How does an electric motor work? Simple explanation

With the advent of e-mobility, the topic of electric motors is also becoming increasingly important. But how does such an engine work? We explain it to you in this article.

How does an electric motor work? Magnetic fields and Lorentz force explained

The electric motor makes use of an essential force of nature - the Lorentz force. We'll explain how this works and why an electric motor can do this on the basis of simplified basics before we go into the assembly.

• Each magnet has two poles: the north pole and the south pole. The magnetic forces always act from the north to the south pole and on so-called ferromagnetic substances (cobalt, iron, nickel).
• Solid materials such as iron are always attracted to a magnet. If two magnets are present, however, the following applies: the same poles repel each other (south and south poles, north and north poles) - different poles attract each other (south and north poles).
• Electricity also has two different poles. There is a plus and a minus pole here. This is called electrical charge. Plus means that a particle is positively charged. Minus means a particle is negatively charged.
• The effect within a magnetic field on a charge (plus or minus) is called the Lorentz force. To put it simply: The magnetic north pole repels the plus charge and attracts the minus charge. The magnetic south pole attracts the plus charge and repels the minus charge.
• Every electric motor is based on this. It uses the magnetic effect of a permanent magnet on an electromagnet (which is energized and has a charge).

Structure and function of the engine

• The so-called stator is located under the housing of an electric motor. It consists of a stable magnetic field (permanent magnet). This means that the north and south poles have a fixed place and are not variable.
• The rotor (lat. Rotare = turn) is located in the motor itself. It is attached to a shaft and therefore rotatable. Its electric magnetic field changes constantly: the north and south poles swap places. The rotor is surrounded by the stator.
• The anchor is the iron core of the rotor. The coils of the rotor, through which the current flows, are wound around it. The changing magnetic field is built up using these coils. If the armature is a permanent magnet, there are no coils.
• The commutator (also called a pole changer) sits on the shaft of the rotor. The current flows through it. The task of the commutator is to turn the magnetic field of the rotor and thus to exchange the poles. This always happens when a certain position is reached. Sliding contacts are attached to the commutator, which supply the rotor with current.
• If the electric motor is now energized, the magnetic field builds up in the rotor. Only then will it become a rotating electromagnet.
• According to the principle described above that the same poles always repel each other, the rotor begins to turn. The commutator always sets the electromagnetic field of the rotor so that the north pole of the rotor and the north pole of the stator (analogous to the south pole) face each other. Simply put, the polarity of the rotor is changed after every half turn. Otherwise the North Pole and South Pole would face each other and the engine would stop.
• There is also a variant of the electric motor without a commutator. With AC motors, the magnetic field changes in rhythm with the speed of the rotor. The same poles face each other "automatically". In this case, the structure is somewhat different. The basic parts are retained.

More on the subject at EFahrer.com

Everything about electric cars: You can find current tests and a range calculator on our e-mobility portal EFahrer.com. There you will also find a large advisory area around electric cars.

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