Affine Nonlinear Control of a Multivariate Inductive Power Transfer System With Exact Linearization

In this article, an exact linearization algorithm and nonlinear control scheme of the inductive power transfer (IPT) system for electric vehicles (EVs) are proposed, considering a variation in system operating point. For ease of modeling, the secondary side of IPT system is equivalent to a reflected reactor and resistor on primary side at different operating frequencies. By utilizing the exact linearization method, the nonlinear model is accurately transformed into a linear one at whole operating points. Besides, to acquire constant current
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voltage (CV/CC) charging and zero voltage switching (ZVS) operating for EVs, the controllers are designed and optimized in the linear space, and then inverse mapped to the nonlinear space. This avoids designing different controllers for each operating point. Compared with a traditional PI controller, the nonlinear control scheme suggested in this article enables the system to obtain a fixed dynamic response even if the operating point of the IPT system changes. Finally, practical results obtained from a hardware prototype are included. They confirm the performances of the system and indicate that the proposed nonlinear control scheme can automatically maintain CC
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CV output and ZVS operation with a constant response time of 10 ms.