive device includes a drive signal generation unit driven by the power. The drive signal generation unit generates drive signals driving the plurality of switching elements, and outputs the generated drive signals to the plurality of switching elements. The motor drive device includes a power supply switch operating so as to allow supply of the power from the control power supply to the drive signal generation unit when a rotation speed of the motor is higher than a threshold.

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: 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: A motor driver includes an inverter used for driving a motor and configured to apply an alternating-current voltage to the motor. The inverter drives, during start operation, a switching element of the inverter with a first PWM signal that is PWM modulated with a carrier frequency that is a first integer multiple of a frequency of the alternating-current voltage, and thereafter drives the switching element with a second PWM signal that is PWM modulated with a carrier frequency that is a second integer multiple of the frequency of the alternating-current voltage. The second integer is smaller than the first integer.

Abstract: An electric quantity of a power supply of a connection switching device for switching the connection state of a motor, or at least one electric quantity which varies with the first-mentioned electric quantity is detected, the result of the detection is used to detect or predict a fall of a voltage of the switching power supply. Based on the result of the detection or prediction, an inverter is so controlled as to stop the motor before the voltage of the switching power supply falls below the minimum voltage required for the operation of the connection switching device. Breakdown of the connection switching device can be prevented.

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: A motor drive device includes a single-phase inverter converting a direct-current voltage output from a power supply that is a direct-current power supply into an alternating-current voltage having a high level, low level, or zero level potential. The inverter outputs the alternating-current voltage as a motor applied voltage to be applied to a motor. The alternating-current voltage is a voltage that has a high level, low level, or zero level potential. When a rotation speed of the motor is to be reduced, a section in which a potential of the motor applied voltage is zero level is widened.

Abstract: An electric motor drive unit includes a winding switching unit that switches a configuration of windings of an electric motor, a winding switching instruction unit that generates an instruction signal for the winding switching unit, and a winding configuration retention unit to which the instruction signal generated by the winding switching instruction unit is input, and if the input instruction signal has a first value, outputs a signal corresponding to the input instruction signal to the winding switching unit, and if the input instruction signal has a second value different from the first value, continues outputting a signal that has been output to the winding switching unit before the reception of the second value, the first value indicating an instruction on the configuration of the windings.

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 device includes an inverter to apply power to a motor, and a plurality of relays to switch a connection state of the motor by each switching its state between a first state and a second state. A timing at which at least one of the plurality of relays switches from the first state to the second state is different from a timing at which the other relays switch from the first state to the second state.

Abstract: The present invention includes a plurality of fan motors, first and second inverters for individually driving the fan motors, respectively, and one and a common control unit that performs a control arithmetic for each of the fan motors and generates an individual driving signal given to each of the inverters.