1. What is a motor?

Answer: The motor is the component that converts battery electrical energy into mechanical energy.

2. What is winding?

Answer: The armature winding is the core part of the DC motor, which is a coil wound with copper enameled wire. When the armature winding rotates in the magnetic field of the motor, it will generate electromotive force.

3. What is magnetic field?

Answer: The force field around a permanent magnet or electric current and the space or range of magnetic force that can be reached.

4. What is magnetic field strength?

Answer: The magnetic field strength of an infinitely long wire carrying a current of 1 ampere at a distance of 1/2 meter from the wire is defined as 1A/m (ampere/meter, SI). In the CGS unit system (centimeter-gram-second), in order to commemorate Oersted's contribution to electromagnetism, the magnetic field strength of an infinitely long wire carrying a current of 1 ampere at a distance of 0.2 cm from the wire is defined as 10e (Oersted), 10e=1/4.103/m. The magnetic field strength is usually represented by H.

5. What is Ampere's law?

Answer: Hold the wire with your right hand, with the direction of your extended thumb aligned with the direction of the current. Then the direction pointed by the four bent fingers is the direction of the magnetic lines of force.

6. What is magnetic flux?

Answer: Magnetic flux is also called magnetic flux: suppose there is a plane perpendicular to the direction of the magnetic field in a uniform magnetic field, the magnetic induction intensity of the magnetic field is B, and the area of the plane is S. We define the product of the magnetic induction intensity B and the area S as the magnetic flux passing through this surface.

7. What is a stator?

Answer: The part of a brushless or brushless motor that does not rotate when it is working. The motor shaft of a hub-type brushless or brushless gearless motor is called a stator, and this type of motor can be called an internal stator motor.

8. What is a rotor?

A: The rotating part of a brushless or brushless motor when it is working. The outer shell of a hub-type brushless or brushless gearless motor is called a rotor, and this type of motor can be called an external rotor motor.

9. What is a carbon brush?

A: The brushed motor is mounted on the surface of the commutator. When the motor rotates, it transmits electrical energy to the coil through the commutator. Since its main component is carbon, it is called a carbon brush, which is easy to wear. It should be regularly maintained and replaced, and the carbon deposits should be cleaned.

10. What is a brush holder?

A: A mechanical guide groove inside a brushed motor that holds and maintains the position of the carbon brushes.

11. What is a commutator?

Answer: Inside the brushed motor, there are mutually insulated strip metal surfaces. As the motor rotor rotates, the metal strips alternately contact the positive and negative poles of the brushes, realizing the alternating positive and negative changes in the direction of the motor coil current, thus completing the phase change of the brushed motor coil.

12. What is phase sequence?

Answer: The arrangement order of brushless motor coils.

13. What is magnet?

Answer: It is generally used to refer to magnetic materials with high magnetic field strength. Electric vehicle motors all use neodymium iron boron rare earth magnets.

14. What is electromotive force?

Answer: It is generated by the motor's rotor cutting the magnetic lines of force. Its direction is opposite to the external power supply, so it is called back electromotive force.

15. What is a brushed motor?

A: When the motor is working, the coil and commutator rotate, while the magnet and carbon brush do not rotate. The alternating change of the coil current direction is achieved by the commutator and brushes that rotate 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. From the word, it can be seen that brushed motors have carbon brushes, while brushless motors do not.

16. What is a brushless motor?

Because the controller provides direct current with different current directions to achieve the alternating change of the current direction of the coil in the motor. There are no brushes and commutators between the rotor and stator of the brushless motor.

17. How does the motor achieve phase commutation?

A: When a brushless or brushed motor is rotating, the direction of the current flowing through the coil inside the motor needs to be changed alternately so that the motor can rotate continuously. The commutation of a brushed motor is completed by the commutator and brushes, while the commutation of a brushless motor is completed by the controller.

