Voltage supply for inverter controller - has intermediate circuit connected via power Zener diodes and isolation diodes

摘要

The voltage supply circuit detects a reduced voltage in the aux. voltage intermediate circuit (7), during mains (L1, L2, L3) voltage drop-out, via a comparator (8). The comparator (8) is used to establish whether sufficient voltage (UD2) to control (drive) the self-commutated inverter exists the voltage intermediate circuit (7). The output of the comparator (8) is connected to a logic AND-gate (14) whose output signal is used to close a contact (17) for controlling the protection (12), and the intermediate circuit is connected via power zener diodes (5.3) and isolation diodes (5.4), since direct coupling of both intermediate circuits is difficult at mains voltages above the necessary aux. voltage (i.e. e.g. greater than 380V). ADVANTAGE - Assures back-up of supply voltage in event of mains voltage drop-out.