| The development of renewable energy helps to solve global environment and energy problems,but it also brings challenges to conventional power systems.So,the power systems have to upgrade themselves to meet various demands in future applications.By combining information technology and power electronics to achieve power conversion and data modulation simultaneously,the power/data integrated modulation technique caters to the power and communication demand of future power systems.This paper focuses on the power/data integrated modulation technique for the basic DC-DC conversion,and aims at integrated modulation schemes for high-effeicency data modulation.By analyzing the power conversion restrictions on the control degrees of freedom(Do F),multi-Do F power/data integrated modulation theory is proposed,and the coordinated-control-based multi-Do F schemes are designed for pulse width modulation(PWM)and pulse frequency modulation(PFM).Moreover,by giving priority to data modulation and redesigning the power control scheme,the switching-state-based multi-Do F power/data integrated modulation scheme is proposed to further improve the data modulation efficiency.First,the basic theory of multi-Do F power/data integrated modulation is proposed.By deconstructing the power converter into switching networks and passive networks,the processes of data generating,transferring and receiving are analyzed in details,and the existence of the data carrier is specified.By discussing the signal characteristics in the integrated modulation,the existence of the basic modulation unit is specified,and the power conversion entropy is defined to be the evaluating parameter of data modulation efficiency.Based on the parameter,the restriction of power conversion on controllable Do F and the data modulation compatibility between different controllable Do F is discussed.According to the discussion,the coordinatedcontrol-based and the switching-state-based multi-Do F power/data integrated modulation principles are proposed,providing the basic theories for the following researches.Second,coordinated-control-based multi-Do F power/data integrated modulation schemes are proposed for PFM.PFM is classified by the number of controllable Do F into two categories——rigorous PFM and lenient PFM.In rigorous PFM,an integrated modulation scheme that uses frequency and phase for data modulation is proposed,which decouples the power control and communication control by frequency encoding.In lenient PFM,the power control strategy is optimized,and an integrated modulation scheme that uses the pulse width for secondary power control and modulates data on the phase is proposed,where the frequency can change only among certain values according to the output power.The scheme can work when multiple converters exist.The above schemes are verified on an LLC experimental platform and a Buck platform.Third,a coordinated-control-based multi-Do F power/data integrated modulation scheme is proposed for PWM.The influence between power control and communication is analyzed.The transition process is introduced to help to change the phase,which suppresses the influence on power control.Then the data modulation compatibility between different Do F is discussed,and by introducing the duty cycle encoding,a combined three-Do F power/data integrated modulation scheme is proposed,where data is modulated on the duty cycle and the phase,and the frequency is for the converter state identification and helping to change the phase.The scheme is verified on a PWM experimental platform.Finally,despite the existing basic DC-DC conversion,by giving priority to data modulation,a switching-state-based multi-Do F power/data integrated modulation scheme is proposed.The scheme chooses the switching state to be the basic modulation unit,and the power control is redesigned based on PWM and PFM.By analyzing the inter-symbol interference(ISI),the passive network of the converter is optimized for ISI suppression,decoupling the power control and communication.Then,a switching state encoding method is discussed for high data modulation efficiency,and a switching-state-based modulation scheme is proposed,which enhances the power conversion entropy by sending baseband data.The scheme is verified on a visible light communication experimental platform. |
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