Small-Signal Phasor Modeling of an Underwater IPT System in Constant Current Distribution

The use of inductive power transfer (IPT) technology is advancing rapidly in the area of wireless charging of electric vehicles and beginning to expand into emerging areas such as wireless charging of autonomous underwater vehicles. For long distance power distribution to transmitter pads in underwater applications, the use of constant dc current distribution is being considered to reduce the impact of line voltage drop. One challenge for designing such systems is the availability of dynamic small-signal models for controller design and stability analysis. This paper presents a small-signal phasor model for dc current input series-series compensated IPT systems targeted for underwater vehicle charging applications. The proposed small-signal modeling approach eliminates complicated mathematics for obtaining transfer functions, and can be easily applied to other current input IPT topologies. Simulation and experimental results are provided to validate the models based on a 16 V, 100 W hardware prototype operated at 250 kHz switching frequency, and supplied from 1 A dc input.