QUASI-STATIC MODEL OF RESONANT POWER CONVERTER

In this paper, a quasi-static model of the resonant power converter with inverter, LLC circuit, and diode rectifier is obtained, which is a linear mathematical model derived from the analysis of quasi-steady-state processes of the substitution circuit for constant values of input and output signals. The quasi-static model is determined on the basis of the dynamic model of the resonant converter for infinite time, which made it possible to obtain analytical expressions of static characteristics based on transient functions. As a result of calculations based on the quasi-static model, the family of static characteristics of the resonant converter, which is replaced by the structure with equivalent voltage generators and a passive part of the circuit, is obtained. The passive part contains the resonant circuit, the voltage transformer, and some parasitic parameters of the transformer and other circuit elements. Equivalent voltage generators replace the voltage inverter with the power source and the rectifier with the load. Thus, the switched power circuit of the resonant converter is replaced by the non-switched circuit with voltage generators and the passive multipole. The input values of the substitution circuit are the voltages of equivalent generators, and their currents are the output values. Quasi-steady-state processes are represented as a set of stationary functions consisting of stationary transient functions. Stationary functions are the sum of individual transient functions that repeat from period to period of the operating frequency. To determine the transient functions according to the finite value theorem of the z-image, we use the transfer functions obtained from the discrete dynamic model of the resonant converter. The algorithm for switching power valves is taken into account when formulating the steady-state current formula of the output equivalent generator, at the intervals of non-zero voltage of which the average load current is determined by integrating the steady-state current. Comparison of the calculated static characteristics with the experimental characteristics confirmed the correctness of the theoretical results. References 24, figures 6, table 1.