Briefly describe the difference between switching power supply and linear power supply

Switching power supply is a power supply that utilizes contemporary power electronics technology to control the switching time ratio of switch tubes and provide the required stable output voltage for electrical appliances. A switching power supply typically consists of a pulse width modulation (PWM) controller and MOSFET. Switching power supply is a system. At present, switching power supplies are widely used in the vast majority of electronic products due to their small size, light weight, and high efficiency. This is an indispensable power supply mode for the rapid development of the electronic information industry today.

A general power supply usually refers to a linear power supply, which refers to a power supply where the voltage regulator operates under linear conditions. Switching power supply is a relatively new type of power supply. It has advantages such as high efficiency, light weight, voltage fluctuation, and strong power. But due to the circuit working in the on/off state, the noise is very loud. Due to the inverse ratio between the size of the transformer core and the square of the output power of the switching power supply, the higher the frequency, the lower the core. This can greatly reduce the transformer, reduce the weight and volume of the power supply. Moreover, due to direct control of direct current, the power efficiency is much higher than that of linear power sources.

Compared to the difference between a switching power supply and a linear power supply, simply put, the pressure regulation of a linear power supply can be regarded as a resistance regulation value, which is equivalent to changing the voltage by adjusting the sliding rheostat, while a switching power supply promotes the voltage change by adjusting the number of switches. At the same time, compared to linear power sources, the cost of switching power sources increases with increasing power, but the growth rate is different.

1. At a certain power point, the cost of linear power supply is higher than that of switching power supply.

Therefore, with the development and innovation of power electronics technology, switch power supply technology continues to break through and innovate. This cost issue has moved switch power supply technology to the low output power supply end, bringing widespread development prospects for switch power supply.

2. Power electronic equipment is increasingly closely related to the work and life of the public, and reliable electricity is indispensable for electronic products. After the 1980s, computers fully implemented switching power supplies, and in the 1990s, switching power supplies entered various electronic and electrical industries.

3. In just ten years, switching power supply technology has rapidly occupied the core position of power electronic equipment. Is this just because the switching power supply is very small?

In fact, from the schematic diagram of the switching power supply, it can be seen that it does not use a heavy-duty power frequency transformer, and the dissipated power on the regulating tube is greatly reduced, thereby saving a larger heat sink. This reduces the volume and weight of the switching power supply. But the biggest advantage of switching power supply is its low power consumption and high efficiency. In the switching power supply circuit, encouraged by the excitation signal, the transistor repeatedly repeats the "off" and "off" switching states, with a very fast conversion speed and a frequency of only 50Hz, greatly improving the power efficiency.

4. The switching power supply has a wide range of voltage stabilization. Adjusting the output voltage of the switching power supply through frequency modulation or width modulation can compensate for changes in the input signal voltage. In this way, when there is a significant change in the voltage of the DC power grid, the output voltage can still be relatively stable. Therefore, it is unreasonable for the effectiveness of switching power supply technology to become a part of power electronic equipment.

5. At present, the output power of switching power supplies is basically 50kHz, which is 1000 times that of linear regulated power supplies. The filtering efficiency after rectification has almost increased by 1000 times; Even if we choose the capacitor filter after half wave rectification, the efficiency is increased by 500 times. When selecting a switching power supply with the same ripple output voltage, the capacity of the filter capacitor is only 1/500-1/1000 of that of the filter capacitor in a linear regulated power supply.

Compared to linear power supplies, switching power supplies. The input terminal directly rectifies alternating current into direct current, and then, under the action of a high-frequency oscillation circuit, uses a switch to control the current on and off, generating high-frequency pulse current. Stable low-voltage direct current can be exported through inductors (high-frequency transformers). The switch operates in two situations: low conduction resistance; The cutoff resistance is high. Switching power supplies are generally composed of pulse width modulation (PWM) control ICs and MOSFETs. With the development and innovation of power electronics technology, current switching power supplies are widely used in the vast majority of electronic products due to their small size, light weight, and high efficiency.

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