Analysis, Design, and Implementation of a Quasi-Proportional-Resonant Controller for a Multifunctional Capacitive-Coupling Grid-Connected Inverter

Abstract

The capacitive-coupling grid-connected inverter (CGCI) is coupled to the point of common coupling via a second-order LC branch. Its operational voltage is much lower than that of a conventional inductive-coupling grid-connected inverter (IGCI) when it serves as a multifunctional inverter to compensate reactive power and transfer active power simultaneously. It is a promising solution for micro-grid and building-integrated distributed generator systems. A quasiproportional-resonant (quasi-PR) controller is applied to reduce steady-state current tracking errors of the CGCI in this paper. The quasi-PR controller generates the voltage reference for use of carrier-based pulse width modulation, which can effectively reduce output current ripples. The second-order coupling impedance of the CGCI causes its modeling and controller design to differ from that of the conventional IGCI. A comprehensive design method for the quasi-PR controller in a CGCI is developed. The quasi-PR controller is also compared with a proportional-integration current controller. Simulation results are provided to verify the effectiveness of the quasi-PR controller and its design method in a CGCI. The current tracking errors are greatly reduced when the quasi-PR controller rather than the proportional-integration controller is applied. Experimental results are also provided to validate the CGCI as a multifunctional grid-connected inverter.

A Doubly-Fed Induction Generator Adaptive Control Strategy and Coordination Technology Compatible with Feeder Automation

“…The space vector reference of the rotor excitation currents (i r * ra , i r * rb and i r * rc ), which correspond to the actual excitation currents of rotor (i r ra , i r rb and i r rc ), different between which is based on to obtain the three-phase excitation voltages of the rotor (u r ra , u r rb and u r rc ) through the G QPR (s) control. G QPR (s), quasi-proportional resonant controller (QPR), better fits for precision control of sinusoidal signal as compared with traditional PI controllers, and the transfer function can be expressed as [33,34]:…”

“…where P QPR is the proportional coefficient, K QPR the resonance term gain, ω i the resonance term bandwidth (actual value), and ω r the slip angular frequency (actual value). The design of QPR parameters can be found in [33,34]. (QPR), better fits for precision control of sinusoidal signal as compared with traditional PI controllers, and the transfer function can be expressed as [33,34]:…”

“…where QPR P is the proportional coefficient, QPR K the resonance term gain, i ω the resonance term bandwidth (actual value), and r ω the slip angular frequency (actual value). The design of QPR parameters can be found in [33,34].…”

Model-Based Current Sharing Approach for DCM Interleaved Flyback Micro-Inverter

“…Meanwhile, these methods are inapplicable to the dual flyback converters when the duty cycles of two flyback converters are unfixed. For the CCM interleaved flyback micro-inverter, the multiple PI controllers are developed in [17,18] to achieve the current sharing, but they could not track the sinusoidal reference current without static error [36] and may increase the total harmonic distortions (THDs) of system. Besides, there are several parameters require to design for PI controllers, which increase the design complexity.…”

A Multifunctional Isolated and Non-Isolated Dual Mode Converter for Renewable Energy Conversion Applications

“…Nevertheless, these converters only control the power flow from the input array to loads in a unique direction or could not achieve galvanic isolation applications. With the emergence of new energy applications, compared with the single-function of a grid-connected or off-grid (stand-alone) system, new dual-mode [22,23] or multifunctional applications [24,25] have become more popular, which are a new trend in the future for renewable energy applications [19]. As different conversion modes are required in different applications, more flexible and reliable conversion circuits are needed.…”