Comparison of the principles of linear power supplies and switching power supplies
A linear power supply first transforms AC power through a transformer, and then rectifies and filters it through a rectifier circuit to obtain an unstable DC voltage. To achieve high-precision DC voltage, the output voltage must be adjusted through voltage feedback. From the perspective of main performance, this power supply technology is very mature, can achieve high stability, has very small ripple, and does not have the interference and noise of switching power supplies. The voltage feedback circuit operates in a linear state, with a certain voltage drop on the regulating tube. When outputting a large operating current, the power consumption of the regulating tube is too high, resulting in low conversion efficiency.
A linear power supply refers to a tube used for voltage regulation that operates in the linear region. Correspondingly, switch mode power supply refers to the operation of transistors used for voltage regulation in the saturation and cutoff regions, that is, in the switching state.
A linear power supply generally samples the output voltage and sends it to a comparison voltage amplifier with a reference voltage. The output of this voltage amplifier is used as the input of a voltage regulator to control the regulator so that its junction voltage changes with the input, thereby adjusting its output voltage. But the switching power supply changes the output voltage by adjusting the on and off time of the regulating tube, that is, the duty cycle.
The tube used for voltage regulation in a linear power supply operates in the linear region. Correspondingly, switch mode power supply refers to the operation of transistors used for voltage regulation in the saturation and cutoff regions, that is, in the switching state.
A linear power supply generally samples the output voltage and sends it to a comparison voltage amplifier with a reference voltage. The output of this voltage amplifier is used as the input of a voltage regulator to control the regulator so that its junction voltage changes with the input, thereby adjusting its output voltage. But the switching power supply changes the output voltage by adjusting the on and off time of the regulating tube, that is, the duty cycle. 2, The principle of linear power supply: Linear power supply mainly includes power frequency transformer, output rectifier filter, control circuit, protection circuit, etc. A linear power supply first transforms AC power through a transformer, and then rectifies and filters it through a rectifier circuit to obtain an unstable DC voltage. To achieve high-precision DC voltage, the output voltage must be adjusted through voltage feedback. This power supply technology is very mature and can achieve high stability with minimal ripple and no interference or noise from switching power supplies. But its disadvantage is that it requires a large and bulky transformer, and the volume and weight of the required filtering capacitors are also quite large. In addition, the voltage feedback circuit works in a linear state, and there is a certain voltage drop on the adjustment tube. When outputting a large working current, the power consumption of the adjustment tube is too high, the conversion efficiency is low, and a large heat sink needs to be installed. This type of power supply is not suitable for the needs of computers and other devices, and will gradually be replaced by switch mode power supplies. 3, Comparison of Switching Power Supply: Switching power supply mainly includes input grid filter, input rectifier filter, inverter, output rectifier filter, control circuit, and protection circuit.
