Today voltage and current source inverter/converter are widely used in
electrical machines. In this electrical machines, DC voltage or current are
usually obtained by using rectifiers with phase control and line commutation
converter. This type of rectifiers is the most used method in industrial
applications. The most important disadvantages of classical rectifiers are low
order current harmonics generation on the AC line, lagging displacement
factor establishment to the utility grid that in its turn consume an important
amount of reactive power. Thanks to well known capabilities such as power
regeneration, low harmonic input current, sinusoidal input current wave form,
high total power factor, controlled DC link voltage, small filter, bidirectional
power transmission, PWM converter become more and more popular in
industry application.
Control strategies for the PWM converter are adapted from the electrical
drive applications and are still examined and developed. In most industrial
applications with the PWM converter the linear control is implemented. The
PI control performance is strictly dependent on the proper identification of the
line chokes inductance and the DC-link capacitance. The values of the line
and power circuit parameters may also vary under the influence of the
electromagnetic interference generated by the converter itself.
The sensorless control in power electronics and electrical drive has evolved
from simple solutions based on the state simulators and estimators up to the
advanced state observers using numerous approaches.
In this paper, Direct power control system for three-phase PFC AC/DC
converter without the source voltage sensors is proposed. The sinusoidal
input current and unity effective power factor are realised based on the
estimated flux in the observer. Both active and reactive power calculated
using estimated flux. The estimation of flux is performed based on the
Reduced-order virtual flux observer using the actual currents and the
command control voltage. The source voltage sensors are replaced by
estimated flux and The DC link voltage has been compensated by DC link
ripple voltage estimation algorithm. The active and reactive powers
estimation are performed based on the estimated flux and Phase angle.
The proposed algorithm is verified through simulation and experiment.