The application of common dual power generation method in precision measurement
Many of the data processing uses dual power supplies, such as data acquisition cards.
If the post-stage using the precision preamplifier is not a data acquisition card, but an ordinary AD chip, it is best to use a bipolar AD chip.
Here are some commonly used dual power generation methods:

Method A: Directly generate dual power through batteries

Features: The power supply has the least noise, and is most suitable for ultra-high precision


Method B: Directly generate dual power supply through dual power supply industrial frequency transformer

Feature: low power noise, most suitable for high precision



Method C
Convert single power supply to dual power supply:


1. Dual power supplies that use op amp output to generate virtual ground

Features: low noise, but the load capacity is not good, the noise is serious when the load is large



2. Use a charge pump to generate dual power supplies

Features: There is AC high-frequency noise, but the frequency is relatively high



3. The oscillating circuit generates dual power after rectification and filtering

Features: AC high-frequency noise, low frequency
 

First. The concept of power isolation and non-isolation
 

    The isolation and non-isolation of power supply are mainly for switching power supplies. The industry's more common view is:

 

    1. Isolated power supply: There is no direct electrical connection between the input circuit and the output circuit of the power supply, and the input and output are in an insulated high-impedance state, and there is no current loop;

    2. Non-isolated power supply: There is a direct current loop between the input and output, for example, the input and output share a common ground.

 

    Take BuckBoost and its isolated version of the flyback circuit as an example. The schematic diagrams are shown in Figure 1 and Figure 2.

Figure 1 Non-isolated power supply


Figure 2 Isolated power supply using transformer

Second. The advantages and disadvantages of isolated power supply and non-isolated power supply
 

Table 1 Advantages and disadvantages of non-isolated power supply


Table 2 Advantages and disadvantages of isolated power supply

    We understand most of the above advantages and disadvantages. After the power supply is abnormal, whether the power supply isolation is harmful to the load, we use Buck and its corresponding isolation circuit, namely the forward circuit, to analyze briefly, as shown in the following figure.

Figure 3 Buck circuit


Figure 4 Electric energy trend after Buck switch tube breakdown


Figure 5 Forward circuit


Figure 6 Schematic of the switch tube of the forward circuit after breakdown
Third. Applications of isolated and non-isolated power supplies

Basic principles and characteristics

Features

　　1) Non-contact arc welding, solderless-flux-free soldering (completely lead-free) for small parts

　　Environmental pollution-free. After soldering, there will be no flux fouling and solder ball phenomenon.

　　2) Because it is heated instantaneously, it has little effect on the surrounding heat, so local bonding can be performed. After welding

　　3) The processing time of each solder joint is less than 0.1 second, and high-speed automatic processing is possible.

　　4) It is most suitable for joining ultra-fine wires with a diameter of 0.1 mm or less. The minimum diameter of a thin wire that can be welded is about 0.01mm.

　　5) Compared with the soldering process, the heat resistance of the welded parts is greatly improved and the production and operation cost is greatly reduced.

　　6) The winding wire burnt phenomenon that occurs during the soldering immersion treatment does not occur.

Welding realization process

　　 Here, take the welding process of the coil end shown in Fig. 2 as an example for description.



　　1) As shown in the figure, determine the position of the coil; the other end of the soldered terminal is grounded.

　　2) An arc occurs at the tip of the terminal, and the terminal melts instantly.

　　3) The melted terminal becomes a ball (commonly known as an arc ball), and the winding process is wrapped during the lower melting process. at this time

　　The heat generated burns the protective film of the wire to form an integrated melting. (Picture 3) The inside of the arc ball can be clearly seen

　　'S wire traces (Figure 4)

　　4) The soldering time varies with the shape of the terminal and the wire, but the general end treatment is within 0.1 seconds, which can be high

　　 speed up processing. In addition, since the welding time is very short, the thermal influence on the resin part of the coil bobbin also disappears instantaneously.

main application

　　Micro arc spot welding is applied in the following industries.

Bonding of various coil ends, electronic components, motor winding terminals, motor housing bonding, light bulbs, inductive coils, small electronic transformers, sensors, detectors, relays, thermocouples, precision medical equipment, precious metals, high melting point materials, dissimilar metals Materials, etc. See legend on back cover.

　　In the case of coil end processing, the most suitable terminal materials are copper and phosphor bronze.

　　As long as it is a material that can be processed with solder, micro-arc spot welding can be used to achieve welding.

Comparison of micro arc welding and tin welding•YAG laser welding

　　 Compared with soldering, micro-arc spot welding has little effect on other parts other than the solder joint, and there is no phenomenon that the heat generated during soldering will diffuse to the coil frame resin outside the soldering part. In addition, there is no problem with flux and lead in solder that inevitably occur during soldering.

　　Laser welding not only has extremely high production and operation costs, but also requires high precision in the installation position of the workpiece; when the coil ends are welded by laser, the wire is also very easy to be blown.

