With the rapid development of electric bicycles, the original noun of HALL (Holzer) is familiar to everyone, but in actual use, its existence does increase the failure rate of brushless motor. More often, industry engineers will look into the quality and stability of HALL devices, and ignore an important question -- how should HALL use? Let me make a little bit of my opinion on my personal understanding, only industrial people refer to:
First of all, a brief introduction to HALL:
Holzer device is a semiconductor magnetic sensor which is used to measure the magnitude and direction of magnetic field. Because of its sensitivity to magnetic, the amplifier itself is integrated in the interior, so the output signal is large, and it is very convenient to use it without amplifier and amplifier.
From the application point of view, it is divided into two categories: linear and switch, and the switch application is divided into three modes: unipolar, bipolar and latch.
Second, look at what HALL is afraid of:
1. precautions in testing and welding process to prevent static burn
The destructive effect of electrostatic on semiconductor devices is becoming more and more prominent. As semiconductor devices are micro power devices, the power of each transistor in the integrated circuit is very small, and pressure resistance has a certain requirement. If the shock of the static electricity, it is easy to damage.
Static electricity exists everywhere in daily life and laboratories. Static electricity is caused by friction of two or more items, such as friction between sweater and nylon clothes, which can generate electrostatic discharge. We can see sparks in the dark and hear the discharge. Sometimes, cutting materials also cause friction and cause static electricity. Static electricity is produced by friction, so the electrostatic potential is determined by different substances and friction.
According to the size of the static electricity, it is divided into three types:
(1) the first type is the components used, the most sensitive to electrostatic discharge, and the electrostatic voltage between 0-1000 volts will damage the device.
(2) the second category is the components used, which are sensitive to electrostatic discharge, and the static voltage is between 1000-4000 volts. At this voltage, the device will be damaged.
(3) the third category is the components used, which are not sensitive to electrostatic discharge charger, and the electrostatic voltage is high to 4000-15000 volts before damaging the device.
General Holzer switches and linear circuits belong to the first kind of devices, so they are easily damaged by static electricity. HALL devices are packed in metal paper bags or sealed in electrostatic plastic bags to prevent static damage. But in the course of transportation, because of friction, the surface of the packing will also produce static electricity. In order to prevent the static damage to the device, the following procedures are strictly followed after the seal is opened.
(1) for the tester, it is best to wear cotton cloth without static electricity. If you wear sweaters or nylon clothes, you will generate static electricity. Therefore, it is necessary to bring a metal ring on the wrist or foot. The ring is connected with the ground wire. If there is static electricity, it can be quickly eliminated.
(2) the test bench and other metal parts should also be grounded. If no measures are taken and the body is loaded with high voltage static electricity, the situation is that the Holzer device is insulated from the ground. When taking the Holzer device, the Holzer device has the same potential as the operator. When the test system is grounded, it will cause short circuit to the ground. In contact with Holzer devices, the device will be damaged by the discharge of the Holzer device.
(3) the test requires the use of the output low impedance constant voltage source and requires a higher load capacity, for example, when the load is free, the voltage is 5 volts, and after the Holzer device, it is still 5 volts. In the test system, the protection circuit should be added to absorb the influence of the external circuit and the ups and downs of the power supply. It has been said that static electricity is caused by the friction of the object, so the voltage of the electrostatic is uncertain and the charge is uncertain, which means that the Holzer device that has been impacted by electrostatic discharge is not always damaged. They will undergo different degrees of damage after electrostatic discharge. However, this kind of damage will affect its life expectancy in future use. Some serious damage may not be used at that time, which has lost its logical function. The devices that are slightly damaged will gradually appear in the future use.
2. deformation of pins in welding process - stop mechanical damage
It should be said that this is a very common phenomenon in the whole electric motor industry. As an electronic device, there may not be any device that can be directly installed on the iron core as well as HALL, using the device itself as a fixed body, and using the heel of the device to connect the wire directly. This method of use is very important to the device itself. In the process of severe damage, the connection between the pin and the internal crystal of the HALL device is a very fine wire. If the tube is mechanically deformed, it will also cause soft damage to the device. The performance of the device is the same as that mentioned earlier, and is not measurable. At present, our company has successfully developed a protective sleeve with pin protection function to cooperate with AKE company in Japan to fundamentally eliminate this incident.
3. motor testing and customer testing process to prevent two injuries
The two damage is mainly from the factory factory inspection and the vehicle battery charger manufacturers' feed detection, among which the most important two damage points are two times of static damage and miscontact damage, and the fundamental reason here should be unsuitable for the use of standard plug-ins, 5 HALL.