A motor control device controls the drive of a motor including a motor winding. The motor control device is provided with an energization control unit and a standstill determination unit. The energization control unit controls the energization of the motor winding in accordance with a detection value of a rotational position sensor that detects a rotational position of the motor. The standstill determination unit determines a standstill of the motor. When a standstill of the motor is detected, the energization control unit controls energization in a change pattern that is an energization pattern different from a preset regular pattern in accordance with the detection value of the rotational position sensor.

A control method for restarting a permanent magnet synchronous motor (PMSM) in a rotating condition, and a device and a system thereof are provided. In the method, an electrical angular speed .sub.e of the PMSM is obtained based on a speed of a trailer to obtain a back electromotive force of the PMSM. The back electromotive force is compared with a voltage at a side of an inverter, and if the electromotive force of the permanent magnet synchronous motor is higher than the voltage at the side of the inverter, the restarting of the PMSM is forbidden, otherwise, the restarting of the PMSM is allowed. Therefore, in the present disclosure, the low-speed operating condition and the high-speed operating condition correspond to different position angles of the rotor, and the PMSM is started based on the position angle of the rotor.

The present disclosure relates to an inverter, and more specifically to an inverter that can be restarted stably by determining whether to restart it when power is supplied after a failure has occurred in the inverter due to a fault in the main supply.

A sensorless electric motor control device is provided that completes a phase detection of a rotor before an activation signal is received, so as to shorten a time period from when the activation signal is received to when the rotor reaches a target number of rotations. The control device for a sensorless electric motor 10 includes an inverter 11 that drives the electric motor 10 and a first processor 18 that serves as a phase detection unit that causes the inverter 11 to perform a phase detection before the inverter 11 receives an activation signal that activates the electric motor 10, wherein the phase detection aligns a magnetic pole of a rotor of the electric motor 10 with a predetermined position with respect to a stator.

To avoid control failure resulting from startup of a PMSM that is windmilling, initial speed and position are determined before startup. A controller uses a FOC routine having a speed PI control loop, field-weaken control, a current PI control loop, and a speed observer. When the controller receives an instruction to start the PMSM, it delays startup and executes an estimation stage, in which the controller executes the FOC routine but with the speed PI control loop and the field-weaken control disabled. The estimation stage is repeated multiple times, with estimates converging to actual speed and position through successive iterations. When estimated speed and position values have stabilized, the motor is started using the estimates as initial speed and position for driving the PMSM. The FOC routine, with the speed PI control loop and the field-weaken control enabled, is used to drive the PMSM.

A method of synchronizing a synchronous reluctance electric machine wherein the machine has no speed and/or residual magnetization voltage sensor and includes power terminals and rotating masses whose mechanical rotation frequency is subjected to speed transients caused by power cut-off conditions. The method includes at least one step of applying a control voltage with predetermined amplitude and duration to the terminals after the transients, and one step of detecting the electric current induced by the control voltage, the current induced by the voltage having a harmonic spectrum variable according to the frequency differential between the frequency of the control voltage and the mechanical rotation frequency of the rotating masses, to restore power and synchronous rotation control of the machine.

A method and apparatus for operating a pump system comprising a rotary pump, a three-phase induction motor operably coupled to the rotary pump, and an AC drive operably coupled to the induction motor, the apparatus being configured to supply the induction motor with a three-phase AC voltage at multiple different angular velocities, monitor an output current of the AC drive generated in response to the supplied voltage at the multiple different angular velocities, determine an angular velocity of the supplied voltage at which at least one predetermined characteristic in the monitored output current is detected and determine a rotational velocity corresponding to the determined angular velocity as an estimate of the rotational velocity of the motor, wherein the pump system is operated on the basis of the determined estimate of the rotational velocity of the motor.

A motor control apparatus includes: a rectifier converting AC power into DC power; a smoothing capacitor provided for a DC link; an inverter connected to the DC link and mutually converts power between DC power and AC power; an AC voltage detector detecting voltage of a power supply; a voltage amplitude calculator converting the AC voltage value into a power supply voltage amplitude value; a power failure detector detecting a state of power failure when the power supply voltage amplitude value has continued to be equal to or lower than a first threshold for a predetermined period; a DC voltage detector detecting the DC voltage of the smoothing capacitor; and, a protecting operation start determining unit notifying the inverter of the actuation of axis stoppage or axis retraction when a power failure is detected and when the DC voltage value is equal to or lower than a second threshold.

Disclosed embodiments relate to apparatuses, methods, and systems for restarting an induction machine. In some embodiments, a method includes estimating a position of a rotor and a speed thereof in a position and speed estimation Operation, resetting a speed reference to correspond to the speed of the rotor in a speed reference resetting Operation, generating a control voltage corresponding to the speed reference to regulate a voltage magnitude using the control voltage in a voltage magnitude regulation Operation, and re-accelerating the induction machine up to a target speed after the regulation of the voltage magnitude in a re-acceleration Operation.

A power conversion device includes an inverter which can convert between DC and AC power by turning on and off bridge-connected semiconductor switching elements with free wheel diodes connected in reverse parallel; and a rotating electric machine, such as an AC generator or motor, which is connected to the AC terminals of the inverter, where when the DC voltage of the inverter is below a specified value when starting the machine, the speed of the machine is detected in a condition where the DC voltage of the inverter is boosted to at least a specified value of the induced voltage of the machine, by intermittently turning on and off at least one of the switching elements, so as to accurately detect the speed of the machine and stably start it even when the DC voltage of the inverter is lower than the induced voltage of the machine.