How to Choose an AC-DC Power Converter
Power supplies are used in most electrical equipment ranging from consumer appliances to industrial utilities, from milliwatts to megawatts, and from handheld tools to satellite communications.
Most of this electrical equipment runs on electricity not provided directly from the wall to every component. Instead, the electricity routes from the alternating current (AC) into the direct current (DC) used by the components in the required voltage. So a power supply converts the output from an AC power line to a steady DC output or multiple outputs.
However, some builders find it challenging to choose a suitable power supply. If the quality of the power supply is low, your build will not run, or it will suffer over the long term. Also, if you don't understand how much power your system needs to power efficiently, you could end up spending so much towards your power supply than is necessary.
Choosing the suitable power converter will give you the best possible performance and help contribute to a lifetime of reliability. This article seeks to let you understand how to choose a suitable power converter for your specific needs.
Things to Consider Before Choosing a Power Converter
1. Power Wattage
The most suitable power supply for your system is the one that provides the right amount of wattage to all components simultaneously. If your application is robust, it will require more power, and the higher the wattage you'll need from the power supply.
The proper power supply will indicate the continuous rated power, while other power supplies may only show the peak output power, which means they cannot provide the needed power. Let's take a look at a detailed explanation a continuous rated output power and peak output power:
● Rated Power
Continuous maximum power is a value within the range the power supply can continuously provide under any input voltage and temperature. Every power supply device must have a label that shows the total rated output power it offers.
● Peak Output Power
The peak output power is the value of power the power supply can provide in a short time(T<10mS) before triggering the protection mechanism.
Usually, the peak output power of a power supply is designed to be 1.1 times the rated power; most power supplies do not indicate the peak output power. The instantaneous maximum output power for an 850W power supply is about 935W (850W x 1.1 = 935W).
Sometimes you will find that the value of the rated output power specified on the label is different from the value of the wattage. Ensure you carefully check the indicated total rated output power to make sure you're getting the right amount of wattage.
2. Safety protection
The Safety protection function is another thing to look out for when choosing a power supply. This is to ensure that the power supply will be protected during times of abnormal activities. The safety protection functions include:
● OVP/OCP/OPP(Over Voltage/Current/Power Protection)
Overvoltage Protection (OVP) prevents the downstream circuitry from damage due to excessive voltage. The OCP protects the power supply unit from the dangers of too much current. Overpower protection (OPP) prevents the power supply from damage resulting from excessive power output.
These three protections all prevent the power supply unit from damage resulting from excessive bear. The protection will cut the power supply immediately to prevent further damage. After the abnormality is resolved, the power supply can be restarted.
● OTP (Over Temperature Protection)
Over Temperature Protection (OTP) shuts down the power supply when the internal temperature exceeds the needed operating temperature. The power supply can be restarted when the internal temperature is back to normal.
● SCP (Short Circuit Protection)
When the output circuits are short-circuited, the short circuit protection will cut off the power supply to avoid damage.
How to choose an AC/DC Power Converter
AC-DC converter or power supply is an electrical device that obtains alternating current (AC) input and transforms it into direct current (DC) output.
AC-DC Converters are necessary to provide the right power that an electrical component needs. They are utilized in power electronic applications that run on batteries and have no other power source uses.
Below you can find more information on the two main types of AC/DC converters to help you choose the right type for your needs.
1. Linear devices
While simple and relatively inexpensive, linear devices are usually in a large size and inefficient. Linear devices are designed for low noise and are often very quiet because of the absence of high-frequency switching. A linear power supply utilizes a large transformer to drop voltage from an AC line to a much lower AC voltage and then uses a series of rectifier circuitry and filtering process to produce a very clean DC voltage.
Some examples of linear power supply applications are A/D converters, laboratory test equipment, automatic test equipment, low noise amplifiers, medical equipment, communication equipment, signal processing, data acquisition including sensors, multiplexers, sample & hold circuits, control circuits, computer, and industrial applications.
2. Switching devices
Switching devices are AC to DC converters that utilizes SMPS (switched-mode power supply). A switching regulator shifts extremely quickly between full-on and full-off states to minimize wasted energy. These devices are smaller, lighter, and efficient but also more complicated. If not carefully suppressed, they can cause electrical noise problems, and simple designs may also have a poor power factor.
Applications that use switching devices are manufacturing, communication systems, mobile stations, network equipment, electroplating, anodizing, and many more.
The power supply solutions offered by MORNSUN meet the IEC 62368 and IEC 60950 safety standards. You can get wattages from 1W to1000W.
● Ensure that all necessary peripheral components are correctly connected
● Connect a fuse in the input AC line (L) to meet the safety requirements in operation.
● Verify all parameters and circuits before completing the circuit design.
● Do not operate the general AC/DC converter for a long time under high temperatures. If it must be operated under high temperature, get a new converter every one or two years.
● Avoid large heating devices around the converter, such as CPU, electric machine, etc.
● Don't worry about the slight noise inside the converter; it is normal when you operate it at light load or no load.
● The installation of the converter should be guided by professional designers.
● The converter case should be next to the device shell with heat-conducting glue if operated in an enclosed environment.
Solutions to heat dissipation in AC/DC converter applications
● Natural Air Cooling
Natural air cooling is commonly used as the primary heat dispatch method due to cost and space concerns. In this case, heat may dissipate to the ambient air through the converter shell, a gap between the converter and the PCB. Also, heat may dissipate from the converter shell, and exposed surfaces to PCB by radiation or heat conducts through terminals (pins) to PCB.
● Forced Air Cooling
This method involves installing a fan as the primary heat dissipation method since the operating condition of most applications is not well improved even when a heat sink is installed.
The fan's direction can be horizontal for the long-shaped converters, and the fan's direction in the channel can be vertical to form a chimney. Another way is to coat with a layer of thermal grease to make the fan and the converter shell combine tightly.
When designing circuitry for electrical equipment, you need power supplies that are able to withstand even the most unfavorable conditions. The reliability of power supplies is an important factor to consider when selecting a manufacturer for your electrical projects.
MORNSUN has over 23 years of experience in the power supply industry and we have applied for more than 1300 patents for inventions. We are one of the few power supply manufacturers with an independently designed and intellectual-property-protected integrated circuit, innovative transformer structure, distinctive assembly system, and unique appearance design.