Analysis and Control of the Output Instantaneous Power for Three Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Conditions

This paper proposes a new method to analyze the output instantaneous power of the three phase PWM boost rectifier under unbalanced supply voltage conditions. An analytical expression for the output instantaneous power has been derived and presented, which provides the link between the output dc linkage voltage and the instantaneous output power. Based on the mathematical model of the three phase PWM rectifier in the rotating synchronous frame, the physical concept of the output instantaneous power has been explained from the analytical point of view. A direct relationship between the dc link voltage ripples and the second harmonic component in the instantaneous output power has been derived. A simple cascaded PI control scheme has been developed for the dc output voltage control. The controller ensures that the dc link voltage is maintained constant and the supply side power factor is kept close to unity under the unbalanced supply voltage operating conditions. Simulation and experimental test results are provided on a 1.6 kVA laboratory based PWM rectifier to validate the proposed analysis and control scheme