AC-DC converters are electrical circuits that transform alternating current (AC) input into direct current (DC) output. They are used in power electronic applications where the power input a 50 Hz or 60 Hz sine-wave AC voltage that requires power conversion for a DC output.

AC to DC converters use rectifiers to turn AC input into DC output, regulators to adjust the voltage level, and reservoir capacitors to smooth the pulsating DC. This video explains how AC is converted into DC.

Types

• Linear devices are simple and relatively inexpensive, but also large and inefficient. They process excess power as heat, which can be problematic for some temperature-sensitive applications.
• Switching devices are more complex AC to DC converters that use a switched-mode power supply (SMPS). A switching regulator shifts very quickly between full-on and full-off states, minimizing wasted energy. Switching converters are more efficient, smaller, and lighter, but also more complicated. They can cause electrical noise problems if not carefully suppressed, and simple designs may also have a poor power factor.

Video credit: Jeff Regester

Specifications

• Allowable AC input can be set (e.g., 115, 208, or 230 VAC only) or a range (e.g., 85-264 VAC).
• DC output is measured in watts (e.g., 3 to 1,000), volts (e.g., 3 to 380), and amps (positive or negative; 1.6 to 6,000).
• Operating temperature ranges (e.g., -20 to 70 C) are also given for AC DC converters.

Features

AC-DC converters can have more than one output and may feature overcurrent, overvoltage, or short circuit protection. Ruggedized devices are suitable for hard-wearing and shock-resistant, and used in military applications. Some switching converters feature active or passive power factor correction to counteract the distortion and raise the power factor. A remote on/off switch may be available.

Applications

AC-DC converters are used in computers, televisions, cell phone chargers, and other electronic consumer devices. They are also used in medical, military, and telecommunications equipment; kitchen appliances; industrial machinery; and commercial products that use DC motors.

Resources

AC-DC Voltage Conversion

How to Convert AC to DC Power

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Acopian