Improving output current distortion in hybrid BCM current controlled three-phase micro-inverter

Hybrid boundary conduction mode (BCM) current controlled inverters have an ability to achieve high efficiency and high power density. Due to easy digital implementation and no requirement of additional components this current control method is very promising for low power applications such as three-phase micro-inverters. However, some practical aspects of its implementation such as dead-time insertion can degrade the performance of the micro-inverter. This paper presents a dead-time compensation method that improves the performance of hybrid BCM current control by decreasing the output current THD and reducing the zero crossing distortion. A brief analysis of hybrid soft switched BCM inverter is given in the paper. The proposed method has been implemented for a 400W 208VAC three-phase prototype. The experimental results show that the output current THD is reduced to 2.5% and thus satisfies the THD requirements under different load conditions.