Method and device for matching impedance of generator with unknown load impedance

PURPOSE: To maximize the power to be transferred to a load by matching the impedance of a generator with an unknown variable load impedance. CONSTITUTION: This device is equipped with an impedance-matching network 18 and a network model for estimating the impedance ZL, of a load 12 from a known present network value and an output impedance ZG of a generator 10 and estimating an optimum network value from the output impedance ZG of the generator 10 and the estimated impedance ZL of the load 12. A controller computes a new fresh network value on the basis of the present value and the optimum value and outputs the fresh value to the network 18. This process is repeated by using the fresh network value, so as to estimate the impedance ZL of the load 12 and to generate a new optimum value set. According to this constitution, the power transferred to the load 12 can be maximized.