Transient State of Transformers Modelling and Study

This paper presents studies about the transient state of circuits and the behaviour of a transformer at on/off switching. The transient state is a short event of energy modification in a system caused by a change in state. This energy variation produces impulses which propagate through the network and influence or can even destroy other devices. Because there are a lot of devices operating in switching mode, it is important to study the transient state. To study and model the transient state differential equations are written for the circuits. This article presents the mathematical base of the transient state and the types of response to it. To create a simple model, state parameters and transfer function were used. An important circuit element is the transformer which has a nonlinear characteristic caused by the magnetic coil material. The equivalent circuit for a real transformer is presented with and without load connected to the output. The differential equations were written using the equivalent circuit. The behaviour of the transformer was studied while functioning in an open circuit. The transfer function is deduced when a load is connected to the output. The step and sin response are studied in different cases, and values of the load.