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One hundred thousand why of the motor?

Views: 10     Author: Site Editor     Publish Time: 2023-01-11      Origin: Site

Q. What is an electric machine?

A: The motor is the part that converts battery electricity into mechanical energy and drives the wheels of an electric vehicle to spin.


Q. What is motor winding?

Answer: Armature winding is the core part of DC motor, is copper enamelled wire wound coil. Electromotive force is generated when the armature winding rotates in the magnetic field of the motor.


Q. What is a magnetic field?

A: The force field around a permanent magnet or an electric current and the space or extent of magnetic action that can be reached by magnetic forces.


Q. What is a magnetic field?

A: The force field around a permanent magnet or an electric current and the space or extent of magnetic action that can be reached by magnetic forces.


Q. What is the Ampere Rule?

A: Hold the wire with your 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 sensing wire.


Q. What is magnetic flux?

A: 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, and the area of the plane is S. We define the product of the magnetic induction intensity B and the area S, which is called the magnetic flux through the surface.


Q. What is a motor stator?

A: Brush or brushless motor work does not turn the part. The motor shaft of a hub type brushed or brushless toothless motor is called a stator, which can be called an inner stator motor.


Q. What is a motor rotor?

A: The part of a brushed or brushless motor that turns when working. Hub type brush or brushless toothless motor shell called rotor, this motor can be called external rotor motor.


Q. What is a carbon brush?

A: Brush motor inside the top of the commutator surface, when the motor rotates, the electric energy through the commutator to the coil, because its main component is carbon, known as the carbon brush, it is easy to wear. Regular maintenance and replacement, and clean up carbon deposits.


Q. What is a brush grip?

A: The mechanical guide groove containing and maintaining the position of the carbon brush inside the brushed motor.


Q. What is a phase changer?

A: Inside the brushed motor, there are mutually insulated strip metal surfaces. When the rotor of the motor rotates, the strip metal alternately contacts the positive and negative poles of the brush, realizing the alternating positive and negative changes in the direction of the current of the motor coil, and completing the commutation of the coil of the brushed motor.


Q. What is a carbon brush?

A: Brush motor inside the top of the commutator surface, when the motor rotates, the electric energy through the commutator to the coil, because its main component is carbon, known as the carbon brush, it is easy to wear. Regular maintenance and replacement, and clean up carbon deposits.


Q. What is a brush grip?

A: The mechanical guide groove containing and maintaining the position of the carbon brush inside the brushed motor.


Q. What is a phase changer?

A: Inside the brushed motor, there are mutually insulated strip metal surfaces. When the rotor of the motor rotates, the strip metal alternately contacts the positive and negative poles of the brush, realizing the alternating positive and negative changes in the direction of the current of the motor coil, and completing the commutation of the coil of the brushed motor.


Q. What is phase sequence?

A: Brushless motor coil arrangement sequence.


Q. What is magnetic steel?

A: Normally used for magnetic material with high magnetic field intensity, the electric vehicle motor uses neodymium ferrosteel.


Q. What is electromotive force?

A: generated by the rotor of the motor cutting the line of magnetic force, its direction and the external power supply is opposite, so called back electromotive force.


Q. What is a brushed motor?

A: When the motor is working, the coil and commutator rotate, while the magnetic steel and carbon brush do not rotate. The alternating change in the direction of the coil current is accomplished by the commutator and brush rotating 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 brushed motor and brushless motor. From the word, it can be seen that brushed motor has carbon brush and brushless motor has no carbon brush.


Q. What is a low speed brushed motor? What are its characteristics?

A: In the electric vehicle industry, low-speed brushed motor refers to the hub-type low-speed high-torque gearless brushless DC motor, and the relative speed of the fixed rotor of the motor is the speed of the wheel. There are 5~7 pairs of magnetic steel on the stator and 39~57 slots on the rotor armature. 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!


Q. What are the characteristics of brushed and toothed motors?

A: Brush motor because of the brush, its main hidden danger is "brush wear", users should note that brush motor is divided into toothed and toothless two. At present, many manufacturers choose brush toothed motor, which is a kind of high-speed motor. The so-called "toothed" is to lower the motor speed through the gear reduction mechanism (because the national standard stipulates that the speed of electric vehicles shall not exceed 20 kilometers per hour, so the motor speed should be about 170 RPM). Because the high-speed motor decelerates through the gears, it is characterized by a strong feeling of power and strong climbing ability when the rider starts. But the electric hub is closed, just before the factory added lubricant, users are difficult to carry out daily maintenance, and the gear itself also has mechanical wear, a year or so due to insufficient lubrication lead to increased gear wear, noise, the use of current is also increased, affecting the motor and battery life.



