★How to repair the abnormal heating of the motor?
Answer: The method of maintenance is generally to replace the motor, or to carry out maintenance.
★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 fault. What are the reasons? how to repair
A: The internal mechanical friction is large; the coil is partially short-circuited; the magnetic steel is demagnetized; the DC motor commutator deposits carbon. The maintenance method is generally to replace the motor, or replace the carbon brush to clean the carbon deposits.
★What is the maximum limit no-load current of various motors without failure?
Motor type When the rated voltage is 24V When the rated voltage is 36V
Side mounted motor 2.2A 1.8A
High-speed brushed 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
★How to measure the motor idling current?
A: Put the multimeter in the 20A gear, and connect the red and black test leads to the power input of the controller. Turn on the power, and record the maximum current A1 of the multimeter at this time when the motor does not rotate. Turn the handle to make the motor rotate at high speed and no load for more than 10s. After waiting for the motor speed to stabilize, start to observe and record the maximum value A2 of the multimeter at this time. Motor no-load current =A2-A1.
★Comparison of commonly used motors for electric vehicles:
Motor Type Transmission Type Motor Efficiency Climbing Performance Maintenance Period Volume Maintenance Content Noise Cost
Brushless, toothless, brushless low-speed external rotor motor, direct drive > 80% Normal None Large None Small Low
Brushless with teeth High-speed brushless motor, planetary gear reduction > 83% Good about 3 years Small Lubricated gears Medium High
Brushed and toothed High-speed brushed motor, 2-stage gear reduction < 78% Good about 1 year Big Replace carbon brushes, lubricate gears Big High
Brushed without teeth Low-speed brushed external rotor motor, direct drive < 76% difference about 2 years Small Replace carbon brushes and clean carbon deposits Small Low
★How to identify the quality of the motor? What are the key parameters?
Answer: It is mainly the size of no-load current and riding current, the comparison with normal values, and the level of motor efficiency and torque, as well as the noise, vibration and heat generation of the motor. The best way is to use a dynamometer to test the efficiency curve.
★ What is the difference between 180W and 250W motors? What are the requirements for the controller?
Answer: The 250W riding current is large, which requires high power margin and reliability of the controller.
★Why in the standard environment, the riding current of the electric vehicle will be different due to the different ratings of the motor?
Answer: As we all know, under standard conditions, calculated with a rated load of 160W, the riding current on a 250W DC motor is about 4-5A, while the riding current on a 350W DC motor is slightly higher. For example: If the battery voltage is 48V, and the two motors are 250W and 350W, and their rated efficiency points are both 80%, the rated operating current of the 250W motor is about 6.5A, and the rated operating current of the 350W motor is about 9A. In general, the efficiency point of the motor is that the farther the working current deviates from the rated working current, the smaller the value is. Under the same load condition of 4-5A, the efficiency of the 250W motor is 70%, and the efficiency of the 350W motor is 60%. Under the load of 5A,
The output power of 250W is 48V*5A*70%=168W
The output power of 350W is 48V*5A*60%=144W
In order to make the output power of the 350W motor reach 168W (almost the rated load) in order to meet the riding requirements, it is only necessary to increase the power supply, thereby increasing the efficiency point.
★Why is the continuation mileage of an electric vehicle with a 350W motor shorter than that of a 250W motor in the same environment?
A: In the same environment, the electric vehicle with 350W motor has a large riding current, so in the case of the same battery, its continuation mileage will be shorter.
★How should electric moped manufacturers choose a motor? According to what to choose the motor?
A: For electric vehicles, the most critical factor in motor selection is the selection 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 others according to the load power.
The third step is to check the preselected motor. Generally, first check the heating temperature rise, then check the overload capacity, and check the starting capacity if necessary. All passed, the pre-selected motor is selected; but the pass is repeated from the second step until it passes.
Do not make the motor's rated power smaller the more economical it is under the condition of meeting the load requirements.
After the second step is completed, temperature correction should be carried out according to the different ambient temperature. The rated power is carried out under the premise that the national standard ambient temperature is 40 degrees Celsius. If the ambient temperature is low or high all the year round, the capacity of the motor should be fully utilized in the future, and the rated power of the motor should be corrected. 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 the year round, the rated power should be reduced.
In general, when the ambient temperature is determined, the selection of the motor of the electric vehicle should be determined according to the riding state of the electric vehicle. The more the riding state of the electric vehicle can make the motor close to the rated working state, the better. The driving status is generally determined according to the road conditions. If the road in Tianjin is smooth, a small-power motor is sufficient; if a larger-power motor is used, it will cause waste of energy and short mileage. If there are many mountain roads in Chongqing, it is suitable to use a motor with a higher power.
★ 60 degree BLDC motors are stronger than 120 degree BLDC motors, right? Why?
A: It is found from the market that there is such a fallacy when communicating with many customers! Think a 60 degree motor is stronger than a 120 degree motor. We think this is probably a kind of propaganda for manufacturers that produce 60-degree brushless motors. From the principle of brushless motor and the fact that it has been proved, in fact, 60-degree motor or 120-degree motor is fine! The so-called degree is only used to tell the brushless controller when to let the two phase wires in mind conduct. There is no one who is more powerful than the other! 240 degrees and 300 degrees are the same, no one is stronger than the other.
