Digital simulation of power electronics systems. II - Application of the n-terminal analysis method and the representation of electric valves in the form of switches

A description is presented of the simulation program KOPL for circuits of power electronics with arbitrary characteristics. The approach used for the representation of the valves in the form of switches takes into account cases in which parts of the model circuits remain unconnected as a consequence of the blocking action of very many valves. In addition, cases are considered in which, in connection with a conduction in many valves, there are parallel paths along valves that are only conducting. A procedure reported by Arremann (1977) is employed for the derivation of the equations which describe the system. The KOPL program makes use of the Runge-Kutta standard method of the 4th order and the Runge-Kutta procedure of the 2nd order. The modified Merson integration algorithm described by Chai (1974) can also be employed. The usefulness of the KOPL program is illustrated with the aid of examples related to a six-pulse bridge circuit, a pulse inverter, a static converter, a static frequency changer, and a power supply system.