The most comprehensive motor knowledge is here
Time:2024-06-12
Views:54
1. What is a motor?
The motor is the part that converts battery electricity into mechanical energy and drives the wheel rotation of the electric vehicle.
2. What is winding?
Armature winding is the core part of DC motor. It is a coil made of copper enamelled wire. When the armature winding rotates in the magnetic field of the motor, it generates an electromotive force.
3. What is a magnetic field?
The force field occurring around a permanent magnet or an electric current and the extent of space or magnetic action that any magnetic force can reach.
4. What is the magnetic field strength?
An infinite wire carrying a current of 1 amp has a magnetic field strength of 1A/m (amps /m, SI) at a distance of 1/2 m from the wire; In the CGS system of units (centimeter-gram-second), in honor of Oersted‘s contribution to electromagnetism, it is defined that the magnetic field strength of an infinite wire carrying a current of 1 amp at a distance of 0.2 cm from the wire is 10e (Oersted), 10e=1/4.103/m, and the magnetic field strength is usually expressed by H.
5. What is the Ampere Rule?
Hold the wire with the right hand, so that the direction of the extended thumb is the same as the direction of the current, then the direction of the bent four fingers is the direction of the magnetic induction line.
6. What is magnetic flux?
Magnetic flux is also called magnetic flux: there is a plane perpendicular to the direction of the magnetic field in the uniform magnetic field, the magnetic induction intensity of the magnetic field is B, the area of the plane is S, we define the product of the magnetic induction intensity B and the area S, called the magnetic flux through this surface.
7. What is a stator?
The part of a brushed or brushless motor that does not rotate during operation. The motor shaft of the wheel type brush or brushless toothless motor is called the stator, which can be called the inner stator motor.
8. What is a rotor?
The part of a brushed or brushless motor that turns during operation. The shell of the wheel type brushless or brushless toothless motor is called the rotor, and this motor can be called the external rotor motor.
9. What is a carbon brush?
Brush motor inside the top of the commutator surface, when the motor rotates, the electrical energy through the commutator to the coil, because its main component is carbon, called carbon brush, it is easy to wear. Regular maintenance and replacement should be done, and carbon deposits should be cleaned up
10. What is a brush grip?
A mechanical guide groove containing and holding the carbon brush position in the brushed motor.
11. What is a phase changer?
Inside the brush motor, there are mutually insulated strip metal surfaces. When the motor rotor rotates, the strip metal alternately contacts the positive and negative poles of the brush, realizing the positive and negative alternating changes in the current direction of the motor coil, and completing the commutation of the brush motor coil.
12. What is phase sequence?
Brushless motor coil arrangement sequence.
13. What is magnetic steel?
Generally used to call magnetic materials with high magnetic field strength, electric vehicle motors are made of neodymium ferrorare earth magnetic steel.
14. What is electromotive force?
It is generated by the rotor of the motor cutting the magnetic force line, and its direction is opposite to the external power supply, so it is called the back electromotive force.
15. What is a brushed motor?
When the motor is working, the coil and the commutator rotate, the magnetic steel and the carbon brush do not rotate, and the alternating change in the direction of the coil current is completed by the commutator and the brush rotating with the motor. In the electric vehicle industry, brushed motors are divided into high-speed brushed motors and low-speed brushed motors. There are many differences between brushed motors and brushless motors, and it can be seen from the word that brushed motors have carbon brushes, and brushless motors have no carbon brushes.
16. What is a low speed brush motor? What are its characteristics?
In the electric vehicle industry, the low-speed brush motor refers to the hub-type low-speed high-torque gearless brushless DC motor, and the relative speed of the motor fixed rotor is the speed of the wheel. The magnetic steel on the stator is 5~7 pairs, and the number of slots of the rotor armature is 39~57. Since the armature winding is fixed in the wheel housing, heat is easily dissipated with the help of the rotating housing. The rotating shell is woven with 36 spokes, which facilitate heat transfer. Technical training micro signal worth your attention!
