Motore 30 hp prezzu monofase prezzu dinamo in Pakistan
Construction of DC motor
It is divided into two parts: stator and rotor. Remember that the stator and rotor are composed of those parts. Note: do not confuse the commutator pole with the commutator, and remember their roles.
The stator includes: main magnetic pole, frame, reversing pole, brush device, etc.
The rotor includes: armature core, armature winding, commutator, shaft and fan, etc.
Characteristics of four excitation modes of DC motor
A prestazione di u mutore DC hè strettamente ligata à u so modu di eccitazione. In generale, ci sò quattru modi di eccitazione di u mutore DC: un mutore eccitato DC separatamente, un mutore eccitato DC parallelo, un motore eccitato serie DC e un motore eccitato DC composto. Maestru e caratteristiche di i quattru metudi:
1. DC separately excited motor:
The excitation winding has no electrical connection with the armature, and the excitation circuit is supplied by another DC power supply. Therefore, the excitation current is not affected by the armature terminal voltage or armature current.
2. DC shunt motor:
The voltage at both ends of the shunt winding is the voltage at both ends of the armature. However, the excitation winding is wound with thin wires and has a large number of turns. Therefore, it has a large resistance, making the excitation current passing through it small.
3. DC series motor:
The excitation winding is connected in series with the armature, so the magnetic field in the motor changes significantly with the change of armature current. In order not to cause large loss and voltage drop in the excitation winding, the smaller the resistance of the excitation winding, the better. Therefore, DC series excited motors are usually wound with thicker wires, with fewer turns.
4. DC compound excitation motor:
The magnetic flux of the motor is generated by the excitation current in both windings.
Left and right hand rule
[left hand rule] the left hand rule is also called "motor rule". It is a rule to determine the force direction of the electrified conductor in the external magnetic field. The method is to stretch out the left hand so that the thumb is perpendicular to the other four fingers and on the same plane as the palm. Imagine putting your left hand into the magnetic field so that the magnetic line of force vertically enters the palm, and the other four fingers point to the direction of the current. At this time, the direction pointed by your thumb is the direction of the magnetic field acting on the current. The right hand rule is also known as the "generator rule". A rule for determining the direction of the induced current in a conductor as it moves in a magnetic field. Stretch out the stone hand so that the thumb is perpendicular to the other four fingers and in the same plane as the palm. Suppose you put your right hand into the magnetic field, let the magnetic line of force enter vertically from the palm of your hand, and make your thumb point to the direction of conductor movement. At this time, the direction indicated by the other four fingers is the direction of induced current.
Right hand rule
right-hand rule
For the cross product of a vector, we define
A × B=C
Note that the order of a and B cannot be reversed
Make the direction of vector a along the back of the hand and vector B along the direction of four fingers, then the direction of vector C is the direction of thumbs up (perpendicular to the plane formed by a and b)
Motore 30 hp prezzu monofase prezzu dinamo in Pakistan
This is the right hand rule.
Keep your right hand flat so that your thumb is perpendicular to the other four fingers and in the same plane as your palm. Put your right hand into the magnetic field. If the magnetic line of force vertically enters the palm (when the magnetic line is a straight line, it is equivalent to the palm facing the N pole), and the thumb points to the direction of wire movement, the direction indicated by the four fingers is the direction of induced current in the wire.
In electromagnetics, the right hand rule mainly judges the direction independent of force.
If it is related to force, it all depends on the left-hand rule.
That is, the left-hand rule for force and the right-hand rule for others.
Current element i1d ι Pair distance γ Another current element i2D of 12 ι The acting force DF12 of is:
μ 0 I1I2d ι two × (d ι one × γ 12)
df12 = ── ───────────
4π γ one hundred and twenty-three
Where d ι 1、d ι 2 is the direction of current; γ 12 is from i1d ι Point to i2D ι Radial vector of. Ampere's law can be divided into two parts. One is current element ID ι (i.e. i1d above ι ） stay γ (i.e. above γ 12) The magnetic field generated at
μ 0 Id ι × γ
dB = ── ─────
4π γ three
This is the Biot - SA - La law. The other is current element IDL (i.e. i2D above ι 2) The force DF (i.e. DF12 above) received in the magnetic field B is:
df = Id ι × B
The rule for determining the direction of induced current in a conductor moving in an external magnetic field is also called the generator rule. It is also a rule for judging the relationship between the direction of induced current, the direction of conductor movement and the direction of magnetic lines of force.
Handshaking is applicable to the rule that the palm of the generator is in the direction of the magnetic field, the thumb is in the direction of the object movement, and the finger is in the direction of the current ~ ~ ` to determine the direction of the dynamic electromotive force generated in the conductor when the conductor cuts the magnetic induction line. The content of the right hand rule is: stretch out your right hand,
Motore 30 hp prezzu monofase prezzu dinamo in Pakistan
Make the thumb perpendicular to the other four fingers and in the same plane with the palm of the hand, put the right hand into the magnetic field and let the magnetic induction line penetrate vertically
The palm and thumb point to the moving direction of the conductor, and the other four fingers point to the direction of the motional electromotive force. The direction of electromotive force and its generation
The direction of the induced current is the same.
The direction of the electromotive force determined by the right-hand rule conforms to the law of energy transformation and conservation.
