What is 'Alternating Current', 'rectified Direct Current' and 'flat Direct Current'?

Altenating current

Alternating Current (AC) refers to an electrical current that periodically reverses direction. Alternating Current changes periodically reverses direction and changes its magnitude continuously with time, typically in the form of a sinusoidal wave. The standard frequency of AC is 50 Hz or 60 Hz, depending on the region.

The RMS value (Root Mean Square) of voltage is what we know as the nominal voltage, like: 230VAC, 115VAC, 24VAC.

Key characteristics:

• Voltage and current vary with time.
• Reverses direction periodically.

Usage:

• Efficient for long-distance transmission due to reduced energy losses.
• Commonly used for household appliances, lights, and most industrial equipment.

Direct current (rectified DC)

Rectified Direct Current is a form of DC power that results from converting AC to DC using a process called rectification. In this process, the negative part of the AC wave is flipped or removed, creating a pulsating direct current. This current is not perfectly flat, as there are still ripples or fluctuations in the voltage.

We distinguish between half-wave and full-wave rectifiers.

A half-wave rectifier consists of a single diode and a load resistor, converting the positive half-cycle of AC to DC, and suffering from inefficiency due to lost input power and higher ripples in the output.

Full-wave rectifiers, including center-tapped and bridge configurations, provide a more efficient and consistent DC output, making them suitable for demanding applications.

Key characteristics:

• Derived from AC using diodes or rectifiers.
• Flows in one direction but with ripples.
• The shape of the waveform may still resemble parts of the AC wave.

Usage:

• Often used in power supplies and electronics where full DC isn't necessary.

Direct current (flat DC)

Flat Direct Current refers to pure, steady DC power where the voltage remains constant over time. Unlike rectified DC, flat DC has no ripples or fluctuations and is perfectly smooth.

Key characteristics:

• Constant voltage and current.
• No ripples, unlike rectified DC.

Usage:

• Common in batteries, solar panels, and electronic devices that require consistent power.

In summary:

AC changes direction periodically, rectified DC flows in one direction with some ripples, and flat DC is smooth and constant without any variation in voltage.

Source:

https://www.electronics-tutorials.ws/

https://www.rohm.com/electronics-basics/ac-dc/rectification

https://www.electronics-tutorials.ws/power/switch-mode-power-supply.html