A bridge circuit includes a high-side transistor connected between a power supply terminal and an output terminal, and a low-side transistor connected between the output terminal and a ground terminal. A high-side pre-driver and a low-side pre-driver drive the high-side transistor and the low-side transistor. A first transistor is connected between the output terminal and the ground terminal in a manner to form the regenerative path parallel to the low-side transistor. In a regenerative state in which a current sinks from the output terminal, a regenerative control circuit controls the voltage of a control terminal of the first transistor in a manner that an output voltage of the output terminal approaches a target voltage higher than the power supply voltage of the power supply terminal by a first voltage width.

Included are a drive control signal generation unit configured to generate a drive control signal for a motor in accordance with a target rotation speed of the motor and a rotation speed of the motor calculated in response to a rotation position detection signal of the motor; a rotation speed signal generation unit configured to generate a rotation speed signal having a frequency corresponding to the rotation speed of the motor, in response to the rotation position detection signal of the motor; an abnormality determination processing unit configured to determine whether a condition value for abnormality determination of the motor has reached a predetermined threshold value, for each predetermined abnormality determination period, and generate an abnormality determination signal distinguishable from the rotation speed signal when the abnormality determination processing unit determines that the condition value has reached the predetermined threshold value; and a signal output unit configured to output the rotation speed signal generated by the rotation speed signal generation unit when the abnormality determination signal is not generated, and output the abnormality determination signal instead of the rotation speed signal when the abnormality determination signal is generated.

A permanent magnet synchronous machine (1) having a rotor (R) and a stator (S). Connection terminals (2) apply a feed alternating voltage with a feed frequency (f.sub.0). The permanent magnet synchronous machine (1) has a motor controller (10). The controller (10) has an assembly (11) to detect the terminal voltage on the connection terminals (2) and the current frequency (f.sub.a). Also, the controller has an analysis device (12). The analysis device (12) ascertains whether the current frequency (f.sub.a) contains a frequency component (f.sub.r) with a frequency that deviates from the feed frequency (f.sub.0).

A motor driver control system is configured for connection to a plurality of motors, the motor control system includes a motor driver command module, and the motor driver command module is configured to: access information related to one or more operating metrics of the plurality of motors; analyze the information to determine whether a maintenance condition exists in any of the plurality of motors; and if a maintenance condition exists in any of the plurality of motors: prevent electrical power from reaching any of the plurality of motors, identify which one or more of the plurality of motors has the maintenance condition, disconnect the one or more identified motors from the motor driver control system, and restore electrical power to all of the plurality of motors other than the identified motors after disconnecting the one or more identified motors.

A frequency converter module includes a frequency control management module. An input port of the frequency conversion control management module is electrically connected to an input port of a power supply module. The power accuracy monitoring module includes an initial power measuring module, a power prediction correction module, and an actual power display storage module. An output port of the initial power measuring module is electrically connected to an input port of the power prediction correction module. An output port of the power prediction correction module is electrically connected to an input port of the actual power display storage module.

A hydraulic fracturing system for fracturing a subterranean formation is disclosed. In an embodiment, the system can include a plurality of electric pumps fluidly connected to a well associated with the subterranean formation and powered by at least one electric motor, and configured to pump fluid into a wellbore associated with the well at a high pressure; at least one generator electrically coupled to the plurality of electric pumps so as to generate electricity for use by the plurality of electric pumps; a gas compression system fluidly coupled to the at least one generator so as to provide fuel for use by the at least one generator; and a combustible fuel vaporization system gaseously coupled to the gas compression system so as to provide at least one of vaporized fuel or gasified fuel, or a combination thereof, to the gas compression system.

A motor control apparatus includes: a main power conversion circuit that converts power that is supplied from a power supply into alternating current power for driving a motor, and outputs the alternating current power; a counter electromotive force protection circuit including a rectifier unit that rectifies alternating current power based on counter electromotive force of the motor and outputs direct current power, a short-circuit unit that short-circuits terminals on a direct current output side of the rectifier unit, and an alarm signal output unit that outputs an alarm signal at occurrence of an abnormality; a monitoring unit that monitors whether the alarm signal is output from the alarm signal output unit; and a protection operation unit that performs a protection operation for preventing damage to the main power conversion circuit when the monitoring unit determines that the alarm signal is output from the alarm signal output unit.

In a method for operating an electric machine a first test signal is fed into the electric machine and a first response signal of the electric machine is measured. A first state variable for a rotor of a synchronous reluctance motor of the electric machine is determined as a function of the first response signal, and a second state variable for the rotor of the synchronous reluctance motor is determined. The first state variable and the second state variable are evaluated together.

A system for active short circuit notification in an electric motor of a hybrid electric vehicle including a traction battery, an internal combustion engine in mechanical communication with the motor, and a propulsion system driven by the motor or engine. The system includes an inverter and inverter controller to generate signals to operate inverter switches to produce AC for the motor or DC for battery charging. In response to motor speed exceeding a threshold, the inverter controller is configured to generate signals to operate the switches to produce an active short circuit in the motor to prevent battery overcharging. In response to an active short circuit, the inverter controller is configured to transmit a notification signal to a vehicle controller configured to generate an engine stop control signal operative to stop the engine to reduce current circulation between the inverter and motor caused by the active short circuit.

A motor-drive system may include a rectifier, a metal-oxide varistor (MOV) assembly, and an inverter. The rectifier may generate a direct current (DC) voltage based on a first voltage received from at least one supply voltage line coupled to a voltage source. The MOV assembly may include at least two metal-oxide varistors (MOVs) respectively coupled to the at least one supply voltage lines. The MOV assembly may couple between the voltage source and the rectifier. The motor-drive system may also include a permanently-installed jumper to couple at least one MOV of the at least two MOVs of the MOV assembly to a system ground. The inverter of the motor-drive system may convert the DC voltage to an alternating current (AC) voltage, which may be provided to a load of the motor-drive system.