There is an instantaneous voltage difference at the DC terminals of the two converters. It produces enormous circulating current between the converters and that will flow through the load. Therefore, in the practical dual converter, it is necessary to control the circulating current.
What is the condition to be satisfied by a dual converter to operate in circulating current mode?
Circulating Current Mode
Converter 1 performs as a controlled rectifier when firing angle be 0
What happens if there is no circulating current in dual converter?
1) Dual Converter Operation without Circulating Current
In this type of dual converter, only one converter is in conduction and another converter is temporarily blocked. So, at a time one converter operates and the reactor is not required between the converters.
How does the DC circulating current can be controlled in dual converter fed drives?
In a three-phase dual converter, inductors are chosen to allow a circulating current of 30% of full load current. This completely eliminates discontinuous conduction, and therefore, gives good speed regulation in the complete range of the drive.
What are circulating currents?
Circulating currents are a result of an asymmetry in the motor and the voltage it creates between the stator and rotor iron, but not related to the motor drive or method used to drive the motor. Specifically, the asymmetry in a motor comes from imbalanced windings, the differences in the iron core, and air gaps.
What is circulating current in power electronics?
Circulating current are those which keep circulating between transformers and does not contribute to load current. This causes unnecessary ohmic losses and decreased efficiency. Also transformer heats up due to increased current flow.
What is ideal condition of dual converter?
Dual converters are ideal that means they produce pure DC output terminals without containing any ripples. Each two-quadrant converter is assumed to be a controllable direct voltage source, connected in series with a diode.
How does a dual converter work?
Dual Converter is an Electronic Device or Circuit made by the combination of two bridges. One of them works as Rectifier(Converts A.C. to D.C.) and other bridge works as Inverter(converts D.C. into A.C.). Thus an electronic circuit or device in which two processes take place at same time, is known as Dual Converter.
What converts to second quadrant?
Explanation: The C2 converter will supply the load current in direction opposite to that supplied by the converter C1. For converter C2, when α> 90 it operates in 2nd quadrant and if α
What is the effect of circulating current in a circuit having two transformers in parallel?
When two transformers are in a parallel group, a transformer with a higher tap position will typically have a higher (LV side) no-load voltage than the other one with a lower tap position.
What is circulating current and why it should be avoided in parallel operation?
Circulating currents that diminish load capability and increased losses. The bus ratings could be too high. Paralleling transformers reduce the transformer impedance significantly, i.e. the parallel transformers may have very low impedance, which creates the high short circuit currents.
What causes shaft current?
Shaft circulating currents are caused from “dissymmetries” in the magnetic paths through the stator and rotor iron. As the rotor rotates within the stator and as the stators magnetic field rotates, small differences in the magnetic “reluctance” of the core parts generate small voltages between the ends of the shaft.
