The Basics of Linear Power Supplies
Compared with switching power supplies, linear power supplies have always been criticized for their low conversion rate. But since the technology exists, it must have its uses. And compared to the switching power supply, the technology of the linear power supply is more mature than it. The so-called existence is reasonable. Since something exists, it must have its uniqueness.
The linear regulated power supply is a type of DC regulated power supply that was used earlier. According to the working state of the regulating tube, we often divide the regulated power supply into two categories: linear regulated power supply and switching regulated power supply. The characteristics of the linear regulated DC power supply are: the output voltage is lower than the input voltage; the response speed is fast, the output ripple is small; the noise generated by the work is low; the efficiency is low (the LDO that is often seen now appears to solve the efficiency problem) ; Large heat generation (especially high-power power supply), which indirectly increases thermal noise to the system.
The characteristics of the linear regulated DC power supply are: the output voltage is lower than the input voltage; the response speed is fast, the output ripple is small; the noise generated by the work is low; the efficiency is low (the LDO that is often seen now appears to solve the efficiency problem) ; Large heat generation (especially high-power power supply), which indirectly increases thermal noise to the system. Moreover, the adjustment tube of the linear power supply works in an enlarged state, so it generates a lot of heat and has low efficiency (about 35%). It needs to add a bulky heat sink, and also needs a large-volume power frequency transformer. When making multiple sets of voltage The output transformer will be more bulky. The adjustment tube of the switching power supply works in the saturated and cut-off state, so the calorific value is small, the efficiency is high (over 75%) and the large-volume transformer is omitted.
working principle
The working process of the main circuit of the linear power supply is that the input power supply is initially stabilized by the pre-stabilized voltage circuit, and then converted into a DC power supply through the isolation and rectification of the main working transformer, and then controlled by the control circuit and the single-chip micro-processing controller. The linear adjustment element is finely adjusted to make it output a high-precision DC voltage source.
Power Transformer and Rectification: Transform 380V AC into required DC.
Pre-stabilization circuit: Use relay elements or thyristor elements to pre-adjust and initially stabilize the input AC or DC voltage, thereby reducing the power consumption of linear adjustment elements and improving work efficiency. It also ensures that the output voltage source is high-precision and high-precision Stablize.
Linear adjustment element: Finely adjust the filtered DC voltage to make the input voltage meet the required value and accuracy requirements.
Filtering circuit: The pulsating wave, interference, and noise of the DC power supply are prevented and absorbed to the greatest extent, so as to ensure that the output voltage of the DC power supply has low ripple, low noise, and low interference.
Single-chip microcomputer control system: the single-chip micro-processing controller compares, judges, calculates, analyzes and processes the various signals detected, and then issues corresponding control instructions to make the overall voltage stabilization system of the DC stabilized power supply work normally, reliably and harmoniously. .
Auxiliary power supply and reference voltage source: provide high-precision reference voltage source and power supply required for electronic circuit work for the DC voltage stabilization system.
Voltage sampling and voltage adjustment: detect the output voltage value of the DC stabilized power supply and set and adjust the output voltage value of the DC stabilized voltage power supply.
Comparing and amplifying circuit: After comparing the output voltage value of the DC stabilized power supply with the voltage of the reference source to obtain the error voltage signal, amplify the feedback and control the linear adjustment element to ensure the stability of the output voltage.
Current detection circuit: Obtain the output current value of the DC stabilized power supply for current limiting or protection control information.
Drive circuit: a power amplifier circuit set up to drive executable components.
Display: Display of the output voltage value and output current value of the DC regulated power supply.
