WIRELESS UAV CHARGING SYSTEM WITH BATTERY BALANCING FUNCTIONALITY

Abstract

The issue of creating a wireless charging system for an on-board battery of an unmanned aerial vehicle
(UAV) is considered, taking into account the need to balance the voltages of its elements. When designing
the system, based on a brief overview of the principles of wireless energy transmission, the principle
of using magnetically coupled circuits is taken as the most suitable in terms of its technical and economic
properties. The aim of the work is to develop a circuit solution for a UAV's wireless battery charging
system with the ability to balance voltages both during charging and during load operation. The use of
such a system will improve the safety of battery operation and extend its service life by leveling the degree
of wear (aging) of the elements. As a result of the research, a circuit was developed and an experimental
sample of the specified wireless charging system was manufactured. When synthesizing the circuit, the
task was to minimize the number of components in the power circuits in order to reduce the mass of the
system and its cost. The maximum power of the experimental wireless charging system exceeds 100 Watts
(25 V · 4 A) and is somewhat excessive for an on-board battery with a capacity of 1,500 mAh. Forced
cooling of the receiving part is not required. The weight of the receiving part mounted on an unmanned
aerial vehicle is 79 g (40 g is the receiving coil and 39 g is the electronics unit) and has reserves for reduction
by reducing the cross–section of the receiving coil conductors, using a textolite with a lower
thickness in the electronics unit, sealing the installation and using a two–sided arrangement of components.
Laboratory tests have been carried out, confirming the operability of the proposed technical solutions,
and the effectiveness of balancing during charging has been evaluated. In order to evaluate the
effectiveness of the balancing system during the experiments, the output resistance of the receiver (U/I)
was calculated relative to one of the elements of the on-board battery when the voltage on it changes.
The result was 1.9 ohms with a charge current of 0.8 A (6S 1500 mAh battery).