15kw sew gears bldc motor manufacturers in india
At present, there are three types of motors used in electric bicycles:
Brush low speed motor. The motor has brush, no reducer and simple structure. The cost is low, but the efficiency is low, and the uphill and overload capacity is poor. No reducer gear device, simple structure, low cost, poor starting and uphill overload capacity, large power consumption.
Brush high speed motor. The motor has a brush, which has a long service life and is easy to replace and maintain. It has a reducer, which has high efficiency, strong overload climbing ability, large starting torque, but a little noise. The motor has high efficiency, strong overload climbing ability and large starting torque. It outputs power after decelerating through the variable speed gear device, with noise. Because the brush high-speed motor has a high speed (3000 rpm for high-speed motor and 500 rpm for low-speed motor), it needs to output large torque power after deceleration through the reduction gear device, so its noise is relatively higher than that of low-speed motor. The production process of high-speed motor is more complicated than that of low-speed motor. The cost is high and the price is about 200 yuan.
Brushless low speed motor. The motor has no brush and no reducer. It has the advantages of maintenance free and noise free, but the controller is complex, there are many motor control lines, the starting current is large, and the overload uphill ability is poor.
These three kinds of motors have their own advantages. At present, high-speed motors are widely used.
The difference between them is that the reasons for the rotation of the rotating magnetic field are different: (1) for AC synchronous motor, the reason for the rotation of the stator magnetic field is the three-phase symmetrical alternating current that lags behind each other by 120 degrees, and the rotation of the stator magnetic field is the change speed of the alternating current; (2) The DC motor is formed by the change of the actual position connected with the coil due to the constant voltage of the DC power supply, and the change of the actual position connected with the coil is the speed of rotor rotation; In this way, their speed regulation methods are different: (1) for AC synchronous motors, the reason for the rotation of stator magnetic field is the three-phase symmetrical alternating current that lags behind each other by 120 degrees, and the rotation of stator magnetic field is the change speed of alternating current; As long as the speed of AC change is changed, the motor speed can be changed, that is, variable frequency speed regulation; (2) The DC motor is formed by the change of the actual position of the coil connection with the constant voltage of the DC power supply, and the change of the actual position of the coil connection is only related to the speed of rotor rotation; As long as the rotor speed is changed, the speed can be adjusted, and the rotor speed is directly proportional to the voltage. Changing the voltage can change the speed, that is, voltage regulation;
15kw sew gears bldc motor manufacturers in india
DC speed regulation does not change the load property of the motor, while AC speed regulation changes the load property; AC speed regulation (frequency conversion), when the frequency is different, the inductive reactance of AC motor is different, and the load property changes accordingly. It is a very unstable system, and it is difficult to realize fine speed regulation. DC speed regulation (voltage transformation) is a very stable system, which is easy to realize fine speed regulation, and the voltage and speed of several millivolts can be distinguished.
Since the excitation of the brushless DC motor comes from the permanent magnet, there is no excitation loss. Since there is no alternating magnetic flux in the rotor, there is neither copper nor iron loss on the rotor, and the comprehensive efficiency is about 10~20% higher than that of the asynchronous motor with the same capacity (depending on the power). Brushless DC motor has the three high characteristics of high efficiency, high torque and high precision. It is very suitable for machinery running continuously for 24 hours. At the same time, it has small volume, light weight, and can be made into various volume shapes. Its product performance exceeds all the advantages of traditional DC motor. It is the most ideal speed regulating motor today.
The difference between them is that the reasons for the rotation of the rotating magnetic field are different: (1) for AC synchronous motor, the reason for the rotation of the stator magnetic field is the three-phase symmetrical alternating current that lags behind each other by 120 degrees, and the rotation of the stator magnetic field is the change speed of the alternating current; (2) The DC motor is formed by the change of the actual position connected with the coil due to the constant voltage of the DC power supply, and the change of the actual position connected with the coil is the speed of rotor rotation; In this way, their speed regulation methods are different: (1) for AC synchronous motors, the reason for the rotation of stator magnetic field is the three-phase symmetrical alternating current that lags behind each other by 120 degrees, and the rotation of stator magnetic field is the change speed of alternating current; As long as the speed of AC change is changed, the motor speed can be changed, that is, variable frequency speed regulation; (2) The DC motor is formed by the change of the actual position of the coil connection with the constant voltage of the DC power supply, and the change of the actual position of the coil connection is only related to the speed of rotor rotation; As long as the rotor speed is changed, the speed can be adjusted, and the rotor speed is directly proportional to the voltage. Changing the voltage can change the speed, that is, voltage regulation;
15kw sew gears bldc motor manufacturers in india
DC speed regulation does not change the load property of the motor, while AC speed regulation changes the load property; AC speed regulation (frequency conversion), when the frequency is different, the inductive reactance of AC motor is different, and the load property changes accordingly. It is a very unstable system, and it is difficult to realize fine speed regulation. DC speed regulation (voltage transformation) is a very stable system, which is easy to realize fine speed regulation, and the voltage and speed of several millivolts can be distinguished.
