What Is a Power Supply, and How Does It Work?

What is a Power Supply and How Does it Work graphic

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  1. What is a Power Supply?
  2. What Does a Power Supply Do?
  3. How Does a Power Supply Work?
  4. Parts of a Power Supply and Their Functions
  5. How Does a Power Supply Convert AC to DC?
  6. What is a Capacitor Filter?
  7. How Does a Regulated Power Supply Work?
  8. How Does a Linear Regulated Power Supply Work?
  9. What Is a Regulated Switching Power Supply?
  10. What Is the Use of a Power Supply?
  11. Who Needs Power Supplies?

Power supplies appear everywhere, and knowing how they work will help you select the best options for your applications. Whether you need high-voltage power on board a ship or need to plug in a notebook computer to charge, you need a power supply. Because not all models are the same, you need to know what makes an ac-dc power supply unique, how you can choose the best supplies for your electrical devices, and much more. If you’ve ever had questions about how a power supply works, its definition, or what it does, discover the answers to your queries here.

What Is a Power Supply?

Do not confuse a power supply with a power source. The source is the origin of incoming electricity. In most cases, the electricity source is an outlet, battery, or generator. The power supply works to convert the power from the source into the correct format and voltage. Because a variety of options exist, the specific power supply function depends on whether it needs to regulate energy or convert power. To understand a power supply and how it works, you must know its parts and their contributions to the device’s operation, which is discussed below.

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What Does a Power Supply Do?

Power supplies have essential functions found in all models with additional operations added depending on the device type. Power supplies may need to change voltage up or down, convert power to direct current, or regulate power for smoother outcoming voltage. These functions will help you choose which supply you need for your electrical needs. Getting a device with too many features could cost you more money than you need to spend, but if you don’t get the features you require, you could damage the devices you need to power.

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Power Supplies Change Voltage

Changing voltage is the prime use of power supplies. The source of power has a steady output, regardless of the type of device that must use it. To prevent overload, power supplies step down the voltage — or, conversely, step it up — to match the requirements of the device.

Too much power coming out of a power supply can severely damage a device, but if the power supply does not deliver enough voltage, the device will not operate as it should. Energy changing is the main task of power supplies, and the bulk of their construction comes from the transformer used to move the voltage up or down as needed.

Power Supplies Convert Power

Power conversion changes the incoming electricity to a format that the electrical device can use. Two types of power supplies exist, DC-DC and AC-DC. DC-DC power supplies allow you to plug in electrical devices into car outlets or similar sources that supply direct current, or DC, power. These power supplies are not the most commonly used, though.

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While DC-DC power supplies exist, the most common type is the AC-DC type. Electrical outlets deliver alternating current, or AC, power. Most electrical devices require direct current to function. A power supply converts AC to DC. During this conversion, the output may waver, occasionally requiring regulation. However, for general use, you may not need regulated power supplies.

Power Supplies Regulate Power

Most electronics require regulated power. When a power supply changes the voltage and type of power, the result is not always a steady output. Though it does not turn on and off completely, fluctuations in the outcoming voltage still occur without regulation. An unregulated power supply can deliver more power than expected. Such a surge fed to delicate electronics like computers and televisions could cause severe damage to the parts or even permanent harm that could cause damage beyond repair.

The added function of regulating power increases the cost of the device, but it can save you the price of having to purchase new electronics to replace those ruined by unregulated voltage overwhelming them. To save money while powering devices with loads that closely match the power supply’s output, use unregulated power supplies. But electronics require regulated power. Don’t make the mistake of selecting the wrong supply.

How Does a Power Supply Work?

Basic power supplies will change the voltage and convert to DC power. These standard operations send unregulated voltage out of the power supply, but if you need regulated power, the devices have an additional step of regulating the voltage to smooth out waves. To discover more about how a PSU (power supply unit) works, read on to learn about the individual parts and their functions, which will clarify your view of the entire operation of the power unit.

Parts of Power Supplies and Their Functions

Basic power supplies consist of several parts. These components help the unit to step up or down voltage, convert power and reduces ripple voltages, which are residual variations in the voltage and results in wasted power and overheating.

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  • Transformer: The transformer changes the incoming voltage to the needed outgoing voltage level. These devices may step up or step down the voltage. Typically, the DC voltage required is much less than the incoming AC voltage from the primary power source.
  • Rectifier: To convert the incoming power from AC to DC, the power supply uses a rectifier, which may be half-wave, full-wave, or bridge.
  • Filter: When AC power changes to DC, it still has distinct waves that need smoothing out. The filter does not completely smooth out the waves to nothing, but it does reduce them considerably. The output from this part is unregulated power.
  • Regulator: A voltage regulator reduces the ripple voltages left by the filter, getting rid of any voltage surges or drops that could damage devices plugged into the power supply.

Power supply components are essential to the particular function of the power supply unit. As a result, not all power supplies will consist of the same parts.

Power Supply Transformers

The power supply transformer raises or lowers the voltage as needed. Most devices require stepped down voltage from standard AC outlets, which output 100 to 240 volts, to a much lower amount. Some transformers, however, will step up the voltage and isolate the incoming and outgoing circuits.

The incoming power enters the transformer through the primary winding. Outgoing electricity connects to the secondary winding. These two windings have no physical connection between them. This isolation of the windings ensures the safety of the transformer. Faraday’s Law allows for electromagnetic energy to be induced on the secondary winding from the primary winding without the need for contact between these parts.

Once finished stepping up or down the voltage, the transformer sends the outgoing power to a rectifier to convert the alternating current into direct current.

