Nowadays,
Electric Scooters have a booming trend, and more and more companies will enter this industry. There will be more and more manufacturers, and it is estimated that the number may exceed 500 within half a year. Manufacturers in the motor industry will also transform and focus on Electric Scooters 8.5 inch or
Sharing Electric Scooters 10 inch models, as well as motor for
Electric Bikes. Motor manufacturers and controller manufacturers are mainly concentrated in Changzhou, Jiangsu and Taizhou, Zhejiang. There are no less than 100 factories engaged in the motor industry. But there are not many people who really understand the working principle of motors and have rich motor knowledge. A lot of it is based on experience. After visiting many places and communicating with many electrical engineers, Gofunow was able to summarize a lot of electrical knowledge. hope that it can help our customers to understand it more clearly.
1. The Components of The Motor:
There are tires and aluminum alloy wheel hub when you look from the outside. Tires are devided into solid tires and pneumatic tires (including inner tube and tubeless). The aluminum alloy wheel hub is a sealed container used to hold the motor magnet sheets and stator. It is generally required to have good sealing performance to prevent water from entering.
The interior is composed of magnetic steel sheets and stators.
Magnetic steel sheet: size 11.3mm (width) * 30mm (height) * 3mm (thickness)
Of course there are also other shapes. But the most common ones are magnets steel with a width of 11.3 mm. The main changes are in height and thickness. Taking Xiaomi's 8.5 inch motor as an example, our Gofunow currently uses a 30X3mm motor, which means 30mm high and 3mm thick. The 30mm height we are talking about refers to the net height. Some supplier or manufacturer, in order to reduce materials and costs, make it 28.5mm. With the addition of insulation sheets, the height can barely reach 30mm. The actual magnetic flux is only 28.5mm high, so the cost can be reduced a bit.
In order to control costs, everyone is making a fuss about the thickness and height of magnetic steel, so there is the following arrangement and combination.
30H and 25H
If it is 3mm thick, it becomes Alpha (A), and if it is 2.5mm thick, it becomes Beta(B).
30H is 30mm high, H=HEIGHT, which means its height. (30H is divided into net height and gross height)
25H is 25mm high, H=HEIGHT, which means height.
The thicker, wider and taller the magnetic steel sheet must be, the better, because in this case, the more magnetism it will hold. But the cost is higher.
so 3mm is definitely better than 2.5mm thick, so we call 3mm A, as A grade. Then 2.5mm is regarded as B. It means slightly worse.
The arrangement is as follows:
30HA: 30mm high x 3mm thick (commonly known as 3030)
30HB: 30mm high x 2.5mm thick
25HA: 25mm high x 3mm thick
25HB: 25mm high x 2.5mm thick (commonly known as 2525)
The height of the magnet steel must be consistent with the height of the stator, otherwise too much magnetism will not work. It doesn't work that well when cutting magnetic fields. That is, for 25MM high magnets steel, the stator must also be made 25MM high. For 30MM high magnets steel, the stator must also be 30MM high.
Then the cost of 25HA will be cheaper than 30HB. Because the magnets and stators of 25HA are both 25MM high, while the 30HB magnets are 30MM
The stator consists of stator base, copper wire, Hall plate and other auxiliary materials.
The height of the stator is also very interesting. It is also divided into 25mm height and 30mm height, and there are also high gross heights (actually to reduce costs, fooling and take advantages from Buyer).
Our Gofunow only uses 30HA. We may even use 32HA or 35HA.
Regarding the expression method of the motor, for example:
CD36V35H2403280001
CD is the English capital letter of Wanbo. the motor brand name of motor.
36V: Motor voltage
35H: 35MM high X 3.0MM thick
240328: 8th March 24
0001: Serial number.
If we change to another supplier, we will also mark it like this, just replace the first two letters with the manufacturer's initials.
2. Knowledge about motor power
We often hear people say that my motor is 350W, not 250W. Or the motor will be rated at 350W. So where did this number come from?
Under normal circumstances, the motor power we talk about refers to the rated output power of the motor. It means: under the rated voltage and rated current conditions of the motor, the scooter rider (load) is a person of 75KG, at 25 degrees Celsius, on a flat road with no wind, the output power of the motor. for example.
It can be seen from this figure.
The rated power is 322W. The working efficiency is 78.7%.
Maximum torque point: This means that the motor has the maximum torque at this moment. The picture shows 16.24 Nm. At this moment the speed is only 12 rpm. This is equivalent to one revolution every 5 seconds, which means the speed is already very slow. This situation usually occurs when climbing hills.
Maximum output point: The input power at this moment is 548W > 410W, which is greater than the rated power, and the output power is 410W > 322W. This means that the vehicle should be accelerating on a flat road at this moment, and the speed should be as fast as the maximum speed. However, its rotational speed is 523, which is far smaller than the 618 rpm at the highest efficiency point. It means that at this moment, the load is relatively small and the speed is fastest.
No-load point: when there is no load. The front and rear wheels are suspended and there is no resistance.
Stalled point: refers to the wheel being blocked and unable to move forward. The motor cannot rotate at this moment, so the speed is 0. The output power becomes 0. The controller can protect.
Through this picture, we will understand that we need to increase the discharge current of the controller to at least 17A. In this way, the maximum power of the motor can be exerted. If the controller's current limit is too small, such as less than 15A, then the motor's performance cannot be maximized. The high configuration of the motor is wasted.
If the current limit is adjusted to 25A, the motor will still discharge when locked, causing the motor to overheat and eventually burn out the motor.
3. The relationship between rotation speed and maximum speed of the motor
The no-load speed of the motor = 1.2 X the speed of the 75KG load. That is, the no-load speed is 1.2 times of the load speed.
The rotational speed is directly proportional to the rotational speed of the
Motorized Scooter (i.e. maximum speed).
For example (see the picture above), the motor speed when no load is 719/min. Then it is 719X60=43140 circles per hour.
The 8.5-inch motor wheel is 21.5cm, and the circumference is 21.5X3.1415926=67.54cm=0.6754m
Then 43140 circles per hour is 43140 circles
That is, the maximum speed V=29.14KM/H
The speed at the rated point is 603 rpm, then the speed is 603/719 X 29.14=24.43KM/H
The fastest speed is 618 rpm, that is, 618/719X29.14=25KM/H
Therefore, if you want to reach the highest speed (75KG load), then the no-load speed of the motor is 719 rpm.
The no-load speed is 719/618=1.16 times the maximum speed.
Gofunow Tech Co.,Ltd.
