All about SMPS(Function, Components, Principle, Types)

Hey, In this article we are going learn about a very important topic of power electronics which is SMPS or Switched Mode Power Supply. Nowadays, all the power electronic devices we see around us use the Switched Mode Power Supply due to its amazing advantages over other types of power supply systems.

An SMPS or Switch Mode Power Supply is also known as a Switching Power Supply, Switching Regulator, Switcher, etc. Here, we will try to learn how much is possible in a very simple language. So this will be very helpful for electrical or electronics engineering students to clear their all doubts.

SMPS(Switched Mode Power Supply)

What is an SMPS?

An SMPS or Switch Mode Power Supply is a power system that converts electrical power using switching regulation techniques. It is nothing but an electrical or electronic circuit consisting of different types of active, passive, and switching electronic components. As it converts electrical power supplies using a switching technique, it is called Switched Mode Power Supply.

Like other types of power supply systems, SMPS also converts electrical power from one form to another form as per requirement but it provides a very high efficiency than others.

It can be a part of a large electrical or electronic system or device(e.g.; computer) that provides proper electrical power supply to each part of that system for their operation. Or it can be a stand-alone device(e.g.; charger, adapter) specially designed to power up any external load or device.

The function of SMPS

The main function of an SMPS is to convert electrical power from one form to another form such as AC to DC, DC to AC, or other conversions, and provide proper output to the connected load as per its requirement such as voltage, current, etc. So, the SMPS not only makes conversion of electrical power, it also controls the voltage and current if required.

Types of SMPS

SMPS can be classified based on many factors. But the most common types of SMPS are given below,

According to Power Conversion,
  1. AC to DC Converter
  2. DC to DC Converter
  3. AC to AC Converter
  4. DC to AC Converter

According to Input-Output Voltage Transformation,
  1. Buck Converter(Voltage Step Down)
  2. Boost Converter(Voltage Step UP)

According to the Switching Principle,
  1. Flyback Type
  2. Converter Type

Important Parts and Components of SMPS

As we know there are different types of SMPS are there so their parts and components also be different but all types of SMPS have a common part which is the switching part where the switching components are used to switch the electrical power by continuously turning On and Off.

The switching part of an SMPS includes Switching Devices or Components such as MOSFETs or IGBTs, a Reference signal generator circuit, Pulse Width Modulation(PWM) signals(that is actually used for switching) generator circuit, an error detection circuit, a feedback circuit, etc.

The important parts of an SMPS are,
  1. Rectifier Circuit
  2. Filter Circuit
  3. Switching Circuit
  4. Transformer

All the SMPS may not have all the parts listed it depends upon their types. 

For Example, an AC to DC SMPS has the following parts,
  1. Input Rectifier
  2. Switching Circuit
  3. Transformer
  4. Output Rectifier
  5. Output Filter

And, an DC to DC SMPS has the following parts,
  1. Switching Circuit
  2. Transformer
  3. Output Rectifier
  4. Output Filter

So may now understand the AC to DC SMPS has an input rectifier circuit but the DC to DC SMPS has not any input rectifier as the input source is DC.

Also, remember that sometimes two different types of SMPS have all the same parts but their arrangement may be different.

How SMPS Works? Working Principle

Here, we will learn how an AC to DC SMPS works that are mostly used and it has the maximum parts or Components. Also, here we will discuss the function of each part. So, once you know the function of each part of an SMPS you can understand the working principle of any type of SMPS.

The first part of an AC to DC SMPS is the Input Rectifier. The main function of the Input Rectifier is to convert the input AC supply into DC Supply. It is built with PN Junction Diodes. So, in the first stage, the input AC supply is converted into DC without stepping up or stepping down.

The second part is the switching circuit. As we discussed earlier the switching circuit is built with switching Components and other auxiliary circuits. So, in the second stage, the unregulated DC supply from the input filter is applied to the switching circuit. Now the switching circuit converts this DC supply into a high-frequency switching signal.

At the next stage, the High-frequency Switching signal is applied to the transformer. If the SMPS is buck converter type then a step-down transformer is used or if the SMPS is boost converter type then a step-up transformer is used. So, according to the type of transformer it steps up or steps down the high-frequency switching or AC supply.

The next part is the output rectifier circuit. The output rectifier circuit again converts the AC supply from the transformer into a DC supply.

At last, the output filter circuit filters the DC supply from the output rectifier and provides a pure filtered output DC supply at the output.

The output of the SMPS is also connected to the Switching Controller circuit, so it can monitor the output voltage and current and regulate the output as per requirement.

Advantages of SMPS(Switched Mode Power Supply)

  1. As the SMPS uses a high-frequency switching principle, the size of the Transformer reduces so the circuit is compact and light. The cost also decreased.
  2. Output voltage and current regulation can be achieved more accurately by controlling the switching circuit.
  3. SMPS provides a very high efficiency(68% to 93%) than other supplies.
  4. Power loss and heat generation are very less.
  5. Easy Voltage and Current Adjustments.
  6. Low Harmonics.

Disadvantages of SMPS

  1. SMPS creates Electromagnetic Interference(EMI) during its operation.
  2. Due to High-frequency Switching noise can be produced.
  3. Complex Circuitry.

Applications and Uses of SMPS

  1. Computer
  2. Laptop, Mobile Charger
  3. Automation Systems such as PLC
  4. Modern LED, OLED, and Smart TVs
  5. Power Supply for CCTV Cameras
  6. Modern Music Players e.g; Home Theaters

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All about SMPS(Function, Components, Principle, Types) All about SMPS(Function, Components, Principle, Types) Reviewed by Author on May 07, 2023 Rating: 5
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