Control circuit for inductive load e.g. electric motor, relay or valve, has free-running circuit with diode and Zener diode connected across connection terminals for switched inductive load

摘要

The control circuit uses a first semiconductor switch (T1) with a control terminal (G) and a load path (D-S) connected in series with the switched inductive load via a pair of connection terminals (K1,K2) across which a free-running circuit (10) is connected. The free-running circuit has a diode (D1) and at least one Zener diode (Z1,Zn) connected in series so that one or other conducts when a voltage is applied across the free-running circuit, the zener diode connected to the control terminal of a second semiconductor switch (T2), connected in series with the diode between the connection terminals.