Abstract: To enable overmodulation control having high controllability and low noise characteristics, a control device of an AC motor includes an inverter for driving an AC motor and a controller for controlling the inverter by pulse width modulation. The controller, when over-modulating the inverter, limits the amplitude of the voltage command in the pulse width modulation to a predetermined upper limit value or less.

Abstract: A control device of a synchronous electric motor includes: the synchronous electric motor with three-phase stator windings Y-connected; a detection unit that detects a neutral point potential which is a potential at a Y connection point; and an inverter that drives the synchronous electric motor. The control device of the synchronous electric motor which controls the synchronous electric motor using the inverter, includes a measurement mode in which the neutral point potential is detected in a state in which the synchronous electric motor is energized by an AC current and controls the synchronous electric motor based on a value of the neutral point potential detected in the measurement mode.

Abstract: To enable overmodulation control having high controllability and low noise characteristics, a control device of an AC motor includes an inverter for driving an AC motor and a controller for controlling the inverter by pulse width modulation. The controller, when over-modulating the inverter, limits the amplitude of the voltage command in the pulse width modulation to a predetermined upper limit value or less.

Abstract: Before sensorless control is performed on a three-phase brushless motor by sequentially switching between six energization modes each for selecting two phases to be energized from the three phases, the initial position of the rotor is estimated based on a change in a second induced voltage by: momentarily energizing the three-phase brushless motor according to each of the six energization modes, and detecting six first induced voltages each generated in a non-energized phase by the energization; calculating three induced voltage differences corresponding respectively to three non-energized phases, each induced voltage difference being a difference between two of the six first induced voltages that are detected during energization according to two energization modes that share a non-energized phase; and energizing the three-phase brushless motor according a predetermined energization mode selected based on the three induced voltage differences, and detecting the second induced voltage generated in a non-energi

Abstract: A control device of a synchronous electric motor includes: the synchronous electric motor with three-phase stator windings Y-connected; a detection unit that detects a neutral point potential which is a potential at a Y connection point; and an inverter that drives the synchronous electric motor. The control device of the synchronous electric motor which controls the synchronous electric motor using the inverter, includes a measurement mode in which the neutral point potential is detected in a state in which the synchronous electric motor is energized by an AC current and controls the synchronous electric motor based on a value of the neutral point potential detected in the measurement mode.

Abstract: Before sensorless control is performed on a three-phase brushless motor by sequentially switching between six energization modes each for selecting two phases to be energized from the three phases, the initial position of the rotor is estimated based on a change in a second induced voltage by: momentarily energizing the three-phase brushless motor according to each of the six energization modes, and detecting six first induced voltages each generated in a non-energized phase by the energization; calculating three induced voltage differences corresponding respectively to three non-energized phases, each induced voltage difference being a difference between two of the six first induced voltages that are detected during energization according to two energization modes that share a non-energized phase; and energizing the three-phase brushless motor according a predetermined energization mode selected based on the three induced voltage differences, and detecting the second induced voltage generated in a non-energi

Abstract: A method for detecting a potential (Vn) includes stator wirings in a Y connection, and automatically adjusting a relationship with a position of a rotor as a system for realizing rotor position-sensorless stable drive of an AC motor where the three-phase stator wirings are in Y connection in the stop and low-speed ranges. A synchronous motor control apparatus includes a three-phase synchronous motor in which three-phase stator wirings are in a Y connection, and an inverter for driving the motor, wherein the synchronous motor is DC-conducted thereby to move a rotor to a predetermined position, and is applied with a pulse-shaped voltage from the inverter in the moved state so that a neutral point potential as potential (Vn) of the Y connection point is acquired when the pulse voltage is applied, thereby driving the synchronous motor based on the acquired value.

Abstract: A method for detecting a potential (Vn) includes stator wirings in a Y connection, and automatically adjusting a relationship with a position of a rotor as a system for realizing rotor position-sensorless stable drive of an AC motor where the three-phase stator wirings are in Y connection in the stop and low-speed ranges. A synchronous motor control apparatus includes a three-phase synchronous motor in which three-phase stator wirings are in a Y connection, and an inverter for driving the motor, wherein the synchronous motor is DC-conducted thereby to move a rotor to a predetermined position, and is applied with a pulse-shaped voltage from the inverter in the moved state so that a neutral point potential as potential (Vn) of the Y connection point is acquired when the pulse voltage is applied, thereby driving the synchronous motor based on the acquired value.

Abstract: When a set duty Dt of a PWM signal is less than a minimum duty (Dmin) that allows for pulse induced voltage detection, the PWM signal in which a duty D1 during a predetermined period is limited to Dmin and in which a duty D2 during the other period is adjusted so as to satisfy Dt=(D1+D2)/2 is applied to the switching elements connected to one of the two phases. When the duty D2 during the other period takes a negative value, the pulse-voltage application target during the other period is changed to the switching elements connected to the other of the two phases, and the duty D1 during the predetermined period is corrected and increased so as to compensate for an actual drop in the duty D2 during the other period corresponding to a dead-time period in a complementary PWM method.

Abstract: When a set duty Dt of a PWM signal is less than a minimum duty (Dmin) that allows for pulse induced voltage detection, the PWM signal in which a duty D1 during a predetermined period is limited to Dmin and in which a duty D2 during the other period is adjusted so as to satisfy Dt=(D1+D2)/2 is applied to the switching elements connected to one of the two phases. When the duty D2 during the other period takes a negative value, the pulse-voltage application target during the other period is changed to the switching elements connected to the other of the two phases, and the duty D1 during the predetermined period is corrected and increased so as to compensate for an actual drop in the duty D2 during the other period corresponding to a dead-time period in a complementary PWM method.