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This paper presents a unified approach to the analysis of DC/AC converters based on an equivalent representation of their AC circuit as a series RLC circuit. The resonant DC/AC converter with reverse diodes was chosen as the basis of the examination, and the obtained ratios for this device were used to derive the main ratios describing the operation of the other types of DC/AC converters—voltage source inverters (VSI) and current source inverters (CSI). Based on the commonality of electromagnetic processes in power circuits, the expressions for the current through the inductance and the voltage of the capacitor are found in a compact form with their initial phases. The base ratios found through the analysis are normalized to the control frequency, thereby summarizing all possible operating modes. In this way, electromagnetic processes in a whole class of power electronic devices are described from general positions, which is convenient from a methodical point of view with a view to improving power electronics education. The proposed analysis approach is also applicable to three-phase DC/AC inverters, taking into account the specifics related to the presence of three phases and, accordingly, their mutual influence in the formation of the output currents and voltages. On the other hand, the basic ratios determined through the application of the unified analysis approach are also useful with a view to creating engineering design methodologies, in which the values of all circuit elements are determined with comparatively simplified calculation procedures. [ABSTRACT FROM AUTHOR]

A method is developed for reducing the power inverter electrical circuit of fourth order to an electrical network of second order. The reduction is based on the assumption that the output inverter voltage is practically with a sine-wave shape. The normalized form guarantees novelty and versatility of the investigation on one hand and independency in relation to the concrete inverter parameters like output power, supplying voltage and operating frequency on the other. From the whole power network of fourth order for the first time two sub circuits are suggested to be outlined: the output (load) sub circuit and the inverter commutating sub circuit. Both sub circuits of a second order define the parameters of the endmost inverter circuit again of the same order and consequently the mode of operation and parameters of the power inverter itself. The transformation is possible owing to the newly found fact that the frequency dependencies of the output (load) sub circuit can be separated from the dependencies that describe the structural relationships between the two sub circuits. The results from that conversion are of course more accurate when the resonant frequencies of the both sub circuits and the operating frequency do not differ substantially. The suggested approach is useful on order to obtain a simplified engineer method for precise and fast design of large class of static power converters applicable in electronic technology like induction heating and melting. [ABSTRACT FROM AUTHOR]