Project 2

Note : The Equations and Scope outputs are attached in the attached word file. Please do check all the attached files. Full explanation is in the word file of this project.

(Equations are not visible here in text)

Power Converters for EV : Project 2

Design an interleaving DC/DC converter system for a data centre application with the following specifications:

• Input voltage: 45 – 60 v
  • Output voltage: 3 V
  • Output current: 100A
  • Efficiency > 85% (extra credit for efficiency higher than 90% on a spice-based software simulation tool)

Simulate the system using a Spice-based software simulation tool such as LT-Spice, Pspice, PowerSim, TINA, etc...

Show your design in details (most probably, you will need to use an isolated system to achieve this low voltage conversion ratio, you might also need to use a multiphase system to increase the efficiency).

Show the input voltage, the output voltage, the input current, the output current, the system efficiency and any other simulation plots necessary to evaluate your design.

Solution :

Given Data :

Input Voltage = 45-60V

Output Voltage = 3V

Output Current = 100A

Efficiency > 85%

Assumptions :

Switching Frequency = 20000H

Duty Ratio = 0.5 (50%)

Calculations :

For this design we are using forward converter formulas :

• Duty Cycle :

Let’s assume that we will design for 50% duty ratio :

These we choose the following :

N1 = 500

N2 = 50

• Since we choose D = 0.5 then using equation we found that,
  
  
  Thus we will choose,
  N3 = 150turns

• Now we will choose an inductor for 40% current ripple :

• Now we are calculating 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, uninterruptible power supplies and fuel cell systems. By paralleling the converters the input current can be shared among inductors so that high reliability and efficiency in power electronic

systems can be obtained. In this paper, the conventional 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 in-out voltage with a constant duty cycle in continuous 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:

• Capacitor:
• Output Load (Resistor) :

6) Gate Pulse (Pulse Generator) :

As we required the 3V so we have given Amplitude : 10, Frequency (Periods) : 20000hz Now we run the model for 0.1 sec and get the output.

Output Voltage :

As we getting the output voltage 3volts same as we required with some ripples. The output voltage and output current are shown below the graph is identical for both.

Output Current :

Inductor Voltage :

As our input voltage is 60V given in the converter.

Beacause of switching action of MOSFET input current is looking like this if we zoom it.

The current amplitude is max 100A and the minimum voltage id near to zero as calculate the average value then we are getting 3V approximately.

Magnitude of inductor voltage is varies between 3V and -3V.

The main aim is to get the efficiency as higher as possible and as you see in our requirement 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 above data we get the input power is 300W and output power is also 300W.

So our efficiency as 100% without considering the ripple in voltage and 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 : Thus, we have designed the DC-DC converter successfully from the given data and got the required output with more than 90% efficiency.

Interleaving DC-DC Converter reduces ripple currents at the input and output.