Development of a New Mathematical Model of Three Phase PWM Boost Rectifier Under Unbalanced Supply Voltage Operating Conditions

This paper proposes a new mathematical model of the three-phase PWM boost rectifier in the positive and negative synchronous rotating frames under the unbalanced operating conditions. A detailed analytical expression for dc link voltage has been presented, from which the presence of the even harmonic components in the dc output voltage and odd harmonic components in the ac input current can be deduced. A simple algorithm for the reference current calculation is proposed from the analytical point of view. The dual frame PI control scheme developed based on this model can maintain the dc output voltage almost constant and keep the supply side power factor close to unity under the unbalanced operating conditions. The feasibility of this dual rotating d-q frame control scheme is verified by experimental results on a 1.6 kVA three-phase PWM rectifier. The test results demonstrate that the control scheme based on the new mathematical model can reduce the even-order harmonics at the dc link voltage and the odd-order harmonics in the ac input current