Maintenance fault method of motor coil
The winding method of motor winding coil is as follows:
1. Pre-baking: In order to remove the moisture in the coil, pre-baking must be carried out, and the temperature should be controlled at 100- 1 10℃ for 4-8 hours.
2. After prebaking, let the iron core cool to 60-70℃ before soaking. All parts of the winding must be dipped in paint until no bubbles appear, then placed vertically, and the residual paint is dripped off, and then the residual paint outside the upper coil of the iron core is wiped off with toluene.
3. Drying: after the residual paint drops dry, it can be put into a drying room or oven for baking, and the temperature is kept at 100- 1 10℃, and the time depends on the size of the motor. When drying, heating is carried out in two stages. Bake at 60-70℃ for a certain period of time to volatilize the solvent, dry the internal paint, and then heat to the baking temperature.
Important motors should be dipped in paint for the second time.
Other faults of the motor
1, no-load current of motor is large.
When the no-load current of the motor is greater than the limit data, it indicates that the motor is faulty. The reasons for the large no-load current of the motor are: large mechanical friction inside the motor, local short circuit of the coil and demagnetization of the magnetic steel. We continue to do relevant tests and inspections to further determine the cause or location of the fault.
When the no-load/load speed ratio of the motor is greater than 1.5, turn on the power supply and turn the handle to make the motor rotate at no-load and high speed for more than 10s. After the motor speed is stable, measure the no-load maximum speed N 1. Under standard test conditions, after driving more than 200m m, measure the maximum load speed N2 .. No-load/load ratio =N2? N 1 .
When the no-load/load speed ratio of the motor is greater than 1.5, it shows that the demagnetization of the magnetic steel of the motor has been quite severe, and the whole set of magnetic steel in the motor should be replaced. In the actual maintenance process of electric vehicles, the whole motor is usually replaced.
2. Exercise fever
The direct cause of motor heating is caused by large current. The relationship between motor current I, motor input electromotive force E 1, motor rotation induced electromotive force (also called back electromotive force) E2 and motor coil resistance R is: I=(E 1-E2)? The increase of R and I means that R decreases or E2 decreases. The decrease of R is generally caused by short circuit or open circuit of coil, and the decrease of E2 is generally caused by demagnetization of magnetic steel or short circuit or open circuit of coil. In the maintenance practice of electric vehicles, the method to deal with the problem of motor heating is generally to replace the motor.
3. There is mechanical collision or noise inside the motor during operation.
No matter high-speed motor or low-speed motor, there should be no mechanical collision or discontinuous and irregular mechanical noise when the load is running. Different types of motors can be maintained in different ways.
4. The vehicle mileage is shortened and the motor is weak.
The reasons for short driving range and motor fatigue (commonly known as motor fatigue) are complicated. However, when we have eliminated the above four kinds of motor faults, generally speaking, the fault of short driving range of the whole vehicle is not caused by the motor, but is related to the battery capacity attenuation, insufficient charging of the charger, and controller parameter drift (PWM signal can not reach 100%).
5. The brushless motor is out of phase.
The lack of phase of brushless motor is generally caused by the damage of Hall element of brushless motor. We can judge which Hall element is out of order by measuring the resistance of the output lead of Hall element relative to Hall ground wire and relative to Hall power supply lead.
In order to ensure the accuracy of motor commutation position, it is generally recommended to replace all three Hall elements at the same time. Before replacing the Hall element, it must be clear that the phase algebraic angle of the motor is 120? Still 60? , generally 120? The placement positions of the three Hall elements of the phase angle motor are parallel. There are still 60? Phase angle motor, one of the three Hall elements inverted 180? The position is positive.