Normal motor technichal information and questions


1. Motor’s Function

What is motor’s function in electric scooter electric skateboard?

The motor is used to convert battery electrical energy into mechanical energy and drives the wheels of an electric vehicle to rotate.

2.The components and functions of the motor

  • What is a stator?

The part that does not rotate when a brush or brushless motor is working. The motor shaft of a hub-type brushed or brushless toothless motor is called a stator, and this type of motor can be called an inner stator motor.

  • What is a rotor?

The part that rotates when a brush or brushless motor is working. The shell of the hub-type brushed or brushless gearless motor is called the rotor, and this type of motor can be called an external rotor motor.

  •  What is carbon brush?

The inside of the brushed motor rests on the surface of the inverter. When the motor rotates, the electric energy is sent to the coil through the inverter. Since its main component is carbon, it is called a carbon brush, which is easy to wear out. It should be regularly maintained and replaced, and carbon deposits should be cleaned up.

  •  What is a brush grip?

 The mechanical guide groove that holds and maintains the position of the carbon brush in the brushed motor.

  •  What is a phase inverter?

Inside the brushed motor, there are mutually insulated strip-shaped metal surfaces. When the motor rotor rotates, the strip-shaped metal alternately contacts the positive and negative poles of the brush to achieve alternating positive and negative changes in the current direction of the motor coil to complete the brushed motor coil. Commutation.

  • What is the phase sequence?

The arrangement order of the brushless motor coils.

  •  What is magnetic steel?

 Generally used to refer to magnetic materials with high magnetic field strength. Electric vehicle motors use neodymium iron boron rare earth magnets.

spintend 11'' 3500W hubmotor magents picture

 3.The common types of motors

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

 What’s Brushless motorThe controller provides direct current with different current directions to achieve the alternating current direction of the coil in the motor. There are no brushes and inverters between the rotor and the stator of the brushless motor.

 What is a brushed motor:  When the motor is working, the coil and commutator rotate, but the magnetic steel and carbon brushes do not rotate. The alternating current direction of the coil is changed by the inverter and brushes that rotate with the motor. In the electric vehicle industry, brush motors are divided into high-speed brush motors and low-speed brush motors. There are many differences between a brushed motor and a brushless motor. From the name, you can see that the brushed motor has carbon brushes, and the brushless motor does not have carbon brushes.

4.How to distinguish high and low speed motors?
  • brushed hub motor, brushless geared hub motor are high-speed motors; The high-speed motor has an overrunning clutch (function like a flywheel), which makes it easy to turn in one direction and laborious to turn in the other direction;
  • brushed gearless hub motor, brushless gearless hub motor are low-speed motors. the low-speed motor is equally easy to turn in both directions. B. The high-speed motor has a louder noise when rotating, and the low-speed motor has a smaller rotating noise. It is easy for an experienced person to recognize it by ear.

5.How are brushless motors classified?

From the phase angle, it can be divided into two categories, namely, brushless motors with 60° and 120° phase angles; according to the speed, they can be divided into high-speed brushless motors and low-speed brushless motors; according to whether the motor has The position sensor is divided into a brushless motor with a position sensor and a brushless motor without a position sensor.

6.What is a sensorless brushless motor?

For a position sensorless brushless motor, the vehicle must be pedaled up to make the motor have a certain rotation speed before the controller can recognize the phase of the brushless motor, and then the controller can supply power to the motor. Because it cannot achieve zero-speed start, it is rarely used. Now most skateboard motors are sensorless brushless motor.

Normal hubmotors are brushless motor

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

Turn on the power of the controller, and the controller will supply 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 file of the multimeter, connect the red test lead to the +5V line, and the black test lead to measure the high and low voltages of the three leads (there is a trick on the usage of the red and black test leads), press 60° and 120 °The commutation table of the motor can be compared.

 8.How does the motor realize commutation?

When the brushless or brushed motor is rotating, the energization direction of the coil in the motor needs to be alternately changed, so that the motor can continuously rotate. The commutation of the brush motor is completed by the commutator and the brush, and the brushless motor is completed by the controller.

9.How is the efficiency of the motor defined?

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

Motor efficiency calculation formula: η=(P2/P1)/100%. The percentage of the ratio of the motor output power P2 to the motor input power P1 is called the efficiency of the motor. It is represented by the letter "η". That is: η = (P2/P1 )× 100%

10.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.

11. What is the voltage range of the brushless motor Hall?

The voltage range of the brushless motor Hall is generally 3-24V.

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

 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 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, causing the coil to short circuit. When the coil temperature is above 150 degrees, the temperature of the motor housing is about 100 degrees, so if the temperature of the housing is used as the basis, the maximum temperature the motor can withstand is about 100 degrees.

 13.What is the reason for the motor heating over 20℃?

The direct cause of the motor heating is due to the large current. Generally, it may be caused by short circuit or open circuit of the coil, low efficiency of the motor in the demagnetization of the magnetic steel, etc. The normal situation is that the motor runs for a long time with high current.

 14.What will happen if motor is lack of phase?

In the three-phase circuit of the brushless motor or the brushless controller, one phase cannot work. The lack of phase is divided into main phase lack of phase and Hall lack of phase. The performance is that the motor is shaking and can not work, or the rotation is weak and the noise is loud. The controller is easy to burn out when it works in the state of lack of phase.

15.What will happen if a 60° brushless controller is used on a 120° brushless motor? How about vice versa?

It will cause phase loss and cannot operate normally; but an intelligent brushless controller developed by Tianjin Songzheng can automatically identify 60° motor or 120° motor, so that it can be compatible with the two motors, so that it can be repaired and replaced. much easier. 

16. How is the starting current of the motor defined?

  Generally, it is required that the starting current of the motor cannot exceed 2 to 5 times of its rated current. This is also an important reason why current limiting protection is implemented on the controller.

 17.Why are the motor speeds on the market getting higher and higher and what is the impact?

On the supplier's side, increasing speed can reduce costs. The same is for low-speed motors. The higher the speed, the fewer the number of turns of the coil, the saving of silicon steel sheets, and the number of magnets. Buyers think that higher speed is better.

When working at rated speed, the efficiency remains unchanged, but the efficiency is significantly lower in the low-speed zone, that is, it is weak to start.

The efficiency is low, it needs to start with a large current, the riding current is also large, and the current limiting requirement of the controller is large, and it is not good for the battery.

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

The maintenance method is generally to replace the motor or perform maintenance.

 19. When the no-load current of the motor is greater than the limit data of the reference table, it indicates that the motor has malfunctioned. What are the reasons? How to repair?

The internal mechanical friction of the motor is large; the coil is locally short-circuited; the magnetic steel is demagnetized; the inverter of the DC motor has carbon deposits. The maintenance method is generally to replace the motor, or replace the carbon brush, and clean up the carbon deposits.

20. What is the maximum no-load current without failure of various motors?

      Motor type: when rated voltage is 24V, when rated voltage is 36V

      Side-mounted motor    2.2A           1.8A

      High-speed brush motor   1.7A            1.0A

      Low speed brush motor    1.0A          0.6~0.8A

      High-speed brushless motor  1.7A       0.6~0.8A

      Low speed brushless motor  1.0A      0.6~0.8A


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