Virtual Multiple Input Multiple Output Simultaneous Wireless Power and Information Transfer Technology

Most devices need wireless power function and regular communication in wireless power transfer applications, such as autonomous guide vehicles and implantable medical devices. Multiple input multiple output (MIMO) antenna technology is widely used to enhance wireless communication speed and channel capacity. The traditional energy modulation method relies on a single pair of coils to realize the power transfer and communication, which makes parallel communications hard to achieve. This paper proposes a virtual MIMO-SWPIT technology to meet multi-terminal communication requirements in the wireless power transfer system. The proposed system has two working styles. When wireless power transfer is required only, the system works under the resonant state with the highest efficiency and power transfer ability. When the system needs wireless power and communication transfer simultaneously, the phase-shift angle and the frequency in inverters are modulated to a specific waveform in the transmitting coil. The fundamental and harmonic components in the specific waveform are used as the multi-carrier to transmit information. The receiving side demodulates the information contained in the fundamental and harmonic components, and the harmonic components are used to power the load. A full bridge inverter is built with the series-series compensation for wireless power transfer on both sides. The power transmission characteristics are analyzed under the two styles. Under the given working conditions, the effect of the coupling coefficient on the transmitting current is shown in both the time domain and frequency domain. Theoretically, power transfer capability achieves the maximum value when the coupling coefficient κ is 0.1. When κ is larger than 0.1, the larger κ results in smaller power transfer capability and larger power efficiency. Three communication modes are the phase shift modulation, the frequency modulation, and the combination of the phase shift and frequency modulation. The phase shift angle range and frequency deviation are analyzed based on the speed requirements of signals and wireless power transfer quality. The results show that the system can realize wireless power and information transmission under three communication modes. The deviated position between coils only affects power transmission. The proposed circuit structure and the modulation strategy are simple and easy to realize. The modulation process has little impact on wireless power transfer quality. The weak coupling relationship between power supply and communication is achieved. The system shows good anti-disturbance under different working conditions and has good application prospects for multi-channel communication in wireless power transfer fields. The experimental results show that stable wireless power transfer with dual-channel information transmission is achieved, and the voltage fluctuation is less than 3% under a 4.0 kbit/s data rate. © 2024 China Machine Press. All rights reserved.