3) A series of problems in the existing brushless motor solutions: A certain evening paper "Brushless wins brushes" arbitrarily accused the brush motors of "short life, high noise and low efficiency", and even pointed out that "general use 6 The carbon brushes in the motors need to be replaced every month to a year.” Voice of Crusade has no worries! For this reason, this article will do what it does, and briefly discuss the disadvantages of brushless motors for electric bicycles. To
A) The poor working environment of the sensor causes the system to fail! Formal brushless motor design generally requires a photoelectric or magnetic (Hall element) sensor in the non-heat source area to detect the rotation position of the motor and send a signal to control the commutation. Most of the so-called electric bicycles currently on the market are dedicated Due to the limitation of the design size and installation method, the hub of the brushless motor cannot isolate the sensor from the heat source. Almost all use the method of positioning and slotting on the iron core stator and fixing the three Hall elements with glue to install the sensor. , The heat source of the motor is an objective existence, it comes from the copper loss and iron loss of the motor, especially when the motor is working in the lower efficiency area, the heat accumulation speed is very fast, so the iron core will heat up and set directly in the heat source area The sensor element of the sensor will exhibit performance drift, resulting in commutation errors. Once the commutation error, it will cause the large amplitude of the motor efficiency to drop, and the temperature will further rise, so that it will enter a vicious circle, which will directly cause the electronic commutator to burn out, and the general performance Is "short circuit". Once "short-circuited", the brushless motor will have a feeling of "stuck", it is very difficult to rotate, and the user cannot even pedal on it. Only ask a tricycle or a taxi to bring it back. Experienced users will bring a pair of scissors. Once the short circuit is stuck, the motor input line will be cut to "open the circuit". In this way, the burned "brushless" will be fine. Back to the maintenance department. To
B) Induction of electromotive force, causing the controller to burn out: When the author visited the market as a customer, a brushless salesman proudly introduced the "silent" feature to me, and then enthusiastically demonstrated the magic of the brushless motor Self-charging function: Turn off the main power supply, shake the middle axle to make the rear wheel rotate, and then buzzer to indicate that it has generated electricity, and the electricity from the foot is recycled into the battery. She told me "If the battery does not have electricity, it can generate electricity by itself. "It’s so magical, and don’t comment on how absurd the "perpetual motion machine" attribute shown in this demonstration violates the basic law of conservation of energy. It is okay to deceive individual consumers, but it is absolutely impossible to deceive connoisseurs. On the contrary, This situation is precisely the sadness of "brushless". Because the brushless motor does not overrun the clutch, when the wheel rotates quickly, an induced electromotive force will be formed at the input of the motor. The faster the wheel rotates, the higher the induced electromotive force will be. The withstand voltage value of the device will cause the "voltage breakdown" of the electronic commutation system, the motor will be short-circuited, the wheels will be stuck suddenly, and the "one cut to open the circuit" will be required. This situation often occurs on a downhill slope. In the process, the user rode a brushless electric vehicle uphill with difficulty. When it came downhill, he thought he could have a relaxing time and let it slide freely. The speed became faster and the induced electromotive force became higher and higher, which finally caused the component to be damaged. Breakdown and stop without braking. This is why many users report that the "brushless electric car" is not broken when going uphill, and it does not turn well when going downhill. To
C) Just say that the motor will never wear out, the life span is ten years, and the warranty is two years, not the controller! Brushless is different from brushed. The brushed commutator is placed inside the motor, while the brushless is placed outside the motor. Therefore, the brushless motor system is actually composed of "motor" and "electronic commutator". Partially composed. The brushless motor part does have a certain "never wear" attribute, while the brushless electronic commutator is a component with a high failure rate. As mentioned above, various failures occur on the controller. . At present, many brushless salesmen promise customers that the motor will be guaranteed for 2 years, 5 years or even 10 years. However, the controller (electronic commutator) can only be guaranteed for one year, and the cost of replacing a controller is as high as 200 yuan. In fact, if the maintenance cost of the brushless system controller is included, the maintenance cost will greatly exceed the cost of replacing several brushes of a brushed motor. Once individual manufacturers withdraw their warranty commitments to the controller (commutator), the consumer's cost of use will increase rapidly. To
D) The contradiction between system reliability and performance: Needless to say, the reliability of brushless motors has a great relationship with the maximum operating current. Reducing the maximum operating current will improve the reliability, but if the maximum operating current is greatly reduced, it will The negative effects of weak operation and poor performance of brushless electric vehicles are unwelcome by consumers, and there is no market for brushless electric vehicles. This is indeed a very serious issue facing the brushless system. To
E) Brushless need to talk more about "waterproof": Not only did the author once see some brushless motor promoters immersing the entire brushless wheel in a "fish tank" to rotate, in order to show off the "excellent" characteristics of its "amphibious" operation, Under water, brushed motors do have the defect of difficulty in commutation. However, electric bicycles are not submarines. Why do they need to travel in the water? This kind of seemingly learned presentation is really incomprehensible! In fact, this can be regarded as a kind of "magic", because the brushless uses electronic commutation, the demonstrator did not put the electronic commutation device also in the water, if the entire controller (reversing device) is also placed in the fish tank, nothing The situation of the brushed motor will be worse than that of the brushed motor. In fact, NdFeB is used as a permanent magnet material whether it is brushless or brushed. This material has many excellent characteristics, but one of its biggest shortcomings is its poor oxidation resistance. Putting it in the worst conditions will cause the life of the motor to fail due to oxidation. In addition, there are a large number of silicon steel sheets in the brushless motor, which will also rust, and it is necessary to talk about waterproofing. Such a demonstration can mislead some audiences, but it is meaningless if it is explained

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