Study On Characteristic Of Bifurcation Of Frequency And Application In Control Of IPT System

Wireless power transfer(WPT) technology is born to remove the shortcomings of exposure to electric spark and coke and mechanism wear in the direct wireless power supply mode. Inductive Power Transfer(IPT) technology is relatively general and mature compared with other contactless power transfer technologies.In the IPT system design, in order to achieve soft-switching condition which can reduce switching losses and EMI, the primary resonant compensator need to compensate for the voltage and current of the inverter output links to the same phase state. When doing research on IPT system, we found it will bring some strange phenomena when the system parameters change, the most common phenomenon is the bifurcation of the soft-switching frequency, as a result, it will reduce the power transmission capability of the system and system work unstable. So it not only promotes the theory of multi-load IPT system but also plays an important role on IPT systems engineering applications that studying the mechanism of soft-switching frequency bifurcation point IPT system and method for controlling the bifurcation.In this paper, based on the IPT system structure of the whole bridge as the research object. According to the fixed frequency work proposes a parameters optimization strategy based on frequency characteristics. Aiming at the floating frequency control, put forward a kind of bifurcation control strategy based on the fixed frequency disturbance perturbation The main research contents include:①Analyzing and comparing the differences between traditional modeling and stroboscopic map modeling; modeling a precise mathematical model based on stroboscopic map modeling and periodic fixed point theory; analyzing the soft-switching frequency characteristics and the state of the system like efficiency, power and other characteristics under conditions of load and resonance frequency changes based on this method. This paper also analyze other topologies of IPT system.② Analyzing the relationship between soft-switching frequency and primary resonant current and output voltage of load based on AC impedance analysis and Stroboscopic map modeling and Periodic fixed point theory. This paper proposed a new parameter optimization method to solve the problem of frequency stability and bifurcation area, it can stabilize system operating frequency.③Frequency domain nonlinear dynamics bifurcation and limit cycle attractor and draw corresponding has carried on the analysis in the phase plane analysis based on the Floquet stability theorem; IPT system for multi resonant soft switching points based on autonomous oscillation; frequency disturbance on the system frequency bifurcation function and puts forward a transmission control strategy based on the analysis of the frequency disturbance, it is verified by simulation; fixed frequency perturbation and time delay perturbation control strategy based on the comparison of the similarities and differences, and discusses two kinds of control method of the equivalence and unity.