17. What are the characteristics of brushed and toothed motor?
Because there is a brush in the brush motor, its main hidden danger is "brush wear", the user should note that the brush motor is divided into two kinds of teeth and no teeth. At present, many manufacturers choose brush toothed motor, which is a high-speed motor, the so-called "toothed" is through the gear reduction mechanism, the motor speed is reduced (because the national standard stipulates that the electric vehicle speed should not exceed 20 kilometers, so the motor speed should be about 170 RPM).
Because the high-speed motor is decelerated through the gear, it is characterized by the rider feeling strong power when starting, and the climbing ability is strong. However, the electric wheel is closed, just before the factory added lubricant, the user is difficult to carry out daily maintenance, and the gear itself also has mechanical wear, about a year due to insufficient lubrication lead to increased gear wear, noise increases, the use of current also increases, affecting the motor and battery life.
18. What is brushless motor?
Because the controller provides direct current in different current directions, it can achieve the alternating change of the current direction of the coil inside the motor. There is no brush and commutator between the rotor and the stator of the brushless motor.
19. How is the motor commutated?
When the brushless or brushed motor is rotating, the direction of power of the coil inside the motor needs to be alternately changed, so as to achieve continuous motor rotation. The commutation of the brush motor is completed by the commutator and the brush, and the brushless motor is completed by the controller.
20. What is a lack of phase?
In the three-phase circuit of a brushless motor or brushless controller, one phase does not work. The missing phase is divided into main phase missing and Hall phase missing. The performance is that the motor jitter can not work, or the rotation is weak and noisy. The controller is easy to burn out when it works in the absence of phase.
21. What are the common types of motors?
Common motors are: brushed with gear hub motor, brushed with gear hub motor, brushless with gear hub motor, brushless with gear hub motor, side hanging motor, etc.
22. How to distinguish between high and low speed motors from the types of motors?
A brushed motor with gear hub, brushless motor with gear hub belong to high-speed motor;
B Brushless gearless hub motor, brushless gearless hub motor is a low-speed motor.
23. How is the power of the motor defined?
The power of the motor refers to the ratio of the mechanical energy output by the motor to the electrical energy provided by the power supply.
24. Why choose the power of the motor? What is the significance of choosing motor power?
The choice of motor rated power is a very important and complicated problem. When the load is too large, if the rated power of the motor is too large, the motor is often in light load operation, the capacity of the motor itself is not fully played, and it becomes a "big horse car", while the motor operation efficiency is low and the performance is not good, which will increase the operating cost.
In turn, the motor rated power requirements are small, that is, the "small horse cart", the motor current exceeds the rated current, the motor loss increases, the efficiency is low, the important thing is to affect the life of the motor, even if the overload is not much, the motor life will be reduced more; More overload will destroy the insulation performance of the motor insulation material and even burn. Of course, the rated power of the motor is small, and the load may not be dragged at all, which will cause the electric power to be in the starting state for a long time and be overheated and damaged. Therefore, the rated power of the motor should be selected strictly in accordance with the operation of the electric vehicle.
25. Why do general DC brushless motors have three halls?
In brief, in order for a brushless DC motor to be able to rotate, there must always be an Angle between the magnetic field of the stator coil and the magnetic field of the permanent magnet of the rotor. The process of rotor rotation is also the process of rotor magnetic field direction change, in order to make the two magnetic fields exist Angle, to a certain extent, the stator coil magnetic field direction must be changed. So how do you know to change the direction of the stator‘s magnetic field? Then it‘s up to the three Hols. It can be thought that the three halls are tasked with telling the controller when to change the direction of the current.
26. What is the approximate power consumption range of brushless motor Hall?
The power consumption of brushless motor Hall ranges from 6mA to 20mA.
27. At what high temperature can the general motor work normally? What is the maximum temperature the motor can withstand?
If the temperature of the motor cover exceeds the ambient temperature by more than 25 degrees, it indicates that the temperature rise of the motor has exceeded the normal range, and the general motor temperature rise should be below 20 degrees. Generally, the motor coil is wound by enameled wire, and when the temperature of the enameled wire is higher than 150 degrees, the paint film will fall off because of high temperature, resulting in short circuit of the coil. When the coil temperature is above 150 degrees, the motor housing shows a temperature of about 100 degrees, so if the housing temperature is based on the motor to withstand the maximum temperature of 100 degrees.
