Motor is the key component of electric bicycle.
Due to the limited energy brought by the e-bike, as an all-weather vehicle, the motor is required to be able to withstand relatively harsh environment, with high reliability.
The motor is divided into brushless motor and brushless motor. Brush motor is a traditional product with stable performance. Should be the preferred motor for electric bicycles. Brushless motor is a new product, its life performance is better than brush motor. But the control circuit is more complex and the aging screening of components is more strict. Although the motor has a long life, the control circuit is prone to malfunction. Therefore, the selection of brushless motor to pass a strict reliability test to ensure quality.
The motor is divided into wheel type, middle type and friction type in the output transmission mode
Wheel type simple structure, good appearance, but the motor shaft stress, high requirements on the motor. This kind of motor is optional for electric bicycles.
Middle type structure is more complex, but the motor shaft force is small, small damage to the motor, electric bicycle can also choose this motor.
The friction type structure is simple, but the damage to the tire is great, and the wheel slips on rainy days. Electric bicycles should be carefully selected for this kind of motor.
Motor in the running speed is divided into: low speed and distance motor direct drive motor and high speed motor deceleration type; The former saves gearbox, so it has low noise, simple structure and high reliability. But it’s heavier than the latter. The wheel type should adopt low speed direct drive, while the middle type is generally high speed motor deceleration type.
Although there are many kinds of motors, as far as the mainstream is concerned, the current electric bicycles on the market can be divided into rare earth permanent magnet brushless motor, rare earth permanent magnet brushless dc motor, and rare earth permanent magnet brushless dc motor.
In the actual production process, as the brushed-tooth dc motor is a high-speed motor, the tooth of the gear is very small, easy to wear, but the power is large, strong climbing ability. The brushless dc motor saves the trouble of replacing the carbon brush for two or three years. But because in the control brushless motor process, the request precision is extremely high. Also, the brushless motor controller costs more. In comparison, for the brushless dc motor, although the carbon brush should be replaced, it is very easy to replace the carbon brush. Moreover, the motor control is relatively simple, and the motor runs smoothly with high safety coefficient.
Electric bicycles are powered by chemical power. At present, electric vehicles are mainly closed maintenance-free lead-acid battery as the leading. Batteries change with the development of electrical appliances. Now there are nickel hydride batteries, lithium ion batteries, sodium nickel chloride batteries, proton exchange membrane fuel cells and so on. At present, the development of fuel cell and air aluminum battery is gradually improving.
Nanotechnology will be a hot topic in the new century. Qian xuesen predicted in 1991: “the structure of nanometer and below will be the focus of the next stage of scientific and technological development, will be a technological revolution, thus, will be another industrial revolution in the 21st century. It is possible to use nanoparticles as anode and cathode materials for batteries. If nanomaterials are used in batteries, the performance of batteries may reach a new level. The practical application of fuel cell in vehicle power source will be the goal at the beginning of this century, but the cleanest fuel is hydrogen. But hydrogen has a storage problem.
As the lead-acid battery widely used in electric vehicles, the charger is the earliest use of transformer charger. However, transformer chargers are rarely used due to their large size, unwieldy, low cost and low charging efficiency. Electronic chargers are now widely used. The charger input ac voltage is about 200V, and the output end is connected to the battery, and its charging mode;
Firstly, intermittent discharge and compensation with large current pulse charge; Second, the constant current, constant voltage floating charge to maintain the battery to be charged to provide a stable voltage and current. The charger has the functions of output short circuit protection, output overvoltage, overcurrent protection and overshoot protection, which guarantees the service life of the battery.
Due to the recent development of rapid charging technology, the concept of poor quick charging performance of traditional lead-acid batteries has been changed. Experimental results show that most valve-controlled lead-acid batteries can withstand rapid charging, and reasonable rapid charging is not only harmless but also beneficial to prolong battery life.
However, lithium ion battery as a hidden battery has waterproof, long life, but also can yet be regarded as the best choice of the public.
Brushless motor requires complicated controller. At present, most of the electric bicycles on the market use a brush motor, and its control system is relatively simple. In the beginning, people can achieve the function of starting by using relay control. As people’s requirements for electric bicycles are getting higher and higher, electronic controllers or even digital controllers are generally adopted now. The controller can cooperate with the speed control handle to control the motor speed, current, motor terminal voltage, undervoltage and motor speed, the controller can make the current control output, generate the required power will not burn out the motor.
Governor handle has three forms: hall element type, new electric type, potentiometer type, the current new electric technology is the most mature, reliable work, so the most widely used. At present, pulse width governor is widely used. The successful development of the all-digital controller of the e-bike makes the e-bike step into the digital high-tech field as the first step and will open up a wider market for the e-bike.