Comparison of micro arc welding with tin welding and YAG laser welding

	锡焊	微电弧点焊	激光焊
加热时间	需要1秒钟以上	瞬间完成（0.1秒以下）	瞬间完成（0.1秒以下）
效率	浸渍方式，下一次可焊接数点	一点一焊	一点一焊
热扩散	热扩散会影响到焊接部以外的线圈骨架树脂	局部 （对其他部位 的影响很小）	局部（但是如焊接焦 点偏移就会影响到其 他部位。）
安装使用	容易	容易	使用维护·调整麻烦困难
端子材料的选用	无特别限制	CP线·黄铜不可用铜和磷青铜最合适	CP线·黄铜不可用铜和 磷青铜最合适
线圈形状	无特别限制	端子形状需要可接地	部件位置精度要求高
设备运转成本	发生焊锡·助焊剂费用	廉价的氩气费 （0.3L/每分使用）	消耗部件非常昂贵
使用维护	焊锡·助焊剂费 （填充/液面管理）	焊锡·助焊剂费 （填充/液面管理）打弧焊接约1万次后需要 研磨电极	每发光焊接10万~100万 次后， 需更换励起灯管 甚至研磨光纤端面；冷却 水的管理·装置的移动困 难
装置价格	便宜	便宜	昂贵
焊接引起的污垢	有助焊剂·焊锡飞溅	少	少
微小部位的焊接	困难	可以	可以
焊接部耐热性焊后树脂成型 状况）	焊锡熔化有时会发生偏移·助焊剂的污垢会弄脏模具	没问题	没问题
对环境的影响	焊锡中的铅会污染环境	没问题	没问题
应用实例	应用广泛	在欧洲已经普及，但在日本和亚洲还不普及

　　有关微电弧焊接

　　有关微电弧焊接

基本原理、特点

特 点

　　1)非接触式电弧焊接，可进行微小部位的无焊锡-无助焊剂的焊接(完全无铅化)，对周

　　围环境无污染。焊后也不会发生助焊剂污垢、焊锡球现象。

　　2)因为是瞬间加热，对周围的热影响很小，所以可进行局部的接合。焊后

　　3)每个焊点的处理时间在0.1秒以下，可进行高速自动化处理。

　　4)最适合直径0.1 mm以下的超细线的接合。可焊接细线的最小直径为0.01mm左右。

　　5)与锡焊处理相比，大幅度提高了被焊件的耐热性也大幅度降低了生产运行成本。

　　6)不发生锡焊浸渍处理时出现的绕线烧细现象。

焊接实现过程

　　这里以图2所示线圈末端的焊接过程为例进行说明。

　　1)如图所示，确定线圈的位置;被焊端子的另一端接地。

　　2)在端子的先端部发生电弧，端子瞬间熔化。

　　3)熔化的端子成球状(俗称电弧球)，在下熔过程中将经过绕线处理的线材包住。此时

　　发生的热使线材的保护膜燃烧，形成一体化熔融。(图3) 可清晰地看到电弧球内部

　　的线材痕迹(图4)

　　4)焊接时间因端子形状、线形状的不同而不同，但一般的末端处理在0.1秒以内，可高

　　速化处理。另外，因为焊接时间非常短，所以对线圈骨架树脂部的热影响也瞬间消失。

主 要 应 用

　　微电弧点焊在以下的行业得以应用。

　　各种线圈末端的接合、电子部件、马达绕线终端、马达外壳接合、灯泡、电感线圈、小型电子变压器、传感器、探测器、继电器、热电偶、精密医疗器械、贵金属、高熔点材料、异种金属材料等。参见封底图例。

　　在线圈末端处理的场合，最适用的端子材料为铜和磷青铜等。

　　只要是能用焊锡处理的材料，都可以利用微电弧点焊来实现焊接处理。

微电弧焊接与 锡焊•YAG激光焊接的比较

　　与锡焊相比微电弧点焊对焊点以外其他部分的影响很小，不出现像锡焊时发生的热量会扩散到焊接部以外的线圈骨架树脂的现象。而且，也没有锡焊时必然产生的助焊剂、焊锡中的铅等问题。

