Design And Implementation Of An Integrated MPPT Controller Used For Solar Panel

Nowadays, accompanying with the rapid developments of global economy, China has become increasingly industrialized in the world, thus bringing a huge energy demand. With the depletion of conventional energy sources and the deterioration of the environment, the development of alternative energy such as solar energy is promoted.Due to openair work conditions, the output power of the PV panel is susceptible to environment and load. In response, MPPT (Maximun Power Point Tracking) technology is proposed. Traditionally, a centralized MPPT controller is embeded into the inverter between PV array and dc line. However, the array’s overall efficiency is decreasing dramatically in the case of partial shading and module mismatch, and the hot spot may even destroy the PV panel, thus affect the output power of the whole PV array. To mitigate the adverse effect mentioned above, a new topology called "DMPPT"(distributed MPPT) is proposed and studied recent years.In this paper, based on the research of different kinds of MPPT technology and the characteristics of DMPPT, an analog integrated MPPT controller together with its application circuit is presented, which is suitable for DMPPT topology. The proposed chip integrates all needed modules, and produces a PWM signal as output provided to DC/DC converter. Meanwhile, an improved P&O (perturb&observe) algorithm is adopted to achieve MPPT.The main advantages of the proposed integrated MPPT controller compared to others are shown below:1. The analog circuit design leads to a smaller chip area and a lower cost.2. The proposed improved P&O algorithm is load irrelevant. It can achieve a fast and precise tracking especially in fast changing weather conditions and unstable load conditions.3. A dual module control (PWM+burst) is used in the control system, leading to a stable and efficient DC/DC conversion. Meanwhile, a voltage mode negetive feedback loop is embeded in the system to mitigate the mutual effect in DMPPT topology.4. Without large numbers of external circuit components, the DC/DC converter together with its MPPT controller can be made small enough to be integrated into the junction box, which is practical, stable and cost effective for DMPPT topology. Meanwhile, different kinds of protective circuits and alarm circuits further enhance the entire system reliability.The proposed chip is fabricated in CSMC0.5μm mix-signal CMOS process. The simulation and experimental results show that all the parameters of the chip meet the specifications, and the chip is able to track the maximun power point of the PV panel.