A protection device provided between a synchronous motor having a plurality of windings and a motor driving device for driving the synchronous motor includes: a switching unit for making and breaking the connection between the motor driving device and the synchronous motor; a dynamic brake circuit including resistors and switches, to short-circuit the plurality of windings between the switching unit and the synchronous motor via the resistors; and a control device for controlling the switching unit and the dynamic brake circuit. The control device controls the switches in the dynamic brake circuit to short-circuit the plurality of windings, and then controls the switching unit to cut off the connection between the motor driving device and the synchronous motor.

A power tool includes a motor, a power circuit coupled to the motor, and a speed sensor coupled to the motor. The power circuit provides power to the motor. The speed sensor detects a position of the motor. The power tool also includes an electronic processor coupled to the motor and the speed sensor. The electronic processor is configured to receive an output signal from the speed sensor indicative of a measured speed of the motor at a first time, determine a cumulative value based on the measured speed of the motor, and interrupt power from the power circuit to the motor when the cumulative value exceeds an accumulator threshold.

A power tool includes a motor, a power circuit coupled to the motor, and a speed sensor coupled to the motor. The power circuit provides power to the motor. The speed sensor detects a position of the motor. The power tool also includes an electronic processor coupled to the motor and the speed sensor. The electronic processor is configured to receive an output signal from the speed sensor indicative of a measured speed of the motor at a first time, determine a cumulative value based on the measured speed of the motor, and interrupt power from the power circuit to the motor when the cumulative value exceeds an accumulator threshold.

A method for fail-safe monitoring of the speed of a drive that includes at least a converter, a motor, and a rotational speed sensor, wherein a target rotational speed is specified to the drive and an actual rotational speed is sensed via the sensor, where a substitute rotational speed is calculated and three plausibility checks are performed in a safety program of a safety CPU, the substitute rotational speed being determinable, for example, from the initial frequency of a converter or from the quotient of EMF and magnetic flux, in each case two of the following three values being checked: target rotational speed, actual rotational speed and substitute rotational speed to achieve a high safety integrity level while avoiding disadvantages of conventional solutions, and because the calculated substitute rotational speed is independent of the sensor, even sensor errors that are difficult or impossible to detect via conventional solutions become detectable.

A method for fail-safe monitoring of the speed of a drive that includes at least a converter, a motor, and a rotational speed sensor, wherein a target rotational speed is specified to the drive and an actual rotational speed is sensed via the sensor, where a substitute rotational speed is calculated and three plausibility checks are performed in a safety program of a safety CPU, the substitute rotational speed being determinable, for example, from the initial frequency of a converter or from the quotient of EMF and magnetic flux, in each case two of the following three values being checked: target rotational speed, actual rotational speed and substitute rotational speed to achieve a high safety integrity level while avoiding disadvantages of conventional solutions, and because the calculated substitute rotational speed is independent of the sensor, even sensor errors that are difficult or impossible to detect via conventional solutions become detectable.

A drive controller comprises an evaluation unit to receive and evaluate a first item of feedback information from a motor connected to the drive controller, a control-signal block connected to secure inputs of the drive controller to receive condition control signals and to provide the condition control signals as input signals, a drive-signal block connected to the evaluation unit to calculate a first speed and/or a first position on the basis of the first item of feedback information on at least a first channel and to provide a first speed signal and/or a first position signal, a programmable logic unit connected to the control-signal block and the drive-signal block to realize the safety functions and the speed signal and/or the position signal to provide switch-off signals, and an output unit connected to the logic unit and to secure outputs of the drive controller to output switch-off signals on safety-switch-off paths.

A method and a device for monitoring the rotational speed of an element are disclosed. The element may be part of a centrifuge, e.g. a motor, drive shaft, or rotor of a laboratory centrifuge. The rotational speed of the element is not determined directly, but rather clock cycles are counted while the element rotates by a predetermined rotational angle. Exceeding a predetermined rotational speed is determined by comparing a number of counted cycles with a predetermined value. The method and device can be implemented in hardware without requiring a microcontroller with corresponding software, thereby eliminating a need to software certification.

A method and a device for monitoring the rotational speed of an element are disclosed. The element may be part of a centrifuge, e.g. a motor, drive shaft, or rotor of a laboratory centrifuge. The rotational speed of the element is not determined directly, but rather clock cycles are counted while the element rotates by a predetermined rotational angle. Exceeding a predetermined rotational speed is determined by comparing a number of counted cycles with a predetermined value. The method and device can be implemented in hardware without requiring a microcontroller with corresponding software, thereby eliminating a need to software certification.

A surgical instrument is disclosed. The surgical instrument includes a drive system and a control circuit. The drive system includes an electric motor. The control circuit includes an acoustic sensor, and is configured to utilize a parameter of the drive system measured by the acoustic sensor to control a speed of the electric motor.

A safety device for an actuator that can modulate power to an electric motor in response to a fault condition (e.g., stall). In one embodiment, the actuator can include a motor with a shaft, a sensor disposed in proximity to the shaft, and a control processor coupled with the sensor and the motor. The control processor can be configured to receive a signal from the sensor that conveys operating data that relates to rotation of the shaft, use the operating data to identify a fault condition on the motor, and change the motor from an energized condition to a de-energized condition in response to the fault condition.