A single phase half wave controlled SCR converter with a commutating d...
Single Phase Half Wave Controlled SCR Converter with Commutating Diode and RL Load
Problem Statement
A half wave controlled SCR converter with a commutating diode and RL load is operating at an average load voltage of 150V and a firing angle of 60 degrees. What is the supply voltage to the converter?
Solution
The half wave controlled SCR converter with a commutating diode and RL load can be represented by the following circuit diagram:
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Calculating the Load Voltage
The load voltage for an RL load can be calculated using the following formula:
VL = Vm * (1 - e-R/L * t)
Where Vm is the peak voltage of the AC supply, R is the load resistance, L is the load inductance, and t is the time.
For a half wave controlled SCR converter, the average load voltage can be calculated using the following formula:
VL,avg = Vm / π * (1 - cos(α))
Where α is the firing angle.
Substituting the given values, we get:
150 = Vm / π * (1 - cos(60))
Vm = 150 * π * 2 / √3
Vm = 546.76V
Calculating the Supply Voltage
The supply voltage can be calculated by adding the voltage drop across the SCR and the commutating diode to the peak load voltage.
The voltage drop across the SCR can be calculated using the following formula:
VSCR = VT * ln(IL / I0)
Where VT is the voltage drop across the SCR, IL is the load current, and I0 is the holding current.
The voltage drop across the commutating diode can be assumed to be negligible.
Assuming a typical value of VT = 1V and I0 = 10mA, we can calculate the load current as:
IL = VL / R
IL = 150 / 10
IL = 15A
Substituting the values, we get:
V