Types of Power Supplies: A Beginner’s Guide

You might encounter terms like ruggedized power supply or linear power supply and get confused. There are many types of power supplies and all of them are meant for specific applications. What is more, it is possible for one power supply to belong to two classifications. Unless you work for a power management systems company, you’re bound to be confused by all the different types at some point.

In this article, we’ll look at the major classifications of power supplies, and then at some of the minor types of power supplies. Hopefully, in the end, you’ll be less confused.

Power Supplies Are Mainly Classified By Type of Current

AC Power Supply

Alternating current (AC) power supplies that have standard power characteristics (voltage and frequency) are used to power common household electrical appliances such as electrical fans, air conditioners, and refrigerators. They also power other electrical appliances such as pumps and motors.

AC has no polarity, unlike direct current. (DC) Its polarity changes with time, in accordance with frequency. In an AC power supply, the magnitude and direction of current changes with time.

The main source of power for an AC power supply is mains electricity. However, an alternator can also serve as a power source. An alternator is a machine that converts mechanical energy into electrical energy in the form of alternating current.

DC Power Supply

Most of the electronic circuits in printers, computers, and televisions use DC power. Direct current does not keep reversing polarity like alternating current. Instead, the direction and magnitude of the current are fixed. When dealing with DC power supplies, you won’t encounter terms such as frequency and power factor.

Sources of power for a DC power supply include a battery and a solar panel. However, AC from mains electricity can also be converted into DC using a rectifier.

Classification According to Function

Regulated Power Supply

As the name suggests, a regulated power supply regulates power by keeping the output constant regardless of varying input. Such power supplies typically convert AC to DC. They contain several components, all of which have a specific function. These include: a step-down transformer, a rectifier, a regulator, and a DC filter.

In an unregulated power supply, the power output can change significantly when input voltage and current changes.

Programmable Power Supply

In a programmable supply, you are usually able to control the output power without touching any knobs. This is done by connecting the power supply to a computer through an interface, then controlling everything from the computer.

This also means that you can control the power supply remotely. The interfaces available are USB, RS232, GPIB, or an analog interface that consists of a keypad.

Programmable power characteristics include output voltage, current, and frequency. These depend on whether it’s an AC or DC power supply. Only AC power supplies have frequency.

A programmable power supply usually includes such features as temperature regulation, overvoltage and overcurrent compensation, and short-circuit protection.

Linear Power Supply

A linear power supply uses a transformer to step down input voltage into the required output voltage. It then rectifies and filters the voltage. It uses a linear regulator to maintain constant voltage at the output and any excess voltage is dissipated in the form of heat.

Such power supplies have been around for long and offer the best performance. They are often preferred because of their low noise. They are common in communication, laboratory and medical applications.

Switching Power Supply

Switched-mode power supplies were developed to overcome the shortcomings of linear power supplies. As a result, they are more efficient, more compact, and have a wide range of applications.

They use pulse-width modulation (PCM) to regulate output voltage. Properly designed, they can have excellent line and load regulation.

A disadvantage of these is that they generate a lot of noise, making them unsuitable for some applications. This noise can be reduced through filtering.

Special Power Supplies

There are some use-cases that usually require special power supplies. To get most of them, you usually have to get in touch with a specialized power management systems company, such as a military power supplies company.

Outdoor Power Supply

These are also called ruggedized power supplies. They are built so that they can be exposed to extreme weather conditions and continue operating optimally. They are usually acquired from a military power supplies company and are also used in defense applications.

Military Power Supply

While an outdoor power supply is ruggedized and can withstand harsh conditions, there are many other requirements for power supplies used in defense. For example, these military power supplies have to meet military standards. These standards are defined for different use-cases, including ship-board use, ground vehicle use, and aerial use, as well as communication.

Compliance with such standards ensures high performance and reliability. After all, you can’t have the power supply to a helicopter’s weapons systems fail during combat.