Load-relief network for branch pairs, which are free of off-state voltage, of a multiphase converter

摘要

Electronic power circuits using GTO thyristors (T1...T6) or transistors as controllable electronic switches require a load-relief network for operation, which network delays the current rise during switching on and the voltage rise during switching off. In detail, a switching-off load-relief capacitor (CEA, CEB, CEC) and two switching-off load-relief diodes (D1...D6) are provided per branch pair, as well as a load-relief resistor (RO) or DC/DC voltage converter (4) which is common to all branch pairs (1, 2, 3). In order reliably to prevent dangerous voltage spikes when switching the GTO thyristors off, it is proposed to provide a dedicated storage capacitor (CPA, CPB, CPC) per branch pair and to arrange one decoupling diode (DA, DB, DC) in each case between the load-relief resistor (RO) and the individual storage capacitors. As an alternative to this, the DC/DC voltage converter (4) can also be constructed as a voltage-stabilising energy recovery transformer (feedback transformer). <IMAGE>