28. The temperature of the motor should be below 20 degrees Celsius, that is, the temperature of the motor end cover should be less than 20 degrees Celsius above the ambient temperature, but what is the reason for the motor heating more than 20 degrees Celsius?
The direct cause of motor heating is due to the large current. Generally, it may be caused by short circuit or open circuit of the coil, demagnetization of the magnetic steel or low efficiency of the motor, and the normal situation is that the electric current runs for a long time.
29. What causes the motor to heat up? What is the process?
When the motor load is running, there is power loss in the motor, which will eventually become heat energy, which will increase the temperature of the motor and exceed the ambient temperature. The value where the motor temperature is higher than the ambient temperature is called warming. Once there is a temperature rise, the motor must dissipate heat around; The higher the temperature, the faster the heat dissipation. When the heat emitted by the motor per unit time is equal to the heat emitted, the motor temperature is no longer increased, and a stable and unchanged temperature is maintained, that is, in a state of balance between heat and heat dissipation.
30. What is the normal temperature rise allowed by a click? Which part of the motor is most affected by the temperature rise of the motor? How is it defined?
When the motor load is running, from the point of trying to play its role, the greater the load, that is, the better the output power (if the mechanical strength is not considered). But the higher the output power, the higher the loss power, the higher the temperature. We know that the weakest thing in the temperature resistance of the motor is the insulating material, such as enamelled wire. There is a limit to the temperature resistance of insulating materials, within this limit, the physical, chemical, mechanical, electrical and other aspects of the insulation material are very stable, and its working life is generally about 20 years.
Beyond this limit, the life of the insulation material will be dramatically shortened, and even burn. This temperature limit is called the allowable temperature of the insulation material. The allowable temperature of the insulation material is the allowable temperature of the motor; The life of the insulating material is generally the life of the motor.
The ambient temperature varies with time and place, and 40 degrees Celsius is specified as the standard ambient temperature in our country when designing the motor. Therefore, the allowable temperature of the insulating material or the motor minus 40 degrees Celsius is the allowable temperature rise, the allowable temperature of different insulating materials is not the same, according to the allowable temperature, the commonly used insulating material of the motor is A, E, B, F, H five.
Calculated at an ambient temperature of 40 degrees Celsius, the five types of insulation materials and their allowable temperature and allowable temperature rise are shown below, corresponding to the grade, insulation material, allowable temperature, and allowable temperature rise respectively.
A impregnated cotton, silk, cardboard, wood, etc., common insulating paint 105 65
E Epoxy resin, polyester film, green shell paper, triacid fiber, high insulating paint 120 80
B Mica, asbestos, and fiberglass compositions using organic paints with improved heat resistance as adhesives 130 90
F Mica, asbestos and glass fibre compositions bonded or impregnated with epoxy resins of excellent heat resistance 155 115
H Mica, asbestos or fiberglass compositions bonded or impregnated with silicone resin and silicone rubber 180 140
31. How to measure the phase Angle of brushless motor?
The phase Angle of the brushless motor can be detected by connecting the controller power supply to the Hall element. The method is as follows: use the +20V DC voltage file of the multimeter, and connect the red pen to the +5V line, and measure the high and low voltage of the three leads respectively with the black pen, according to the commutation meter of the 60 degree and 120 degree motor.
32. Why can‘t any brushless DC controller and brushless DC motor be connected at will to rotate normally? Why is there an inverted phase sequence in brushless DC?
In general, DC brushless motor in actual motion is such a process: Motor rotation - rotor magnetic field direction change - when the Angle between the stator magnetic field direction and the rotor magnetic field direction to 60 degrees electrical Angle - Hall signal change - phase line current direction change - stator magnetic field forward across 60 degrees electrical Angle - stator magnetic field direction and rotor magnetic field direction Angle is 120 degrees electrical Angle -- The motor continues to rotate.
