Bidirectional DC motor control circuit including overcurrent protection PTC device and relay

摘要

A system for controlling electric motors in binary and hybrid applications, particularly motors which are used to control windows which can be moved downwards from one extreme position to another extreme position by a single touch of the switch, and between other positions by depressing the switch so long as movement is desired. In this system, a control element is placed in series with the electric motor. The control element has an interrupt component and a sense component which are coupled in series, and the series combination is coupled in parallel with a control component. When the electric motor reaches one of its extreme positions, the sense component senses an increase in the current drawn by the motor. The sense component then signals the control component to cause the interrupt component to interrupt the current and stop the motor. In one embodiment of this system, the sense component is a PTC device, the control component is a relay coil, and the interrupt component is a set of relay contacts coupled with the relay coil.