1. What do you mean by electric motor?
Motor is the part that converts battery electric energy into mechanical energy and drives the wheels of electric vehicles to rotate.
2. What is winding?
Armature winding is the core part of a DC motor, which is a coil wound by copper enameled wire. When the armature winding is rotated in the magnetic field of the motor, it generates electric potential.
3. What do you mean by magnetic field?
The force field that occurs around a permanent magnet or current and the space or range of magnetic force that can be reached by any magnetic force.
4. What is meant by magnetic field strength?
The strength of the magnetic field of an infinitely long wire carrying a current of 1 ampere at a distance of 1/2 meter from the wire is 1A/m (ampere/m, International System of Units SI); in the CGS system of units (cm – g – sec), in honor of Oster’s contribution to electromagnetism, the strength of the magnetic field of an infinitely long wire carrying a current of 1 ampere at a distance of 0.2 centimeters from the wire is defined as 10e (Oster), 10e = 1/1.103/m. 4.103/m, and the magnetic field strength is usually expressed as H.
5. What is meant by Ampere’s rule?
Hold the wire in your right hand, so that the direction of the straightened thumb is the same as the direction of the current, then the direction of the bent four fingers is the direction of magnetic induction lines around.
6. What is magnetic flux?
Magnetic flux is also called magnetic flux: located in a uniform magnetic field there is a plane perpendicular to the direction of the magnetic field, the magnetic induction of the magnetic field is B, the area of the plane is S, we define the product of the magnetic induction B and the area S, called the magnetic flux through this surface.
7. What is a stator?
The part of a brush or brushless motor that does not turn when it is operating. The motor shaft of a hub-type brush or brushless gearless motor is called the stator, and such a motor can be called an internal stator motor.
8. What is the rotor?
The part of a brush or brushless motor that rotates during operation. The housing of a hub type brush or brushless gearless motor is called the rotor, and such a motor can be called an external rotor motor.
9. What is called carbon brush?
Brush motor inside the top on the surface of the phase converter, the motor rotation, the electrical energy through the phase converter to the coil, because its main component is carbon, called carbon brushes, it is easy to wear. It should be regularly maintained and replaced, and clean up the carbon accumulation
10. What is brush grip?
The mechanical guide groove inside the brush motor that holds and keeps the carbon brush in position.
11. What is phase changer?
Inside the brush motor, there is a mutually insulated strip metal surface, when the motor rotor rotates, the strip metal alternately touches the positive and negative poles of the brush to realize the alternate positive and negative changes of the motor coil current direction and complete the phase change of the brush motor coil.
12. What is phase sequence?
The arrangement order of brushless motor coils.
13. What is magnet?
Generally used to call the magnetic material of high magnetic field strength, electric car motor are used neodymium boron rare earth magnets.
14. What is electric potential?
It is generated by the rotor of the motor cutting the magnetic lines of force, and its direction is opposite to the applied power supply, so it is called counter-electromotive force.
15. What is a brush motor?
When the motor works, the coil and commutator rotate, the magnet and carbon brush do not rotate, the alternate change of coil current direction is done by the commutator and brush which rotate with the motor. In the electric vehicle industry brush motor is divided into high speed brush motor and low speed brush motor. There are many differences between brush and brushless motors, from the word brush motor has carbon brush, brushless motor has no carbon brush.
16. What is a low-speed brush motor? What are the characteristics?
In the electric vehicle industry, low speed brush motor is a hub type low speed high torque gearless brush DC motor, the relative speed of the stator and rotor of the motor is the speed of the wheel. The magnets on the stator are 5~7 pairs and the number of slots in the rotor armature is 39~57. Since the armature windings are fixed in the wheel housing, heat is easily dissipated with the help of the rotating housing. The rotating housing is also woven with 36 spokes, which is more favorable for heat conduction. GIS training micro signal is worth your attention!
17. What are the characteristics of brushed and toothed motors?
Brush motor because there are brushes, its main hidden trouble is “brush wear”, users should note that the brush motor is divided into two kinds of tooth and toothless. At present, many manufacturers choose brushed and toothed motor, which is a high-speed motor, the so-called “toothed” is through the gear reduction mechanism, the motor speed is lowered (because the national standard stipulates that the speed of electric vehicles shall not exceed 20 km/h, so the motor speed should be about 170 rpm).
Since the motor is decelerated by gears at high speed, it is characterized by strong power and climbing ability when starting. But the electric hub is closed, only before the factory filled with lubricant, it is difficult for the user to carry out daily maintenance, and the gear itself also has mechanical wear, about a year due to insufficient lubrication led to increased gear wear, noise increases, the use of the current also increases, affecting the motor and battery life.
