UC Irvine

This thesis applies a fixed ON-time switching technique to a resonant switched-capacitor converter, called the 3X RTBSC-A converter, which is studied for maximum power point tracking (MPPT) applications. The previous converter, the 3X RTBSC converter, was unable to achieve full-range voltage gain regulation for relatively light loads. However, with a new switching technique known as Switching Technique A, full-range voltage gain regulation for all loads is completely possible. In addition, the converter achieves zero-voltage switching (ZVS) to retain a high efficiency. A mathematical analysis of the ideal circuit was completed to show the conducting states, voltage gain derivation, and component stresses. Under this analysis, the prototype circuit was designed with a maximum power level of 162 W and a resonant frequency of 100 kHz. Simulations in the LTspice software proved that the circuit would not be able to achieve full-range voltage gain regulation with regular 50% duty cycle switching. In addition, details are provided in the design of the prototype's control circuit and driver circuit used to create and execute Switching Technique A. An open loop experiment demonstrates that the voltage gain of the prototype circuit closely resembles the waveforms calculated from the ideal gain formula. Also, a relatively high efficiency is recorded for each load tested with a maximum recorded efficiency of 0.9544. In addition, examination of the steady state waveforms prove that the prototype circuit is executing ZVS. To prepare the prototype for the MPPT experiment, a sensing circuit is designed to feed data to the microcontroller. A simple perturb and observe (P&O) algorithm is programmed to find the maximum power point (MPP). The specifications of the solar panel are also presented. The results of the MPPT experiment demonstrate that the MPP found by the MPPT algorithm closely follows the actual MPP that was found manually. In addition, the prototype achieved efficiencies between 0.87 and 0.92 during the MPPT experiment. The 3X RTBSC-A converter still has the potential to achieve higher efficiencies as indicated by the report on the original circuit.