Your guide to electric motors

I still remember the first time using an electric motor in a RC car. Two AA batteries and some wires powered the car through my childhood until I crashed it to a fence. And now life-sized electric cars are powering (no punt intended) sedans and SUVs that can accelerate faster than a supercar.

The immense capabilities of these turning machines makes buying a suitable electric motor for various uses more difficult than before, and likely to be even more complicated in the future. So, to clear all doubts, here’s your electric motor 101.

Now, how does an electric motor work? Known for converting electrical energy into mechanical energy, magnets are involved in the process as well. The interaction of a magnetic field and electric current creates a force to move an object (or the Faraday’s law of electromagnetic induction). And depending on factors including size and voltage, electric motors can push items as small as RC cars to something as heavy as turbines.

(Side fact: electric motors when reversed will become a generator.)

Electric motors have fundamental differences considering the electric current that is used. Direct current (DC) motors are often powered by batteries while alternating current (AC) motors are usually drawing electricity from power grids or electrical generators. Universal motors also exist to be used for both current, but often comes with a higher price tag.

In advanced usage, AC motors also vary from single-phase and three-phase motors for domestic application to heavy-duty work in industrial and manufacturing projects.

The speed of electric motors can be adjusted with the change in electricity energy level. Constant-speed motors are usually directly connected to the power source. Variable-speed motors would require additional equipment or appliances like power inverters, variable-frequency drives or electronic commutators to achieve such feature.

Important measurement units needed to know when learning or even choosing for an electric motor are segmented to the input and output side. The voltage (V) and current (A) are key in knowing what power source is suitable for the motor and how to setup the electric motor. On the output side, torque (Nm) and speed (RPM) offer insights to the power of the motor and if it is suitable for the use case you are planning for.

Electric motors are considered greatly efficient in energy conversion, especially when compared to internal combustion engines which a lot of heat is wasted. Therefore, despite the use of fossil fuels in generating electricity, the higher efficiency of generators in power plants combined with the benefit of electric motors still makes electric cars a better option than petrol- or diesel-powered vehicles.

The innovation of electric motors has been exponential recently with more of the highly advanced variants entering daily usage. Ex-Top Gear host, current host of the Grand Tour, Richard Hammond, famous known for crashing a Rimac electric hypercar off a cliff. The car, powered by none-but-electric-current, has 1224 horsepower and can accelerate from nought to 100 km/h in 2.5 seconds. Delicate motors are also benefitting our lives with stabilisation gimbals and drones.

Less prominent use of electric motors including air compressors, fans and air blowers, despite being less significant, are still a huge part in easing our chores. The next time when you see something moving silently without a noisy engine, take your time to appreciate the benefits of an electric motor in our lives.

Louise Author