Project 2
QUESTIONS -1
Solution:
Given data:
Input voltage = 45-60V
Outut Voltage = 3V
Output Current = 100A
Efficiency > 85%
Assumptions:
Switching Frequency = 20000H
Duty ratio = 0.5
Calculations:
For this design we are using the Forward converter formulas:
1) Duty cycle:
Vout/Vi = D.(N2/N1)
Let's assume that we will design for 50% Duty ratio:
N2/N1 = 0.1
These we choose the following:
N1 = 500
N2 = 50
2) Since we choose D = 0.5 then using equation we found that,
Thus we will choose,
N3 = 150turns
3) Now, we will choose an inductor for 40% current ripple:
4) Now we are calculate the capacitor:
From all the above all calculations we are model now the interleaving DC/DC converter:
The recent development of battery powered applications is improving the need of efficient step up dc-dc converters. Now a days step up conversion is widely used in many applications like electrical vehicles, Photovoltaic systems, uninteruptible power supplies and fuel cell systems. By parallelling the converters the input current can be shared among inductors so that high reliability and effcieny in power electronic
systems can be obtained. In this paper, the conventonal boost dc-dc converter and interleaved boost dc-dc converter are simulated using matlab/simulink and MULTISIM software.The converters are tested by varying the inout voltage with a constant dutycycle in continous conduction mode. The performance parameters of the converters are compared. The converters are controlled by interleaved switching signals, which have the same switching frequency but the shift in phase. Using interleaved converter we can get improved efficiency, reduced ripple voltage, reduced inductor current ripple, fast switching speed.
As for high efficiency we used multiphase system to increase the efficiency
In this model we are using the following parameters which we calculated.
1) Input Voltage:
2)Transformer Capacity:
3) Inductor Value:
3) Inductor Value:
4) Capacitor:
5) Output Load:
6) Gate Pulse:
As we required the 3V so we were given the reference as the constant 3 and PID get the tuned so PID value are as follows:
The frequency is choosen is 20000hz:
Now we run the model for 0.5 sec and get all outputs:
Output VOltage:
Output VOltage:
As we output voltage is getting 3 Volt same as we required with some ripples and ripple also same as we calculated which is shown in the following graph.
The ripple of output voltage:
Output Current:
Current is 100A this is because of the isolated system and multiphase system getting the oerfect as same as requirments:
Output voltage and current:
Input Voltage:
As our input voltage is 60 V given the converter.
Input current:
Because of switching action of MOSFET input current is looking like this if Zoon it, it will look like steo voltage which is shown in the following graph
The current amplitude is max is 10volt and the minimum voltage is near to zero so as calculate the average value then ware getting 4.7A approximately.
Inductor Voltage:
Voltage is as pus and magnitude are 2V and -4V.
- The main aim is to get the efficiency as higher as possible and as ypu see in our requirment are getting approximately same.
so we can say that our efficiency is above/more than 90%.
- As efficiency is calculated from output power/input power so as we calculated for this converter as following:
Input Voltage = 60V
Input Current = 5A
Output Voltage = 3V
Output Current = 100A
from all the above data we get the input power is 300w and output power is also 300W
So our efficiency os 100% without considering the ripple in voltage anf current, if we consider the ripple in voltage and current, if we consider the ripple also we can get the efficiency more than 90%.
Conclusion:
Those we designed the DC/DC converter the given data and get the required output with more than 90% efficiency.
QUESTION-2
Two H-Bridge DC/AC inverters are used for the microgrid.
AC load is 5KW and 2KVAR.
AC amplitude is 170V
Frequency: 60Hz
Vs1 and Vs2 are the DC sources with an operating value of 220V.
Inverter_1 capacity is 4KVA
Inverter_2 Capacity 3KVA.
C1 and C2 are sized as 2mF.
R_1, R_2, L_1, L_2 can be ignored.
As Output Voltage amplitude Vo =
I/p AC voltage = 220V
= 0.772
Amplitude Modulation ratio
Freq modulation ratio = Fc/Fr
Fcà carrier wave frequency = 1MHx
Frà ref wave frequency = 50Hz
Load KVA: sqrt((Kw*KW) +(KVAR*KVAR)) = 5.38 KVA
Peak voltage is 170V and Vout _rms = 121V
I_out RMS = 44.46A
Impedence = V/I = 2.721Ohms
Resistive Load: Active power is I*I*R = 5000Watt
Based on the above calculations, below is the simulation diagram in the Simulink.
In the simulation, PWM signaling is done with Bipolar switching.
Which is shown below.
The circuit’s PWM signaling is as shown below.
The above PWM signal shows that Switch 1, 2 are on and 3 and 4 are on at other times.
