Provided are a method and system for controlling an electric motor, and a controller. The method comprises: controlling an electric motor to operate in an open-loop manner; determining whether a rotational speed of the electric motor reaches a preset rotational speed; if so, determining whether the absolute value of an angle difference between an open-loop angle and a calculated position angle of the electric motor is greater than a preset angle; and if the absolute value of the angle difference is less than or equal to the preset angle, controlling the electric motor to operate in a closed-loop manner so as to avoid the situation where the electric motor cannot operate stably due to problems such as electric motor speed vibration caused by too large an angle difference between the open-loop angle and the position angle.

In a resonance suppression control device that controls suppression of vibrations in a resonance frequency in each vibration mode of a control target having a plurality of vibration modes, a configuration that is simple, and can suppress vibrations in a resonance frequency in the plurality of vibration modes is provided. A control device is a resonance suppression control device that controls suppression of vibrations in a resonance frequency in each vibration mode of a control target having a plurality of vibration modes. The control device includes a plurality of feedback loops that provide negative feedback of output of the control target corresponding to the plurality of vibration modes to an input side. The plurality of feedback loops respectively include band-pass filters that extract one or more vibration modes from the plurality of vibration modes, phase compensators, and amplitude adjusters. The band-pass filters and the phase compensators function as differentiators.

In a resonance suppression control device that controls suppression of vibrations in a resonance frequency in each vibration mode of a control target having a plurality of vibration modes, a configuration that is simple, and can suppress vibrations in a resonance frequency in the plurality of vibration modes is provided. A control device is a resonance suppression control device that controls suppression of vibrations in a resonance frequency in each vibration mode of a control target having a plurality of vibration modes. The control device includes a plurality of feedback loops that provide negative feedback of output of the control target corresponding to the plurality of vibration modes to an input side. The plurality of feedback loops respectively include band-pass filters that extract one or more vibration modes from the plurality of vibration modes, phase compensators, and amplitude adjusters. The band-pass filters and the phase compensators function as differentiators.

A method for operating a motor vehicle having at least one electric machine, which is electrically coupled across a pulse inverter to a DC distribution bus of a high-voltage onboard network of the motor vehicle, includes, by means of a compensation unit electrically coupled to the DC distribution bus, feeding an electric compensation voltage to the DC distribution bus such that ripple of the electric DC voltage present in the DC distribution bus which is caused by the pulse inverter is at least partly compensated.

A method for operating a motor vehicle having at least one electric machine, which is electrically coupled across a pulse inverter to a DC distribution bus of a high-voltage onboard network of the motor vehicle, includes, by means of a compensation unit electrically coupled to the DC distribution bus, feeding an electric compensation voltage to the DC distribution bus such that ripple of the electric DC voltage present in the DC distribution bus which is caused by the pulse inverter is at least partly compensated.

This motor control device receives a speed command from an upper layer system control device having a position controller, the motor control device having: a position command estimator that calculates an estimate of a position command on the basis of the speed command and a motor axis position response; and a speed command generator that generates an actual speed command on the basis of the estimate so that an end section of a machine connected to the motor does not oscillate, wherein the actual speed command is output from the speed command generator to a speed controller.

This motor control device receives a speed command from an upper layer system control device having a position controller, the motor control device having: a position command estimator that calculates an estimate of a position command on the basis of the speed command and a motor axis position response; and a speed command generator that generates an actual speed command on the basis of the estimate so that an end section of a machine connected to the motor does not oscillate, wherein the actual speed command is output from the speed command generator to a speed controller.

A wiper motor control circuit controls a drive circuit such that an actual speed of a wiper speed computed based on change in a rotation angle of an output shaft of the wiper motor detected by a rotation angle sensor that detects the rotation angle becomes a target speed corresponding to a position of a wiper blade indicated by the rotation angle detected by the rotation angle sensor. The wiper motor control circuit also controls the drive circuit so as to apply a braking current in the wiper motor when the actual speed has exceeded a threshold value when the rotation angle detected by the rotation angle sensor indicates a return position of the wiper blade.

A wiper motor control circuit controls a drive circuit such that an actual speed of a wiper speed computed based on change in a rotation angle of an output shaft of the wiper motor detected by a rotation angle sensor that detects the rotation angle becomes a target speed corresponding to a position of a wiper blade indicated by the rotation angle detected by the rotation angle sensor. The wiper motor control circuit also controls the drive circuit so as to apply a braking current in the wiper motor when the actual speed has exceeded a threshold value when the rotation angle detected by the rotation angle sensor indicates a return position of the wiper blade.

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.