18. What is brushless motor?
As the controller provides DC power in different current directions to achieve alternating changes in the direction of the coil current inside the motor. Brushless motors do not have brushes and commutators between the rotor and stator.
19. How does a motor achieve phase change?
When a brushless motor or a brush motor is rotating, the direction of energization of the coil inside the motor needs to change alternately so that the motor can rotate continuously. The phase change of brush motor is done by phase commutator and brush together, while brushless motor is done by controller.
20. What is phase loss?
In the three-phase circuit of brushless motor or brushless controller, one phase is not working. Phase loss is divided into main phase loss and Hall phase loss. The performance of the motor jitter can not work, or rotation powerless and noisy. Controller working in the state of phase loss is very easy to burn up.
21. What are the common types of motors?
The common motors are: brushed geared hub motor, brushed gearless hub motor, brushless geared hub motor, brushless gearless hub motor, side hung motor, etc.
22. How to distinguish from the type of motor is high and low speed motor?
A Brushed geared hub motors, brushless geared hub motors are high speed motors.
B Brushed gearless hub motor, brushless gearless hub motor belong to low speed motor.
23. How is the power of a motor defined?
The power of a motor is the ratio of the mechanical energy output by the motor to the electrical energy provided by the power supply.
24. Why should we choose the power of the motor? What is the significance of choosing the power of the motor?
The choice of motor power rating is a very important and complex issue. When the load, if the rated power of the motor is too large, the motor is often in the light load operation, the motor itself does not fully play the capacity, into a “big horse-drawn car”, while the motor operating efficiency is low, bad performance, will increase operating costs.
On the contrary, the motor rated power requirement is small, that is, “small horse-drawn car”, motor current exceeds the rated current, motor internal consumption increased, low efficiency is a small matter, the important thing is to affect the life of the motor, even if the overload is not much, the life of the motor will be reduced more; overload more, will destroy the insulation of the motor insulation material insulation performance or even burned. . Of course, the motor rated power is small, it may not be able to drag the load at all, which will make the motor overheat and damage it by being in the starting state for a long time. Therefore, the rated power of the motor should be selected in strict accordance with the operation of the electric vehicle.
25. Why do DC brushless motors in general have three halls?
Briefly, in order to be able to rotate, a DC brushless motor must always have a certain 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 angle between the two magnetic fields, to a certain extent, the stator coil magnetic field direction must be changed. So how to know to change the direction of the stator magnetic field? That depends on the three Hall. It can be assumed that the three Hall shoulders the task of telling the controller when to change the direction of the current.
26. What is the approximate power consumption range of the brushless motor Hall?
The approximate power consumption of brushless motor Hall is in the range of 6mA-20mA.
27. At what temperature can a typical motor operate normally? What is the maximum temperature that the motor can withstand?
If the temperature of the motor cover exceeds the ambient temperature by more than 25 degrees, the temperature rise of the motor has exceeded the normal range. Generally, the motor coil is made of enameled wire, and the enameled wire will fall off when the temperature is higher than 150 degrees, causing the coil to short circuit. When the coil temperature is above 150 degrees, the motor casing shows a temperature of about 100 degrees, so if the casing temperature is used as the basis, the maximum temperature that the motor can withstand is 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 over the ambient temperature, but what is the reason for the motor to heat up more than 20 degrees Celsius?
The direct cause of motor heating is caused by high current. Generally, it may be caused by short circuit or open circuit of coil, demagnetization of magnet or low efficiency of motor, etc. The normal situation is that the motor runs with high current for a long time.
29. What causes a motor to heat up? What is the process?
There is power loss in the motor when the motor is running under load, which will eventually turn into heat, which will make the motor temperature rise and exceed the ambient temperature. The value of the motor temperature above the ambient temperature is called temperature rise. Once there is a temperature rise, the motor must be dissipated to the surrounding area; the higher the temperature, the faster the heat dissipation. When the heat emitted by the motor unit time is equal to the heat dissipated, the motor temperature no longer increases, but maintains a stable and constant temperature, that is, in a balanced state of heat generation and heat dissipation.
30. What is the general click allowable temperature rise? Which part of the motor is most affected by the temperature rise of the motor? How is it defined?
When the motor is running under load, the greater the output power, the better (if the mechanical strength is not considered). But the higher the output power, the higher the power loss, the higher the temperature. We know that the weakest thing in the motor temperature resistance is the insulation material, such as enameled wire. Insulation material temperature resistance has a limit, within this limit, the physical, chemical, mechanical, electrical and other aspects of the insulation material performance is very stable, its working life is generally about 20 years.
Beyond this limit, the life of the insulating material will be sharply shortened, or even burned. This temperature limit, known as 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 insulation material is generally the life of the motor.
