The safe operation of the generator plays a decisive role in ensuring the normal operation and power quality of the power system. At the same time, the generator itself is also a very valuable electrical component. Relay protection device with perfect performance. Let's learn the basic knowledge about generators below!
▓What is a motor?
A motor is a component that converts battery electrical energy into mechanical energy and drives the wheels of an electric vehicle to rotate.
▓What is winding?
The armature winding is the core part of the DC motor and is a coil wound with copper enameled wire. Electromotive force is generated when the armature winding rotates in the magnetic field of the motor.
▓What is a magnetic field?
The force field that occurs around a permanent magnet or current and the space or range of magnetic force that can be achieved by any magnetic force.
▓What is the magnetic field strength?
The magnetic field strength of an infinite wire carrying a current of 1 amp at a distance of 1/2 m from the wire is 1 A/m (Ampere/m, SI); in CGS (cm-gram-second), it is To commemorate Oersted's contribution to electromagnetism, define the magnetic field strength of an infinite wire carrying a current of 1 ampere at a distance of 0.2 cm from the wire as 10e (Oersted), 10e=1/4.103/m, the magnetic field strength is usually given by H means.
▓What is Ampere's Law?
Hold the wire with the right hand, and make the direction of the straight thumb consistent with the direction of the current, then the direction pointed by the four curved fingers is the direction of the magnetic field line.
▓What is magnetic flux?
Magnetic flux is also called magnetic flux: 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, which is called passing through this plane the magnetic flux.
▓What is a stator?
The part that does not rotate when a brushed or brushless motor works. The motor shaft of the hub-type brushed or brushless gearless motor is called the stator, and this type of motor can be called an inner stator motor.
▓What is a rotor?
The part that rotates when a brushed or brushless motor works. The housing of the hub-type brushed or brushless gearless motor is called the rotor, and this type of motor can be called an outer rotor motor.
▓What is a carbon brush?
The brushed motor is placed on the surface of the commutator. When the motor rotates, the electric energy is delivered to the coil through the phase converter. Because its main component is carbon, it is called carbon brush, which is easy to wear. Regular maintenance and replacement, and cleaning of carbon deposits
▓What is a brush grip?
A mechanical guide groove that holds and maintains the position of the carbon brushes in the brushed motor.
▓What is a commutator?
Inside the brushed motor, there are strip-shaped metal surfaces that are insulated from each other. When the motor rotor rotates, the strip-shaped metal alternately contacts the positive and negative poles of the brush to realize the alternating positive and negative change of the current direction of the motor coil, and complete the replacement of the brushed motor coil. Mutually.
▓What is phase sequence?
The arrangement order of the brushless motor coils.
▓What is magnetic steel?
Generally used to call magnetic materials with high magnetic field strength, electric vehicle motors all use NdFeS rare earth magnets.
▓What is electromotive force?
It is generated by the rotor of the motor cutting the magnetic field lines, and its direction is opposite to the external power supply, so it is called back electromotive force.
▓What is a brushed motor?
When the motor is working, the coil and the commutator rotate, but the magnetic steel and the carbon brush do not rotate. The alternating change of the current direction of the coil is accomplished by the commutator and brush 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. It can be seen from the words that brushed motors have carbon brushes, and brushless motors do not have carbon brushes.
▓What is a low-speed brushed motor? What are the characteristics?
In the electric vehicle industry, a low-speed brushed motor refers to a hub-type low-speed and high-torque gearless brushed DC motor, and the relative speed of the stator and rotor of the motor is the speed of the wheel. The number of magnets on the stator is 5~7 pairs, and the number of slots of the rotor armature is 39~57. Since the armature windings are fixed in the wheel housing, the heat is easily dissipated by the rotating housing. The rotating shell is woven with 36 spokes, which is more conducive to the conduction of heat. Skilled training WeChat account deserves your attention!
▓ What are the characteristics of brushed and toothed motors?
