Design and analysis of a control scheme for variable frequency delta modulated buck - boost inverter

Abstract

This thesis proposes, analyzes and verifies a control scheme for buck-boost inverter using hysteresis band delta modulation to regulate the output voltage of the buck-boost inverter in variable frequency operation. At first a conventional boost inverter is investigated for variable frequency operation. To sort out the distortion of the output voltage for variable frequency operation a voltage controlled dual slope integrating delta modulator is designed. To remove the constrain of the conventional boost inverter, a buck-boost topology is proposed to obtain output voltage higher or lower than the input voltage. The limitations of the conventional controllers are eliminated with the use of the delta modulation technique. The output waveshapes of the proposed control scheme for buck-boost inverter assure reliable performance of the buck-boost inverter with this controller. It was found that each of the waveshape of the output voltage is almost pure sinusoidal in nature and maintains almost constant amplitude irrespective of the frequency.