Test: Phase Controlled Rectifiers - 1 - Electrical Engineering (EE) MCQ

As the supply voltage is 400 sin 314t
V_m = 400 V,
Peak invesre voltage (PIV)

RMS value of current = 20 A 
Average value of current,

Input power factor = 

For α = 90^o
Input power factor = 
= 0.6363 lag

The average output voltage of a semiconverter 
Maximum output voltage = 

1 + cos α = 0.5
α = 120^o
Average load current, 

Average output voltage 


L_S = 17.11 mH
Average load current 

µ = 6.627^o

The average output voltage for a single-phase full converter is

Maximum voltage across SCR in single-phase mid-point converter is 2V_m. Therefore, this converter can be design for a maximum voltage of

∴ Maximum average power that the mid-point converter can handle is

Circulating current gives rise to more losses in the converters, hence the efficiency and power factor are low. Thus, statement-1 is false.
In a non-circulating current type dual converter, the normal delay period of 10 to 20 ms is required while no delay period is required in circulating current type dual converter. Therefore, circulating current type dual converter is faster than non-circulating type dual converter. Thus, statement-2 is true.
As the dual converter with circulating current has to handle load current as well as circulating currents, therefore the thyristors are rated for higher currents. Hence statement-3 is false.

In a four-quadrant operation, a system must be capable of handling both directions of current and voltage, meaning it can operate in all four quadrants of the voltage-current plane. This is commonly required in applications like regenerative braking, where power needs to flow in both directions.

• Two full converters connected back to back allow for bidirectional power flow and can handle both positive and negative voltages and currents, making them suitable for four-quadrant operation.
• The other configurations (series or parallel) do not provide the necessary bidirectional control needed for full four-quadrant operation.

Thus, two full converters connected back to back is the correct configuration for four-quadrant operation.