Multi-input single output wireless power transmission (MISO-WPT) systems have decisive advantages concerning flexible receiver position in comparison to single coil systems. However, the supply of the primary side brings a large uncertainty in case of variable positions of the secondary side. In this paper, a compact multiplexed primary side electronic circuit is proposed, which includes only one signal generator, a passive peak detector, a communication module, and a compensation capacitor. The novel approach has been studied and evaluated for a MISO-WPT system having a 16 coils on primary side and one coil on secondary side having the double diameter. Results show that a standard microcontroller, in this case an STM32, is sufficient for the control of the whole system, so that the costs and the energy consumption are significantly reduced. An activation strategy has been proposed, which allows to determine the optimal transmitting coil for each position of the receiving coil and to switch it on. The time-to-start-charging at different positions of the receiving coil and different number of neighbors has been determined. It remains in all cases under 2.5 s.This reduces the size of the supply circuit relative to the previous solutions. In [19], a multi-coil system with multiplexed solution is presented with a singular supply circuit. However, the selection of the appropriate coil requires dual MOSFET switches, which presents some similarity to a switch-based multi-coil system. Nevertheless, the control of the multi-coil system switches needs microcontrollers with a high number of pins. For that, in case of a big number of transmitting coils, an FPGA [22] is proposed as processing unit, leading to an increase of both energy consumption and costs.In this paper, we investigate the feasibility of a multiplexed circuit on the primary side supply approach, with the aim to reduce the circuit size and to control the system by a simple microcontroller with a limited number of pins. The main objective is to significantly decrease both energy consumption and system costs. To this end, we propose to use receiving coils having the double diameter of the transmitting coils. This is important to cover at least a singular transmitting coil for different possible positions on the top of the pad to power the device for all the possible positions. In order to enable the detection and the powering of even battery-free wireless sensor nodes, we propose that the communication between the transmitting and receiving coil is started from the transmitting side and supplied from the transferred energy on the secondary side.The paper is organized as follows: In Section 2, the primary side supply circuit for a system is presented. The description of the proposed multi-coil system control algorithm is detailed in Section 3. The experimental evaluation of the developed algorithm are reported in Section 4. Section 5 shows the analysis of the required time to start the charging process. A conclusion is provided in Section 6.
Design of the Primar...