A three phase bridge inverter is fed from a 500 V dc source. The inverter is operated in 180° conduction mode and it is supplying a purely resistive, star – connected load. The RMS value of the output (line) voltage is
= 0.816 × 500 = 408 V
In a three phase voltage source inverter operating in square wave mode, the output line voltage is free from
The rms nth component of the line voltage is
where Vdc is the input source voltage for n = 3, line voltage
Third harmonic component would not appear in the output
In single pulse modulation of PWM inverter, 3^{rd} harmonic can be eliminated if pulse width is equal to______ (in degrees)
Pulse width for eliminating
n^{th} harmonic
A three – phase bridge inverter delivers power to a resistive load from a 450 V dc source. for a star connected load if 10Ω per phase. What is the load power for 180° conduction mode ______________ (in kW)
A 3 ϕ bridge inverter delivers power to a resistive load from a 400 V dc. For a star – connected load of 15 Ω per phase, determine load power and R.M.S value of thyristor current for 120° mode
load power = 3I^{2}_{or }R = 3 × (10.87)^{2} × 15 = 5.317kW
A 3 phase MOSFET inverter is connected between a balanced star connected resistive load with R_{L} = 10 Ω and a 250 V dc supply. The inverter frequency is set at 33 Hz, and the switches have 120° conduction periods. Calculate the load power _______ (in kW)
= 3.13 kW
for a single pulse – width modulation of a single phase inverter, The distortion factor for pulse width of π/2 is ___________
given, 2d = π/2
single pulse modulation output for pulse width 2d = π/2 is shown below.
from Fourier series, fundamental output voltage is
from output voltage wave form
For a load of R = 10 Ω and L = 0.03 H, Find the RMS value of the fundamental component of inverter output current in case inverter of part Quasisquare output with 120° pulse width. The source voltage is 230 V and frequency 50 Hz
Concept:
The output voltage is controlled by varying the pulsewidth 2d. This shape of the output voltage is called Quasisquare wave.
Fourier series of this wave from is
Fundamental component of output voltage
Calculation:
Load impedance at Fundamental Frequency is
For Quasisquare wave or singlepulse modulated wave where pulse width, 2d = 120° or d = 60°
∴ R.M.S value of fundamental current
The inverter is operated at 50 Hz. In 180° square wave mode. Find the peak to peak inductor i_{0} in the circuit shown in figure.
at, t = 0, i_{0} = i_{p} and t = t_{1}, i_{0} = i_{p
}
For the symmetrical two pulse modulation with pulse width 36°. Find the percentage of 3^{rd} harmonic in the output voltage is_______
Concept:
In multiphase pulse modulation, several equidistant pulses per half cycle are used.
Fourier series of multiple pulse modulation is
N = pulse per half cycle
Calculation:
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