This paper proposes solutions for an IPT system to operate efficiently when large changes in coupling take place. To achieve high power-efficiency independent of coupling, we utilise inherent regulation properties of resonant converters to avoid losing soft switching for any coupling value, and present the optimal load to the IPT-link at the maximum energy-throughput coupling. A probability-based model is introduced to assess and optimise the IPT system by analysing coupling as a distribution in time, which depends on the dynamic behaviour of the wireless charging system. The proposed circuits are a Class D rectifier with a resistance compression network (RCN) in the receiving-end and a load-independent Class EF inverter in the transmitting-end. Experiments were performed at 6.78 and 13.56 MHz verifying high efficiency for dynamic coupling and variable load resistance. End-to-end efficiencies of up to 88% are achieved at a coil separation larger than one coil-radius for a system capable of supplying 150 W to the load, and the energy-efficiency was measured at 80% when performing a uniformly-distributed linear-misalignment of 0-12.5 cm, corresponding to a receiver moving at constant velocity over a transmitter without power throughput control.