Precautions for applying the right hand rule
When applying the right-hand rule, note that the object is a straight wire (of course, it can also be used for energized solenoids）And the velocity V and magnetic field B should be perpendicular to the conductor, and V and B should also be perpendicular,
The right-hand rule can be used to judge the direction of the induced electromotive force. For example, the right-hand generator rule can be used to judge the direction of the induced electromotive force of the three-phase asynchronous motor rotor.
The reason for the right-hand rule lies in the three-dimensional structure of electricity, magnetism and mass. The right-hand rule represents the electric dimension, magnetic dimension and quality information gradient dimension
Left hand rule
zu ǒ sh ǒ udìngzé
left-hand rule
Keep your left hand flat so that your thumb is perpendicular to the other four fingers and is in the same plane as your palm.
Put your left hand into the magnetic field and let the magnetic induction line vertically penetrate the palm (the palm is aligned with the N pole and the back of the hand is aligned with the S pole,
Four fingers point to the current direction (i.e. the direction of positive charge movement)
Then the direction of thumb is the force direction of conductor.
Used in motor
Motore 30 hp prezzu monofase prezzu dinamo in Pakistan
[principle]: when you draw the magnetic induction lines of the magnet and the current, the two kinds of magnetic induction lines are intertwined. According to the vector addition, where the magnetic induction lines of the magnet and the current have the same direction, the magnetic induction lines become dense; In the opposite direction, the magnetic induction lines become sparse. A characteristic of magnetic induction lines is that each magnetic induction line in the same direction repels each other! Where the magnetic induction lines are dense, the pressure is high, and where the magnetic induction lines are sparse, the pressure is low. So the pressure on both sides of the current is different, pushing the current to one side. The direction of the thumb is the direction of the pressure. Distinction and right hand rule.
[applicable]: the current direction is perpendicular to the magnetic field direction
(calculation method)
As follows```
Current element i1d ι Pair distance γ Another current element i2D of 12 ι The acting force DF12 of is:
μ 0 I1I2d ι two × (d ι one × γ 12)
df12 = ── ───────────
4π γ one hundred and twenty-three
Where d ι 1、d ι 2 is the direction of current; γ 12 is from i1d ι Point to i2D ι Radial vector of. Ampere's law can be divided into two parts. One is current element ID ι (i.e. i1d above ι ） stay γ (i.e. above γ 12) The magnetic field generated at
μ 0 Id ι × γ
dB = ── ─────
4π γ three
This is the Biot - SA - La law. The other is current element IDL (i.e. i2D above ι 2) The force DF (i.e. DF12 above) received in the magnetic field B is:
df = Id ι × B
Ampere rule
règuli
The rule indicating the relationship between the current and the direction of the magnetic induction line of the magnetic field excited by the current is also called the right-hand spiral rule.
(1) Ampere rule in the energized straight wire (ampere rule 1): hold the energized straight wire with your right hand and point your thumb to the direction of current, then the direction of four fingers is the surrounding direction of the magnetic induction wire
(2) Ampere rule in energized solenoid (ampere rule 2): hold the energized solenoid with your right hand so that the four fingers bend in the same direction as the current, and the end pointed by your thumb is the N pole of the energized solenoid
a natura
Motore 30 hp prezzu monofase prezzu dinamo in Pakistan
The ampere rule of linear current is also applicable to a small segment of linear current. The ring current can be regarded as many small segments of linear current. For each small segment of linear current, the ampere rule of linear current is used to determine the direction of magnetic induction intensity on the central axis of the ring current. The direction of the magnetic induction line on the central axis of the ring current is obtained by superposition. The ampere rule of the linear current is basic. The ampere rule of the ring current can be derived from the ampere rule of the linear current. The ampere rule of the linear current is also applicable to the magnetic field generated by the linear motion of the charge. At this time, the current direction is the same as that of the positive charge, but opposite to that of the negative charge.
Inspired by H.C. Auster current magnetic effect experiment and a series of other experiments, a.-m. ampere realized that the essence of magnetic phenomenon is current, reduced various interactions involving current and magnet to the interaction between currents, and put forward the basic problem of finding the interaction law of current elements. In order to overcome the difficulty that the isolated current element can not be directly measured, four zero indicating experiments were carefully designed and accompanied by careful theoretical analysis, and the results were obtained. However, because ampere holds the concept of over distance action on electromagnetic action, he once imposed the assumption that the force between two current elements is along the connecting line in theoretical analysis, expecting to abide by Newton's third law, which makes the conclusion wrong. The above formula is the result after discarding the wrong assumption that the force is along the line. It should be understood from the viewpoint of close action that the current element generates a magnetic field and the magnetic field exerts a force on the other current element.
Ampere's law, equivalent to Coulomb's law, is the basic experimental law of magnetic interaction. It determines the nature of magnetic field and provides a way to calculate current interaction.
Ampere force formula
Current element i1d ι Pair distance γ Another current element i2D of 12 ι The acting force DF12 of is:
μ 0 I1I2d ι two × (d ι one × γ 12)
df12 = ── ───────────
4π γ one hundred and twenty-three
Where d ι 1、d ι 2 is the direction of current; γ 12 is from i1d ι Point to i2D ι Radial vector of. Ampere's law can be divided into two parts. One is current element ID ι (i.e. i1d above ι ） stay γ (i.e. above γ 12) The magnetic field generated at
μ 0 Id ι × γ
dB = ── ─────
4π γ three
This is the Biot - SA - La law. The other is current element IDL (i.e. i2D above ι 2) The force DF (i.e. DF12 above) received in the magnetic field B is:
df = Id ι × B
