Improved Operation of the Step-Up Converter with Large Voltage Gain and Low Voltage on Capacitors

Abstract

This work proposes an improvement for a recently proposed converter. The discussed converter is the so-called low-voltage in capacitors (LVC). It offers a larger voltage gain compared to the standard step-up or boost converter while operating with a relatively low voltage in their capacitors (lower than the voltage at the output port). The improvement consists of a modification in the pulse width modulation (PWM) scheme. The new modulation scheme allows for a reduction in the voltage ripple at the output port, which means an improvement in the power quality. The LVC converter contains two transistors, but it was proposed to operate with a single switching signal. The new PWM scheme is based on two switching signals with the same duty cycle (same waveform and same average time in high) but 180° of phase shift among them. The PWM scheme significantly affects the voltage ripple at the converter’s output port. The voltage ripple reduction at the converter’s output port is achieved without increasing the transistor switching frequency and without modifying the circuit parameters (capacitance in capacitors or inductance in inductors). The article starts by introducing the converter. Then, it presents its mathematical model, including the calculation of the voltage ripple at its output port. The experimental results performed on the LCV in both the former and the proposed operation prove the reduction in the voltage ripple, and the comparison also includes the traditional boost converter.

Keywords

• step-up converter
• low voltage in capacitors converter
• PWM power conversion