Liu Hao, Shao Qi, Fang Xuelin
IEEE Trans Biomed Circuits Syst. 2017 Feb;11(1):35-43. doi: 10.1109/TBCAS.2016.2538320. Epub 2016 Jun 15.
For the class-E amplifier in a wireless power transfer (WPT) system, the design parameters are always determined by the nominal model. However, this model neglects the conduction loss and voltage stress of MOSFET and cannot guarantee the highest efficiency in the WPT system for biomedical implants. To solve this problem, this paper proposes a novel circuit model of the subnominal class-E amplifier. On a WPT platform for capsule endoscope, the proposed model was validated to be effective and the relationship between the amplifier's design parameters and its characteristics was analyzed. At a given duty ratio, the design parameters with the highest efficiency and safe voltage stress are derived and the condition is called 'optimal subnominal condition.' The amplifier's efficiency can reach the highest of 99.3% at the 0.097 duty ratio. Furthermore, at the 0.5 duty ratio, the measured efficiency of the optimal subnominal condition can reach 90.8%, which is 15.2% higher than that of the nominal condition. Then, a WPT experiment with a receiving unit was carried out to validate the feasibility of the optimized amplifier. In general, the design parameters of class-E amplifier in a WPT system for biomedical implants can be determined with the proposed optimization method in this paper.
对于无线电力传输（WPT）系统中的E类放大器，其设计参数通常由标称模型确定。然而，该模型忽略了MOSFET的导通损耗和电压应力，无法保证用于生物医学植入物的WPT系统具有最高效率。为了解决这个问题，本文提出了一种新型的次标称E类放大器电路模型。在胶囊内窥镜的WPT平台上，验证了所提出的模型是有效的，并分析了放大器设计参数与其特性之间的关系。在给定占空比的情况下，推导了具有最高效率和安全电压应力的设计参数，该条件被称为“最优次标称条件”。在0.097的占空比下，放大器的效率可达到最高99.3%。此外，在0.5的占空比下，最优次标称条件下的测量效率可达到90.8%，比标称条件下高15.2%。然后，进行了带有接收单元的WPT实验，以验证优化后的放大器的可行性。总体而言，本文所提出的优化方法可以确定用于生物医学植入物的WPT系统中E类放大器的设计参数。
