A control device for an AC rotary machine includes: a DC power supply; an inverter; a magnetic flux generator; an angle detector; and a control arithmetic unit; wherein the control arithmetic unit is configured to: calculate, based on a positional relationship between a current path and the angle detector, a correction signal for correcting signal errors of a cosine signal and a sine signal, which are caused by a noise magnetic flux component due to at least one of a DC current flowing between the DC power supply and the inverter and multi-phase AC currents flowing between the inverter and armature windings; and control the inverter by using angle information obtained from values after the correction by the correction signal.

The present disclosure provides a system and method that provides active damping at the input of a motor drive system without the need for the hardware used in conventional and RC damping circuits. According to the disclosure a virtual damping network is realised at the input of the motor drive system based on modification of field-oriented control, FOC. More specifically, a control algorithm creates a virtual damping impedance at the motor drive input by applying a damping algorithm to both q and d components of the motor current.

The present disclosure provides a system and method that provides active damping at the input of a motor drive system without the need for the hardware used in conventional and RC damping circuits. According to the disclosure a virtual damping network is realised at the input of the motor drive system based on modification of field-oriented control, FOC. More specifically, a control algorithm creates a virtual damping impedance at the motor drive input by applying a damping algorithm to both q and d components of the motor current.

A damper for a power train, comprising a piezoelectric transformer and a load element connected across the output of the piezoelectric transformer.

A damper for a power train, comprising a piezoelectric transformer and a load element connected across the output of the piezoelectric transformer.

An electric motor control device performing feedback control of a state amount of an electric motor or a load and being capable of changing a control bandwidth of a feedback control system includes: a notch filter arranged in the feedback control system and having a filter coefficient which is changeable; a notch control section which changes a notch frequency as a center frequency of the notch filter to remove an oscillation component attributable to mechanical resonance related to the electric motor; and a control coefficient setting section which changes at least one of the control bandwidth or the filter coefficient of the notch filter in accordance with the control bandwidth and the notch frequency to stabilize the feedback control system.

An electric motor control device performing feedback control of a state amount of an electric motor or a load and being capable of changing a control bandwidth of a feedback control system includes: a notch filter arranged in the feedback control system and having a filter coefficient which is changeable; a notch control section which changes a notch frequency as a center frequency of the notch filter to remove an oscillation component attributable to mechanical resonance related to the electric motor; and a control coefficient setting section which changes at least one of the control bandwidth or the filter coefficient of the notch filter in accordance with the control bandwidth and the notch frequency to stabilize the feedback control system.

A system and a method for driving a motor to rotate at a high speed are provided. The system includes a lookup table, a command detector, a pattern selector and a motor driver. The lookup table module is configured to store a reference waveform pattern and a modulated waveform pattern. An amplitude of the modulated waveform pattern is larger than an amplitude of the reference waveform pattern. The command detector is configured to receive a rotating speed command. The pattern selector is configured to receive the reference waveform pattern and the modulated waveform pattern, and select the reference waveform pattern or the modulated waveform pattern according to the rotating speed command. The motor driver is configured to output a driving signal to drive the motor according to the selected reference waveform pattern or modulated waveform pattern.

A system and a method for driving a motor to rotate at a high speed are provided. The system includes a lookup table, a command detector, a pattern selector and a motor driver. The lookup table module is configured to store a reference waveform pattern and a modulated waveform pattern. An amplitude of the modulated waveform pattern is larger than an amplitude of the reference waveform pattern. The command detector is configured to receive a rotating speed command. The pattern selector is configured to receive the reference waveform pattern and the modulated waveform pattern, and select the reference waveform pattern or the modulated waveform pattern according to the rotating speed command. The motor driver is configured to output a driving signal to drive the motor according to the selected reference waveform pattern or modulated waveform pattern.

Permanent magnet motors (PMMs) can develop oscillations during motor startup that can cause damage to electric submersible pump (ESP) components. A system and method are presented for identifying mechanical and/or electrical caused oscillations in a PMM through the analysis of oscillations in current and torque measurements. A control system within a surface motor controller receives current and/or torque measurements from downhole sensors. The control system employs one or more algorithms designed to detect oscillations in the measurements. Upon detecting oscillations that are consistent with oscillations in the motor from mechanical or electrical causes, the control system automatically initiates protective action to prevent damage to the ESP components.