Q. How is the power of a motor defined?

A: The power of a motor is the ratio of the mechanical energy output by the motor to the electric energy provided by the power supply.


Q. Why choose the power of the motor? What is the significance of choosing motor power?

A: The choice of motor rated power is a very important and complex problem. Load, if the motor rated power is too large, the motor is often in light load operation, the capacity of the motor itself can not be fully played, become a "big horse car", while the motor operation efficiency is low, the performance is not good, will increase the operation cost. Conversely, the rated power of the motor is small, that is, the "little horse", 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 life of the motor will be reduced more; Too much overload will destroy the insulation performance of motor insulation materials and even burn. Of course, the rated power of the motor is small, may not drag the load at all, will make the electric long time in the starting state and overheating damage. Therefore, the rated power of the motor should be selected strictly in accordance with the operation of the electric vehicle.


Q. Why do general brushless DC motors have three halls?

A: Briefly, in order for a brushless DC motor to rotate, there must always be an Angle between the magnetic field of the stator coil and that of the permanent magnet of the rotor. The rotating process of the rotor is also the process of changing the direction of the rotor magnetic field. In order to make the two magnetic fields exist at an Angle, the direction of the stator coil's magnetic field must be changed to a certain extent. So how do I know to change the direction of the stator's magnetic field? Well, then it's up to the three halls. You can think of the three halls as being tasked with telling the controller when to change the direction of the current.


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

A: The power consumption of brushless motor Hall ranges from 6mA to 20mA.


Q. At what temperature can the general motor work normally? What is the maximum temperature the motor can withstand?

Answer: 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 temperature rise of the motor should be below 20 degrees. General motor coil is wound by enamelled wire, and enamelled wire in the temperature above 150 degrees when the film will fall off because of high temperature, resulting in coil short circuit. When the coil temperature is above 150 degrees, the motor shell shows a temperature of about 100 degrees, so if the shell temperature is based on the motor to withstand the highest temperature of 100 degrees.


Q. 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 why the motor heats up more than 20 degrees Celsius?

A: The direct cause of motor heating is caused by large current. Generally may be coil short circuit or open circuit, magnetic steel demagnetization or low motor efficiency caused by the normal condition is a long time of large current operation.


Q. What causes electric motors to heat up? What is the process?

A: When the motor is running under load, there is power loss in the motor, which will eventually become heat energy, which will make the temperature of the motor rise beyond the ambient temperature. The value where the motor temperature is higher than the ambient temperature is called warming. Once there is a heating, the motor to the surrounding heat dissipation; 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 maintains a stable temperature, that is, in a state of balance between heat and heat dissipation.

Q. What is the normal temperature rise of a click? Which part of the motor is most affected by the temperature rise of the motor? How is it defined?

A: When the motor is running under load, it should start from trying to play its role, and the larger the load is, the better the output power is (if the mechanical strength is not considered). But the higher the output power, the higher the loss power, the higher the temperature. As we know, the weakest thing in the motor temperature resistance 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 properties of insulating materials are very stable, and their working life is generally about 20 years. Beyond this limit, the life of insulation materials will be shortened dramatically, and even burn. This temperature limit is called the allowable temperature of the insulating material. The allowable temperature of insulating materials is the allowable temperature of the motor; The life of the insulating material is generally the life of the motor.

The environment temperature varies with time and place, and 40 degrees Celsius is the standard environment temperature when designing the motor. Therefore, the allowable temperature rise of insulation material or motor is reduced by 40 degrees Celsius.

