A system and method of predicting motor failure based on relationships of motor pair characteristics, such as temperatures. One method includes receiving, by a controller, a parameter of a first motor on a mining machine from a first parameter sensor on a mining machine. The method also includes receiving, by the controller, a parameter of a second motor on the mining machine from a second parameter sensor on the mining machine. The method also includes outputting an alarm signal, by the controller, upon (1) determining that at least one of the parameters of the first motor and the second motor exceeds a parameter threshold and (2) determining that the parameter of the first motor differed from the parameter of the second motor by at least a difference threshold for a predetermined amount of time.

Temperature-dependent motor control device, including: a motor controller configured to switch a motor control state among an activated state in which the motor is activated by a first current, an activation stopped state in which activation of the motor is stopped by stopping current supply, and an activation suspended state in which activation of the motor is suspended with a second current smaller than the first current kept supplied; and a temperature estimator configured to calculate an estimated motor temperature value and to perform a first calculation for gradually increasing the estimated value when the motor is in the activated state, a second calculation for gradually decreasing the estimated value when the motor is in the activation stopped state, and a third calculation for gradually decreasing the estimated value at a rate of decrease lower than that in the second calculation when the motor is in the activation suspended state.

A motor according to the present invention includes an output axis, a brake for holding the output axis, a sensor for detecting an external torque applied to the output axis from outside, and a controller for decreasing or increasing the torque of the brake during operation of the brake in accordance with an increase or decrease in the external torque detected by the sensor.

A motor control apparatus controlling current feeding and a rotational direction of a motor includes: four bridge-circuit switches between a high and low potential lines; two current feeding line switches connected through the motor between a first and second nodes in series to arrange two parasitic diodes facing each other; a pull-up resistor between the high potential line and a third node; a pull-down resistor between the low potential line and a fourth node to interpose the motor between the third and fourth nodes; a protective diode blocking current; and a fault diagnostic device having: a driver turning on or off the switches; and a voltage determinator determining suitability of a first and second voltages and performing initial fault diagnosis for at least one of the switches.

A method for operating power semiconductors arranged in converters, includes measuring with a temperature sensor a temperature of at least one of the power semiconductors, performing a comparison of the temperature of the at least one power semiconductor with a reference temperature and providing a result of the comparison; activating a pre-heating phase for preheating the power semiconductors as a function of the result; during the pre-heating phase, defining a pre-heating current; and impressing the pre-heating current into an electrical load.

An electric motor includes a stator and a rotor. The stator has a plurality of low speed windings and a plurality of separate high speed windings. A first type of thermal overload protector is coupled with at least one of the low speed windings and a second type of thermal overload protector is coupled with at least one of the high speed windings.

An electric oil pump constructed by integrally combining an electric motor with an oil pump, wherein the electric motor is composed of a motor casing, a drive shaft that is disposed in a motor housing chamber formed inside the motor casing and is rotatably supported, a rotor that is disposed on the drive shaft, and a stator that is located inside the motor housing chamber and is attached to the motor casing. The electric oil pump is equipped with an internal controller that controls application of electric power to the stator so as to cause the drive shaft to be driven to rotate via the rotor.

A motor driving apparatus includes: a switch having a first terminal that receives an external voltage, and a second terminal; a driving circuit coupled to the first terminal of the switch, and powered by the external voltage; a control circuit coupled to the second terminal of the switch; and a power circuit coupled across the switch, and outputting an internal voltage associated with the external voltage to power the control circuit to control the driving circuit to drive a motor of a power tool to rotate in a first direction when the switch operates in the ON state and to rotate in a second direction for a predetermined time period counting from each instance the switch transitions to the OFF state.

A control unit for driving a motor mainly includes an input circuit for inputting various kinds of information pieces, an output circuit for driving the coil windings of the motor, an MPU for calculating a control amount based on the information from the input circuit and outputting a control signal to the output circuit; the control unit has two pieces each of the input circuit, the output circuit, and the, and can supply respective electric currents to the windings of the motor or can cut off the supply; the MPUs each have a CPU incorporated therein, a trigger circuit for a trigger signal having a predetermined period; the two CPUs synchronize at least control commands in accordance with the trigger signal and output the control commands.

The structure for detecting tooth-skipping of the speed reducer of the rotary driver is reduced in weight and size. In the rotary driver the occurrence of tooth-skipping is detected based on the difference in outputs from the encoders located at the input side (the side of the motor) and at the output side (the side of the load), which is opposite the input side in relation to the speed reducer. The rotary driver comprises a motor, a speed reducer located between the motor and a load to reduce the rotary speed of a rotary shaft at the side of the motor, to thereby transmit the reduced rotary speed to a rotary shaft at the side of the load, a first encoder for detecting a rotation of the rotary shaft at the side of the motor, a second encoder for detecting a rotation of the rotary shaft at the side of the load, a section for detecting any difference between a first detected value that is obtained by dividing an output of the first encoder by a rate for reducing the speed by the speed reducer and a second detected value that is obtained from an output of the second encoder, and a section for detecting tooth-skipping that detects tooth-skipping of the speed reducer based on the difference.