Ultrahigh Step-Up Coupled-Inductor DC-DC Converter With Soft-Switching for Driving Piezoelectric Actuators

DC-DC Converters for driving microactuators in microelectromechanical systems (MEMS) normally demand higher conversion ratios and stricter volume and weight than those in solar photovoltaic (PV) applications. This brief proposes a novel ultrahigh step-up coupled-inductor DC-DC converter with soft-switching cell, which operating in DCM with a minimum number of devices. In the circuit topology, a coupled-inductor is inserted into the conventional boost converter to extend the voltage gain dramatically and decrease the switch voltage stress effectively. In addition, an auxiliary switch, which is connected back to back with the main switch, is used to implement zero-voltage switching (ZVS) and zero-current switching (ZCS) to reduce the switching loss. This brief describes the steady state waveforms in details, and the voltage gain and conduction loss of the converter theoretically. The boost and soft-switching performance are evaluated. An experimental circuit, which is with 3.7V input to 209V output at 200mW, has been built to validate the operations and confirms the theoretical waveforms.