Energy Recovery Circuit for LC Cell Driver

Smart glass products use liquid crystal cells to alter glass’s state from transparent to opaque. These products are developed for everyday glass objects to combat light-related issues such as energy loss in buildings or drastic changes in incoming light. Some LC cells require an AC voltage applied to their terminals to transition states. Existing circuit topologies achieve this functionality but have limited output voltage range. They also do not conserve energy, and this is problematic for low-power applications that use batteries. The proposed energy recovery circuit (ERC) topology overcomes these obstacles by combining a boost converter with a series-resonant circuit. This work presents theoretical analysis and experimental results for the ERC. The results show that the proposed ERC can (1) switch LC cells from the OFF-state to the ON-state, (2) achieve a wide range of output voltages, and (3) recover the energy used to charge an LC cell.