Synchronous Switching and Control of WPT Systems With an Active Rectifier Based on Recursive Current Tracking

The control of wireless power transfersystems with an active rectifier can be implemented on the secondary side, which avoids the need for real-time wireless communication between the primary and secondary sides to construct the feedback loop, thus facilitating the control design. However, in secondary control we encounter the challenge of synchronous switching. In this article, a data-based approach is proposed to address this challenge, which first applies a recursive algorithm to estimate in real time the amplitude and phase of the input current of the active rectifier from sampled data, then generates the driving signals based on the estimated phase for the active rectifier to control the relative phase angle between the input voltage and current of the active rectifier, and finally performs secondary phase-shift control to regulate the load power. The recursive algorithm for current tracking has the merits of relying on data only, so it requires less peripheral circuit components, and shows high accuracy in current phase detection and synchronous switching because the current parameters are optimized in a minimal prediction error sense. Moreover, it also shows good tracking ability under conditions such as system detuning, harmonic distortion, primary-secondary frequency mismatch, etc. At the same time, it has a moderate computational burden, each recursion consuming about 487 clock periods when implemented on the 200-MHz digital signal processor TMS320F28377D. To facilitate control design, a low-order model is identified from sampled data to characterize the dominant dynamic behavior of the system and, then, used to tune the proportional-integral-derivative control parameters. The effectiveness of the proposed control method is validated on a 1.5-kW level prototype.