Why does the switching power supply produce strong electromagnetic disturbance?

The power modules used in modern electronic equipment are all so-called switching power supplies. The figure shows the basic schematic diagram of the switching power supply. The input power is connected to a switch that controls the energy delivered to the load through intermittent switching, which is a bit like using a thyristor to control the power to the load in AC. Here, the rms value of the voltage on the load is controlled by the switch. The instant the switch is closed and opened causes a dramatic change in current in the power loop, as shown in loop 1 in the figure. This drastic current change will produce electromagnetic disturbances, on the one hand, the conduction emission on the power line, and on the other hand, the radiated emission caused by the current in the loop. As we will see later, the electromagnetic radiation emitted by the input line of the DC/DC module is much higher than the radiation of the module itself. In addition to the first loop, the second loop is also a sudden change of current, and the period of change is the same as that of the first loop. This also produces electromagnetic radiation. In fact, although the voltage on the capacitor is called a DC voltage, there are actually many small fluctuations on it. The period of this small fluctuation is the period of the switching action. When a long wire is connected to the output end of the power module, the wire constitutes an electromagnetic radiation antenna. The electromagnetic disturbance of the DC module is not only reflected in the module itself, but mainly conducted through the input and output lines, and produces strong electromagnetic radiation. In particular, some modules have metal shells, and the electromagnetic radiation of the module itself is not the main factor.

2020-04-02

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What is the difference between Chinese linear chargers and switching chargers?

Linear and switching chargers are used in a wide variety of applications: hearing aids, smart watches, sensor nodes, cell phones, laptops... the list goes on! Whenever a rechargeable battery is used, a charger is required. However, given the pros and cons associated with the different charging topologies available, you may need to consider more factors when choosing a charger. Each method has its pros and cons. Linear chargers are small, easy to use, and low cost. Without any switching, they are suitable for noise-sensitive applications; however, when the charging current is large, the power consumption is high. Switching chargers are known for their high efficiency and minimize power consumption over a wide variation of input adapter voltage. But compared to it, additional inductors and capacitors consume more board space, increasing BOM cost and design complexity. Due to the above advantages, switch-mode chargers have been used in the past to power modern lithium batteries, wireless power, energy harvesting, solar charging, etc. However, there is now an opportunity for an ultra-low current consumption, high voltage linear battery charger that does not have the drawbacks associated with typical linear chargers. In order to adapt to the development of the times and reduce the energy consumption of products, the company started to develop the research and development of switching power supply chargers, switching power supplies and smart chargers, and put into mass production in 2008, which further upgraded the company's products and technology. It has laid a solid foundation for the stable development of the enterprise. The company has the "China Charger Network" industry website and the "China Charger Portal" mobile portal website. For more information about linear chargers, China linear chargers, linear charger manufacturers - Changzhou Shengdan Electric Co., Ltd. page, I hope to be able to help you.

2020-04-07

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Can a transformer act as a charger?

Under normal circumstances, most chargers have a transformer inside, which means that the transformer is a component, not all. So the two are not equivalent. Specifically: 1. The so-called transformer means that it has output and output ports, and both input and output are AC. It is composed of iron core, copper wire and skeleton, and belongs to accessories. The charger also has input and output ports, but the input is AC or DC, and the output is DC, which belongs to a finished product. The two are completely different concepts. There is a transformer (low frequency or high frequency transformer) in the charger, because it is just an accessory. If you want to charge, you also need rectification (filtering), (current limiting), (charging control), etc., It is a static converter device that uses power electronic semiconductor devices to convert alternating current with constant voltage and frequency into direct current. It is widely used in various fields, especially in the field of life. It is widely used in common electrical appliances such as mobile phones and cameras. 2. If your so-called transformer is a finished product (that is, the power supply we usually see), there is a transformer inside, but the output is DC, it is not called a transformer, it is called a power adapter. Usually, in some cases, the power adapter can also be used as a charger, but most of them are not so compatible and need to be modified. 3. Whether it can be used as a transformer depends on the structure and where it is used. There are many kinds and cannot be generalized. In other words, these 2 are completely different things, the structure is suitable, and they can be modified, but they cannot be directly replaced. It's like a cart and a wheel, one is a finished product, the other is an accessory, and that's it. Changzhou Shengdan Electric Co., Ltd. has the industry website of "China Charger Network" and the mobile portal website of "China Charger Portal". If you have any further ideas, please get in touch. Hope the above answers can help you.

2020-04-08

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