Constant Voltage and Constant Current Control Method of Undersea Wireless Power Supply System Based on Frequency Tracking Method

This article presents a combined control method of resonant frequency tracking and constant voltage/constant current charging mode for undersea wireless power transfer (UWPT) systems. This control method can quickly respond to the change of the resonant frequency of the system. It could solve the problem of UWPT system mismatch caused by complex marine environment with the help of a digital phase-locked loop. The circuit structure is simplified without adding any additional components or changing the topology. In addition, the constant voltage level or the constant current level of the dc output of the UWPT system is realized by adjusting the phase shift angle. The control method can adjust the resonant frequency and the dc output voltage or current without requiring an external circuit. Finally, an experimental platform of 500 W UWPT system is built to verify the theory analysis and the design. The experimental results show that this control method could track the resonant frequency well when the resonant frequency of the UWPT system is offset. At the same time, it can effectively maintain a constant output voltage or current when the load impedance of the system changes.