Adaptive Dc link voltage control scheme for single phase inverters with dynamic power decoupling

摘要

Power density and efficiency are important metrics for power converters in many applications including renewable energy interface. Combined with the desire to replace the bulky, unreliable electrolytic dc link capacitors with film or ceramic capacitors due to reliability concerns, this has led to the trend of allowing increasingly higher double line frequency dc link voltage ripple. This paper discusses a scheme to improve the system overall efficiency by implementing an adaptive dc link voltage control scheme under different operating conditions for a recently introduced class of single phase inverter topologies that operate with very large dc link voltage ripple. The relationship between the minimum necessary dc link voltage for different input voltage, apparent power and power factor are analyzed and the optimal dc link voltage average value are derived analytically. The analysis and benefits of the proposed scheme are validated on a single-phase inverter hardware prototype employing SiC MOSFETs and DSP28335 for control implementation. The scheme can decrease the dc link voltage average value by 24.1% while decreasing the total loss of the inverter by around 20% compared to a design that does not use the adaptive dc link approach.