SMPS technology rests on power semiconductor switching devices such as Metal Oxide Semiconductor Field Effect Transistors

SMPS technology rests on power semiconductor switching devices such as Metal Oxide Semiconductor Field Effect Transistors (MOSFET) and Insulated Gate Bipolar Transistors (IGBT). These devices offer fast switching times and are able to withstand erratic voltage spikes. Equally important, they dissipate very little power in either the On or Off states, achieving high efficiency with low heat dissipation. For the most part, the switching device determines the overall performance of an SMPS. Key measurements for switching devices include: switching loss, average power loss, safe operating area, and more.

Choice of Topology
There are several different topologies for the switched mode power supply circuits. Some popular ones are:

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

Fly-back
Forward
Push-pull
Half bridge
Full-bridge

A particular topology may be more suitable than others on the basis of one or more performance criterions like cost, efficiency, overall weight and size, output power, output regulation, voltage ripple etc. All the topologies listed above are capable of providing isolated voltages by incorporating a high frequency transformer in the circuit.

?
Block diagram

FIGURE 1 : Forward Converter Block diagram

A bridge rectifier takes input as 230 V AC and supply from mains which is converted into DC.
After that capacitor will be connected to pass out the AC ripple signal and to get the pure DC.
Here the ferrite core is working at high frequency, using transistor or mosfet switching device.
The output of the rectifier is compared with the reference and corrected is given to switching device through opto-isolator which prevents high voltage from damaging the circuit.
Here AC power supply is converted into DC power supply by means of diode rectifier circuit.
After this the dc supply passes through capacitor to filter out the ripple content to have pure DC supply.

COMPONENTS

Ferrite Core Transformer
MOSFET
IC 3525

Ferrite Core Transformer

FIGURE 2 : Ferrite Core Transformer

SMPS transformer-core, because of high frequency operation, is made of hard magnetic material like ferrites whereas the low frequency power transformers mostly use soft magnetic material like silicon steel. consequently even at very high frequency operation, the hysteresis and eddy current losses are low.
It also provides low eddy current losses over many frequencies. Its high permeability adds to its ideal combination for use in high frequency transformer sand adjustable inductors. In fact, the high magnetic permeability along with a low electrical conductivity of ferrites helps in the prevention of eddy currents.
In electronics, a ferrite core is a type of magnetic core made of ferrite on which the windings of electric transformers and other wound components such as inductors are formed. It is used for its properties of high magnetic permeability coupled with low electrical conductivity (which helps prevent eddy currents).
MOSFET

FIGURE 3 : MOSFET

The working of a MOSFET depends upon the MOS capacitor. The MOS capacitor is the main part of MOSFET. The semiconductor surface at the below oxide layer which is located between source and drain terminals. It can be inverted from p-type to n-type by applying positive or negative gate voltages.
Here the MOSFET is used in primary side of the ferrite core transformer . it is used for high switching frequency in primary side . it converts fixed DC into pulsating DC. By using MOSFET in ferrite core emf is generated in primary side .
According to the mosfet frequency variation the output is changed .

IC 3525

FIGURE 4 : IC 3525

SPECIFICATION OF IC3525
999998.0 V to 35 V Operation
5.1 V ± 1.0% Trimmed Reference
100 Hz to 400 kHz Oscillator Range
Separate Oscillator Sync Pin
Adjustable Deadtime Control
Input Undervoltage Lockout
Latching PWM to Prevent Multiple Pulses
Pulse–by–Pulse Shutdown

CIRCUIT DIAGRAM

FIGURE 5 : CIRCUIT DIAGRAM

DC supply of 12v is provided in the in the input side of the circuit and it is connected with diode rectifier . If the AC supply is used then diode D1 will work as a rectifier .
By providing capacitor we can eliminate ripple content in the input side .
D2 is the ferrite core transformer tertiary winding. Ferrite core is used to reduce the saturation in the circuit .
MOSFET is connected in primary side of the ferrite core transformer . high frequency switching is done by MOSFET which result in generation of emf .
Output of secondary side of transformer is of pulsating DC which is converted into pure DC with diode D3, D4 .
Here the LC filter is provided to maintain constant ration of current and voltage .
Now by use of LC circuit we can get pure DC output .

SIMULATION

FIGURE 6: Simulation

The circuit is designed in the PSIM software and the obtained wave form is given below .

Voltage DC in
Input current
Primary current of ferrite core
Voltage across MOSFET
Secondary side voltage
Secondary side current
Output current
Output voltage
load voltage

WAVEFORM

V dc in

FIGURE 1.1 : V DC INPUT

I pri

FIGURE 1.2 : Primary current

V pri

FIGURE 1.3: primary voltage

Vmosfet

FIGURE 1.4 : voltage across MOSFET

Vsec

FIGURE 1.5: secondary voltage

I sec

FIGURE 1.6 :secondary current

I o/p

FIGURE 1.7 :output current

V o/p

FIGURE 1.8 : output voltage

V o/p load

FIGURE 1.9 : load voltage

Calculation
Output voltage – Vo = 24v
Output ripple – % = 1% of Vo
Output current – Io = 10A
Switching freq – Fs = 20KHz
Supply voltage – Vcc = 24 ± 10%
Diode drop – Vd = 1.5V
Wdg resistance – Vrl = 10% of Vo
Saturating flux density – Bs = 0.3 T
Core flux density – Bm = 0.2T
Current density – J = 3 A/?mm?^2
Duty cycle – Dmax = 0.45
Window utilization factor – K = 0.4
Efficiency of transformer – ? = 0.8

