Types of SMPS
Dr. Paras Trivedi
Shree J.P. Arts & Science College

SWITCHINGDCPOWER SUPPLIES
INTRODUCTION
LINEAR POWER SUPPLY
OVERVIEW OF SWITCHING POWER SUPPLIES
DC – DC CONVERTER WITH ELECTRICAL
ISOLATION
CONTROL OF SMPS
POWER SUPPLY PROTECTION
APPLICATION

Introduction
Like a linear power supply, the SMPS too converts
unregulated ac or dc input voltage to a regulated dc
output voltage
The input voltage is first rectified and filtered using a
capacitor at the rectifieroutput
unregulated dc voltage across the capacitor is then
fed to a high frequency dc-to-dc converter
The high frequency transformer used in a SMPS

LinearPowerSupplies

Disadvantagesof LPS
The output fluctuates with input
which is not desirable
Isolation is not possible
Efficiency is very low
Bulky and noisy

SMPSBlockDiagram

SwitchingDCPowerSupplywith
Multiple Outputs
In most applications, several dc voltages are required, possibly
electrically isolated from eachother

FlybackConverter

Fly-back Converter Waveforms

Types of flyback converters
1.Two transistor flyback converter
2. Parallelled flyback converter

ForwardConverter
Derived from Buck; idealized to assumethatthe
transformer is ideal (not possible inpractice)

Half-Bridge Converter
Derived from Buckconverter

Full-BridgeConverter
Usedat higher power levels (> 0.5 kW
)

InputFilter
Needed to comply withthe EMI and harmonic
limits

Conclusion
• One of the most important applications of power
electronics is SMPS
• High efficiency and small weight and size
• In SMPS multiple outputs are possible
• Losses is minimum and only switching losses are
present
• Current rating is medium
• The high frequency transformer used in a SMPS