18. What is missing phase?

A: One phase of the three-phase circuit of the brushless motor or brushless controller cannot work. Phase loss can be divided into main phase loss and Hall phase loss. The motor will vibrate and cannot work, or it will rotate weakly and make loud noises. The controller will easily burn out if it works in the phase loss state.

19. What are the common types of motors?

Answer: Common motors include: brushed geared hub motor, brushed gearless hub motor, brushless geared hub motor, brushless gearless hub motor, side-mounted motor, etc.

20. How to distinguish high-speed motors and low-speed motors based on their types?

Answer: A. Brushed geared hub motors and brushless geared hub motors are high-speed motors;

B Brushless gearless hub motors and brushless gearless hub motors are low-speed motors.

21. What are the common types of motors?

Answer: Common motors include: brushed geared hub motor, brushed gearless hub motor, brushless geared hub motor, brushless gearless hub motor, side-mounted motor, etc.

22. How to distinguish high-speed motors and low-speed motors based on their types?

Answer: A. Brushed geared hub motors and brushless geared hub motors are high-speed motors;

B Brushless gearless hub motors and brushless gearless hub motors are low-speed motors.

23. How is the power of a motor defined?

Answer: The power of a motor refers to the ratio of the mechanical energy output by the motor to the electrical energy provided by the power supply.

24. Why do we need to choose the power of the motor? What is the significance of choosing the power of the motor?

Answer: The selection of motor rated power is a very important and complex issue. When under load, if the motor rated power is too large, the motor will often be under light load operation, and the capacity of the motor itself cannot be fully utilized, becoming a "big horse pulling a small cart". At the same time, the motor has low operating efficiency and poor performance, which will increase operating costs. Conversely, if the motor rated power is required to be small, it will be a "small horse pulling a big cart". The motor current exceeds the rated current, the internal loss of the motor increases, and 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 greatly reduced; if the overload is too much, the insulation performance of the motor insulation material will be damaged or even burned. Of course, if the motor rated power is small, it may not be able to drag the load at all, and the motor will be in the starting state for a long time and overheated and damaged. Therefore, the rated power of the motor should be selected strictly according to the operation of the electric vehicle.

25. Why does a general brushless DC motor have three Halls?

A: In short, in order for a brushless DC motor to rotate, there must always be a certain angle between the magnetic field of the stator coil and the magnetic field of the rotor permanent magnet. The process of rotor rotation is also the process of changing the direction of the rotor magnetic field. In order to make the two magnetic fields have an angle, after a certain degree, the direction of the magnetic field of the stator coil must be changed. So how do you know when to change the direction of the stator magnetic field? That depends on the three Hall sensors. It can be considered that the three Hall sensors are responsible for telling the controller when to change the direction of the current.

26. What is the approximate range of power consumption of brushless motor Hall?

Answer: The power consumption of brushless motor Hall is roughly in the range of 6mA-20mA.

27. At what temperature can a motor generally work normally? What is the highest temperature a motor can withstand?

A: If the measured 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. Generally, the temperature rise of the motor should be below 20 degrees. Generally, the motor coil is wound with enameled wire, and when the temperature of the enameled wire is higher than about 150 degrees, the paint film will fall off due to the high temperature, causing the coil to short-circuit. When the coil temperature is above 150 degrees, the temperature of the motor shell is about 100 degrees, so if the shell 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 higher than the ambient temperature. But what is the reason why the motor heats up more than 20 degrees Celsius?

A: The direct cause of motor heating is high current. Generally, it may be caused by coil short circuit or open circuit, magnetic steel demagnetization or low motor efficiency. Normally, it is caused by long-term high current operation of the motor.

29. What causes the motor to heat up? What is the process?

A: When the motor is running under load, there is power loss inside the motor, which will eventually turn into heat energy, which will increase the motor temperature and exceed the ambient temperature. The value by which the motor temperature is higher than the ambient temperature is called temperature rise. Once the temperature rises, the motor will dissipate heat to the surroundings; the higher the temperature, the faster the heat dissipation. When the heat generated by the motor per unit time is equal to the heat dissipated, the motor temperature will no longer increase, but maintain a stable and unchanged temperature, that is, it is in a state of balance between heat generation and heat dissipation.