　　激光焊接不仅生产运行成本极高，而且对工件安装位置的精密度要求也很高;线圈末端等利用激光焊接时，线材也极易被熔断。

微电弧焊接 与 锡焊和YAG激光焊接的比较

	Soldering	Micro arc spot welding	Laser welding
heating time	Need more than 1 second	Instant completion (less than 0.1 second)	Instant completion (less than 0.1 second)
efficient	Dipping method, several points can be welded next time	One point one welding	One point one welding
Thermal diffusion	Thermal diffusion will affect the coil bobbin resin outside of the welding part	Partial (for other parts Has little impact)	Local (but such as welding coke Point offset will affect its His part. )
Install and use	easy	easy	Troublesome and difficult to use, maintain and adjust
Selection of terminal materials	No special restrictions	CP wire and brass are not available. Copper and phosphor bronze are most suitable.	CP wire·Brass is not available with copper and Phosphor bronze is most suitable
Coil shape	No special restrictions	The shape of the terminal needs to be grounded	High requirements for component position accuracy
Equipment operating cost	Incurred solder and flux costs	Cheap argon fee (0.3L/per minute use	Consumable parts are very expensive
Use and maintenance	Solder and flux fee (filling/liquid level management)	Solder and flux fee (Filling/Level Management) Needed after about 10,000 times of arc welding Grinding electrode	100,000 to 1 million per luminous welding After the second time, the excitation tube needs to be replaced Even polish the fiber end face; cool down Water management and movement of equipment difficult
Device price	Cheap	Cheap	expensive
Fouling caused by welding	With flux and solder spatter	few	few
Welding of tiny parts	difficulty	Can	Can
Heat-resistance of the welded part and resin molding after welding situation)	Displacement may occur when the solder melts, and the dirt of the flux may stain the mold	no problem	no problem
the effect on the environment	Lead in solder will pollute the environment	no problem	no problem
Applications	Wide range of applications	It has been popularized in Europe, but not yet popularized in Japan and Asia

As far as wireless communication products are concerned, because the radio frequency signal is not touchable and invisible, and the high-frequency circuit, antenna matching, etc. need to test N multiple parameters, and these parameters cannot be measured by experience alone, so we must rely on a set of sufficient strength Radio frequency detection equipment. Today, the editor got permission from the company to take you to visit the powerful experimental instruments and equipment supporting the wireless communication product line of Guangzhou Zhiyuan Electronics Co., Ltd. online.

　　Figure 1 Sectional view of the hotel

　　 instance site

Figure 2 Smart wireless door lock 1

Figure 3 Smart wireless door lock 2

Figure 4 Gateway + bridge + wireless door lock

Figure 5 Wireless gateway using ZM5168 module (user product)

　　 internal structure revealed

The door lock uses ZM5168 series ZigBee wireless module, equipped with FastZigbee networking protocol, and has been successfully applied to wireless smart door locks in large hotels and office buildings. This solution saves the trouble of networking wiring and easily realizes the networking control and management of hotel door locks. Compared with other wireless solutions (such as WiFi or Bluetooth), this type of door lock has the characteristics of convenient networking, large number of nodes, long distance, low power consumption, and strong anti-interference. The hotel smart door lock control system is shown in Figure 6:

　　 Figure 6 Topology diagram of hotel smart door lock control system

The system is mainly composed of wireless smart door locks, wireless network bridges, gateway base stations and servers. The following table is a detailed introduction of the system's field application of our products.

　　Wireless smart door lock

　　 The wireless smart door lock is mainly composed of an access card recognition system, an acquisition system, an electric lock control system and a wireless zigbee communication system as shown in Figure 7. Mainly responsible for controlling door locks, identifying access control cards, collecting electricity, door lock status alarms and other functions. Among them, the wireless zigbee communication part, using the ZM5168 module of Zhiyuan Electronics, can easily join the Fastzigbee wireless network to realize the communication with the gateway base station.

Wireless smart door lock power consumption description: Among them, ZM5168 module can be controlled by IO to enter low-power mode, the current in low-power mode is 100nA, the lowest in the industry, the current in sending mode is 18mA, and the power consumption in lock low-power mode is 15uA; equivalent For using four AA batteries to send data every 5s, each sending and receiving data takes 10ms, and it can be used for more than 3 years.

　　 Figure 7 Block diagram of a wireless smart door lock

　　Wireless Gateway Base Station

　　 Scheme 1: This part mainly consists of CPU processing unit, zigbee communication and Ethernet communication. The CPU is responsible for storing and forwarding and processing the authorization and control instructions of the server, storing the collected information uploaded from the door lock, and forwarding it to the server as shown in Figure 8. For the Ethernet communication part, using the IPort module of Zhiyuan Electronics, only one serial port is needed to easily realize the Ethernet remote communication with the server. The wireless zigbee communication uses the ZM5168 module of Zhiyuan Electronics to easily join the Fastzigbee network to realize the communication control with the door lock.

Solution 2: Adopt ZBNET-300C-U all-in-one solution as shown in Figure 9. ZBNET-300C-U is a ZigBee to Ethernet transparent transmission device with basically the same function as solution 1. The device can be used with software configuration without the need for users The secondary development provides great advantages for the rapid development of users' products and systems.

　　Figure 8 Scheme 1: Block diagram of gateway base station

Figure 9 Scheme 2: ZBNET-300C-U

　　 wireless bridge

The wireless network bridge uses ZBCOM-300IE of ZHIYUAN Electronics as shown in Figure 10, with embedded ZM5168 series modules, responsible for forwarding smart door lock data, and its main function is to expand the signal coverage of the wireless base station. This unit is not necessary for the system, but is used to expand the network coverage to achieve communication when the wireless zigbee signal cannot be reached.

　　 Figure 10 ZBCOM-300IE used as a wireless bridge

　　 server

　　The server is used to install management software, realize the networked control of the entire intelligent door lock control system, and provide more humanized services. This part is generally provided by smart door lock manufacturers.