The ambient temperature varies with time and place, and the design of the motor is specified to take 40 degrees Celsius as our standard ambient temperature. Therefore, the allowable temperature of the insulation material or motor minus 40 degrees Celsius is the allowable temperature rise, the allowable temperature of different insulation materials is different, according to the allowable temperature, the common insulation materials for motors are A, E, B, F, H five kinds.
According to the ambient temperature of 40 degrees Celsius, these five types of insulation materials and their allowable temperature and allowable temperature rise are shown below, corresponding to the grade, insulation material, allowable temperature, allowable temperature rise.
A impregnated cotton, silk, cardboard, wood, etc., ordinary insulating paint 105 65
E Epoxy resin, mylar film, green shell paper, triac fiber, highly insulating varnish 120 80
B Mica, asbestos, and glass fiber compositions with organic lacquer as binder with improved heat resistance 130 90
F Mica, asbestos and glass fiber compositions bonded or impregnated with epoxy resins with excellent heat resistance 155 115
H with silicone resin bonded or impregnated mica, asbestos or glass fiber combination, silicone rubber 180 140
31. How to measure the phase angle of a brushless motor?
The phase angle of the brushless motor can be detected by turning on the power supply to the controller and powering the Hall element from the controller. The method is as follows: use the +20V DC voltage file of the universal meter, and connect the red pen to the +5V line, and the black pen to measure the high and low voltage of the three leads respectively, according to the phase change table of the 60 degree and 120 degree motor can be compared.
32. Why can’t any DC brushless controller and DC brushless motor be connected at random and turn normally? Why is there a reverse phase sequence of DC brushless?
Generally speaking, the actual movement of DC brushless motor is such a process: the motor rotates — the rotor magnetic field direction changes — when the angle between the stator magnetic field direction and the rotor magnetic field direction reaches 60 degrees of electrical angle — the Hall signal changes — the phase line changes. – Hall signal changes – the direction of the phase line current changes – the stator field crosses 60 degrees of electrical angle forward – the stator field direction and the rotor field direction The angle between the direction of the stator field and the direction of the rotor field is 120 degrees of electrical angle – the motor continues to rotate.
So we understand that there are six correct states of Hall. When a specific Hall tells the controller, the controller has a specific phase output state. So inverting the phase sequence is to accomplish the task of making the electrical angle of the stator always step in one direction at 60 degrees of electrical angle.
33. What happens if a 60 degree brushless controller is used on a 120 degree brushless motor? And vice versa?
The controller used by Jenergy is an intelligent brushless controller that can automatically identify 60 degree motor or 120 degree motor, so it can be compatible with both motors, making it more convenient for maintenance and replacement.
34. How can the DC brushless controller and DC brushless motor reverse the correct phase sequence?
The first step is to ensure that the Hall line power line and ground line and the corresponding line on the controller plugged in, and three motor Hall line and three motor line to the controller connection a total of 36 kinds, the most simple and stupid method is to test each state one by one. Switching can be done without power, but must be careful, but also in a certain order. Be careful not to twist too much each time, if the motor does not rotate smoothly, then this state is not right, turn the twist too much damage to the controller, if there is a reversal of the situation, in the case of knowing the phase sequence of the controller is the controller Hall line a, c interchange, click line A phase and B phase interchange, can be inverted for the positive rotation. Finally, verify that the correct method of connection is normal when running at high current.
35. How to control 60 degree motor with 120 degree brushless controller?
Add a directional line between the Hall signal line b phase of brushless motor and the sampling signal line of controller.
36. What is the intuitive difference between a brush high-speed motor and a brush low-speed motor?
A. High-speed motors have overrunning clutches, so it is easy to turn in one direction and exhausting to turn in the other direction; low-speed motors turn buckets in both directions as easily.
B. High-speed motors are noisier when the car is turning, and low-speed motors are less noisy when they are turning. Experienced people can easily identify by ear.
37. What is the rated operating condition of the motor?
When the motor is running, if each physical quantity is the same as its rated value, it is called rated operating condition. Working under the rated operating condition, the motor can operate reliably and has the best overall performance.
38. How is the rated torque of the motor calculated?
The rated torque output on the click axis can be expressed as T2n, the size of which is the rated value of the mechanical power output divided by the rated value of the transfer speed, i.e. T2n=Pn where the unit of Pn is W, the unit of Nn is r/min, and the unit of T2n is N.M, if the unit of PNM is KN, the factor of 9.55 is 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 higher the torque.
39. How is the starting current of a motor defined?
I Translated with www.DeepL.com/Translator (free version)
40. Why are the speeds of motors on the market getting higher and higher? And what is the impact?
Supplier side speed can reduce costs, the same low-speed click, high speed coil turns is less, but also save the silicon steel sheet, the number of magnets is also less, the buyer believes that high speed is good.
