Lathe control systems and methods are described including stopping a motor prior to reversing direction as well as methods and systems that implement voltage and/or current protection thresholds.

A motor drive device includes a plurality of control systems that individually supply drive currents to a plurality of coil groups included in a motor. The motor drive device independently sets the current command values for the respective control systems. Based on the set current command values, drive instructions are supplied to drive circuits of inverters with respect to the respective control systems, thereby supplying drive currents from the inverters to the coil groups. The motor drive device detects a failure in any of the inverters and the coil groups with respect to each control system, and stops only the failed control system or causes only the failed control system to fall back. The motor drive device further includes a main computing device, and an auxiliary computing device. Consequently, if the auxiliary computing device is normal even in case the main computing device fails, driving of the motor can be continued using one or some of the control systems.

A method and system for operating an electric machine are described. In one example, the system includes a motor stator having a first group of windings and a second group of windings. Each group of the windings is electrically coupled to a different inverter so that the system may have a layer of operational redundancy.

In a motor driving apparatus including an inverter connectable to n motors (n being an integer not less than 2) each including a rotor having a permanent magnet, braking operation is performed on i (i being an integer from 1 to n−1) of the n motors, and then braking operation is performed on j (j being an integer from 1 to n−i) of the n motors other than the i motors. It is possible to reduce the risks of failure of the inverter and demagnetization of the motors due to overcurrent by reducing current flowing through the inverter and the motors when the braking operation is performed.

An apparatus for switching and/or protection of a load connected to said apparatus, said apparatus (1) comprising: a power switch (5) through which the connected load receives an electrical current; a sensor component (4) connected in series with said power switch (5) and adapted to generate directly an electrical voltage drop corresponding to a current rise speed of the electrical current flowing via the sensor component (4) and via the power switch (5) to said load; and a driver circuit (6) adapted to detect an occurring overcurrent depending on a voltage drop generated by said sensor component (4) with or without a voltage drop along the power switch (5) and to switch off said power switch (5) upon detection of an overcurrent within a switch-off period to protect said power switch (5) and said load.

An embodiment of a control system includes a current command module configured to receive a torque command and output a current command for controlling a direct current (DC) motor, and a current capability limiting module configured to receive the current command and a current limit indicating a maximum motor current, limit the current command based on the current limit, and actively further limit the current command based on a capability limit value.

An overload control device for use with a floor machine having an electric motor is disclosed. The overload control device can include a power input and a power output connectable to the electric motor. The device can include a load detector, a current sensor operative to sense a current value supplied to the motor via the power output, and a cutoff relay interconnecting the power input and the power output. The cutoff relay being operative to supply power from the power input to the power output when activated, and interrupt power when deactivated. A controller receives a load present indication from the load detector and activates the cutoff relay if a load is present. The controller receives a current value from the current sensor, determines if the current value is greater than a threshold value, and deactivates the cutoff relay when the current value is greater than the threshold value.

A motor control device controls a drive of a motor having a coil, and includes a drive circuit and a control unit. The drive circuit has a plurality of switching elements, and switches the energization of the coil. The control unit includes an energization control part and a current limit part. The energization control part accelerates and then decelerates the motor, and controls energization of the coil so that a rotation position of the motor stops at a target rotation position. The current limit part limits the current during a deceleration control.

An inverter control device that controls a rotary electric machine drive device that includes an inverter with a plurality of switching elements, where the active short circuit control is executed in a high rotational speed region, and the shut-down control is executed in a low rotational speed region, which is on a low rotational speed side with respect to the high rotational speed region, in accordance with at least a rotational speed of the rotary electric machine.

When a failure of current detection parts occurs while a synchronous machine is operating, the failure of the current detection parts is detected and the operation of the synchronous machine is continued. An open-loop control part for performing control without using the detected current values of the current detection parts and a closed-loop control part for performing control using the detected current values are included, and a failure of the current detection parts is detected while the open-loop control part is operating.