Since the excitation of the brushless DC motor comes from the permanent magnet, there is no excitation loss. Since there is no alternating magnetic flux in the rotor, there is neither copper nor iron loss on the rotor, and the comprehensive efficiency is about 10~20% higher than that of the asynchronous motor with the same capacity (depending on the power). Brushless DC motor has the three high characteristics of high efficiency, high torque and high precision. It is very suitable for machinery running continuously for 24 hours. At the same time, it has small volume, light weight, and can be made into various volume shapes. Its product performance exceeds all the advantages of traditional DC motor. It is the most ideal speed regulating motor today.
The difference between DC motor and AC motor Txt6 tolerance lubricates mutual relations, eliminates mutual estrangement, clears up mutual scruples and enhances mutual understanding. Difference between DC motor and AC motor Views: 4061 reward points: 0 | solution time: 11:15, March 28, 2011 | questioner: aoxiang1208
The function of a motor is to convert electrical energy into mechanical energy. Motors are divided into AC motors and DC motors.
（1） AC motor and its control
AC motors are divided into asynchronous motors and synchronous motors. Asynchronous motors are divided into single asynchronous motor, two-phase asynchronous motor and three-phase asynchronous motor according to the number of stator phases. Three phase asynchronous motor has the advantages of simple structure, reliable operation and low cost, and is widely used in industrial and agricultural production.
1. basic structure of three-phase asynchronous motor
The structure of three-phase asynchronous motor is also divided into two parts: stator and rotor.
(1) Stator:
The stator is a fixed part of the motor, which is used to generate a rotating magnetic field. It is mainly composed of stator core, stator winding and base.
(2) Rotor:
Rotor is the key part to master. There are two types of rotors: squirrel cage and wound rotor. Master their own characteristics and differences. The squirrel cage motor is used for small and medium power (below 100k). It has the advantages of simple structure, reliable operation and convenient use and maintenance. The wound type can improve the starting performance and adjust the speed. The air gap between the stator and the rotor will affect the performance of the motor. Generally, the air gap thickness is between 0.2-1.5mm.
Master the wiring method of stator winding.
15kw sew gears bldc motor manufacturers in india
2. working principle of three-phase asynchronous motor
Master the formulas n1=60f/p, s= (N1-N) /n1, n= (1-s) 60f/p, understand their significance (very important), and be able to flexibly use these formulas for calculation. At the same time, remember that the slip ratio SN of the motor under rated load is about 0.01-0.06. The examples in the book should be focused on.
3. data on nameplate of three-phase asynchronous motor
(1) Model: master the examples in the book.
(2) Rated value: generally understand and master the rated frequency and rated speed. The frequency in China is 50Hz.
(3) Connection method: Y type and angle type.
(4) Insulation grade and temperature rise: master the definition of allowable temperature rise.
(5) Working mode: general understanding.
4. mechanical characteristics of three-phase asynchronous motor
Master the relationship between rated torque, maximum torque and starting torque. The formulas in the book should be mastered and used flexibly for calculation. Also remember the following:
(1) When rotating at constant speed, the torque of the motor must be balanced with the resistance torque.
(2) When the load torque increases, the torque T (3) of the motor at the initial moment is generally 1.8-2.2 for three-phase asynchronous motors
(4) When the motor is just started, n=0, s=1
5. starting of three-phase asynchronous motor
(1) Direct start
When starting, the slip rate is 1, the induced electromotive force in the rotor is very large, and the rotor current is also very large. When the motor is started under the rated voltage, it is called direct start, and the current of direct start is about 5-7 times of the rated current. Generally speaking, small capacity asynchronous motors with rated power below 7.5kW can be started directly.
The electrical appliances used in the direct starting control circuit include combination switch, button, intermediate relay of AC contactor, thermal relay and fuse. Master their respective characteristics and the calculation of Fuse Rated current.
Direct starting control circuit: master its control principle.
(2) Step down starting of squirrel cage asynchronous motor.
Master the working principle of star angle starting and step-down starting of autotransformer
(3) Starting of wound three-phase asynchronous motor
General understanding.
