| Magnetic coupling wireless power transfer(MC-WPT)technology is based on the principle of electromagnetic induction coupling and is used to realize contactless power transmission over a certain distance.MC-WPT technology is a new mode of power transfer or power access and can be widely applied to various movable electrical equipment(such as electric vehicles,rail transit,factory hoisting and handling equipment,etc.),household appliances,and mobile phones and other consumer electronics.This technology is expected to emergy as the best mode of power access for electrical equipment in the future.An MC-WPT system first generates high-frequency current using an inverter and then converters electromagnetic energy to electrical energy using a magnetic coupler to supply power to the load.The high-frequency inverter is a key component that affects the overall performance of an MC-WPT system.Therefore,MC-WPT systems have different special requirements for high-frequency inverters according to different applications and performance indicators.Existing research on high-frequency inverters used in MC-WPT systems primarily focus on the optimization and control of power and efficiency.However,for the specific requirements in different applications,there are some shortcomings in the existing high-frequency inverters.For example,in high-power applications,traditional inverters fail to meet the performance requirements of the system because of the limited capacity of power switches,complicated structure and control,high output harmonic component,and poor reliability.In multi-transmitter applications,such as static wireless power transfer(SWPT)desktops for consumer electronics and home appliances as well as electrical vehicle dynamic wireless power transfer(EV-DWPT)with segmented track supply mode,the pickup coils or loads are time varying and uncertain.Most adopted inverters are single-output inverters,which greatly increases the number of inverters required by the system and reduces its reliability.Additionally,limited research has been conducted on the wide range of dynamic change in loads and coupling coefficient and random discrete changes in the output states of high frequency inverters in EV-DWPT systems.Aiming at the different special requirements for high-frequency inverters in different MC-WPT applications,this paper focuses on the topologies of high-frequency inverters.Specifically,the main research work of this paper are as follows:(1)Aiming at the large number of inverters and complicated phase synchronization control between inverters in multi-transmitter SWPT systems,a dual output inverter is proposed.The proposed inverter can generate two identical output voltages to drive two primary coils synchronously,thus reducing the number of inverters and power switches required for the SWPT system and simplifying the system control.The gain characteristic of the output voltage of the proposed inverter is analyzed,and the comparison with the existing inverters are presented.The equivalent mathematical model of the system is established,and the output power characteristic of the system is analyzed.Furthermore,the voltage and current stress and soft-switching states of the power switches are calculated and analyzed.(2)For EV-DWPT systems with segmented track supply mode,aiming at the single output and the limited research on wide range adaptability and state switching performance of the output of existing inverters,an independent-controllable(IC)dual-output inverter is proposed.The proposed inverter can realize an expanded output range and on-demand driving and fast and smooth switching of two primary tracks.The gain and independent control characteristics of two inverter output voltages are analyzed,and the comparison with the existing multi-output inverters are presented.Additionally,the load voltages in different output states of the proposed inverter are analyzed.The steady-state modulation strategy of the proposed inverter is designed based on this analysis,the output state switching strategy,and the parameters.Furthermore,equivalent topologies of the proposed inverter in different output states are established and the soft-switching states are analyzed accordingly.(3)To overcome the challenges of complex structure and control and high output harmonic component of the existing inverters in high-power MC-WPT systems,a single-source switched-capacitor(S~3C)multilevel inverter is proposed.The proposed inverter can generate a high amplitude and low harmonic output voltage utilizing less number of power switches with low voltage capacity to improve the system output power and power transfer quality with simple structure and control.The self-voltage balancing ability of the switched-capacitor and the inverter output voltage are analyzed,and the comparison with the existing multilevel inverters is presented.The equivalent mathematical model of the system is established to analyze the system output power.The modulation strategy of the proposed inverter and the parameter of the switched-capacitor are designed.Further,the soft-switching state and power loss of the proposed inverter are calculated and analyzed.(4)Aiming at the charging current spikes and voltage decreases in the capacitors of existing multilevel inverters,an inductor-connected single-source cascaded H-bridge(ICSS-CHB)multilevel inverter is proposed to eliminate current spikes and reduce the voltage decreases,thereby improving the service life of the capacitors,waveform quality of the output voltage,and operation reliability of the inverter.Based on the equivalent mathematical model of the system,the charging and discharging processes of the capacitor are analyzed,the expressions of inductor and capacitor currents are obtained,and the parameters of the inverter are designed.Furthermore,the soft-switching state and power loss of the proposed inverter are calculated and analyzed. |
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