A simplified DQ-frame current controller for single-phase grid-connected inverters with LCL filters

In dq-frame current control scheme for single-phase grid-connected inverters, an orthogonal signal generation (OSG) block is required to generate a virtual orthogonal signal. The OSG block makes the control system complicated and introduces extra disturbance, which deteriorates the dynamic performance. This paper presents a simplified dq-frame current controller for single-phase grid-connected inverters. A novel OSG method, which does not introduce any additional dynamics or distortions to the control loop, has been discussed. The decoupling control for the dq-axes cross-coupling is analyzed. Moreover, LCL filters are also implemented to improve grid current quality. Simulation shows that the proposed controller has excellent performance.