Method for overhauling motor of electric vehicle
The motor fault is a mechanical failure and electrical failure in two categories, mechanical failure relatively easy to find, and to electrical fault by measuring the voltage or current analysis, following the introduction of motor common fault detection and elimination method.
Motor heatingThe direct reason is due to the heating of the motor current caused by the motor current I, input electric potential E1 motor, sense of rotation of the motor electromotive force (also called back EMF) E2, and the relationship between the motor coil resistance of R is: I= (E1-E2), R, I increased, R or smaller E2 reduced. R becomes smaller, usually caused by short circuit or open circuit, and the reduction of E2 is usually caused by demagnetization of magnetic steel or caused by short circuit and open circuit of coil. In the maintenance practice of electric vehicle, the method of dealing with the heating and releasing of motor is usually replacing the motor.
The no-load current of the motor is largeWhen the no-load current of the motor is greater than the limit data, it shows that the motor is out of order. The reason of large no-load motor current is that the internal mechanical friction of the motor is large, the coil is partly shorted, and the magnet steel is demagnetization. We continue to do the relevant test and inspection items, we can further determine the cause of the failure or fault location.The no-load / load speed ratio of the motor is greater than 1.5, turn on the power supply, turn the handle, and make the motor rotate at high speed without load at least 10s. When the speed of the motor is stable, the maximum no-load speed of the motor is measured at N1. In the standard test conditions, traveling above 200m distance, began to measure the maximum load speed of motor N2. Load / load transfer ratio of =N2 / N1.When the motor no-load speed / load ratio is greater than 1.5, indicating the motor magnet demagnetization has been quite severe, should replace the motor set inside the magnet, in the process of practical maintenance of electric vehicles in general is the replacement of the entire motor.
When the motor is running, it has mechanical collision or mechanical noiseNo matter the high speed motor or the low speed motor, there should be no mechanical collision or discontinuous and irregular mechanical noise in the running of the load. Different forms of motors can be maintained in different ways.4, the vehicle mileage is shortened, the motor is weakThe reason of short vehicle mileage and motor fatigue (commonly known as motor boring) is complicated. But when we exclude the above 4 kinds of motor fault, generally speaking, the vehicle fault continued short trip mileage is not caused by the motor, and the attenuation capacity of the battery charger, filling electricity, controller parameter drift (PWM signal does not reach 100%) etc..
