Everything You Need to Know About AC – DC Power Supplies

Aegis Power Systems, Inc. is one of the industry’s leading power supply manufacturers. We design, build and deliver off-the-shelf and custom AC-DC units for a wide range of markets, including aircraft, defense, embedded computing, ship, and telecommunications.

Power supplies play a critical role in virtually every sector. Whether you need one when powering a personal laptop in your home or a mission-critical system in a military vehicle, it is vital you choose the right one for your application. Otherwise, you risk damage to your electrical and electronic devices. However, given the broad selection of power supply options available, it can be difficult to select the one that best suits your needs. Fortunately, our experts are here to help. Below, we’ve compiled a list of common questions and answer about power supplies to help you understand what power supplies are, what they do, and how they work.

What Is a Power Supply?

A power supply converts the power provided by the power source into the proper format and voltage for the specific application. It can complete this function in several ways depending on the device type and application. For example:

It can change the voltage. The primary use of most power supplies is changing the voltage of the power. As the power source provides a steady input of power into connected devices, it is important to step down (decrease the voltage) or step up (increase the voltage) to suit the power requirements of the device. Otherwise, it may be overloaded or underloaded.

It can convert the current. Some electrical and electronic devices need power in a different current than is provided by the power source. In these situations, a power supply can convert the power into the proper format. For example, they are used to convert alternating current (AC) into direct current (DC).

It can regulate the power. When a power supply changes the voltage or current of power, it can sometimes produce a fluctuating output. While these fluctuations typically do not affect connected electrical devices with loads close to the output of the power source, they can harm connected electronic devices. For these situations, a power supply with power regulation capabilities is essential. It ensures the flow of power from the source to the device is smoother and steadier.

While each of the above functions is valuable, it is not necessary to choose a power supply with all of them if the application does not call for it. It is better to get a power supply with only the features you need for your application to save on purchasing costs.

How Does an AC-DC Power Supply Work?

As indicated above, power supplies can change the voltage of power, convert the format of power, and regulate the flow of power. However, they may only perform one or some of the functions depending on the application in which they will be used. For example, if the connected device does not need regulated voltage, the power supply does not need to have the power regulating function.

Below, we’ve outlined the process for an AC-DC power supply connected to an AC power source and an electronic device that needs regulation or power conversion:

The AC power enters the power supply unit.
The power supply raises or lowers the voltage to the required level.
The power supply converts the format from AC to DC.
The power supply smooths the waveform of the converted power.
The power flows from the power supply to the connected device.
(Optional) In some cases, the power supply then reports back to the system any monitoring features such as sensor data (temperature, voltage, current, timing counter), device ID, self-test results, or other data as defined in the power supply requirements.

What Are the Important Parts of a Power Supply?

While the components integrated into a power supply can vary depending on the functions needed, they can consist of the following:

Transformer. This component changes (increases or decreases) the voltage of the incoming power to the necessary voltage level for the connected device.
Rectifier. In AC-DC power supplies, this component converts the AC current of the incoming power to the DC format.
Filter. In AC-DC power supplies, this component smooths out the waves of the converted power after it leaves the rectifier. It reduces Electromagnetic Interference (EMI), so that the power supply does not cause damage or functional interference to nearby electronic equipment.
Regulator. In regulated power supplies, this component reduces any ripple voltages left after the power is processed by the filter. It ensures the power does not surge or drop in voltage.

How Does a Power Supply Rectify AC to DC?

Power supplies convert AC to DC using a rectifier. The rectifier component comes in three variations: half-wave, full-wave, and bridge variations.

Half-wave rectifiers convert half of the AC wave to DC. They are less expensive than the other types of rectifiers but perform less efficiently and produce more ripple. As a result, they are best suited for use with low-importance devices.
Full-wave rectifiers convert all of the AC wave to DC with little rippling but require a specialized transformer. While they are more expensive than half-wave rectifiers, they perform more efficiently and produce less ripple.
Bridge rectifiers combine characteristics of both half-wave and full-wave rectifiers. They convert full AC waves without requiring a specialized transformer, which makes them less expensive than full-wave rectifiers and more efficient than half-wave rectifiers.
Multi-stage converters combine several types of AC-DC converter topologies to yield better performance and lower EMI noise in the power supply.

How Does an AC-DC Power Supply provide Power Factor Correction (PFC)?

Power Factor is the ratio of working power to apparent power. Power Factor Correction (PFC) is an element of AC-DC power supply converters which can improve efficiency, reduce power losses, and improve current carrying. This is done by correcting the lagging AC current phase as related to the voltage waveform using capacitors. Power Factor Correction is found in many AC-DC power supplies.

Power Supply Products at Aegis Power Systems

At Aegis Power Systems, we provide a broad selection of standard and custom power supply solutions to suit different customer needs. Our product offerings include:

Single-Phase AC-DC Power Supplies

Our single-phase AC-DC power supplies are typically used to support output power needs of 1,000 watts or less. However, they can be used in specialized applications to support output power needs up to 2,500 watts. They are available with various options for dimensions, mounting types, output configurations, and more.

Three-Phase AC-DC Power Supplies

Our three-phase AC-DC power supplies are typically used to support higher output power needs than our single-phase AC-DC power supplies. They are often utilized when a project requires output power of more than 1,000 watts. They are available with a variety of options for operating frequency, output configuration, and more.

VPX Power Supplies

Our VPX power supplies are rugged and reliable, making them ideal for use in demanding environments. They can be factory configured to provide variable output power while maintaining high efficiency and low weight.

Applications of Aegis Power Supplies

Our power supplies find use in a wide range of markets and applications. The core markets we serve are:

Military. We provide single-phase and three-phase AC power supplies and DC-DC power supplies for many military and defense systems. Typical applications include communications and control systems, security systems, and weaponry.

Aircraft. Our AC-DC power supplies are used in aircraft in both the commercial and military sectors. They support power needs in control systems, radar systems, UMVs, and other critical technologies.
Embedded Computing. Our team develops power supply solutions for an array of embedded technologies, including microprocessors, microcontrollers, and compact PCI computers.
Rack Mount. Our rack mount DC power supplies and slide-in power converter cards are suitable for use in various applications. They can be modified to accommodate different outputs and mounting needs.
Ship and Marine. We design and manufacture quality power supplies for commercial and military marine equipment. From AC-DC and single-phase to three-phase, we can provide solutions for numerous marine vehicle and vessel power needs.

Aegis Power Systems, A Trusted Power Supply Manufacturer Since 1995

Looking for a reliable supplier of quality power supplies? Aegis Power Systems has you covered. Whether you need an off-the-shelf, modified, or fully custom system, our experts can deliver a solution that meets your power needs. To learn more about our power supply solutions, contact us today. To discuss your requirements with one of our team members, request a quote.