News

08

2020

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03


Small power transformer

Small power transformers are widely used, but they also produce different temperatures when used. Don't underestimate this temperature, because the height is important. If the temperature is relatively high, it will not be very good for the iron core inside, and it will also cause burns to some extent. Conversely, the lower the temperature, the lower the output voltage will be. So everyone must control the temperature, how to control it? 1. How is the current loaded? 1. The precise load current balancing of the parallel base units is controlled because of the additional PWM correction. It is also possible to bring several synchronised units for parallel operation and to control the elimination of circulating currents. Each base unit is isolated using electrical load. Each base unit has its own controller and can also supply power to the load through insulated windings. 2. PWM is also an independent, asynchronous, free-running signal, and each basic unit has its own separate DC link. On the grid side, each unit actually has its own sinusoidal LC filter. If the outputs are galvanically isolated, there is no circulating current between the different DC links. 3. This is an easier way to parallelize separate units with standard stand-alone controllers. A simpler design based on generator side electrical isolation. Three parallel independent drivers with discrete click windings. Note that this driver can be used in parallel with one or two. 2. How does the temperature of the small power transformer control system change? 1. All systems are controlled by a controller and PWM signal. All three-phase transformers can be connected to a common DC link voltage. For each independent base unit driver, paralleling of the drivers is also possible. The working time of the driver is relatively small, and this is also compensated by the relatively small AC output choke coil. 2. All three-phase transformers can operate at the same time, but this has a relatively small time extension, which can also be called an additional AC choke coil for compensation. Each cell that employs a symmetrical layout and a positive temperature coefficient of IGBT saturation voltage drop to ensure proper load current balancing essentially carries an additional correction of the signal.

12

2020

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03


Charger manufacturers

I believe many people know that when using the charger manufacturer, it will be plugged in for convenience and will not be unplugged. Now I will introduce to you what are the hazards of such use? 1. Shorten the use time Because it is composed of electronic components, if it is plugged into the socket for a long time, it is easy to heat up, which will also cause the aging of the components, and some short-circuits will occur, which will greatly reduce the heat. reduce its usage time. 2. Power consumption If it is always on the socket but does not charge the mobile phone, then the internal circuit board is actually still powered on, and it will consume electricity in the normal working state. Let's follow the editor to find out what precautions the charger manufacturers have in use! 1. Do not charge in a cold or hot environment When charging, you must keep away from refrigerators, ovens and other items, as well as places that are exposed to direct sunlight. If the family living conditions are high temperature for a long time, it is recommended to use a charging head with high temperature resistance and built-in high-performance switching transformer. 2. Do not charge near pillows, sheets, etc. Many people play mobile phones when it is convenient for charging. Everyone is used to charging near the bedside or pillow, but in this case, it is easy to short circuit or spontaneously ignite, so pillows and sheets are also more dangerous flammable substances. 3. Do not use and damaged charging cable When the metal of the charging cable is exposed, it is easy to cause leakage during use, and the current, the human body, and the floor can easily form a closed circuit, which is a great safety hazard. Therefore, everyone In the process of use, the damaged charging device must be replaced in time.

02

2020

/

04


How to choose a switching power supply What working mode does the switching power supply have?

When decorating wires, you should also pay attention to the choice of power switches. After all, there are many power switches, and they correspond to different voltage ranges, power, load characteristics, and so on. The following describes how to choose a switching power supply and what working modes of the switching power supply. In the process of selecting a switching power supply, you can pay attention to these problems, and then choose a regular switching power supply product as much as possible, so that the effect will be much better. How to choose a switching power supply When choosing a switching power supply, consider the input voltage range, appropriate power, load characteristics, and operating ambient temperature. 1. Select the appropriate input voltage range. Taking AC input as an example, the commonly used input voltage specifications are 110V and 220V, so there are corresponding three specifications of 110V, 220V AC switching, and universal input voltage (AC: 85V-264V). The input voltage specification should be selected according to the region of use. 2. Select the appropriate power. The switching power supply consumes a part of the power during operation and releases it in the form of heat. In order to prolong the life of the power supply, it is recommended to choose a model with an output power rating of 30% more. 3. Consider the load characteristics. In order to improve the reliability of the system, it is recommended that the switching power supply work at 50%-80% load, that is, if the power used is 20W, a switching power supply with an output power of 25W-40W should be selected. If the load is a motor, light bulb or capacitive load, the current is large when the power is turned on, and a suitable power supply should be selected to avoid overload. If the load is a motor, the voltage inversion during shutdown should be considered. 4. In addition, it is necessary to consider the working ambient temperature of the power supply and whether there is any additional auxiliary cooling equipment. The power supply needs to derate the output when the ambient temperature is too high. Refer to the derating curve of ambient temperature to output power. What is the working mode of the switching power supply? Frequency, pulse width fixed mode, frequency fixed, pulse width variable mode, frequency, pulse width variable mode. 1. The former working mode is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two working modes are mostly used for switching regulated power supply. 2. In addition, the output voltage of the switching power supply also has three working modes: direct output voltage mode, average output voltage mode, and amplitude output voltage mode. 3. Similarly, the former working mode is mostly used for DC/AC inverter power supply, or DC/DC voltage conversion; the latter two working modes are mostly used for switching regulated power supply. According to the way the switching devices are connected in the circuit, the switching power supply can be roughly divided into three categories: series switching power supply, parallel switching power supply, and transformer switching power supply. Among them, transformer switching power supply (hereinafter referred to as transformer switching power supply) can be further divided into: push-pull type, half-bridge type, full-bridge type, etc.; according to the excitation of the transformer and the phase of the output voltage, it can be further divided into: forward excitation type , flyback, single-excitation and dual-excitation, etc.; if it is divided into use, it can be divided into more types. The above introduction is how to choose a switching power supply and what working mode of the switching power supply. When choosing a power switch, you still need to know the voltage range and appropriate power. If it is a relatively high voltage, you must also understand the load capacity of these materials. In addition, in fact, the switch has a variety of working modes, including fixed frequency, pulse width, etc., so it should be selected according to the scope of use of the family.

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