30. What is the allowable temperature rise of a general motor? Which part of the motor is most affected by the temperature rise? How is it defined?

Answer: When the motor is running under load, the load, that is, the larger the output power, the better (if mechanical strength is not considered) in order to maximize its role. However, the larger the output power, the greater the power loss, and the higher the temperature. We know that the weakest thing in the motor in terms of heat resistance is the insulating material, such as enameled wire. There is a limit to the heat resistance of the insulating material. Within this limit, the physical, chemical, mechanical, and electrical properties of the insulating material are very stable, and its working life is generally about 20 years. Exceeding this limit, the life of the insulating material will be drastically shortened, and it may even burn out. This temperature limit is called the allowable temperature of the insulating material. The allowable temperature of the insulating 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 location. When designing motors, 40 degrees Celsius is specified as the standard ambient temperature in my country. Therefore, the allowable temperature rise is the allowable temperature of the insulation material or motor minus 40 degrees Celsius.

The allowable temperature of different insulating materials is different. According to the allowable temperature, the commonly used insulating materials for motors are A, E, B, F, and H.

31. How to measure the phase angle of a brushless motor?

Answer: Turn on the controller power supply, and let the controller supply power to the Hall element, then the phase angle of the brushless motor can be detected. The method is as follows: Use the +20V DC voltage range of the multimeter, connect the red test pen to the +5V line, and use the black pen to measure the high and low voltages of the three leads respectively, and compare them with the commutation table of the 60-degree and 120-degree motors.

32. Why can't any brushless DC controller and brushless DC motor just be connected and run normally? Why is there a reverse phase sequence in brushless DC?

Answer: Generally speaking, the actual movement of a brushless DC motor is as follows: the motor rotates ---- the direction of the rotor magnetic field changes ---- when the angle between the stator magnetic field and the rotor magnetic field reaches 60 degrees electrical angle ---- the Hall signal changes ---- the direction of the phase line current changes ---- the stator magnetic field crosses 60 degrees electrical angle forward ---- the angle between the stator magnetic field and the rotor magnetic field is 120 degrees electrical angle ---- the motor continues to rotate. In this way, we understand that the Hall has six correct states. When a specific Hall tells the controller, the controller has a specific phase line output state. So the reverse phase sequence is to complete such a task, that is, to make the stator electrical angle always step in one direction at 60 degrees electrical angle.

33. What will happen if a 60-degree brushless controller is used on a 120-degree brushless motor? And vice versa?

Answer: They will all be inverted and lose phase and cannot rotate normally; but the controller used by Jieneng is an intelligent brushless controller that can automatically identify 60-degree motors or 120-degree motors, so it can be compatible with both types of motors, making maintenance and replacement more convenient.

34. How can the DC brushless controller and DC brushless motor get the correct phase sequence?

Answer: The first step is to ensure that the power line and ground line of the Hall line are plugged into the corresponding lines on the controller. There are 36 ways to connect the three motor Hall lines and the three motor lines to the controller. The simplest and dumbest method is to test each state one by one. The switching can be done without power failure, but it must be done carefully and in a certain order. Be careful not to turn it too much each time. If the motor does not rotate smoothly, this state is wrong. Turning the handle too much will damage the controller. If reverse rotation occurs, if you know the phase sequence of the controller, just swap the controller Hall lines a and c, and click on the line A phase and B to switch between each other, and reverse rotation can be turned into forward rotation. Finally, verify that the correct connection method is normal when running with high current.

35. How to control a 60 degree motor with a 120 degree brushless controller?

Answer: Just add a direction line between the brushless motor Hall signal line b phase and the controller sampling signal line.

36. What are the intuitive differences between brushed high-speed motors and brushed low-speed motors?

Answer: A. High-speed motors have overrunning clutches, so they can turn easily in one direction but difficult in the other; low-speed motors can turn in both directions with equal ease.

