The excitation method of a DC generator is different from that of a DC motor

The excitation mode of the DC generator is separately excited, and the excitation mode of the DC motor is self-excitation.

1. Separate excitation of DC motor: The excitation winding has no connection relationship with the armature winding, and the DC motor supplied by other DC power sources to the excitation winding is called separately excited DC motor, and the wiring is shown in the following figure.

DC motor self-excitation, divided into parallel excitation, series excitation and compound excitation.

1) Parallel excitation: The excitation winding of the DC motor is connected in parallel with the armature winding, and the wiring is shown in the figure below. As a parallel generator, it is the terminal voltage generated by the motor itself that supplies power to the excitation winding.

2) Series excitation: After the excitation winding of the DC motor is connected in series with the armature winding, it is then connected to the DC power supply, and the wiring is shown in the figure below. The excitation current of this DC motor is the armature current.

3) The compound excitation DC motor has two excitation windings, parallel excitation and series excitation, and the wiring is shown in the figure below. If the magnetic flux potential generated by the series winding is in the same direction as the magnetic flux potential generated by the parallel winding, it is called product compound excitation. If the two magnetic flux potentials are in opposite directions, they are called differential compound excitation.

The excitation of DC generators and DC motors is the same, and they are divided into other excitation and self-excitation.

The difference is only that the DC generator rectifies the alternating current generated in the rotor armature into a DC output, while the DC motor converts the input DC power into AC power through inverter and passes it into the rotor armature. Both have alternating current in the rotor armature!

1. Separately excited DC motor

There is no connection between the excitation winding and the armature winding, and the DC motor supplied by other DC power sources to the excitation winding is called an otherwise excited DC motor, and the permanent magnet DC motor can also be regarded as an otherwise excited or self-excited DC motor, which is generally directly called the excitation mode as a permanent magnet.

2. Parallel excitation DC motor

The excitation winding of the parallel excitation DC motor is connected in parallel with the armature winding, and as a parallel excitation generator, the terminal voltage generated by the motor itself supplies power to the excitation winding; As a parallel excited motor, the excitation winding and the armature share the same power supply, which is the same as the separately excited DC motor in terms of performance.

3. Series excited DC motor

The excitation winding of the series excited DC motor is connected to the armature winding in series and then connected to the DC power supply. The excitation current of this DC motor is the armature current.

Composition of DC motor:

1) Main pole.

The role of the main pole is to generate an air-gap magnetic field. The main pole is composed of two parts: the main pole core and the excitation winding. The iron core is generally made of thick silicon steel plate punching and riveting, and is divided into two parts: the pole body and the pole shoe.

2) Commutation pole.

The function of the commutator electrode is to improve the commutation and reduce the commutation spark that may be generated between the brush and the commutator when the motor is running, which is generally installed between two adjacent main magnetic poles, and is composed of the commutation electrode core and the commutator winding.

3) Brush device.

The brush device is used to introduce or draw DC voltage and DC current. The brush device is composed of a brush, a brush grip, a brush rod and a brush rod base. The brushes are placed in the brush grip and pressed with springs so that there is good sliding contact between the brushes and the commutator.

The above content reference:

The excitation winding and the main winding are connected in parallel, but their power supply and armature power supply are not the same power supply.

Parallel excitation means that the excitation winding and the main winding are in parallel relationship, and their power supply and armature power supply are the same power supply.

Series excitation means that the excitation winding and the main winding are in series relationship, and its power supply and armature power supply are the same power supply.

Series excitation: the starting and overload capacity is large, and the speed changes significantly with the load. The no-load speed is too high, commonly known as "flying car".

Parallel excitation: The speed is basically constant, and it is generally used for loads with small speed changes.

Compound excitation: The compound excitation motor based on parallel excitation has a large torque and a small change in speed, and is mostly used in machine tools. The compound excitation motor based on series excitation has the characteristics close to that of the series excitation motor, but there is no danger of "flying".

Separate excitation: A motor that is individually powered by the excitation circuit, for systems that require wide speed regulation.

The way in which a magnetic field is generated in a rotating machine. Most modern motors are based on electromagnetic induction, and magnetic fields are required in the motor. This magnetic field can be generated by a permanent magnet or by using the current in the electromagnet** circle.

The set of coils in a motor that is specially set up to generate a magnetic field is called an excitation winding. Due to the limitation of the properties of permanent magnet materials, the magnetic field established by permanent magnets is relatively weak, and it is mainly used in small-capacity motors.

However, with the emergence of new permanent magnet materials, especially rare earth materials with high magnetic energy product such as rare earth cobalt and NdFeB, permanent magnet motors with a capacity of 100 kilowatts have begun to be developed.

The current-carrying coil used to excite the magnetic flux in the magnetic circuit is called the excitation coil (or excitation winding), and the current in the excitation coil is called the excitation current (or excitation current).

If the excitation current is DC, the magnetic flux in the magnetic circuit is constant and does not change with time, and this kind of magnetic circuit is called DC magnetic circuit; The magnetic circuits of DC motors fall into this category. If the excitation current is AC, the magnetic flux in the magnetic circuit changes with time, and this magnetic circuit is called an alternating current magnetic circuit; The magnetic circuits of AC core coils, transformers, and induction motors all fall into this category.

Motor excitation method Encyclopedia.

DC motors can be divided into two categories: permanent magnet type and electromagnetic type according to the excitation method.

Excitation of the generator.

There are five modes: separate excitation, self-excitation, hybrid excitation, rotor winding biaxial excitation and stator winding excitation.

1) Other incentives. In this excitation method, the excitation of the generator is not a synchronous generator.

itself, but by other power sources. Depending on the form of power supply, there are usually the following: i0 n2 i

h: t) d 1) Excitation mode of power supply of coaxial DC exciter. This is a method of excitation commonly used in small-capacity generators, and its advantages are reliable excitation and easy adjustment, but commutators and brushes.

The maintenance of the equipment is large.

2) The excitation mode of power supply of DC exciter with different shafts, such as the low-speed DC generator dragged by an induction motor with separate power supply or connected with the large shaft of the generator through a reduction gear.

When the speed is less than 1000r min, it can be applied to large-capacity units, but the structure is complex and there are not many applications. For hydro generators, the commutation of DC generators is not the main problem due to the low speed, but there are also structural difficulties in DC generators with too large capacity at too low speeds. 3 v8 d/ ~ u) d- i# h$ [

3) Coaxial AC exciter Excitation mode (controllable or uncontrollable) for static rectifier power supply. This is a combination of alternator and rectifier and is suitable for larger capacity generators. + c% n2 g( `c; b: b: ]

4) Coaxial AC exciter Rotary rectifier power supply excitation mode. The brushless excitation system is mainly composed of a silicon rectifier device that rotates with a coaxial AC exciter and a spindle.

The excitation mode of the alternator refers to the way in which the magnetic field current of the alternator is established, and there are usually two ways: separate excitation and self-excitation.

There are several forms of self-excitation, other excitation and compound excitation.