A novel DSP-based current-controlled PWM strategy for single phase grid connected inverters

Abstract

The three major approaches for current-regulated inverters are ramp comparison, hysteresis control, and predictive current control. From these three, predictive current control offers the potential for achieving more precise current control with minimum distortion and harmonic noise. But, the predictive method is difficult to implement and needs more computational burden. The traditional predictive current controller has a poor performance under component parameter variations, and is less robust to filters inductance mismatch. A robust predictive current control strategy was proposed and studied. Both simulations and experimental results show that the proposed method is much more robust to parameter mismatch than the traditional one.Index Terms-Grid connected inverter, predictive control, pulse width modulated (PWM), robust control, single phase.

Discrete Wavelet Transforms for Synchronization of Power Converters Connected to Electrical Grids

“…The power stage of the dc/ac converter consists of an IGBT full-bridge with diodes, which synthesizes a low frequency ac voltage by changing the IGBTs' switching states, the gate circuit, which applies the required gate signals in order to 217 Discrete Wavelet Transforms for Synchronization of Power Converters Connected to Electrical Grids switch on and off the controlled power devices, an LCL-filter, employed as a second-order low pass filtering stage which allows the high frequency ripple of the full-bridge output voltage to be filtered out and a dc-side filtering stage, which can be implemented by means of one shunt capacitor (first order) or a series inductance plus a shunt capacitor (second order). Depending on the application characteristics, the converter controller functionalities are implemented using analog or digital circuitries and, in the second case, FPGAs, DPSs and microcontrollers (µCs) allow more flexible and complex controllers to be designed and implemented (Bueno et al, 2008;Koizumi et al, 2006;Kojabadi et al, 2006). In case of grid-connected power converters, both inverters and controlled rectifiers switching at relatively high frequencies (around 10 kHz), the main functionalities that must be implemented are grid synchronization, evaluation of the reference for current injection/consumption, grid side current control and pulse width modulation (PWM) (Kazmierkowski et al, 2002).…”

Design of Grid-Connected Photovoltaic System

“…In particular cases, the line frequency transformer can also be used, but it increases the size and weight of photovoltaic system [6] [7]. The grid-connected photovoltaic systems also need the inverters for power conversion, grid interconnection and control optimization [8] [9]. Pulse width modulation (PWM) voltage source inverters are most commonly used in PV systems to invert DC voltage into AC before feeding to the grid or AC loads.…”

Analysis of a Three-Phase Grid-Connected PV Power System Using a Modified Dual-Stage Inverter

“…In the grid-connected PV system, DC-AC converters (inverters) need to realize the grid interconnection, inverting the dc current that comes from the PV array into a sinusoidal waveform synchronized with the utility grid [2,3]. Besides, the DC-AC converter is used to stabilize the dc-bus voltage to a speci�c value, because the output voltage of the PV array varies with temperature, irradiance, and the effect of MPPT (maximum power point tracking) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”