B. A high-speed motor makes more noise when it rotates, while a low-speed motor makes less noise when it rotates. Experienced people can easily identify it by ear.

37. What is the rated operating state of the motor?

Answer: When the motor is running, if all physical quantities are the same as its rated value, it is called the rated operating state. When working in the rated operating state, the motor can operate reliably and has the best overall performance.

38. How is the rated torque of a motor calculated?

Answer: The rated torque output on the click shaft can be expressed by T2n, and its size is the rated value of the output mechanical power divided by the rated value of the transfer speed, that is, T2n=Pn, where the unit of Pn is W, the unit of Nn is r/min, and the unit of T2n is NM. If the unit of PNM is KN, the coefficient 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 greater its torque.

39. How is the starting current of a motor defined?

Answer: Generally, the starting current of the motor is required not to exceed 2 to 5 times of its rated current. This is also an important reason why current limiting protection is performed on the controller.

40. Why are the speeds of motors sold on the market getting higher and higher? What are the effects?

Answer: Suppliers can reduce costs by increasing speed. For the same low-speed clicking, higher speed means fewer coil turns, which saves silicon steel sheets and reduces the number of magnetic steels. Buyers think that higher speed is better.

When operating at rated speed, its power remains unchanged, but in the low-speed area, the efficiency is significantly lower, which means that it is powerless at starting.

It has low efficiency and requires a large current to start. The current is also large when riding, which places high current limiting requirements on the controller and is not good for the battery.

41. How to repair the motor if it overheats abnormally?

Answer: The general maintenance method is to replace the motor or perform maintenance.

42. When the no-load current of the motor is greater than the limit data in the reference table, it indicates that the motor has a fault. What are the causes? How to repair it?

A: The internal mechanical friction is large; the coil is short-circuited; the magnet is demagnetized; the DC motor commutator is carbonized. The maintenance method is generally to replace the motor, or replace the carbon brush, and clean the carbon deposits.

43. What is the maximum fault-free no-load current of various motors?

Motor type Rated voltage 24V Rated voltage 36V

Side-mounted motor 2.2A 1.8A

High speed brushed motor 1.7A 1.0A

Low speed brushed 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 idling current of the motor?

Answer: Set the multimeter to 20A and connect the red and black test leads to the power input terminal of the controller. Turn on the power and record the maximum current A1 of the multimeter when the motor is not rotating. Turn the handle to make the motor rotate at high speed and no-load for more than 10 seconds. After the motor speed stabilizes, start observing and recording the maximum value A2 of the multimeter at this time. Motor no-load current = A2-A1.

45. How to identify whether a motor is good or bad? What are the key parameters?

Answer: It is mainly the size of no-load current and actual current, compared with normal value, as well as the motor efficiency and torque, as well as the noise, vibration and heat generation of the motor. The best way is to use dynamometer to test the efficiency curve.

46. How should I choose a motor? What should I base my choice on?

A: The most critical factor in motor selection is the choice of motor rated power.

Motor rated power selection is generally divided into three steps:

The first step is to calculate the load power P

The second step is to pre-select the rated power of the motor and other factors according to the load power.

The third step is to check the pre-selected motor. Generally, the temperature rise is checked first, then the overload capacity is checked, and the starting capacity is checked if necessary. If all pass, the pre-selected motor is selected; if not, start again from the second step until it passes.

It is important to note that the smaller the rated power of the motor, the more economical it is while meeting the load requirements.

After the second step is completed, temperature correction should be performed according to the different ambient temperatures. The rated power is based on the national standard ambient temperature of 40 degrees Celsius. If the ambient temperature is low or high all year round, the rated power of the motor should be corrected to make full use of the motor capacity in the future. For example, if the temperature is low all year round, the rated power of the motor should be higher than the standard Pn. On the contrary, if the temperature is high all year round, the rated power should be reduced.

In general, when the ambient temperature is determined, the motor should be selected based on the on-site conditions. The closer the on-site conditions can make the motor close to the rated operating state, the better.