AC or DC? This is not about rock anthems, but about the main types of electric motors
Alternating current (AC) motors and direct current (DC) motors have the same function – the conversion of electrical energy into mechanical energy. However, the difference is in their power supply, use and also in their design and management.
Most of us are notoriously familiar with the acronyms AC and DC thanks to the famous rock band. But these letters are actually the designation of alternating current and direct current . Both types include an incredible story called the war of currents, whose main heroes are none other than Thomas Alva Edison and George Westinghouse. The famous Nikola Tesla also played an equally important role in the question of whether alternating current or direct current is better.
Alternating current and direct current: main differences
Today we already know that the bickering of the great engineers of the 19th century was a bit pointless. Both types of current have their potential and both are still used today, for example to drive AC and DC motors.
It can be said that both types of motors, both AC (alternating current) and DC (direct current), have the same function, which is the conversion of electrical energy into mechanical energy . As the name suggests, the difference is in their power supply and also in their design and management.
AC motors are powered by alternating current, which is electricity that flows through standard wiring and that you can draw from your outlet . On the contrary, a direct current electric motor is powered by direct current, i.e. energy stored, for example, in batteries , supplied by direct current power sources, but we can also power them from a standard socket, we will just need an alternating current converter.
Synchronous vs. induction motors
Motors that run on alternating current have a structure containing so-called brushes and a commutator . These parts allow the engine to run, but at the same time they have a negative effect on its life, the need for more frequent maintenance and also limit the speed of the machine. Nowadays, however, there are also brushless motors that combine the agility of AC motors with the performance of DC motors.
Unlike DC motors, AC motors do not have brushes, so they are very fast, at the same time robust and have a long life. Here, too, we distinguish two basic types, namely the synchronous motor , which rotates at the same speed as the frequency of the supply current, and induction motors . These represent the simplest and most durable type of electric motor . Thanks to this, they are also the most widespread type of electric motor around the world.
Last but not least, we have the speed regulation of both types of motors. In the case of direct current, the speed of the motor is affected by changing the armature winding current . In an AC motor, the speed is controlled by changing the frequency . A frequency converter controller with an adjustable frequency usually takes care of this.
Use in practice
As already discussed, both types of engines have found their place in industry. The end consumer most often encounters devices that use AC motor power . It is most often installed in appliances, we can more often come across it in electric cars, computers, conveyor systems, fans and air conditioners, pumps and in transport systems.
In the case of a DC motor, the use is far more industrial . Its properties are appreciated above all in production, it drives machines that have to provide continuous performance, for example elevators, large industrial vacuum cleaners, sewing machines, etc.