6. forward and reverse rotation control of three-phase asynchronous motor
General understanding
7. speed regulation of three-phase asynchronous motor
This part is more important, so we should understand the formula. There are three possibilities to change the speed of the motor, that is, to change the frequency, to change the number of poles of the winding, or to change the slip rate.
8. synchronous motor
(1) Construction of synchronous motor
It shall be compared with asynchronous motor. (objective questions)
(2) Working principle of synchronous motor
Understand that the speed of synchronous motor is constant and does not change with load. The speed of a synchronous motor cannot be adjusted.
1. Working principle of DC motor
General understanding
2. Construction of DC motor
It is divided into two parts: stator and rotor. Remember that the stator and rotor are composed of those parts. Note: do not confuse the commutator pole with the commutator, and remember their roles.
The stator includes: main magnetic pole, frame, reversing pole, brush device, etc.
The rotor includes: armature core, armature winding, commutator, shaft and fan, etc.
3. Excitation mode of DC motor
The performance of DC motor is closely related to its excitation mode. Generally, there are four excitation modes of DC motor: DC separately excited motor, DC parallel excited motor, DC series excited motor and DC compound excited motor. Master the characteristics of the four methods:
DC separately excited motor: the excitation winding has no electrical connection with the armature, and the excitation circuit is supplied by another DC power supply. Therefore, the excitation current is not affected by the armature terminal voltage or armature current.
15kw sew gears bldc motor manufacturers in india
DC parallel excitation motor: the voltage at both ends of the parallel excitation winding is the voltage at both ends of the armature. However, the excitation winding is wound with thin wires and has a large number of turns. Therefore, it has a large resistance, making the excitation current passing through it small.
DC series excited motor: the excitation winding is connected in series with the armature, so the magnetic field in this motor changes significantly with the change of armature current. In order not to cause large loss and voltage drop in the excitation winding, the smaller the resistance of the excitation winding, the better. Therefore, DC series excited motors are usually wound with thicker wires, with fewer turns.
DC compound excitation motor: the magnetic flux of the motor is generated by the excitation current in the two windings.
4. Technical data of DC motor
Focus on the rated efficiency and rated temperature rise.
Rated efficiency = output power / input power
Rated temperature rise means that the temperature of the motor is allowed to exceed the maximum allowable value of the ambient temperature. The temperature rise on the nameplate refers to the maximum temperature rise of the motor winding.
5. Mechanical characteristics of Shunt DC motor
Master the examples in the book.
6. Starting, reversing and speed regulation of Shunt DC motor
(1) Starting and reversing are generally understood.
(2) Speed regulation: there are three speed regulation methods for shunt motor:
Change the magnetic flux.
Change voltage
Change the loop resistance of rotor winding.
Master their respective advantages and disadvantages.
2. control motor
Control motor refers to the motor used for detection, comparison, amplification and execution in the automatic control system.
(1) DC servo motor
Master the classification and characteristics of permanent magnet DC servo motor; The difference between ordinary rotor permanent magnet DC servo motor and small inertia rotor DC servo motor.
Working principle and performance of permanent magnet DC servo motor
Understand the working principle and master the performance
(2) AC servo motor
Generally understand the structure and working principle of AC servo motor, and focus on its performance.
(3) Stepping motor
Master the advantages and main performance indicators of stepping motor, and other general knowledge is enough
Principle of AC motor: the energized coil rotates in the magnetic field.
Do you know the principle of DC motor? The DC motor uses the commutator to automatically change the current direction in the coil, so as to make the coil rotate continuously in the same force direction.
Therefore, as long as the force direction of the coil is consistent, the motor will rotate continuously. AC motor is the application of this point.
AC motor is composed of stator and rotor. In the model you mentioned, the stator is an electromagnet and the rotor is a coil. The stator and rotor use the same power supply, so the direction of current in the stator and rotor always changes synchronously, that is, the direction of current in the coil changes, and the direction of current in the electromagnet also changes. According to the left-hand rule, the direction of magnetic force on the coil does not change, and the coil can continue to rotate.
About the function of the two copper rings: the two copper rings are equipped with two corresponding brushes, and the current is continuously sent to the coil as a source of energy. The advantage of this design is that it avoids the winding problem of two power lines, because the coil keeps rotating. What would happen if you simply use two wires to supply power to the coil?
Since the current in the coil is AC, there is a moment when the current is equal to zero. However, this moment is too short compared with the time when there is current. Moreover, the coil has mass and inertia, and the inertia coil will not stop.
