[Switching power supply Transformer] What is the difference between switching power supply and transformer?
The difference between switching power supply and transformer
Switching power supply uses modern power electronics technology to control the switching transistor to turn on and off. A power supply that maintains a stable output voltage by switching off time ratio. Switching power supplies can be divided into two categories: AC/DC and DC/DC. They can be divided into two categories according to whether there is electrical isolation between the input and output: one is with The one that is isolated is called an isolated DC/DC converter; the other type without isolation is called a non-isolated DC/DC converter. The switching power supply has overcurrent, overheating, short circuit and other protection functions. It has a wide voltage input range, an isolation voltage between input and output, and an isolated input and output with high isolation voltage.
A transformer is a device that uses the principle of electromagnetic induction to transform voltage, current and impedance. Transformers are mainly used in alternating circuit circuits.
What is a switching power supply?
Switching power supply uses modern power electronics technology to control switching A power supply that maintains a stable output voltage by adjusting the time ratio between the on and off tubes. The switching power supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET.
Advantages and Disadvantages of Switching Power Supply
Advantages:
1 , high efficiency and small size. Since the voltage control of the switching power supply is achieved by using the saturation zone of the power semiconductor device by adjusting its turn-on time or frequency, there is no iron loss and copper loss, and the loss of the components can be ignored. Compared with the transformer, the efficiency is higher. ; Since it only has components and circuit boards, it will be small in size and light in weight.
2, wide voltage input range. Generally it can reach between 160V-270.
Disadvantages:
1, the switching power supply looks small, the power is related to the core transformer and the control method, and the electromagnetic interference is large , the ripple coefficient is large. Especially in the areas of audio and video, it is very sensitive to electromagnetic interference. In audio, the tone is not pure and thick, and there may be a slight sound; in video, the image may have small ripples and is not delicate.
2. The design is complex and maintenance is inconvenient. Often the more complex the equipment, the greater the possibility of problems, andMoreover, once there is a problem with the switching power supply, it is generally impossible for non-professionals to repair it. It is too expensive to find someone else to repair it, so it is better to discard it.
3. Small size is the advantage of switching power supply, but poor design becomes its disadvantage. In order to pursue smaller size, a large number of components are squeezed into a small case,The heat dissipation is not good, I also experience shell deformation.
4. The selection of switching power supply components is not very standardized.,This is a common problem of domestic switching power supplies. . The relevant national quality inspection department inspected the switching power supplies on the market and found that more than half of them were unqualified, including imported switching power supplies.
5. The biggest point is that the lightning resistance is very low. In the monitoring system, the possibility of encountering a lightning strike is also very high, mainly in the form of a series connection from the power supply, and the possibility of a direct lightning strike is very small. Once the voltage of 220V suddenly becomes high, the switching power supply will be burned out in an instant. In a surveillance system some time ago, after a thunderstorm, the main surveillance gate tripped. After closing the gate again, most of the cameras were still working normally, but some monitors showed no video signal. After inspection, it was found that all those without video signals were switching power supplies (some places were inconvenient to install during construction, so switching power supplies were used). Finally, a power box was installed on the camera pole and a transformer power supply was replaced.
What is a transformer
Transformer (Transformer) is a device that uses the principle of electromagnetic induction to change AC voltage. The main components are primary coil, secondary coil and iron core (magnetic core). The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc. According to the purpose, it can be divided into: power transformers and special transformers (electric furnace transformers, rectifier transformers, power frequency test transformers, voltage regulators, mining transformers, audio transformers, medium frequency transformers, high frequency transformers, impact transformers, instrument transformers, electronic transformers , reactor, transformer, etc.). Circuit symbols often use T as the beginning of the number. Example: T01, T201, etc.
Advantages and Disadvantages of Transformers
Advantages:
1. The linear one looks bulky, and the power depends entirely on the transformer and adjustment tube. Although the efficiency is low, it will not introduce additional interference, which means that the electromagnetic interference is small and the ripple coefficient isVery low and can be ignored. For surveillance, there is no better advantage than this. The quality of the image is closely related to the power supply. Especially for small-amplitude analog signals (audio sources and video sources, etc.), the power requirements are very high, so the power supplies in some audiophiles use transformers instead of switching power supplies.
2. The voltage stabilization rate is high, the design is simple, and maintenance is very convenient. If a fault occurs, a technician with a little knowledge of electronics can repair it, and the maintenance cost is much less than that of a switching power supply.
3. Good lightning resistance. Since the structure of the transformer is two coils and an iron core, the voltage applied to both ends of the coil cannot change suddenly, so it has strong suppression of instantaneous high voltage. Therefore, in a lightning strike accident, the power supply of the transformer survived, but the switching power supply burned down without exception.
Disadvantages:
1, low efficiency. Since the transformer is an “electricity-magnetism-electricity” conversion process, iron loss and copper loss cannot be avoided, and the efficiency is low.
2, the input range is narrow. Generally, it is only between 200V–240V. If it is less than this range, the output voltage is not enough. If it is greater than this range, the transformer It might burn down. This voltage range is sufficient in most situations and does not need to be considered too much. Furthermore, the transformer is larger and bulkier than the switching power supply.
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