Circuit for independent switching of parallel inductive loads

摘要

The loads (L1-Ln) in series with their main switches (S1-Sn) are connected by a free-wheel switch (SF) across a DC source (UB), and bypassed by a free-wheel diode (DF) in series with a MOSFET (SSG) driven by a threshold-setting regulator circuit (B). The junction of each load and its main switch is earthed (M) via a blocking diode (e.g. D1). The regulator monitors the voltage at the common node (A) of the inductors and free-wheel switch. When the threshold is attained the MOSFET is driven into linear conduction. For accelerated switch-off the threshold is chosen close to the voltage rating of the free-wheel switch.