ppt on switch mode power supply

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

3. 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 rectifier output
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

4. Linear Power Supplies

5. Disadvantages of LPS
The output fluctuates with input
which is not desirable
Isolation is not possible
Efficiency is very low
Bulky and noisy

6. SMPS Block Diagram

7. Switching DC Power Supply:
Multiple Outputs
In most applications, several dc voltages are
required, possibly electrically isolated from each other

8. Transformer Analysis
Needed for high-frequency isolated supplies

9. PWM to Regulate Output

10. PWM OUTPUT WAVEFORM

11. Flyback Converter

12. FLYBACK CONVERTER WAVEFORM’S

13. Other flyback converters are:~
1. Two transistor flyback converter
2. Parallelled flyback converter
But these are not commonly used

14. Forward Converter
Derived from Buck; idealized to assume that the
transformer is ideal (not possible in practice)

15. Half-Bridge Converter
Derived from Buck converter

16. Full-Bridge Converter
Used at higher power levels (> 0.5 kW )

17. Input Filter
Needed to comply with the EMI and harmonic
limits

18. 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

19. Switched Mode Power Supply

20. THANK YOU
QUESTION??