Adaptive PI gain control to realize sinusoidal ripple current charging

This paper presents the adaptive PI gain control to regulate sinusoidal ripple current, which is for battery charging applications. Typically, sinusoidal ripple current charging (SRC) is an outstanding charging algorithm due to its high charging efficiency. In order to perform SRC, the frequency sweep function and regulation of high frequency ripple current are required. The typically designed charger would not be able to satisfy the aforementioned requirements because the control bandwidth of a PI controller is designed for constant current profile. Therefore, the fixed PI gain control is limited to regulate the wide range frequency of ripple current. This paper proposes the adaptive PI gain control based on Model Reference Adaptive Control so that it can regulate variable frequency of charging ripple current. The proposed approach is realized for an existing charger without any change of switching devices. As a result, there is no attenuation and phase delay under variable ripple frequency condition. The performance of current control is compared with conventional fixed PI gain and the proposed adaptive variable gain. The proposed method is verified by simulation and experimental results.