The allowable temperature of different insulating materials is different. According to the allowable temperature, the commonly used insulating materials of motors are A, E, B, F and H. At an ambient temperature of 40 degrees Celsius, the five insulating materials and their allowable temperatures and temperature rise are shown in the table below:

Allowable temperature of grade insulation material Allowable temperature rise

A Impregnated cotton, silk, cardboard, wood, etc., common insulation paint 105 65

E Epoxy resin, polyester film, green shell paper, three acid fiber, high insulation paint 120 80

B Composition of mica, asbestos and fibreglass using organic lacquers with improved heat resistance as adhesives

F Mica, asbestos and glass fibre compositions bonded or impregnated with a heat-resistant epoxy resin of excellent quality

H Mica, asbestos or fiberglass compositions bound or impregnated with silicone resin, silicone rubber 180 140


Q. How to measure the phase Angle of a brushless motor?

A: Power on the controller, which supplies power to the Hall components, and the phase Angle of the brushless motor can be detected. The method is as follows: the +20V DC voltage file of the multimeter is used, and the red pen is connected to the +5V line, and the black pen is used to measure the high and low voltage of the three leads respectively, according to the commutation table of the motor of 60 degrees and 120 degrees.


Q. Why can't any brushless DC controller and brushless DC motor be connected at will to turn normally? Why does DC brushless have inverted phase sequence?

A: Generally speaking, the actual motion of brushless DC motor 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 ---- The Angle between the stator magnetic field direction and the rotor magnetic field direction is 120 degrees electrical Angle ---- The motor continues to rotate. So we understand that there are six correct states of Hall. 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 electric Angle step in a direction of 60 degrees electric Angle.


Q. What happens if a 60 degree brushless controller is used on a 120 degree brushless motor? What about the other way around?

Answer: will fall to the lack of phase phenomenon, can not rotate normally; However, the controller adopted by Jergon is an intelligent brushless controller that can automatically identify the 60 degree motor or 120 degree motor, so that it can be compatible with the two kinds of motors, making maintenance and replacement more convenient.


Q. How can the brushless DC controller and brushless DC motor pour out the correct phase sequence?

A: The first step is to ensure that the power cord and ground wire of Hall wire are properly inserted with the corresponding wire on the controller. There are 36 ways to connect Hall wire and three motor wires to the controller. The simplest and most stupid way is to test each state one by one. When you change, you can continue to power, but we must be careful, but also have a certain order. If the motor does not rotate smoothly, this state is wrong. If the turn handle is too large, it will damage the controller. If there is a reverse situation, in the case of knowing the phase sequence of the controller, the controller Hall line A and c are exchanged, and click the line A and B to exchange each other, then it can be turned positive. Finally verify that the correct connection method is normal when the large current is running.


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

A: Add a directional line between the brushless motor Hall signal line b and the controller sampling signal line.


Q. What is the visual difference between brushed high speed motor and brushed low speed motor?

A. High speed motor has overrunning clutch, turn easily in one direction, turn hard in another direction; Low speed motor two-way bucket as easy.

B. The noise of high-speed motor is larger while the noise of low-speed motor is smaller. Experienced people can easily tell by ear.


Q. What is the rated running state of the motor?

A: When the motor is running, if each physical quantity is the same as its rating value, it is called the rated running state. Working under the rated running state, the motor can run reliably and has the best comprehensive performance.

Q. How is the rated torque of the motor calculated?

A: The rated torque output on the click-shaft can be represented by T2n, whose magnitude is the rated mechanical power output divided by the rated speed of transfer, i.e. T2n=Pn, where Pn is W, Nn is r/min, T2n is N.M. If the unit of PNM 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.


Q. What is the definition of the starting current of the motor?

A: The general requirements of the motor starting current can not exceed its rated current 2~5 times, which is why on the controller for current limiting protection is an important reason.


Q. Why are the motor speeds on the market getting higher and higher? And what are the implications?

A: Suppliers can reduce costs by speeding up, the same is low speed click, high speed coil turns will be less, also saved silicon steel sheet, the number of magnetic steel is also less, buyers think high speed is good.

When working at rated speed, its power is unchanged, but the efficiency is significantly lower in the low speed zone, that is, the startup is weak.

Low efficiency, need to use a large current to start, riding current is also large, the controller current limiting requirements, also bad for the battery.


Q. How to repair the abnormal heating of the motor?

Answer: The method of maintenance treatment is generally to replace the motor, or carry out maintenance protection.


Q. 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

A: Click the internal mechanical friction; Coil local short circuit; Demagnetization of magnetic steel; Dc motor inverter carbon deposition. The method of maintenance treatment is generally to replace the motor, or replace the carbon brush, clean up the carbon accumulation.


Q. What is the maximum no-load current without fault of various motors?

Motor form rated voltage 24V when rated voltage 36V

Side mounted 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