Abstract: To cope with the wide range voltage variation of photovoltaic (PV) systems and improve the efficiency and flexibility of the photovoltaic-battery system,? a collaborative control strategy of tracking and charging based on impedance regulation characteristics of maximum power point tracking (MPPT) is proposed. The strategy is implemented in an interleaved Boost + Buck-Boost integrated PV charging system. An improved variable step-size perturbation and observation method is employed for MPPT in the front-end boost circuit. Additionally, upper and lower hysteresis limit curves of the boost voltage are designed to cooperatively control the MPPT and constant voltage charging of the back-end Buck circuit. This approach achieves compatibility with a wide input voltage range and maximizes solar energy conversion. Experimental results demonstrate the effectiveness of the control strategy.