  There is a trade-off between transient performance and line current
distortion of the DC bus voltage control of single-phase grid-connected voltage
source converters. This paper presents an improved DC bus voltage control
scheme of such converters using a proportional-integral controller in series
with a first-order low pass filter. The extended symmetrical tuning method was
adopted in the design of a regulator parameter, which greatly reduced the
oscillating component at the double line frequency. The proposed control
methodology allowed the loop bandwidth to increase without distorting the line
current. Consequently, the DC bus voltage fluctuation or DC bus capacitance was
reduced with a shorter settling time during a step load, compared with the
conventional scheme. The proposed voltage scheme was found to be robust to the
grid voltage variation and was less susceptible to the line voltage harmonics.
Simulation and experimental results of a 1.5 kVA PWM rectifier verified the
proposed methodology.