How Does a Power Supply Convert AC to DC? Half wave, full wave, bridge

How Does a Power Supply Convert AC to DC?

Part of how an AC-to-DC power supply works is the rectifier in the unit that changes the current type. Power supply creators choose from three types of silicon diode rectifiers to convert AC power to DC. Each model has its operation and benefits.

  • Half wave:The lowest-cost rectifier uses a single silicon diode, but it only converts half of the AC wave. This half-wave conversion results in a greater ripple, which is more difficult to remove with a regulator. Additionally, half-wave rectifiers do not perform as efficiently as other models and only work for supplying power to low-importance devices.
  • Full wave:A full-wave rectifier requires a center tap in the secondary winding. Because these rectifiers need a specialized transformer, they typically appear in more expensive, though more efficient, power supplies. These models also produce less ripple after conversion into DC power, which is easier for a regulator to remove.
  • Bridge:The most efficient rectifier blends the best of half-wave and full-wave types. The bridge model uses four diodes to convert a full AC wave without the need for a special center-tapped transformer.

See Our 28V AC-DC Power Supply

What Is a Capacitor Filter?

After conversion, most DC power will still have output ripple. A capacitor directly filters out the worst of the ripple as the electricity leaves the rectifier.

Capacitors hold electrons until needed. As the current passes through the capacitor, it moves in waves. The peaks already have enough electrons, but the troughs represent lower amounts of electricity that correspond to lower levels of electrons. As the current waves drop, the need for extra electrons increases. The capacitor feeds electrons into the current, making the waves smoother. Smoother waves provide more even electricity without ebbs and surges.

While capacitors do not create utterly smooth power, they do reduce the highs and lows that leave a rectifier. If you need a consistent flow of electricity, you must have a regulated power supply. These devices fill in the remaining troughs left after the current leaves the capacitor. Power supplies that connect to electronics require regulators to protect the delicate circuitry of such devices.

How Does a Regulated Power Supply Work?

After the current leaves the filter, the power supply’s task ends in an unregulated model. While unregulated power supplies suffice for general use, when you need entirely stable electricity that does not change when the load does, you need regulated power. Regulated power supplies come in two forms based on how they regulate energy — linear and switching.

How Does a Linear Regulated Power Supply Work?

A linear power supply has a simple, straight-forward operation method to convert electricity and nearly eliminate ripple voltage. The design starts with a transformer to reduce the voltage. The device then converts AC to DC power. Then the DC power goes through a regulator that cleans it by reducing the ripple voltage.

This regulated power supply option weighs more due to the large transformer that must step down the power. Fortunately, linear power supplies have a low-noise operation, making them a better choice when you need low-power and a clean, consistent supply. Medical settings, laboratories, and communications facilities get the most benefit from this type of regulated power supply.

What Is a Regulated Switching Power Supply?

Switching power supplies are more efficient, have higher capacities, and are smaller than their linear counterparts. However, these models generate noise during use, especially when switching power. Unlike linear power supplies, which are best for specific applications, switching power supplies are more versatile. The reason for these devices’ flexibility is in their use of pulse width modulation (PWM).

The use of PWM makes switching power supplies much more efficient than linear power supplies and allows them to change to different electricity sources quickly. Select switching regulating power supplies when you require higher power output and more efficiency in a smaller size than you can get from a linear regulated power supply.

What Is the Use of a Power Supply?

When used for personal computers, power supplies tend to be the part most prone to failure due to their frequent temperature fluctuations and intense use. Of course, electronics such as computers and televisions require power supplies and require replacement of these parts more often than compared to other components. However, these are not the only uses of power supplies.

Power supplies do more than provide electricity for electronics. These devices may be internal or external and provide energy to appliances, lights, and more. If you have a part that requires electricity, you probably have a power supply in or connected to that device.

Who Needs Power Supplies? Military, Shipping, Aerospace, Communication, and More

Who Needs Power Supplies?

Anyone who uses electricity needs power supplies. The types of supplies will depend on whether you need AC-DC or DC-DC converters or if you require regulated or unregulated power. High or low voltage is another choice you will need to make. If you need weather- or impact-resistant power supplies, you will also need to add that to the list of requirements.

Learn About Power Supply Applications

Several industries use power supplies daily. Listed here are just some of the industries that can make use of the variety of military-grade power supplies ACT has to offer.

  • Military: The military often requests rugged power supplies to withstand any environmental condition.
  • Ships and Boats (subs): Shipboard power supplies have particular requirements to properly handle electricity without a traditional main power outlet supplied by power lines.
  • Aerospace: Powering the tools used in the aerospace field often requires devices that can handle electricity in remote places.
  • Communications: Quiet, adequate power supplies that provide consistent power for computers and other communications devices have strict requirements for their attributes and use.
  • Many others: If you don’t see your industry listed, don’t worry. You still likely need power supplies, and we can help you with your power needs.

The question is not whether you need a power supply but what type your situation requires. That’s where we at Advanced Conversion Technology (ACT) can help you.

Find the Right Power Supplies

Contact Us Today

Whether you need AC-DC or DC-DC converters for high or low voltage, you can find the power supplies you need at ACT. Because we cater to a wide variety of applications that have innumerable requirements for power supply specifics, we likely have the right products for your use. However, some of those with whom we work cannot find what they need from our listings. Luckily, we have the resources available to create custom power supplies tailored to their needs. If you need a customized solution,contact us via our form or make a product request. We’re available to help you with whatever your power needs may be, from simple to complex.

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