Systems and methods for monitoring and suppressing a back EMF generated by an ESP motor when the ESP system is moved in a well. Embodiments provide both electrical braking to reduce the rotation of the motor (and corresponding back EMF) and warnings to alert users to hazardous conditions caused by the back EMF. One embodiment includes an ESP system having a permanent magnet motor, a back EMF safety system, and a power cable connected between them. The proximal ends of the cable's conductors are connected terminals of the back EMF safety system, which has switches that are closed to short circuit the conductors so that back EMF currents from rotation of the motor induce electrical braking in the motor. Currents and phase-to-phase voltages on the conductors are monitored to detect overcurrent and overvoltage conditions that may trigger alarms or other actions.

Provided are a method and device for testing an adaptor, and a storage medium. The method is applicable to the device. The method includes the following. A test signal is sent to the adaptor. Detect a first voltage, where the first voltage is outputted in a preset first duration by the adaptor according to the test signal. A working state of the adaptor is determined according to the first voltage.

A failure diagnosis system includes a sensor that is provided in a diagnosis target device and detects diagnosis target information of the diagnosis target device, an abnormality determination unit that determines whether or not an abnormality occurs in the diagnosis target device based on the diagnosis target information detected by the sensor, a storage unit that stores a site of the diagnosis target device where the abnormality determination is possible and a sensor installation location where a sensor needs to be installed for the abnormality determination of the site, a designation reception unit that receives designation of a site where the abnormality determination is performed, and a presentation unit that executes predetermined presentation processing. The presentation processing by the presentation unit includes processing of presenting the sensor installation location where the sensor needs to be installed to perform the abnormality determination of the designated site.

A failure diagnosis system includes a sensor that is provided in a diagnosis target device and detects diagnosis target information of the diagnosis target device, an abnormality determination unit that determines whether or not an abnormality occurs in the diagnosis target device based on the diagnosis target information detected by the sensor, a storage unit that stores a site of the diagnosis target device where the abnormality determination is possible and a sensor installation location where a sensor needs to be installed for the abnormality determination of the site, a designation reception unit that receives designation of a site where the abnormality determination is performed, and a presentation unit that executes predetermined presentation processing. The presentation processing by the presentation unit includes processing of presenting the sensor installation location where the sensor needs to be installed to perform the abnormality determination of the designated site.

An open circuit diagnosis apparatus, and method for open circuit diagnosis, for a motor drive circuit with a Miller plateau detection unit that detects whether there is a Miller plateau region in a gate voltage applied to a switching element of a motor drive circuit when the switching element is turned on; a body diode activation detection unit which detects whether the body diode of the switching element has been activated which depends on the on/off state of the switching element; and a control unit which determines whether the motor drive circuit is in the open circuit state on the basis of whether the body diode activation unit has been activated and whether there is a Miller plateau region in a gate voltage.

An open circuit diagnosis apparatus, and method for open circuit diagnosis, for a motor drive circuit with a Miller plateau detection unit that detects whether there is a Miller plateau region in a gate voltage applied to a switching element of a motor drive circuit when the switching element is turned on; a body diode activation detection unit which detects whether the body diode of the switching element has been activated which depends on the on/off state of the switching element; and a control unit which determines whether the motor drive circuit is in the open circuit state on the basis of whether the body diode activation unit has been activated and whether there is a Miller plateau region in a gate voltage.

This three-phase AC motor drive device is provided with: a load; an inverter device 1 for driving the load; an MCOK_A_4 connected between the inverter device 1 and the load and electrically connecting or disconnecting the inverter device 1 to or from the load; a voltage detector 21a having terminals respectively connected to the circuits of at least two phases to detect the voltages between the three phases; and a current detector 11 for detecting the currents of the three phases. In the connection from the inverter device 1 to the load, the inverter device 1, the MCOK_A_4, the voltage detector 21a, the current detector 11, and the load are aligned in this order.

An electric tool includes a drive structure, a motor, a driver circuit, and a controller. The controller is configured to output a first control signal to control the motor to drive the drive structure to operate in a first operation mode for a preset period of time in response to receiving a start instruction. After the preset period of time, the controller will output a second control signal to control the motor to drive the drive structure to operate in a second operation mode to a preset state. The first operation mode and the second operation mode are two opposite operation modes.

An electric tool includes a drive structure, a motor, a driver circuit, and a controller. The controller is configured to output a first control signal to control the motor to drive the drive structure to operate in a first operation mode for a preset period of time in response to receiving a start instruction. After the preset period of time, the controller will output a second control signal to control the motor to drive the drive structure to operate in a second operation mode to a preset state. The first operation mode and the second operation mode are two opposite operation modes.

An electric pump includes a pump, a motor configured to drive the pump, a motor drive unit having a switching element and configured to drive the motor with electric power output from the switching element, and a control unit configured to output a pulse width modulation (PWM) signal for driving the switching element to the motor drive unit. The PWM signal output from the control unit, is used for monitoring a state of the motor. When the motor stops abnormally, the control unit sets a frequency of the PWM signal for use in monitoring the state of the motor to a frequency outside of a frequency band which is used when the motor is normal.