How to improve the commutation of electric vehicle discount micro dc motor
Optimize brush box size and spring pressure:
The function of the brush box is to fix the brush in the proper position, but it is also necessary to ensure that the brush can move freely in the brush box, and the matching gap can neither be too large nor too small. Too large a brush may cause tilt and runout on the commutator surface when the motor is running, thus affecting the commutation. Too small, the brush may get stuck when it heats up under load. The function of the spring is to apply a certain pressure to the brush to ensure that the brush and the commutator always have good contact when the motor is running. When the unit pressure applied to the brush is increased, the contact resistance between the brush and the commutator is reduced, and the electric loss is reduced, but the friction coefficient is increased to increase the friction loss. The total loss is saddle-shaped, and the wear rate of the brush is also minimized at a unit pressure with a minimum total loss. Therefore, when selecting the pressure applied to the brush, the total loss in the motor operation and the corresponding unit pressure at the minimum brush wear should be considered. This pressure is generally between 1.5 and 2.5 n/cm2 for metal graphite brushes. When determining the initial pressure, consideration should be given to the fact that the spring will decrease in pressure due to elongation when the brush wear is shortened. When the unit pressure applied to the brush is reduced below a certain limit, the contact between the brush and the commutator becomes unstable, and a mechanical spark is likely to occur. At this time, the brush should be replaced.
Conduct a rigorous life test:
The easiest way to measure the motor's commutation is to observe the sparking of the brush after the brush is running under rated load. For this purpose, there should be a window that can be opened at the motor brush holder for viewing. However, for a DC motor for an electric bicycle, since the design is compact, there is no such window, and it is impossible to observe the commutation of the motor, and it is impossible to answer the problem of good or bad commutation. The good or bad reversal is an important indicator that affects the performance of the motor. How to do? The best way is to conduct a life test (also known as a trouble-free operation test) according to the standard (currently generally an enterprise standard). After the life test, dissect the motor and check the commutator surface and carbon brush wear. If the life test is qualified, the motor commutation should also be qualified.
At present, because the life test requires equipment and time, some companies do not know how to do life test and what kind of requirements, so few companies do this test, although this is required in the enterprise standard. In fact, only by doing life test, companies can really know what their products are.
