A current source parallel inverter in steady-state operation

The steady-state behaviour of a current source parallel inverter loaded by a resonant circuit is discussed. The state equations are solved by applying the conditions of periodicity. The final results are obtained directly without following the transient changing cycle by cycle which starts with the first cycle. The analysis is based on the symmetrical and periodical behaviour of the inverter (it is assumed that the switching times of thyristors are equal). The advantage of this analysis is that the solution is achieved in a closed form. This method is illustrated by an example of a parallel resonant DC-to-AC inverter analysis in its steady-state operation. The results are also compared with those obtained by applying Fourier series analysis. In both methods the general expressions of the inductor current, capacitor voltage and the input/output power and efficiency as a dependency of the ratio between the switching period and the resonant period, are obtained. The region of the inverter stable behaviour (reliable thyristor switching) is determined.