Automobile servomotor steering circuit - has transistor switch controlled by pulse width modulated signal and parallel relay exhibiting lower losses connected across transistor

摘要

The circuit has a transistor switch (T) in series with a servo steering motor (M) bridged by a parallel relay (R1) exhibiting a lower power loss than the transistor switch and operated by a signal (S1) obtained directly or indirectly from a signal (S2) applied to the transistor switch. Pref. the detected vehicle velocity (V) is used for pulse width modulation of the control signal for the transistor switch. This allows the clamping voltage for the DC servo motor to be varied and provides regulated motor revs. The relay is operated when the detected vehicle voltage lies above or below a defined range. ADVANTAGE - Reduces thermal losses. Reduced heat sink size, and reduced number of parallel switched transistors.