A method for driving an electric motor includes providing two controllers for driving the electric motor. The two controllers use different control methods to drive the electric motor. The method further includes selecting a first controller of the controllers as a primary controller to drive the electric motor and a second controller of the controllers as a secondary controller, monitoring a control of the electric motor, and switching the control of the electric motor from the primary controller to the secondary controller if an error condition is detected in the control of the electric motor.

A method for driving an electric motor includes providing two controllers for driving the electric motor. The two controllers use different control methods to drive the electric motor. The method further includes selecting a first controller of the controllers as a primary controller to drive the electric motor and a second controller of the controllers as a secondary controller, monitoring a control of the electric motor, and switching the control of the electric motor from the primary controller to the secondary controller if an error condition is detected in the control of the electric motor.

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

Examples relate to back electromotive force controllers for influencing movement of a carriage of a device in an unpowered state; the carriage being moveable by a motor responsive to a motor driver; the controller comprising: braking circuitry to couple power associated with a back electromotive force generated by displacement of the motor, due to carriage movement, to power the motor driver to urge the motor in a contrary direction to the displacement.

A motor control system is provided for controlling a speed of a motor system used in a musical instrument. The motor control system includes at least one sensing device attached to the musical instrument, and configured for detecting movement of an object and providing a sensor signal based on the movement of the object. Also included in the motor control system is a control unit having a processor connected to the motor system and the at least one sensing device. The control unit is configured for selectively modulating the speed of the motor system based on the sensor signal.

A motor control system is provided for controlling a speed of a motor system used in a musical instrument. The motor control system includes at least one sensing device attached to the musical instrument, and configured for detecting movement of an object and providing a sensor signal based on the movement of the object. Also included in the motor control system is a control unit having a processor connected to the motor system and the at least one sensing device. The control unit is configured for selectively modulating the speed of the motor system based on the sensor signal.

In an example, a control system for controlling a generator and providing an alarm upon detection of a fault condition. The control system includes a control relay, which includes a normally-open (NO) contact pair and a normally-closed (NC) contact pair, between the transfer switch and a controller. The NO contact pair is provided by a NO contact and a common contact, and the NC contact pair is provided by a NC contact and the common contact. The controller can receive signals indicative of a state of the contact pairs of the control relay and, based on the signals, determine whether to activate the generator and/or activate an alarm system.

An apparatus can comprise a circuit and an electrical element coupled to the circuit. The circuit can include a pulse generator to generate an electrical pulse having a first power and a load. The electrical element can be configured to receive heat that is converted into electrical energy by the circuit to apply a second power, greater than the first power, to the load.

An apparatus can comprise a circuit and an electrical element coupled to the circuit. The circuit can include a pulse generator to generate an electrical pulse having a first power and a load. The electrical element can be configured to receive heat that is converted into electrical energy by the circuit to apply a second power, greater than the first power, to the load.