| In recent years, wireless power transmission (WPT) technology has been widely concerned and investigated as a new way of power supply. It uses the transfer medium (such as high-frequency magnetic field, electric field or ultrasound, etc.) to transfer the electrical energy from the power supply to electrical equipment in the form of electrical isolation. Compared with traditional power transmission, it can almost eliminate mechanical contact friction and sparks. Besides, it also owns the advantages of safety, convenience and flexibility, which make it have a broad application prospect in portable electronics, electric vehicles, medical equipments, underwater, mines and other fields.The paper focuses on the output power and transmission efficiency of the wireless power transmission circuit with different compensation networks. Circuit model is established based on the circuit’s working principle. The relationship between output power, transmission efficiency and compensation topologies and circuit parameters is discussed in detail. Meanwhile, an experimental platform is set up for experimental validation. During the study, the main work of the paper is as follows:First of all, in order to investigate the output power and transmission efficiency of the wireless power transmission circuit, a high-frequency emitting power supply is designed. It mainly includes the full-bridge inverter circuit, driving circuit, PWM controlling circuit and auxiliary power supply circuit. What’s more, the principle of frequency tracking WPT circuit is analyzed in detail. The phase-locked loop circuit, phase compensation circuit and waveform conditioning circuit are designed. The power supply’s input voltage is220V and inverted output voltage is50V. Its frequency adjustment range is50kHz-800kHz. The transmission power is40W.And then, combined with the benefits of series compensation and parallel compensation, a WPT circuit with LCC (inductor-capacitor-capacitor) compound resonance compensation network in the primary side is proposed. Based on the mutual inductance coupling model of the two coils, the equivalent circuit models of primary-side and secondary-side are derived. The closed-form expressions for the output power and transmission efficiency of LCC compensation WPT circuit are obtained. Besides, it is simulated using MATLAB in contrast with the four basic compensation WPT circuits. The compensation capacitors in the primary side of the four basic compensation WPT circuits are optimized considering the equivalent resistance of the coupling coils. Furthermore, the constant current characteristic of LCC compensation WPT circuit is simulated and demonstrated by experiment.During the research on the output power and transmission efficiency of the wireless power transmission circuit, it is found that the transmission efficiency is too low when the SP-type (series-parallel), or SS-type (series-series) compensation WPT circuit is optimized for maximum output power. In order to overcome these disadvantages, an index is presented. When the mutual coupling coefficient is optimized under the index, an overall optimization design for the WPT circuit can be realized. |
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