Large magnetic field volumes associated with core-less high-frequency inductive power transfer (HF-IPT) systems allow multiple receivers to be powered from one transmitter, but also provide greater probability for foreign objects to couple to the system. Knowledge of the types of objects (legitimate receivers or otherwise) that are coupled to the transmitter is critical. Such knowledge on the transmit side would allow the system to be deactivated in the presence of foreign objects, and to determine the exact state of tuning of the receivers so that it may adjust itself accordingly to optimize system performance. This article introduces a technique to calculate the induced voltage generated by coupled receivers and foreign objects on the transmit coil in real time. Changes in the position or electrical quantities of the receivers, and foreign objects, alter the induced voltage on the transmit coil, and with it the trajectory of the switching waveforms of the inverter driving the transmit coil. From the shape of these waveforms, information on the phase and amplitude of the induced voltage can be extracted, thus enabling the induced voltage on the primary to be estimated with a single, easy to access, voltage measurement, which is easier than estimating the induced voltage from measurements of coil current and total coil voltage. We used a support-vector-machine (SVM) to perform regression analysis on the drain voltage data. The experimental setup uses a 100 W, 13.56 MHz Class EF inverter, and the model was generated from a large number of samples of the drain voltage waveforms operating at different known loads. These were generated from our in-house HF-IPT test load, which uses a Class EF synchronous rectifier. The results allow the induced voltage on the transmit coil to be estimated in real time from the drain voltage waveform alone, with a normalized root mean square error of 1.1% for the real part (reflected resistance) and 1.2% for the imaginary part (reflected reactance). This article is accompanied by a video file demonstrating the experiments.

中文翻译：

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使用 EF 类开关波形的高频 IPT 系统中的负载表征

与无芯高频感应电能传输 (HF-IPT) 系统相关的大磁场体积允许多个接收器由一个发射器供电，但也为外来物体耦合到系统提供了更大的可能性。了解耦合到发射器的对象类型（合法接收器或其他）至关重要。发送端的这种知识将允许系统在存在外来物体的情况下停用，并确定接收器的准确调谐状态，以便它可以相应地调整自身以优化系统性能。本文介绍了一种实时计算耦合接收器和异物在发射线圈上产生的感应电压的技术。接收器位置或电量的变化，和异物，改变发射线圈上的感应电压，并随之改变驱动发射线圈的逆变器的开关波形轨迹。从这些波形的形状中，可以提取有关感应电压的相位和幅度的信息，从而能够通过单一的、易于访问的电压测量来估计初级上的感应电压，这比估计感应电压更容易。测量线圈电流和总线圈电压的电压。我们使用支持向量机 (SVM) 对漏极电压数据进行回归分析。实验装置使用 100 W、13.56 MHz EF 类逆变器，该模型是根据在不同已知负载下运行的大量漏极电压波形样本生成的。这些是由我们内部的 HF-IPT 测试负载产生的，它使用 EF 类同步整流器。结果允许仅从漏极电压波形实时估计发射线圈上的感应电压，实部（反射电阻）的归一化均方根误差为 1.1%，虚部（反射电阻）为 1.2%。电抗）。本文附有演示实验的视频文件。