A motor starting state recognition method and device, and a motor. The method includes sampling the counter electromotive forces of any two phases of a motor, and calculating a linear counter electromotive force of the motor according to the counter electromotive forces of the two phases, acquiring a polarity flag bit of the motor, and determining the starting state of the motor according to the polarity flag bit and the linear counter electromotive force. The state of a motor before starting can be recognized effectively using the method, so that the problem where a motor may not be started normally or the success rate of starting is low under the condition of a favorable/dead wind is effectively solved, and the problem where a motor becomes severely worn out and has a shorter service life after frequent starting due to starting failure is avoided. Moreover, the method is simple and highly accurate, and the success rate and reliability of system starting are effectively improved.

A frequency converter includes: at least one bridge arm, wherein a shunt resistor is arranged in the bridge arm; an evaluation device having an input connection, the evaluation device being designed to evaluate a measurement signal which is present at the input connection and which is dependent on a voltage drop across the shunt resistor, in order to determine a measured variable; and a voltage peak suppression device, which is designed to short-circuit the input connection of the evaluation device when a voltage peak occurs at the shunt resistor.

A motor module includes a motor including a commutator, and an apparatus that is attached to the motor and obtains information on rotation of the motor. The apparatus includes a rotation angle calculator that calculates a rotation angle of the motor based on a voltage between terminals of the motor and an electric current flowing through the motor, a first signal generator that generates a first signal based on a ripple component included in the electric current flowing through the motor, a second signal generator that generates a second signal indicating that the motor has rotated by a predetermined angle based on the first signal and the rotation angle, and a rotation information calculator that calculates the information on the rotation of the motor based on an output from the second signal generator.

A control method of a motor rotation speed may include calculating a q-axis potential difference of a synchronous coordinate system for controlling a q-axis current of the synchronous coordinate system based on a target rotation speed of a motor and a measured rotation speed value of the speed sensor, calculating a voltage command of the synchronous coordinate system based on the calculated q-axis potential difference of the synchronous coordinate system, and controlling an inverter connected to the motor according to the calculated voltage command of the synchronous coordinate system.

A method for determining a speed (nG) of a generator unit which has an electric machine (100) with a rotor winding (110) and a stator winding (120) and a rectifier (130) connected thereto, via which rectifier the electric machine (100) is connected to an electrical system (150) of a motor vehicle, the speed (nG) being determined depending on the plot of an excitation current (IE) flowing through the rotor winding (110) of the electric machine (100). In particular, the speed is determined from a known relationship between the speed, the frequency of the excitation current, the number of pole pairs and optionally the number of phases when there is an error that leads to a constant phase voltage being output.

A motor control device for performing sine-wave drive of a motor includes a first physical quantity detection unit, a second physical quantity detection unit, an A/D converter, and a conversion operation control unit. The first physical quantity detection unit outputs a current detection signal according to a terminal voltage of a single shunt resistor in which a three-phase current of the motor flows. The second physical quantity detection unit outputs a physical quantity detection signal corresponding to a physical quantity related to the drive of the motor. The A/D converter performs an A/D conversion of each of the current detection signal and the physical quantity detection signal. The conversion operation control unit controls an operation of the A/D converter so as to perform the A/D conversion of each of the current detection signal and the physical quantity detection signal.

A system, method, and computer-readable medium for determining the flow rate and fluid density in an electrical submersible pump (ESP) and controlling the ESP based on the flow rate and density. In one implementation, an ESP system includes an ESP, drive circuitry, a current sensor, a voltage sensor, and a processor. The ESP includes an electric motor. The drive circuitry is electrically coupled to the ESP and is configured to provide an electrical signal to power the ESP. The current sensor is configured to measure a current of the electrical signal. The voltage sensor is configured to measure a voltage of the electrical signal. The processor is configured to calculate speed of a shaft of the electric motor based on a frequency induced by rotation of the motor detected in the current. The processor is also configured to calculate a density of fluid in the ESP based on the speed.

A control device comprises a driving unit configured to drive a plurality of coils of a multiple-phase motor by pulse width modulation; a detection unit configured to detect currents flowing through the plurality of coils in a time-division manner; and a change unit configured to change, in accordance with a duty in the pulse width modulation, a sequence of detecting the currents flowing through the plurality of coils by the detection unit.

A rotary drive for a medical device (10) includes a rotary motor (14) including a rotor (26). A rotary motion encoder (34) is connected to the rotor. The rotary motion encoder is configured to generate a number of encoder steps measuring a rotational distance of the rotor. At least one electronic processor (18) is programmed to determine at least one of a slippage value of the rotary motor measured during motor operation and a coasting value of the rotary motor measured after stopping motor operation based on comparison of an actual count of encoder steps and an expected count of encoder steps.

A brake control system includes: a plurality of motors each provided with a brake device and a position detecting section; and a brake control device that controls a plurality of the brake devices using one brake-oriented power source. The position detecting section includes a position detecting circuit section and a communication circuit section. The brake device includes: a current detecting section that detects a brake current flowing through a brake coil of an electromagnetic brake; and an insulating circuit section that electrically insulates the current detecting section and the communication circuit section. The communication circuit section transmits to the brake control device the brake current acquired via the insulating circuit section. The brake control device includes a fault specifying section that specifies the faulty brake device based on a plurality of detection signals detected by a plurality of the current detecting sections.