A transformer is a device that transforms voltage, current and impedance based on the principle of electromagnetic induction. The primary application of transformers is in AC circuits. Switching power supply is the use of modern power electronics technology, control switching transistor on and off time ratio, maintain a stable output voltage of a power supply, switching power supply can be divided into AC/DC and DC/DC 2 categories; According to the input and output electrical isolation can be divided into two categories: one is isolated called isolated DC/DC converter; The other is not isolated, called a non-isolated DC/DC converter. Switching power supply overheating, overcurrent, short circuit protection function, wide range of input voltage, input output isolation voltage, isolated high voltage isolation between input and output.
Transformer is a simple coil, is used to change the voltage, the output is AC, if you need DC, but also add rectifier voltage regulation. Switching power supply output is DC, its internal usually includes transformer, rectifier, voltage regulator and other components, is an integrated component. The transformer is two groups of coils, according to the principle of electromagnetic induction, the primary coil is connected to the power supply, the secondary coil is connected to the load, the primary coil voltage and current change causes the magnetic field to change, and the magnetic field changes in the secondary induction voltage, according to the number of turns of the two coils, the primary is more than the secondary, that is, the primary is less than the secondary voltage;
Switching power supply is through the characteristics of electronic components, the power supply voltage (generally 220V 380V AC) rectifier, filter, and then the DC voltage into high frequency pulse, with different duty cycle to get different voltages, and then voltage regulation output, the power requirements are not high and small power transformer relative to the switching power supply is simpler and lower cost, However, in the case of high voltage stability requirements for the power supply, if the transformer is also rectified and regulated, the cost is much higher than the switching power supply with the same efficacy, and the transformer is narrow in the width of the input voltage, the change in the input voltage will cause the output voltage to follow the change, and the switching power supply input voltage range is wide. The input voltage changes have little effect on the output voltage.
The principle of switching power supply is to first turn alternating current into direct current, and then into higher frequency alternating current through a high-frequency transformer for voltage conversion. The common transformer is to convert the power frequency AC voltage directly. The difference is as follows: the switching power supply is lighter, the voltage range is wider, the power utilization efficiency is higher, and the cost is more environmentally friendly, but the cost is correspondingly higher (sometimes not high), and the transformer can be replaced in most cases.
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The difference between the two:
The biggest difference is volume. In general, transformers are bulky and switching power supplies are small. The greater the power, the more noticeable the difference. Conversely, the smaller the power, the smaller the difference. In the early days, due to the high price of semiconductor devices, small power occasions, almost all transformers. In the 1980s and 1990s, black and white TV sets, although the power has exceeded 30w, are still generally powered by transformers. Color TV because of the larger power consumption, switching power supply is generally used. In recent years, due to the semiconductor price, the transformer cost appears high, basically the switching power supply of the world.
Efficiency/heat difference. Transformer efficiency is relatively low, heat is large. Switching power supplies are the opposite. In particular, the transformer does not have a voltage regulator function, and in the case of voltage regulation, a linear regulator with great heat has to be added to further reduce the efficiency. The switching power supply can easily achieve output voltage stability without adding additional heat.
Ripple difference. The frequency of the switching power supply is high, and the voltage regulator circuit makes the output direct current relatively stable, and only a simple filter can get stable direct current. After the transformer transformer is still 50HZ AC, after rectification, the ripple is large, and the filter circuit is relatively complex.
Anti-interference performance. Because the transformer is low-frequency AC transformer, its electromagnetic radiation ability is poor, and the interference to the application circuit is small. The switching power supply, because of the high frequency, there is electromagnetic radiation interference. In some occasions such as HIFI audio, where there are special requirements for combating interference, traditional heavy transformers are generally still used.
The difference in principle. Both are electromagnetic transformations. The transformer is 50HZ low-frequency alternating current directly converted into the required alternating current, and then rectified and filtered into direct current. Switching power supply is first directly rectified into a filter into high voltage direct current, and then through the electronic device high-speed on-off (switch), the formation of high-speed pulse, to achieve high-frequency electromagnetic changes.
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Post time: Nov-21-2024