Because there are brushes in brushed motors, the main hidden danger is "brush wear". Users should note that brushed motors are divided into two types: toothed and toothless. At present, many manufacturers choose brushed and toothed motors, which are high-speed motors. The so-called "toothed" means to reduce the motor speed through the gear reduction mechanism (because the national standard stipulates that the speed of electric vehicles should not exceed 20 kilometers per hour, so the motor speed should be 170 rpm or so). Because the high-speed motor is decelerated by gears, it is characterized by the rider feeling strong power and strong climbing ability when starting. However, the electric wheel hub is closed, and it is only filled with lubricant before leaving the factory. It is difficult for users to carry out daily maintenance, and the gear itself also has mechanical wear. The lack of lubrication leads to aggravated gear wear and noise in about a year, and the current during use is also reduced. increase, affecting motor and battery life.
▓What is a brushless motor?
Since the controller provides direct current with different current directions, the alternating current direction of the coils in the motor can be achieved. There are no brushes and commutators between the rotor and stator of a brushless motor.
▓How does the motor realize commutation?
When the brushless or brushed motor is rotating, the direction of energization of the coil in the motor needs to be alternately changed, so that the motor can rotate continuously. The commutation of the brushed motor is completed by the commutator and the brush, and the brushless motor is completed by the controller
▓What is phase loss?
In the three-phase circuit of the brushless motor or brushless controller, one phase cannot work. The lack of phase is divided into the lack of main phase and the lack of Hall phase. The performance is that the motor shakes and cannot work, or the rotation is weak and the noise is loud. The controller is very easy to burn out when it works in the state of lack of phase.
▓What are the common types of motors?
Common motors include: brushed and geared hub motors, brushed gearless hub motors, brushless geared hub motors, brushless gearless hub motors, side-mounted motors, etc.
▓How to distinguish high and low speed motors from the types of motors?
A Brushed and geared hub motors and brushless geared hub motors are high-speed motors;
B Brushless and gearless hub motors and brushless gearless hub motors are low-speed motors.
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.
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 complex issue. During load, if the rated power of the motor is too large, the motor will often run at light load, the capacity of the motor itself cannot be fully utilized, and it becomes a "big horse-drawn cart". At the same time, the motor has low operating efficiency and poor performance, which will increase running costs. Conversely, if the rated power of the motor is required to be small, it is a "small horse-drawn cart". The motor current exceeds the rated current, the internal loss of the motor increases, and the efficiency is low. The important thing is to affect the life of the motor, even if there is not much overload , the life of the motor will also be reduced more; more overload will damage the insulation performance of the motor insulation material or even burn it. Of course, the rated power of the motor is small, and it may not be able to drag the load at all, which will cause the motor to be in the starting state for a long time and be damaged by overheating. Therefore, the rated power of the motor should be selected strictly according to the operation of the electric vehicle.
▓Why do brushless DC motors have three Halls?
Briefly, in order to rotate the brushless DC motor, there must always be 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 changing the direction of the rotor magnetic field. In order to make the two magnetic fields have an angle, the direction of the magnetic field of the stator coil must be changed after a certain degree. So how do you know to change the direction of the stator magnetic field? Then it's up to those three Halls. Think of those three Halls as tasked with telling the controller when to change the direction of the current.
▓What is the approximate range of power consumption of the brushless motor Hall?
The power consumption of the brushless motor Hall is roughly in the range of 6mA-20mA.
▓How high temperature can the motor work normally? What is the maximum temperature the motor can withstand?
If the temperature of the measured 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 made of 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, resulting in a short circuit of the coil. When the coil temperature is above 150 degrees, the temperature of the motor casing is about 100 degrees, so if it is based on its casing temperature, the maximum temperature the motor can withstand is 100 degrees.
▓The temperature of the motor should be below 20 degrees Celsius, that is, the temperature of the motor end cover should exceed the ambient temperature by less than 20 degrees Celsius, but what is the reason why the motor heats up more than 20 degrees Celsius?
The direct cause of motor heating is due to the large current. Generally, it may be caused by the short circuit or open circuit of the coil, the demagnetization of the magnetic steel or the low efficiency of the motor. The normal situation is that the motor runs with high current for a long time.
▓What causes the motor to heat up? What kind of process is this?
When the motor is running under load, 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 by which the motor temperature is higher than the ambient temperature is called the ramp-up. Once the temperature rises, the motor will dissipate heat to the surroundings; the higher the temperature, the faster the heat dissipation. When the heat emitted by the motor per unit time is equal to the heat dissipated, the temperature of the motor will no longer increase, but maintain a stable and constant temperature, that is, in a state of balance between heat generation and heat dissipation.
