To solve the problem of unstable output voltage of inductively coupled power transfer system (ICPT) subject to disturbance or great load changes

the energy and efficiency of two different compensation topology structures are studied. The output voltage

output power

output efficiency

frequency stability

and load adaptability of the parallel-series (PS) topology and the series-series (SS) topology are also dealt with. Based on the variable structure mode

the method employing different topologies for different loads is given. The switching prerequisite is analyzed in detail and the methods of ensuring safety and effectiveness of switching are recommended. In order to validate the effectiveness of the variable structure mode

two greatly different loads are adopted with their output voltage measured in voltage and current mode ICPT system

respectively. The results show that the variable structure mode is suitable for constant-voltage ICPT system whose load is greatly changed. This work is supported by National Natural Science Foundation of China (No. 51277192).