Comparison of linear power supply and switching power supply
The voltage feedback circuit of the linear power supply works in a linear (amplified) state, and the switching power supply means that the tube used for voltage adjustment works in the saturation and cut-off region, that is, the switching state.
The main working principle of the ordinary half-bridge switching power supply is that the switching tubes of the upper bridge and the lower bridge (when the frequency is high, the switching tube is VMOS) are turned on in turn. First, the current flows in through the switching tube of the upper bridge. In the coil, the switch tube of the upper bridge is finally turned off, and the switch tube of the lower bridge is turned on, and the inductance coil and the capacitor continue to supply power to the outside. Then turn off the switch tube of the lower bridge, and then open the upper bridge to let the current enter, and repeat like this, because the two switch tubes need to be turned on and off in turn, so it is called a switching power supply.
The linear power supply is different. Since there is no switch involved, the upper water pipe is always discharging water. If there is too much water, it will leak out. This is what we often see in some linear power supply adjustment tubes. The endless electrical energy is all converted into heat energy. From this point of view, the conversion efficiency of the linear power supply is very low, and when the heat is high, the life of the components is bound to decrease, affecting the final use effect.
From its main characteristics: the linear power supply technology is very mature, the production cost is low, it can achieve high stability, the ripple is small, and its own interference and noise are relatively small, but because it works at power frequency (50Hz), the transformer The volume is relatively large, and the efficiency is low (generally, the efficiency of full-load operation is only about 80%). The overall volume is relatively large, and it appears to be cumbersome. And the input voltage range is high; and the switching power supply is in a high-frequency state of work, and the volume of the transformer is relatively small. , is relatively lightweight, but the output ripple is larger than that of linear power supplies, but because of its simple structure, low cost, and high efficiency (the efficiency of switching power supplies on the market can also reach more than 90%), it has replaced linear power supplies in many occasions. The trend of future power development.
Simple comparison of linear power supply, thyristor power supply and switching power supply circuit
Regarding the circuit structure, whether it is a linear power supply, a thyristor power supply or a switching power supply depends on the specific occasion and should be used reasonably. These three circuits are widely used both at home and abroad, and each has its own characteristics. SCR power supply, with its powerful output power, makes linear power supply and switching power supply irreplaceable. Linear power supply is widely used for its high precision and superior performance. Because the switching power supply saves the bulky power frequency transformer, the volume and weight are reduced to varying degrees, and it is also widely used in many occasions where the output voltage and output current are relatively stable.
