Classification of Power Supply and Its Different Types

The power supply unit is the part of the hardware that is used to convert the power provided from the outlet into usable power to many parts inside an electrical device. Every energy supply must drive its load, which is connected to it. Depending on its design, a power supply unit may obtain energy from various types of energy sources, like electrical energy transmission systems, electromechanical systems such as generators and alternators, solar power converters, energy storage devices such as a battery and fuel cells, or other power supply. There are two types of power supplies existed, AC and DC power supply. Based on the electrical device’s electric specifications it may use AC power or DC power.

Classification of Power Supply and Its Different Types

Here we will discuss different types of power supplies which have existed in the market world. The below table tells the basic types of power supplies for following conditions.

OUTPUT = DC

OUTPUT = AC

INPUT = AC

  • Wall wart
  • Bench power supplies
  • Battery charger
  • Isolation transformer
  • Variable AC supply
  • Frequency changer

INPUT = DC

  • DC-DC converter
  • Inverter
  • Generator
  • UPS

Variable AC Power Supply

The different AC voltages are generated by using a transformer. The transformer may have multiple windings or taps, in which case the instrument uses switches to select the different voltage levels. Alternatively, a variable transformer (adjustable autotransformer) can be used to continuously vary the voltages. Some variable AC supplies are included meters to monitor the voltage, current, and/or power.

Variable AC Power Supply
Variable AC Power Supply

Unregulated Linear Power Supply

Unregulated power supplies contain a step-down transformer, rectifier, filter capacitor, and a bleeder resistor. This type of power supply, because of simplicity, is the least costly and most reliable for low power requirements. The main disadvantage is that the output voltage is not constant. It will vary with the input voltage and the load current, and the ripple is not suitable for electronic applications. The ripple can be reduced by changing the filter capacitor to an LC (inductor-capacitor) filter, but the cost becomes more.

Unregulated Linear Power Supply
Unregulated Linear Power Supply

Input transformer

The input transformer is used to convert the incoming line voltage down to the required level of the power supply. It also isolates the output circuit from the line supply. Here we are using a step-down transformer.

Rectifier

The rectifier used to convert the incoming signal from an AC format into raw DC. Please refer these links, Different types of rectifiers available are half wave rectifier and full-wave rectifier.

Filter Capacitor

The pulsated DC from the rectifier is fed to the smoothing capacitor. It will remove the unwanted ripples in the pulsated DC.

Bleeder Resistor

Bleeder Resistor is also known as a power supply drain resistor. It is connected across the filter capacitors to drain their stored charge so that the power system supply is not dangerous.

Regulated Linear Power Supply

Regulated linear power supplies are same to the unregulated linear power supply except that a 3-terminal regulator is used in place of the bleeder resistor. The main aim of this supply is to provide the required level of DC power to the load. The DC power supply uses an AC supply as the input. Different applications require different levels of attributes voltages, but nowadays the DC power supplies provide an accurate output voltage. And this voltage is regulated by an electronic circuitry so that it provides a constant output voltage over a wide range of output loads.

Regulated Power Supply Block Diagram
Regulated Power Supply Block Diagram

Here the basic circuit diagram for Regulated Linear Power Supply given below.

Regulated Linear Power Supply
Regulated Linear Power Supply

Smoothing

Once rectified from an AC signal, the DC needs to be smoothed to remove the varying voltage level. Large value capacitors are generally used for this purpose.

Voltage Regulator

A linear regulator has an active (BJT or MOSFET) pass device (series or shunt) controlled by a high gain differential amplifier. It compares the output voltage with a precise reference voltage and adjusts the pass device to maintain a constant level output voltage. There are two main types of linear power supplies. Read more about Different Types of Voltage Regulators with Working Principle.

Series regulator

This is the most widely used regulators for linear power supplies. As the name implies a series element is placed in the circuit as shown in below figure, and its resistance varied via the control electronics to ensure that the correct output voltage is generated for the current taken.

Concept of the Series Voltage Regulator or Series Pass Regulator
Concept of the Series Voltage Regulator or Series Pass Regulator

Shunt regulator

The shunt regulator is less widely used as the main element within a voltage regulator. In this, a variable element is placed across the load as shown in below. There is a source resistor placed in series with the input, and the shunt regulator is varied to make sure that the voltage across the load remains constant.

Shunt Voltage Regulator with Feedback
Shunt Voltage Regulator with Feedback

Switch Mode Power Supply (SMPS)

The SMPS has a rectifier, filter capacitor, series transistor, regulator, transformer, but is more complicated than the other power supplies that we have discussed.

Switching Mode Power Supply
Switching Mode Power Supply

The above-shown schematic is a simple block diagram. The AC voltage is rectified to an unregulated DC voltage, with the series transistor and the regulator. This DC is chopped to a constant high-frequency voltage which enables the size of the transformer to be dramatically reduced and allows for a much smaller power supply. The disadvantages of this type of supply are that all of the transformers have to be custom-made and the complexity of the power supply does not lend itself to low production or economical low power applications. Please refer this link to Know All About SMPS.

Switch Mode Power Supply (SMPS)
Switch Mode Power Supply (SMPS)

Uninterruptible Power Supply (UPS)

UPS is a Backup power source that, in the case of power failure or fluctuations, allows enough time for an orderly shutdown of the system or for a standby generator to start up. UPS consists usually of a bank of rechargeable batteries and power sensing and conditioning circuitry. Furthermore read about the UPS circuit diagram and different types, please refer this link to read more about UPS Circuit Diagram and Working.

Uninterruptible Power Supply (UPS)
Uninterruptible Power Supply (UPS)

This is all about different types of power supplies which include linear power supplies, switching mode power supply, uninterrupted power supply. Furthermore, to implement electronics and electrical projects or any information regarding the types of power supply fell free to give your feedback to give your suggestions, comments in the comment section below.

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