Auto calibrating dc link current sensing technique for transformerless, grid connected, H-bridge inverter systems
Auto calibrating dc link current sensing technique for transformerless, grid connected, H-bridge inverter systems (2006) IEEE Transactions on Power Electronics
Armstrong, M., Atkinson, D.J., Johnson, C.M., Abeyasekera, T.D.
Power electronic inverters are commonly used for the interfacing of distributed generation systems to the electrical power network. These electronic inverters operate in a current controlled mode to inject unity power factor sinusoidal current into the network. To prevent possible dc current injection, a mains frequency isolation transformer is often employed at the inverter output. This isolation transformer is a costly component. An alternative approach is to use current sensing and control techniques to eliminate the dc current component. One method is to use a current controller to force the output dc current to zero. Current controllers are prone to errors associated with nonlinearity and offsets in the current transducers. This paper considers a novel auto-calibrating dc link current sensing technique that eliminates the errors associated with the current transducer, and helps avoid dc current injection into the grid when using a transformerless grid connect inverter system.
