The working principle of voltage regulation of series regulated power supply
Assuming that the output voltage UO decreases due to some reason, that is, the emitter voltage (UT1) E of T1 decreases. Since UD1 remains unchanged, the emitter junction voltage (UT1) BE of T1 increases, causing the base current (IT1) B of T1 to increase, resulting in T1 emission
The pole current (IT1) E is amplified by a factor of β and increases. From the load characteristics of the transistor, it can be seen that T1 is more fully conductive at this time. The voltage drop (UT1) CE will rapidly decrease, and the input voltage UI will be added more to the load, resulting in a rapid recovery of UO. This adjustment process can be represented using the following change relationship diagram:
UO ↓ → (UT1) E ↓ → UD1 constant → (UT1) BE ↑ → (IT1) B ↑ → (IT1) E ↑ → (UT1) CE ↓ → UO ↑
When the output voltage rises, the entire analysis process is opposite to the changes in the above process. We will not repeat it here, but simply use the following change relationship diagram to represent it:
UO ↑ → (UT1) E ↑ → UD1 constant → (UT1) BE ↓ → (IT1) B ↓ → (IT1) E ↓ → (UT1) CE ↑ → UO ↓
Here we only analyzed the working principle of voltage regulation when the output voltage UO decreases. In fact, the working principle of voltage regulation in other situations such as when the input voltage UI decreases is similar to this, and ultimately it is reflected in the decrease of the output voltage UO. Therefore, the working principle is roughly the same.
From the working principle of the circuit, it can be seen that there are two key points for voltage regulation: first, the voltage regulation value UD1 of the voltage regulator D1 should be kept stable; The second is to adjust the tube T1 to work in the amplification area and have good working characteristics.
