摘要 频率调谐方法可以有效解决因耦合机构参数漂移导致的无线电能传输系统频率失谐问题,有利于提高系统的传输效率及运行稳定性。传统的双边频率调谐控制方法不统一,并且控制参数优化复杂。为此,该文提出一种适用于高阶补偿无线电能传输系统的通用调谐解耦控制策略。首先,基于电路理论构建高阶补偿无线电能传输系统的分析模型,揭示双边谐振条件及其特征。其次,基于扰动观察法构建一种通用的双边调谐解耦控制策略,可实现原边和副边谐振参数的自适应调整。最后,搭建180 W LCC/LCC系统实验样机,验证了所提频率调谐解耦控制策略的有效性,在耦合机构偏移等工况下能够有效维持系统双边的谐振状态,提高了系统的传输效率和稳定性。
Abstract:As a non-contact power supply method, wireless power transfer (WPT) technology is widely used in medical, automotive, and cellular devices because of its reliability, safety, and high degree of freedom. However, the parameter drift phenomenon of the coupler inevitably occurs in practical applications, which leads to the fluctuation of self-inductance and makes the WPT system suffer from frequency detuning. Thus, its transmission characteristics and stability are affected. Traditional bilateral frequency tuning methods are non-uniform because of the type of topology, and some require communication equipment and complex optimization of control parameters. This paper proposes a unified decoupling control strategy of frequency tuning for high-order compensated WPT systems. Four T-type higher-order compensation networks of LCC/LCC, LCC/S, CLC/CLC, and CLC/S are analyzed as examples. Based on the impedance model, the bilateral resonance characteristics of the primary-side LCC-compensated WPT system and the primary-side CLC-compensated WPT system are deduced. If the primary side is in a resonant state, the RMS value of the input current will reach the minimum. If the secondary side is in a resonant state, the RMS value of the current will reach the maximum. Finally, the generalized criterion is obtained for bilateral tuning decoupling control of higher-order compensated WPT systems. This paper proposes a control strategy to realize the bilateral tuning decoupling control without communication or parameter identification. Instead of the inherent compensation capacitance, the switched capacitor converter (SCC) structure is used, and the equivalent capacitance of the SCC is varied by changing the conduction angle of the control signal. Based on the generalized tuning criterion, the conduction angle of the SCC control signal is changed with the help of the double-step perturbation observation method, and the primary and secondary currents are searched until the minimum value of the primary input current and the maximum value of the secondary coil current. Therefore, the WPT system reaches the resonant state while the conduction angle is optimal. The primary and secondary resonance parameters are realized independently and adaptively, and the bilateral tuning and decoupling control is achieved. Finally, an experimental prototype of a 180 W LCC/LCC WPT system is built. The experimental results are consistent with the theoretical analysis, verifying the effectiveness of the proposed generalized tuning decoupling control strategy. The results show that the method can effectively suppress the frequency detuning problem caused by the parameter drift of the coupler and the self-inductance fluctuation, improving the transmission efficiency and stability of the WPT system. In addition, the proposed method is applicable to the high-order WPT system with a π-type compensation network.
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