So we understand that Hall has six correct states. When a particular Hall tells the controller, the controller has a particular phase output state. Therefore, the inverted phase sequence is to complete such a task, that is, to make the stator‘s electrical Angle always step in one direction at a 60 degree electrical Angle.
33. What happens if a 60 degree brushless controller is used in a 120 degree brushless motor? What about the other way around?
Will fall to the lack of phase phenomenon, can not rotate normally; However, the controller used by the Jet energy is an intelligent brushless controller that can automatically identify the 60 degree motor or 120 degree motor, so that it can be compatible with two kinds of motors, making maintenance and replacement more convenient.
34. How can brushless DC controller and brushless DC motor pour out the correct phase sequence?
The first step is to ensure that the power cord and ground wire of the Hall line are inserted with the corresponding line on the controller, and the three motor Hall lines and three motor lines are connected to the controller in a total of 36 kinds, and the simplest and stupid method is to test each state one by one. When changing, it can be carried out continuously, but it must be carefully and in a certain order. Should pay attention to each twist is not too large, if the motor rotation is not smooth, then this state is not right, turn the screw is too large on the loss of the controller, if there is a reverse situation, in the case of knowing the phase sequence of the controller is the controller Hall line A, c exchange, click the line A phase and B exchange each other, you can turn positive. Finally verify that the correct connection method is normal when the high current is running.
35. How to control a 60 degree motor with a 120 degree brushless controller?
Add a direction line between the brushless motor Hall signal line b phase and the controller sampling signal line.
36. What is the visual difference between brushed high-speed motor and brushed low-speed motor?
A. The high-speed motor has an overrunning clutch, which is easy to turn in one direction and hard to turn in another direction; Low speed motor two-way turning bucket as easily.
B. The noise of the high-speed motor is larger when the car rotates, and the noise of the low-speed motor is smaller. Experienced people can easily identify it by ear.
37. What is the rated running state of the motor?
When the motor is running, if each physical quantity is the same as its rating, it is called the rated operating state, and the motor can operate reliably under the rated operating state, and has the best comprehensive performance.
38. How is the rated torque of the motor calculated?
The rated torque output on the click shaft can be represented by T2n, and its size is the mechanical power rating of the output divided by the rating of the transfer speed, that is, T2n=Pn, where Pn is W, Nn is r/min, T2n is N.M, if the PNM unit is KN, The coefficient 9.55 was changed to 9550.
Therefore, it can be concluded that if the rated power of the motor is equal, the lower the speed of the motor, the greater the torque.
39. How is the starting current of the motor defined?
It is generally required that the starting current of the motor cannot exceed 2 to 5 times its rated current, which is also an important reason for current limiting protection on the controller.
40. Why are the motor speeds on the market getting higher and higher? And what are the implications?
Suppliers speed up can reduce costs, the same low speed click, high speed coil turns less, but also save the silicon steel sheet, the number of magnetic steel is also less, buyers think that high speed is good.
When the rated speed is working, its power is unchanged, but the efficiency is significantly lower in the low speed zone, that is, the start is weak.
Low efficiency, the need to start with a large current, the current is also large when riding, the current limit requirement of the controller is large, and it is not good for the battery.
41. How to repair abnormal motor heating?
The method of maintenance treatment is generally to replace the motor, or carry out maintenance protection.
42. When the no-load current of the motor is greater than the limit data of the reference table, it indicates that the motor has a failure. What are the causes? How to repair?
Click the internal mechanical friction; Coil local short circuit; Demagnetization of magnetic steel; Dc motor inverter carbon deposits. The method of maintenance treatment is generally to replace the motor, or replace the carbon brush to clean up the carbon deposit.
43. What is the maximum limit no-load current of all kinds of motors without fault?
The following correspond to the motor form, rated voltage 24V, rated voltage 36V:
Side mount motor 2.2A 1.8A
High speed brush motor 1.7A 1.0A
Low speed brush motor 1.0A 0.6A
High-speed brushless motor 1.7A 1.0A
Low speed brushless motor 1.0A 0.6A
44. How to measure motor idling current?
Set the multimeter to 20A and connect the red and black pen to the power input of the controller. Turn on the power, and record the maximum current A1 of the multimeter at this time when the motor does not turn. Turn the handle, make the motor high-speed no-load rotation more than 10s, wait for the motor speed to stabilize, start to observe and record the maximum value of the multimeter A2 at this time. Motor no-load current =A2-A1.
