In order to obtain the mutual inductance and load resistance from the front-end without wireless communication system, this paper proposes a variated-phase-shift based identification method for the inductive power transfer (IPT) system. The principle is using variated-phase-shift strategy to bring in interharmonics for identification. The process includes: firstly, using Fast Fourier transmission (FFT) to find the interharmonics; then, multiple sets of circuit equations can be established with these interharonics; finally, with the least-square approximation, mutual inductance and load resistance can be estimated from the circuit equations. Only the magnitudes of input voltage and current are required, no extra hardware is needed, and the working frequency is fixed. Experimental results show the relative errors of identification are within 5%, fluctuations of efficiency and output voltage are within 4%. This proposal is applicable to any working frequency and topology

Inductive power transfer,load estimation,mutual inductance identification,parameter identification