A door control device includes: a speed control unit configured to perform speed control of an electric motor that drives a door; a speed detection unit configured to detect a speed of the door; and an obstruction detection unit configured to detect obstruction between the door and a door pocket, upon a value of the speed of the door detected by the speed detection unit decreasing by a first predetermined value or more with respect to a speed command value in the speed control during a door opening operation of the door.

An apparatus for injecting impedance into a high voltage (HV) transmission line is disclosed. The apparatus comprises a plurality of modular flexible alternating current transmission systems (FACTS) based impedance injection units (IIUs), each modular FACTS based IIU without fault current protection. The apparatus further comprises a fault current protection module external to the modular FACTS based IIUs. The fault current protection module is coupled to the modular FACTS based IIUs to provide fault current protection to the modular FACTS based IIUs.

A power tool including a housing, a motor having a rotor and a stator, at least one grip sensor configured to generate a grip parameter, and a switching network electrically coupled to the brushless DC motor. An electronic processor is connected to the switching network and the at least one grip sensor and configured to implement kickback control of the power tool. The electronic processor is configured to determine a kickback threshold based on the grip parameter, control the switching network to drive the motor, receive a signal related to a power tool characteristic, determine, based on the power tool characteristic being greater than or equal to the kickback threshold, that a kickback event of the power tool is occurring, and control, in response to determining that the kickback event is occurring, the switching network to cease driving of the motor.

A hand-held electrically powered cut-off tool (100) for cutting concrete and stone by a rotatable cutting disc (105), the cut-off tool (100) comprising an electric motor (130) arranged to be controlled by a control unit (110) via a motor control interface (120), wherein the control unit (110) is arranged to obtain data indicative of an angular velocity of the cutting disc (105), and to detect a kickback condition based on a decrease in angular velocity, wherein the control unit (110) is arranged to control an electromagnetic braking of the electric motor (130) in response to detecting a kickback condition, wherein the control unit (110) is arranged to determine an angular acceleration associated with the electric motor (130), and to detect the kickback condition based on a comparison between the determined angular acceleration and a configurable detection threshold.

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 temperature monitoring device for protecting the winding of an electronically commutated electric motor from being heated over a specified limit temperature T.sub.G regardless of the rotational speed includes a phase current detection device for detecting the phase current I.sub.Wicklung for the motor windings, an overcurrent switch-off device for switching off the electric motor if a maximum permissible phase current I.sub.Abschalt is exceeded, and an overcurrent monitoring device, which is connected to the overcurrent switch-off device, in order to transmit to it a switch-off signal if the detected phase current I.sub.Wicklung exceeds the maximum permissible phase current I.sub.Abschalt ascertained by a detection and computing device, wherein an algorithm in which the measured ambient temperature T.sub.U is incorporated is used when ascertaining the maximum permissible phase current I.sub.Abschalt.

A symptom of malfunction regarding operating characteristics of a switch should be detected exactly. A switch operating characteristic monitoring device is comprised of a current sensor that measures a close command current of a switch, an auxiliary switch that outputs signals from at least two or more auxiliary contacts with reference to positions of a contactor, a measurement unit that measures signals from the current sensor and the auxiliary switch, a diagnosis unit that judges whether or not a malfunction occurs, and a display unit that displays a malfunction when a malfunction has been determined. A threshold is obtained in advance from multiple results of an opening/closing test performed beforehand. A calculation is made for characteristic times which are obtained from the close command current and signals from the auxiliary switch during actual operation of a circuit breaker. If a deviation is found by comparison with a threshold, a malfunction is determined.

A method and apparatus for protecting a circuit are provided. The method and apparatus may measure a physical quantity of a motor by an external physical stimulus, may calculate a counter electromotive voltage generated by the motor, based on the physical quantity, may compare the counter electromotive voltage to an output voltage, and may control a circuit connected to the motor to be open when the counter electromotive voltage is greater than the output voltage.

A door control device includes: a speed control unit configured to perform speed control of an electric motor that drives a door; a speed detection unit configured to detect a speed of the door; and an obstruction detection unit configured to detect obstruction between the door and a door pocket, upon a value of the speed of the door detected by the speed detection unit decreasing by a first predetermined value or more with respect to a speed command value in the speed control during a door opening operation of the door.

According to an aspect of the present disclosure, a motor drive control device includes a motor drive unit having a plurality of switch elements connected to a power supply source and supplying a driving current to a plurality of phase coils of a motor, a control circuit unit outputting, to the motor drive unit, a drive control signal for operating the plurality of switch elements to sequentially switch energization patterns for the plurality of phase coils, and a current detecting circuit for detecting a voltage value corresponding to a magnitude of the driving current, wherein the control circuit unit includes a first determination unit determining whether a state of overcurrent where a magnitude of the driving current exceeds a predetermined overcurrent threshold occurs based on the voltage value each time an energization pattern is switched, and a second determination unit determining whether driving of the motor is in an abnormal condition based on a determination result of the first determination unit for a plurality of energization patterns.