1. SMPS

2. 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

3. 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.

4. 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

5. Block diagram of a SMPS Input rectifier stage:
It is used to convert an AC input to DC.

6. 2. Inverter stage:
The inverter stage converts DC, whether directly from the input or from the rectifier stage
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.
Regulation:
Feedback circuit monitors the output voltage and compares it with the reference voltage.

7. Factors to be considered while selecting a topology for a particular application
1. Is input-to-output?
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

8. 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 Cost
Energy Storage
Voltage Relation
Features
Buck
0-1000
1.0
Single inductor
0 ≤ Out ≤ In
V2=D.V1
Continuous current at output
Boost
0-150
Out ≥ In
V2=V1.[(1)/(1-D)]
Continuous current at input
Buck-boost
Out ≤ 0
V2= -V1[(D)/(1-D)]
No continuous current

9. Use of various transformer isolated topologies

10. 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