Designing the dq-frame current regulator for single-phase voltage-source inverters is a very challenging task. Since only one real current signal exists in the circuit, an orthogonal signal generation (OSG) block is required to generate the virtual orthogonal signal. Thus, ac variables can be turned into equivalent dc quantities through an αβ/dq transformation. However, the OSG block makes the control system complex and introduces an extra transient disturbance. Consequently, the dynamic performance is deteriorated. In this study, the reference-current-based OSG method is analysed thoroughly. Based on this structure, the dq-axes decoupling control, which is widely discussed for three-phase systems and usually neglected for singlephase systems, is studied. Two decoupling techniques, i.e. the reference-current feed-forward control and the quasi-complex vector proportional-integrator control, are implemented and analysed. The proposed theories and control schemes are evaluated by experimental results.
Two-stage single-phase grid-connected converters are widely used in renewable energy applications. Due to the presence of a second harmonic ripple across the DC bus voltage, it is very challenging to design the DC bus voltage control scheme in single-phase grid-connected inverters. The DC bus voltage controller must filter the ripple and balance a tradeoff between low harmonic distortion and high bandwidth. This paper presents a fast DC bus voltage controller, which uses a second order digital finite impulse response (FIR) notch filter in conjunction with input power feedforward scheme to ensure the steady-state and dynamic performance. To gain the input power without extra hardware, a Kalman filter is incorporated to estimate the DC bus input current. At the same time, a modulation compensation strategy is implemented to eliminate the nonlinearity of the grid current control loop, which is caused by the DC bus voltage ripple. Moreover, a novel synchronous frame current controller for single-phase systems is also introduced, and its equivalent model in stationary frame has been derived. Simulation and experimental results are provided to verify the effective of the proposed control scheme.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.