Switch mode power supply
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The document discusses switched mode power supplies (SMPS). It defines SMPS and explains their advantages over linear power supplies, including higher efficiency and smaller size. The document outlines the typical stages in an SMPS, including rectification, inversion and regulation. It examines factors to consider when selecting an SMPS topology for an application and describes the operating principles of common isolated topologies like flyback, push-pull, half bridge and full bridge converters. Finally, it provides examples of SMPS applications and discusses SMPS usage in Indian consumer markets.
![Use of non-isolated topologies:
• Non isolated topologies are the simplest, with the three basic types using a
single inductor for energy storage.
Type Power(W) Relative Energy Voltage Relation Features
Cost Storage
Buck 0-1000 1.0 Single 0 ≤ Out ≤ In Continuous
inductor V2=D.V1 current at
output
Boost 0-150 1.0 Single Out ≥ In Continuous
inductor V2=V1.[(1)/(1-D)] current at
input
Buck- 0-150 1.0 Single Out ≤ 0 No
boost inductor V2= -V1[(D)/(1-D)] continuous
current](https://image.slidesharecdn.com/switchmodepowersupply-130413135720-phpapp02/85/Switch-mode-power-supply-9-320.jpg)
Switch mode power supply
- 1. Switched Mode Power Supply
- 2. Contents:- • General description of Power Supply • Advantages/Disadvantages of SMPS • Block diagram of SMPS • Basic topologies and practical • requirements • Working of various SMPS topologies: 1. Flyback Converter 2. Push-pull Converter 3. Half bridge Converter 4. Full bridge Converter • Applications of SMPS • Conclusion
- 3. Power Supply:- Any device that supplies electric power to an electric load. The different types of power supplies include: -Battery -DC power supply -AC power supply -Linear regulated power supply -Switched mode power supply -Programmable power supply -Uninterruptible power supply
- 4. Switched Mode Power Supply: An electrical power supply that incorporates a switching regulator to convert electrical power efficiently. It transfers power from a source, to a load, while converting voltage and current characteristics. Voltage regulation is achieved by varying the ratio of on- to-off time.
- 5. Advantages of SMPS over Linear Power Supplies: • 1. Lower weight • 2. Smaller size • 3. Higher efficiency • 4. Lower power dissipation • 5. Wide ac input voltage range • 6. Reduced costs Disadvantages of SMPS: 1. Complexity of the circuit
- 6. Block diagram of a SMPS 1. Input rectifier stage: It is used to convert an ac input to dc. A SMPS with dc input does not require this stage. The rectifier produces unregulated dc which is then passed through the filter circuit.
- 7. • 2. Inverter stage: – The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz. 3. Output transformer: - If the output required is to be isolated from input, the inverted AC is used to draw the primary windings of a high frequency transformer. This converts the voltage up or down to the required output level on it’s secondary winding. 4. Output rectifier: - If the dc output is required, the ac output from the transformer is rectified. 5. Regulation: - Feedback circuit monitors the output voltage and compares it with the reference voltage.
- 8. Factors to be considered while selecting a topology for a particular application:- • 1. Is input-to-output dielectric isolation required for the application? • 2. Are multiple outputs required? • 3. Does the prospective topology place a reasonable voltage stress across the voltage semiconductors? • 4. Does the prospective topology place a reasonable current stress across the voltage semiconductors? • 5. How much of the input voltage is placed across the primary transformer winding or inductor? • Typical maximum output power available from each topology: Converter Topology Maximum output power Flyback 200W Forward 300W Push-pull 500W Half bridge 1000W Full bridge >1000W
- 9. Use of non-isolated topologies: • Non isolated topologies are the simplest, with the three basic types using a single inductor for energy storage. Type Power(W) Relative Energy Voltage Relation Features Cost Storage Buck 0-1000 1.0 Single 0 ≤ Out ≤ In Continuous inductor V2=D.V1 current at output Boost 0-150 1.0 Single Out ≥ In Continuous inductor V2=V1.[(1)/(1-D)] current at input Buck- 0-150 1.0 Single Out ≤ 0 No boost inductor V2= -V1[(D)/(1-D)] continuous current
- 10. Use of various transformer isolated topologies:
- 11. Working of various SMPS Topologies: 1. Flyback converter:
- 12. Mode 1 Operation -- Q1 ON • Current builds up in the primary winding • Secondary winding has the opposite polarity D1 OFF • C maintains the output voltage, supplies load current
- 13. Mode 2 Operation -- Q1 turned OFF • Polarity of the windings reverses • Diode D1 conducts, charging C and providing current to the load RL • Secondary current falls to 0 before the next cycle begins
- 16. Operation of the Push-Pull Converter: • Q1 ON, Vs across the lower primary winding • Q2 ON, Vs across the upper primary winding
- 18. Mode 1 Operation • Q1 ON, D1 is conducting • Energy transferred to the load
- 19. Mode 2 Operation • Both transistors are OFF • D1 continues to conduct due to current in L1
- 20. Mode 3 Operation: • Q2 ON, D2 conducting • Energy transferred to the load
- 21. Mode 4 Operation • Both transistors OFF • D2 continues to conduct due to current in L1
- 22. Waveform Summary – k<0.5
- 24. Mode 1 Operation • Q1,Q4 ON, Q2,Q3 OFF • D1 conducting, energy transferred to the load
- 25. Mode 2 Operation • All transistors are OFF • D1 continues to conduct due to current in L1
- 26. Mode 3 Operation • Q2,Q3 are ON, Q1,Q4 OFF • D2 conducting, energy transferred to the load
- 27. Mode 4 Operation • All transistors are OFF • D2 continues to conduct due to current in L1
- 28. Waveform Summary – k<0.5
- 29. Applications of SMPS:- • 1. Machine tool industries • 2. Security Systems • (Closed circuit cameras) • 3. Support supplies with PLC’s • 4. Personal Computers • 5. Mobile Phone chargers
- 30. SMPS in Indian markets: iball 600W Antec 750W Cooler master 550W Rs. 4700 Rs. 6600 Rs. 3800 Seasonic 500W UMAX 450W Corsair 750W Rs. 3600 Rs. 570 Rs. 10700
- 31. Conclusion: • The most common SMPS topologies: flyback, push-pull, half bridge and full bridge converters have been outlined. • Each has it’s own particular operating characteristics and advantages, which makes it suitable to particular applications. • Some of the most common applications of SMPS have been discussed. References: www.wikipedia.org www.howstuffworks.com Philips semiconductors manual Lambda semiconductors manual Motorola semiconductors manual Microchip manual
- 32. Thank you!!