Parameters Design of Composite Resonant Circuit for Outputting Dual Frequency Signals with Different Frequency Ratios

In the past, the parameter approximation design method considering only medium and high frequency applications is reported for the composite resonant circuit applied in the dual-frequency induction heating. In order to expand the output performance of the composite resonant circuit in the frequency range of medium frequency, super-audio and high frequency, and to improve the accuracy of the frequency selection characteristics of the resonant circuit, A new parameter design method for the composite resonant circuit composed of four passive components is proposed in this paper. According to the design principle of the minimum total impedance of the resonant circuit and the transformation of equation and the condition of obtaining effective solution, the parameter design method of the four passive components in the composite resonant circuit is deduced, in which the parameters of inductance, capacitance and the ratio of the two series resonant frequencies are not constrained artificially, and no calculation term is ignored. The design and calculation process of each parameter is given in the paper, and the specific steps of the parameter design of the composite resonant circuit are given. The frequency selection characteristics of the composite resonant circuit are tested in different cases where the ratio of the two resonant frequencies is greater than 10 or less than 10. For the case where the ratio is greater than 10, the comparison test of the frequency selection characteristics of the resonant circuit is performed with the existing parameter approximate design method. The test results show that the design method of resonant circuit parameters proposed in this paper improves the dual frequency output performance of the composite resonant circuit composed of four passive components.