How Do Alternators Supply Power to Aircraft Electrical Systems?

Nearly every system aboard an aircraft depends on a consistent supply of electrical power to function, especially as electrification trends continue. When engines are running, much of this energy is provided by an alternator, a device that converts movement into electrical output. In this blog, we will contextualize their central role in aircraft performance, exploring what sets aircraft alternators apart from non-aviation models while covering the different designs utilized for flight.

Why Aircraft Require Specialized Alternators

As opposed to ground-based vehicles or industrial systems, aircraft operate in a uniquely demanding environment where space, weight, and safety margins are tightly controlled and a diverse range of sensitive avionics and high-load systems are employed. These strict requirements have shaped aircraft alternator design to prioritize:

Lightweight Construction: Built with high-strength, low-weight alloys and composites, aircraft alternators minimize mass to support fuel efficiency without compromising durability.
Redundancy: Larger aircraft usually have at least two alternators to ensure that electrical supply remains uninterrupted.
Flexibility in Output: Modern aircraft alternators focus on producing alternating current (AC) power, which can either be used directly by high-demand systems or rectified into direct current (DC) for avionics, battery charging, and control circuits.
Constant-Frequency Configurations: Some alternators incorporate constant-speed drives (CSDs) to generate a steady 400 Hz output despite variable engine speeds.

Types of Aircraft Alternators

DC Alternators: DC alternators are strictly used for older electrical systems that require DC power. Because they are less efficient at producing higher electrical loads and require heavier wiring for distribution as compared to AC alternatives, DC alternators have been largely phased out in favor of AC-based systems.
AC Alternators: As we previously noted, AC alternators produce alternating current that can either be distributed directly to systems designed for AC power or adjusted to DC. Beyond this capability, their efficiency, ability to support higher loads, and compatibility with complex electrical architectures make them the preferred choice for aircraft today.
Variable Frequency Alternators: Variable frequency alternators are an option that generate AC power with a frequency that varies according to engine speed. Voltage regulation in VFAs is achieved through electronic control systems that adjust the excitation current in rotor windings, removing the need for constant-speed drives to cut down on weight, complexity, and maintenance. These variants primarily find their application in more electrified aircraft designs.

How AC Alternators Work

As AC alternators are the most widely used option in aircraft, they provide a good baseline for explaining how electrical power is generated and managed in such vehicles. Generally speaking, their operation can be broken down into four main stages.

Step 1: Mechanical Input

The alternator is driven directly by an aircraft’s engine as it rotates, its rotor being turned through a belt, gear train, or direct shaft coupling. This establishes the motion needed to begin electrical generation.

Step 2: Magnetic Field Generation

The alternator’s rotor contains field windings that receive a small excitation current, which is initially provided by the aircraft’s battery during startup and then sustained by the alternator once it is running. As the rotor spins, these energized windings create a rotating magnetic field. When this field interacts with a stationary set of conductive coils called the stator windings, an alternating current is induced.

Step 3: Rectification and Regulation

The AC output is continuously monitored by a voltage regulator, which adjusts the excitation current to maintain a stable voltage level under changing loads and engine speeds. Where DC power is required, the regulated AC is passed through rectifier diodes for conversion.

Step 4: Distribution

The conditioned electrical output, whether AC or rectified DC, is finally routed to the electrical bus system, where it can then power essential and auxiliary subsystems like:

Cockpit avionics and instrumentation
Flight control computers and sensors
Cabin lighting, entertainment, pressurization, and climate controls

Reliably Procure Alternators on Internet of Industrials

In summary, aircraft alternators enable efficient energy conversion, consistent regulation, and reliable performance under diverse flight conditions. Because these components are so vital for powering various functions and are engineered specifically for the demands of aircraft, sourcing aviation-grade alternators is non-negotiable when the time comes for their replacement.

Internet of Industrials is a one-stop shop for top-quality aircraft alternators and countless other related products, all of which come directly from reputable manufacturers and suppliers. As an ASAP Semiconductor website, we commit to presenting procurement solutions that save customers time and money while aligning with distinct operational specifications or constraints wherever possible. Bearing this in mind, see how we can streamline fulfillment for you by connecting with our experts at your convenience.