Rated speed work, its power remains unchanged, but in the low speed zone when the efficiency is obviously low, that is, the start is powerless.
Low efficiency, the need to start with high current, riding current is also high, the controller current limit requirements, the battery is also bad.
41. How to repair the abnormal heating of the motor?
The repair treatment method is generally to replace the motor, or to repair the warranty.
42. The no-load current of the motor is greater than the reference table limit data indicates that the motor has a fault, what are the causes? How to repair?
Click on the internal mechanical friction; coil local short circuit; magnet demagnetization; DC motor phase changer carbon accumulation. Maintenance treatment method generally that for the replacement of the motor, or replace the carbon brush, clean up the carbon.
43. What is the maximum limit no-load current of various motors without fault?
The following correspond to the form of motor, rated voltage 24V, rated voltage 36V respectively.
Side hung motor 2.2A 1.8A
High-speed brushed 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 the motor idling current?
Put the multimeter on 20A, connect the red and black meter pen to the power input of the controller. Turn on the power, and then the motor does not turn, record the maximum current A1 of the multimeter at this time. Turn the handle, so that the motor no-load high-speed rotation for more than 10s, wait for the motor speed stability, start to observe and record the maximum value of the multimeter A2. Motor no-load current = A2 – A1.
45. How to identify the good and bad of the motor? What are the key parameters?
The main is the size of no-load current and riding current, compared with the normal value, and the motor efficiency and torque, as well as the motor noise, vibration and heat, the best way is to test the efficiency curve with a dynamometer.
46.What is the difference between 180W and 250W motors? What are the requirements for the controller?
250W has a high riding current and requires a higher power margin and reliability of the controller.
47. Why does the riding current of an electric vehicle vary under standard conditions depending on the motor rating?
As we all know, under standard conditions, the riding current is about 4 – 5A for a 250W DC motor with a rated load of 160W, and a little higher for a 350W DC motor.
As an example: If the battery voltage is 48V and both motors are 250W and 350W, with rated efficiency points of 80%, the rated operating current of the 250W motor is about 6.5A, while the rated operating current of the 350W motor is about 9A.
The general motor efficiency point is the farther the operating current deviates from the rated operating current, the smaller the value, the same in the case of 4-5A load, in the 250W motor efficiency is 70%, 350W motor efficiency is 60%, then at a load of 5A
The output power of 250W is 48V*5A*70%=168W
The output power of 350W is 48V*5A*60%=144W
And 350W motor in order to make the output power to meet the riding requirements that is to reach 168W (almost the rated load), the only way to make the power supply increase, so that the efficiency point increases.
48. Why does a 350W motor have a shorter range than a 250W motor in the same environment?
Under the same environment, the electric bicycle with 350W motor has higher riding current, so its range will be shorter under the same battery condition.
49. How should the electric bicycle manufacturers choose the motor? According to what to choose the motor?
The most critical factor for electric bikes is the selection of the motor power rating.
Motor power rating selection is generally divided into three steps.
The first step is to calculate the load power P
The second step, according to the load power, pre-select the motor power rating and other.
The third step, calibrate the pre-selected motor.
Generally first check the heat temperature rise, then check the overload capacity, if necessary, check the starting capacity. All passed, the pre-selected motor will be selected; pass but from the second step to carry out again, until passed. 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, according to the different ambient temperatures for temperature correction, rated power is in the national standard ambient temperature of 40 degrees Celsius premise. If the ambient temperature is lower or higher all year round, the future full use of the motor capacity, the rated power of the motor should be corrected. For example, if the year-round temperature is low, the rated power of the motor century should be higher than the standard regulation Pn, and on the contrary, if the year-round temperature is high, the rated power should be reduced for use.
Overall, in the case of ambient temperature determination, the choice of electric car motor should be based on the riding state of the electric car, the more the riding state of the electric car can make the motor close to the rated working state, the better, and the riding state of the electric car is generally based on the road conditions. If the road surface is smooth in Tianjin, the low power motor is enough; if you want to use a higher power motor, it will cause the waste of energy and result in a short range. If there are many mountain roads in Chongqing, it is appropriate to use a higher power motor.
50.60 degree DC brushless motor is more powerful than 120 degree DC brushless motor, right? Why?
From the market, we found that when communicating with many customers, there is a common fallacy! They think that 60 degree motor is more powerful than 120 degree motor. From the principle of brushless motor and the facts prove that, in fact, 60 degrees motor or 120 degrees motor! The so-called degrees are only used to tell the brushless controller when to let the two phase wires on. The so-called degree is only used to tell the brushless controller when to let the two phase wires on. 240 degrees and 300 degrees is the same, there is no who is more powerful than who said.
Translated with www.DeepL.com/Translator (free version)