Vcc min = Vcc – 10% Vcc
= 24 – 2.4
= 21.6 V
Vcc max = Vcc + 10% Vcc
= 24 + 2.4
=26.4 V
D min = ( Vcc min × D max ) / Vcc max
= 0.371

POWER CALCULATION
Po2 = ( Vo + Vrl + Vd ) Io
= (24 + 2.4 + 1.5)10
Ap = ?Dmax . Po2 ( 1+ 1/ n) / Kw JB Fs
= ?0.45 * 279 (2.25) / 0.4 * 0.3 * 200000
= 005841 * 10^-8m ?

E/36/18/11
Ac= 0.547?cm?^2
Aw=1.196?cm?^2
Ap=0.71?cm?^2

N1=Vcc max *Dmin/Ac*Bm*fs
=121*0.371/1.31*0.2*20000
=85 turns
N = Vo + Vn1+ Vd/ Vcc min * D max
=24 + 2.4 + 1.5/99*0.45
=0.62
N2= n*N1
=0.62*85
=54 turns

WIRE GAUGE SELECTION
I2=Io?Dmax
= 10?0.45
=6.70A

I1= n * I2
=0.626 * 6.70
=4.19A

L1=(µ0+µr*Ac*N1^2)/lm
=(4?*?10?^(-7)*20000*1.31*7225)/78
=0.304mH

I mg = Dmax*Vcc min / fs *Li
= 0.45 * 99 / 20000 * 0.304
= 0.73A
I3 = I mg ?(1-Dmax)/3
=0.31A

THE WIRE CROSS SECTION AREAS

a1 = I1 / J
= 4.19 / 3
= 1.39
SWG = 17
= 1.4424

a2 = I2 / J
= 6.7 / J
=2.233
SWG = 13
=2.3368

a3 = I3 / J
= 0.31 / 3
= 0.103
SWG = 41
= 0.1117

SUMMARY OF CANVAS

AEIOU

AEIOU canvas is describing all information about activities, environment, interactions, objects and users for our domain

Figure A : AEIOU Canvas
Activities
Equipment maintenance
marketing
Simulation
Designing
Equipment Testing
Production

Environment
Noisy
Neat & clean
Excessive temperature
Eco-friendly environment

Interactions
Engineers
Faculty
Industrialist
Field workers
Lab technician

Objects
Motor
Relay
Supply source
Electronics components
Step down transformer
Various type of machines

Users
Industries
Engineers
Students
Faculties
Testing units
College laboratories

Empathy mapping canvas

The empathy map was created as a tool to help you gain understanding for a targeted personal .Thus you can use it when you want to deliver a better user experience of your product Empathy mapping was one of the main part of our design engineering .It was the point from which we came to know about many things i .e. different users, stakeholder, various activities and the main from the above was two heart touching stories which inspired us and helped us to complete our research work.

FIGURE B : Empathy mapping canvas

Users
Industries
Engineers
Students
Faculties
Testing units
College laboratories

Stakeholders
Distributors
Industrial companies
Universities

Activities
Equipment maintenance
marketing
Simulation
Designing
Equipment Testing
Production

?
PRODUCT DEVELOPMENT CANVAS

FIGURE C : PRODUCT DEVELOPMEENT CANVAS

Purpose
Pure DC output
Efficient working
Fault protection due to high current passout

People
Technicians
Junior Engineer
Workers
Marketing personals

Product Experience
Design of smps as per output requirement
Economical
Easy to use

Product function
make output voltage constant
output current is constant
ferrite core transformer operates at high frequency

Product features
Accurate output
Can vary output voltage
Better efficiency
Reduce weight

Components
Resisters
Inductor
3525 IC
Diode
Ferrite core transformer
Wires
Capacitors
Switches
IGBT

Customer revalidation
Not useful for speed control of motors
High switching frequency

Reject, Redesign, Retain
Proper ferrite core calculation
Complicated control circuit
Losses across switches high

ideation canvas

In this canvas we will expand our list of user activities to list all possible new situations, conditions that user faces or may face. Using the ideation canvas we will look at how we can ideate about solutions to the problems.

Figure D : Ideation canvas

People
project manager
Technicians
Field Workers
Machine operator
Lab in charge

Activities
Maintenance work
Product manufacturing
Assembling
Equipment Testing

Props/ Possible solution
Variable supply voltage
Provide better switching frequency
Reducing harmonic content
Different voltage level
Better control circuit

Situation/Context/Location
Equipment failure
Lab and industries
Production of different kind of tools
Field area
Manufacturing and assembling of products
Different equipment testing
Appropriate temperature and pressure

?
Conclusion

The most common SMPS topologies ,forward , flyback, push pull,half bridge and full bridge converters have been outlined. Each of them have there own operating characteristics and advantages which makes it suitable to particular applications.
Suitable components were selected and tested for desired performance. Functional verification was performed on combined circuit of the selected components for open loop network in PSIM . The Design and implementation of desired SMPS circuit was successfully completed.

Reference

x

Hi!
I'm Mila

Would you like to get a custom essay? How about receiving a customized one?

Check it out