| Summary: | 碩士 === 國立清華大學 === 電機工程學系 === 101 === As oil and gas prices have risen, the demand for alternative energy sources also increased. Photovoltaic (PV), the third important renewable energy has been widely discussed; however, how to transfer solar energy efficiently has become the top issue. In order to deal with the performance degradation caused by sunlight blocking, we used a distributed panel photovoltaic power conversion system, which utilizes maximum power point tracking (MPPT) algorithm to achieve the optimal power conversion rate when being deployed individually on each panel. An internal digital signal processor (DSP) is used to implement MPPT algorithm and predict current to regulate DC/DC boost converter. Moreover, an interface for connecting analog environment and digital control logic is also required. This thesis will mainly focus on designing this interface circuit, which includes an analog to digital converter (A/D Converter) and a digital pulse width modulation (digital PWM).
A successive approximation analog to digital converter (SA-ADC) with 8-bit resolution is used in this circuit. The circuit structure is specifically designed for saving the switching energy and plate area of capacitor. The successive approximation algorithm is controlled asynchronously for reducing the power being consumed by clock generator and control circuits.
This digital pulse width modulator (digital PWM) provides two control channels for switching high-side and low-side switches of DC/DC boost converter. The leakage of this boost converter is effectively suppressed by tuning the dead time between switches. This digital PWM is accompanied with calibration circuit to overcome the process variation and self-rest circuit to lower the power consumption.
This interface circuit was fabricated by TSMC 0.25μm HV CMOS 1P3M process, and 2.5V devices among this process are used. This chip area is 1.7mm×1.9mm, and has been verified in a real PV power conversion prototype.
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