▓What is the allowable temperature rise for a general click? 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, starting from its role as much as possible, the larger the load, the better the output power (if the mechanical strength is not considered). But the greater the output power, the greater the loss of power, the higher the temperature. We know that the weakest thing in the motor is the insulating material, such as enameled 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. Exceeding this limit, the life of the insulating material is shortened sharply, and even burns 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 place. When designing the motor, it is stipulated that 40 degrees Celsius is taken as the standard ambient temperature in my country. Therefore, the allowable temperature of the insulating material or motor minus 40 degrees Celsius is the allowable temperature rise,
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. Calculated at an ambient temperature of 40 degrees Celsius, the five insulating materials and their allowable temperatures and allowable temperature rises are shown in the table below:
Grade Insulation material Allowable temperature Allowable temperature rise
A Impregnated cotton, silk, cardboard, wood, etc., ordinary insulating paint 105 65
E Epoxy resin, polyester film, green shell paper, tri-acid fiber, high insulating paint 120 80
B Mica, asbestos, and fiberglass compositions using organic paints with improved heat resistance as binders 130 90
F Mica, asbestos and fiberglass compositions bonded or impregnated with epoxy resins with excellent heat resistance 155 115
H Mica, asbestos or fiberglass compositions bonded or impregnated with silicone resin, silicone rubber 180 140
▓How to measure the phase angle of a brushless motor?
Turn on the power of the controller, and the controller supplies power to the Hall element, and 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 lead to the +5V line, and 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.
▓Why can't any BLDC controller and BLDC motor be connected at will to rotate normally? Why does the brushless DC have a phase sequence reversal?
Generally speaking, the brushless DC motor is such a process in actual motion: the motor rotates---the direction of the rotor magnetic field changes---when the angle between the direction of the stator magnetic field and the direction of the rotor magnetic field reaches an electrical angle of 60 degrees--- - Hall signal change---- phase line current direction change---- stator magnetic field crosses 60 degree electrical angle forward---- stator magnetic field direction and rotor magnetic field direction included angle is 120 degree electrical angle---- motor Keep turning. So we understand that Hall has six correct states. When a specific Hall tells the controller, the controller has a specific phase output state. So the phase reversal sequence is to complete such a task, that is, to make the electrical angle of the stator always step by 60 degrees in one direction.
▓ What happens if a 60-degree brushless controller is used on a 120-degree brushless motor? What about the other way around?
It will fall to the phenomenon of lack of phase and cannot rotate normally; but the controller used by Jieneng is an intelligent brushless controller that can automatically identify the 60-degree motor or the 120-degree motor, so that it can be compatible with the two types of motors, making maintenance Replacement is more convenient.
▓How can the DC brushless controller and the DC brushless motor pour out the correct phase sequence?
The first step is to ensure that the power and ground wires of the Hall wire are well connected with the corresponding wires on the controller, and there are 36 ways to connect the three motor hall wires and the three motor wires to the controller. The stupid way is to test each state one by one. When switching, it can be carried out without interruption, but it must be carefully and in a certain order. Be careful not to twist too much each time. If the motor does not rotate smoothly, this state is not right. If the handle is twisted too much, it will damage the controller. If it reverses, know the phase sequence of the controller. In the case of the controller, the Hall lines a and c of the controller are exchanged, and the phase A and B of the click line are exchanged with each other, and the reverse rotation can be reversed. Finally, the correct way to verify the connection is that it is normal during high current operation.
▓How to control a 60-degree motor with a 120-degree brushless controller?
A direction line can be added between the b-phase of the brushless motor Hall signal line and the controller sampling signal line.
▓What is the intuitive difference between a brushed high-speed motor and a brushed low-speed motor?
A. The high-speed motor has an overrunning clutch, which is easy to turn in one direction and exhausted in the other direction; the low-speed motor is equally easy to turn the bucket in both directions.
B. The high-speed motor makes a lot of noise when the car rotates, and the low-speed motor makes less noise. It is easy for an experienced person to identify by ear.
▓What is the rated running state of the motor?
When the motor is running, if each physical quantity is the same as its rated value, it is called the rated running state. Under the rated running state, the motor can run reliably and has the best comprehensive performance.
