Full-Wave Controlled Rectifier

Full-Wave Controlled Rectifier

Question 1
Design a single-phase full-wave controlled rectifier. The load is a solenoid coil (inductance
and resistance). Use Simulink software to design the system and obtain the waveforms.
a. Calculate the minimum value of firing angle to ensure continuous current conduction
b. Assuming firing angle now is lesser than the value calculated in (a), show the
waveforms of the supply voltage, the gate pulse, the output voltage, the output current
and the input current. Then explain the operation mode of the rectifier. Now drive the
equation of the average output voltage and find its value.
c. Repeat (b) for firing angle larger than value calculated in (a).
d. Is the input current in (b) and (c) a sinusoidal waveform? If no, explain the problem
associated with the non-sinusoidal current waveform. Suggest at least one solution to
minimize the problem.
Question 2
A press machine supplied by a three-phase source is used to transform copper material shape
from rod to tape. The copper tape is used as earthing conductors. The diagram of the
machine is shown in Figure 1. The machine rotates to move the material in the direction as
shown in Figure 1. The rated pressing torque is 4300 Nm. The rated speed is 1074 rpm.

Figure 1.The diagram of the press machine 

  1. Calculate the output power of the DC motor.
  2. Select the type of DC drives for this application.
  3. Explain why there are four power cables connection from DC drives.
  4. Draw the power circuit for the DC drives selected in part (b).
  5. Determine the firing angle for the DC drives to maintain speed of the motor at 500
    rpm while delivering the rated torque. At this condition, DC drives deliver 100%
    armature current. The armature resistance is 0.1 Ω.
  6. The motor operates 12 hours a day and the loading profile is shown in Figure 2. The
    company works for 20 days in a month. Electricity tariff for industry is 0.27307 $ /unit.
    Calculate the total energy and the electricity cost for the motor in a month. (Hint : 1
    unit = 1 kWh).

Solution 

Question 1

The following is the MATLAB Simulink file and two waveforms of input to the Thyristor when the firing angle is 30 degrees.

These two waveforms show that its frequency is 50Hz which is same as the frequency of the input voltage and 180degree separated each other.

  1. I chose the load resistance to be 100ohm and inductance to be 50 mH.

And the calculation is shown in my image.

B and C, D are all shown in my image.

Question 2

c.We think the 2 lines are for driving motor voltages and  2 of them are for getting feedback from the motor.