An electric pump includes a pump unit, a motor and a controller. The pump unit is configured to pump fluid by a rotating operation. The motor is a brushless direct-current motor and configured to rotationally drive the pump unit. The controller is configured to control a current to be supplied to the motor. The controller is configured to switch between voltage control for controlling the current to be supplied to the motor based on a target voltage and current control for controlling the current to be supplied to the motor based on a target current.

A motor starter has a housing, a contactor portion disposed within the housing, a motor protection system disposed within the housing adjacent to the contactor portion in a vertical direction, and an actuation system disposed within the housing. The contactor portion may switch between an open position and a closed position, in which, in the open position, current does not flow through the motor starter and, in the closed position, current is allowed to flow through the motor starter. The motor protection system includes a plurality of components that may move the contactor portion to the open position based on a current flow, in which the actuation system may move the contactor portion between the closed position and the open position in response to receiving an input.

A motor starter has a housing, a contactor portion disposed within the housing, a motor protection system disposed within the housing adjacent to the contactor portion in a vertical direction, and an actuation system disposed within the housing. The contactor portion may switch between an open position and a closed position, in which, in the open position, current does not flow through the motor starter and, in the closed position, current is allowed to flow through the motor starter. The motor protection system includes a plurality of components that may move the contactor portion to the open position based on a current flow, in which the actuation system may move the contactor portion between the closed position and the open position in response to receiving an input.

Techniques for controlling operations of a motor based on position errors are described. In an example, a user device sends an amount of electrical current to the motor to cause the motor to move. The user device also determines the motor is in position for a time interval despite the amount of electrical current. Based at least one the time interval and the amount of electrical current, the user device determines a position difference associated with a target position and a measured position of the motor during the time interval, and reduces the amount of electrical current based at least in part on the time interval.

Techniques for controlling operations of a motor based on position errors are described. In an example, a user device sends an amount of electrical current to the motor to cause the motor to move. The user device also determines the motor is in position for a time interval despite the amount of electrical current. Based at least one the time interval and the amount of electrical current, the user device determines a position difference associated with a target position and a measured position of the motor during the time interval, and reduces the amount of electrical current based at least in part on the time interval.

The present disclosure provides a motor drive device. The motor drive device includes a current detection unit, a control unit and a determination unit. The current detection unit detects a current flowing through a motor coil. The control unit executes a slow attenuation mode that attenuates the current after an end of a power supply mode. The determination unit determines whether the current at a second time point while a predetermined time has elapsed from a first time point when the power supply mode is switched to a slow decay mode is below a limit value. When the determination unit determines that the current does not fall below the limit value, the control unit is configured to switch from the slow attenuation mode to a fast attenuation mode at the second time point.

The present disclosure provides a motor drive device. The motor drive device includes a current detection unit, a control unit and a determination unit. The current detection unit detects a current flowing through a motor coil. The control unit executes a slow attenuation mode that attenuates the current after an end of a power supply mode. The determination unit determines whether the current at a second time point while a predetermined time has elapsed from a first time point when the power supply mode is switched to a slow decay mode is below a limit value. When the determination unit determines that the current does not fall below the limit value, the control unit is configured to switch from the slow attenuation mode to a fast attenuation mode at the second time point.

A system comprises an electric submersible pump (ESP) motor electrically coupled to a variable speed drive (VSD) that outputs voltage to the ESP motor. The system comprises a magnet on a shaft of the ESP motor and a downhole sensor coupled to the magnet, wherein the downhole sensor is to measure a magnetic flux of the magnet. The system comprises a VSD controller to control the VSD, wherein the VSD controller comprises a processor and a non-transitory memory storage having instructions stored thereon that are executable by the processor to perform operations comprising: obtaining a measurement of at least one pump performance variable and a motor current for a first period of time to establish a first data set and making a first adjustment to a voltage output from the VSD to the ESP motor, the first adjustment having a first adjustment type.

A system comprises an electric submersible pump (ESP) motor electrically coupled to a variable speed drive (VSD) that outputs voltage to the ESP motor. The system comprises a magnet on a shaft of the ESP motor and a downhole sensor coupled to the magnet, wherein the downhole sensor is to measure a magnetic flux of the magnet. The system comprises a VSD controller to control the VSD, wherein the VSD controller comprises a processor and a non-transitory memory storage having instructions stored thereon that are executable by the processor to perform operations comprising: obtaining a measurement of at least one pump performance variable and a motor current for a first period of time to establish a first data set and making a first adjustment to a voltage output from the VSD to the ESP motor, the first adjustment having a first adjustment type.

A sliding door driving device includes: a power source; a motor that outputs power to open and close the door; a motor driving circuit that connects the power source and the motor to each other; and a motor control device that controls the motor driving circuit. The motor control device includes an inverter that converts DC power supplied from the power source into AC power, and a shunt resistor disposed between the power source and the inverter. The position detection unit of the motor control device obtains the rotation angle of the motor based on the output of the shunt resistor.