45. How to identify the quality of the motor? What are the key parameters?
It is mainly the size of no-load current and riding current, compared with normal values, and the level of motor efficiency and torque, as well as the noise, vibration and heat of the motor, the best way is to test the efficiency curve with a dynamometer.
What is the difference between 46.180W and 250W motors? What are the requirements for the controller?
The riding current of 250W is large, which requires higher power margin and reliability of the controller.
47. Why does the riding current of an electric vehicle vary according to the rating of the motor in a standard environment?
As we all know, under standard conditions, calculated at the rated load of 160W, the riding current on the 250W DC machine is about 4-5A, and the riding current on the 350W DC machine is slightly higher.
For example: if the battery voltage is 48V, the two motors 250W and 350W, and their rated efficiency points are 80%, the rated working current of the 250W motor is about 6.5A, and the rated working current of the 350W motor is about 9A.
The efficiency point of the general motor is that the farther the working current deviates from the rated working current, the smaller the value, in the case of 4-5A load, the motor efficiency of 250W is 70%, and the motor efficiency of 350W is 60%, then under the load of 5A,
The output power of 250W is 48V*5A*70%=168W
The output power of 350W is 48V*5A*60%=144W
In order to make the output power meet the riding requirements to reach 168W (almost rated load), the 350W motor can only increase the power supply, so as to increase the efficiency point.
Due to the same environment, the 350W motor of the electric vehicle riding current is large, so in the case of the same battery, its mileage will be short.
49. How should the electric moped manufacturer choose the motor? According to what to choose the motor?
For electric vehicles, the most critical factor in motor selection is the choice of motor rated power.
Motor rated power selection is generally divided into three steps:
First, calculate the load power P
The second step, according to the load power, pre-select the rated power of the motor and other.
The third step is to check the pre-selected motor.
Generally, first check the heating temperature rise, then check the overload capacity, and check the starting capacity if necessary. All passed, the pre-selected motor will be selected; Do not pass from the second step again until you pass. Do not meet the requirements of the load, the smaller the rated power of the motor, the more economical.
After the second step is done, the temperature correction should be carried out according to the different ambient temperature, and the rated power is carried out under the premise of the national standard ambient temperature of 40 degrees Celsius. If the ambient temperature is low or high all year round, the capacity of the motor should be fully utilized in the future, and the rated power of the motor should be corrected. For example, the perennial temperature is low, the rated power of the motor should be higher than the standard Pn, on the contrary, the perennial temperature is high, the rated power should be reduced.
In general, in the case of determining the ambient temperature, the choice of electric vehicle motor should be determined according to the riding state of the electric vehicle, the more the riding state of the electric vehicle can make the motor close to the rated working state, the better, and the riding state of the electric vehicle is generally determined according to the road conditions. If the road surface in Tianjin is flat, the low-power motor is enough; If you want to use a high-power motor, it will cause a waste of energy, resulting in short mileage. If there are many mountain roads in Chongqing, it is suitable to use a motor with larger power.
50.60 degree brushless DC motor is more powerful than 120 degree brushless DC motor, right? Why?
From the market found that when communicating with many customers, there is such a fallacy! A 60-degree motor is considered stronger than a 120-degree motor. From the principle of brushless motor and the facts prove that in fact, 60 degree motor or 120 degree motor worth mentioning! The so-called degree is only used to tell the brushless controller when to let the two phase wires to be connected. There is no one more powerful than others! 240 degrees and 300 degrees is the same, no one is more powerful than the other.
|
Disclaimer: This article is transferred from other platforms and does not represent the views and positions of this site. If there is any infringement or objection, please contact us to delete it. thank you! |
Business consulting
13823761625
Mail me