The Influence of the Input Inductance on the Qualitative Indicators of Active Controlled Rectifier

Abstract

The main part of electricity is used by industrial plants in a converted form and the use of semiconductor converters is growing rapidly. The requirements for the quality of semiconductor converters are increased. And their impact on the power supply, load and related consumers is increased too. One of the most popular converters in the segment of low and medium power drives is a frequency converter made on the basis of a three-phase stand-alone voltage inverter. A significant disadvantage of such converters is the use of a diode rectifier at the input of the circuit, which has disadvantages as the inability to recover electricity to the mains in the mode of dynamic braking of an induction motor and significant distortions of the mains current. These disadvantages can be eliminated by using an active rectifier instead of a diode rectifier, which provides a sinusoidal shape of the mains current in phase with the mains voltage and the possibility of bidirectional energy exchange with the load. The efficiency of the active rectifier-voltage source is determined by the selected control algorithm of the circuit switches and the correct task of the inductance of the input choke. A mathematical model of a three-phase active rectifier-voltage source, working with a fixed modulation frequency with a vector algorithm for building a control system and analysis of the influence of the input inductance on the quality of its work was created. From the simulation results it became obvious that the proposed structure of the control system provides stable operation of the converter and acceptable standards for electromagnetic compatibility with the mains at a fixed modulation frequency; the proposed algorithm for calculating the value of the input inductances allows you to correctly select their allowable value, and obtained in the simulation of the dependence allows you to most accurately determine the value of the input inductances on the allowable level of distortion of mains current and supply voltage.

Determination of the input filter parameters of the active rectifier with a fixed modulation frequency

“…It is known [12] that when the ARVS operates with a fixed modulation frequency, the value of its input inductance can lie within wide limits, ensuring the correct operation of the converter. From the point of view of weight, size and cost characteristics of the converter, it is desirable to reduce the value of the input inductance.…”

“…Having previously calculated the basic values S Sbase and Z Sbase , using ( 8), (11) and (12) it is possible to obtain the value of the power losses in the filter P f , as well as the values of the active resistance R f and capacitance C f of the ARVS input filter in absolute units. Their value will depend on the accepted inductance of the filter input reactor L R at given values of Q and K X .…”

“…The structure of its power circuit corresponds to Fig. 1, and the parameters are taken the same as in previous studies conducted by the authors on this topic [5,6,12]:…”

“…In [12], the required value of the input inductance for such a converter structure was calculated and it was concluded that for the effective operation of the ARVS circuit, its value can be taken in the range of 100-600 µH.…”