Switched-mode power supply for a DC motor

摘要

Switched-mode power supply for a low-voltage DC voltage motor 8 having a flow-through converter, the power part of which contains a switching transistor 1, a rectifier diode 9 and a transformer 2, the primary winding 21 of which is connected in series with the switching path of the switching transistor 1 and the secondary winding 22 of which is connected in parallel with the series connection of the rectifier diode 9 to the DC motor 8, a freewheeling diode 10 being arranged in parallel with the DC motor 8, the control device of the converter being used for driving the switching transistor 1. The control device contains an astable multivibrator 3 which determines the duty ratio of the switching transistor 1, and a comparator 4 with hysteresis and has the voltage across the DC voltage motor 8 applied to its input side, the output signal of which comparator is delivered at an earlier instant in the event of increasing motor voltage. The outputs of the astable multivibrator 3 and of the comparator 4 with hysteresis are connected to the control terminal of the switching transistor 1 via a logic (switching) element 5. <IMAGE>