Excitation is in electrical engineering : the creation of a magnetic flux in an electric machine with which the armature’s magnetic field will interact.
A device for creating an excitation flux is called an inductor; they can be either permanent magnets or electromagnets (windings). The inductor can be located both on the stator of the machine (in a DC machine, MPT), and on the rotor (in a synchronous machine), in this case the stator serves as an anchor and the alternating current in it is created by an external source, whereas in the MPT this role is played by the collector . Its emf depends on the excitation flux of the generator, that is, the output voltage (according to the formula E = CF ω ω is the machine design coefficient multiplied by the magnetic flux multiplied by the angular speed of rotation), and the torque and rotation frequency depend on the motor excitation flux.
In the case of electromagnetic excitation, different options for including field windings (OH) are possible. If the machine operates as a generator , the OM can be powered by the generator itself (self-excitation), in this case, the initial excitation can occur both due to short-term supply of the OM from an external source, and due to the residual magnetization of the machine, and it can be powered all the time from an extraneous source (independent excitation). The role of this source can be played by a special electric machine, which is called a pathogen , or a static converter with the same name. Such a scheme is currently widespread in the power transmission of diesel locomotives [1] .
It is also possible combined excitation used in some aircraft power generators - the main stream is created by permanent magnets, but to control the flow on the stator, windings are additionally wound, the magnetic flux of which is directed against the stream of permanent magnets [2] . In this case, at start-up, the full magnetic flux acts on the armature, which, as the speed of the generator increases, is weakened by applying current to the windings to stabilize the voltage at the generator output.
In motors, both permanent magnet excitation and electromagnetic excitation are also possible. The first option is used in small collector engines (for example, toy engines or a car washer pump motor), as well as in synchronous engines of computer drives . With electromagnetic excitation, it is possible to turn on the OM in series with the armature (mainly used in commutator motors, this circuit is characterized by a soft characteristic of the motor — a smooth increase in torque with increasing load on the shaft), in parallel (in this case, stiff - sharply increase with increasing load anchor current and with it the motor torque), as well as independent excitation - power supply from an external source. There are mixed-excitation motors, both with several windings of the inductor, and with the complex inclusion of a single winding. For example, the engines of electric locomotives 2ES4K and late VL10K can operate in the mode of sequential, independent or mixed excitation - in the third case, the OBs are connected in series with the anchors, but are simultaneously fed from excitation converters [3] .