Protection circuit for an electric motor which is controlled or regulated by phase gating

摘要

A protection circuit for an electric motor which is controlled or regulated by phase gating, for switching off the motor in the event of damage to the controllable semiconductor element located in the operating circuit of the motor, or the electronics driving this element, have a switching-off current path which is connected in parallel with at least that part of the operating current path formed by the armature winding of the motor and in which a semiconductor switch is located which can be driven electronically and is connected to a drive circuit which produces a switching signal (which causes the semiconductor switch to close) in the event of an attempt to reach an unacceptably high rotation speed of the motor which would damage the semiconductor element and/or the electronics driving it, as well as a switching-off element which responds to the current flowing via the closed semiconductor switch and in consequence interrupts the operating current path. <IMAGE>