Working principle of voltage regulation of series regulated power supply
Assuming that the output voltage UO decreases for some reason, that is, the emitter voltage (UT1) E of T1 decreases, and since UD1 remains unchanged, the emitter junction voltage (UT1) BE of T1 increases, causing the base current of T1 (IT1) B As a result, the T1 emitter current (IT1) E is amplified by β times and rises. According to the load characteristics of the transistor, at this time, T1 is more fully turned on. The tube voltage drop (UT1) CE will decrease rapidly, and the input voltage UI will be more Added to the load, UO gets a quick pick-up. This adjustment process can be represented by the following change 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 change of the above process, so we will not repeat it here, but simply express it with the following change relationship diagram:
UO↑→(UT1)E↑→UD1 Constant→(UT1)BE↓→(IT1)B↓→(IT1)E↓→(UT1)CE↑→UO↓
Here we only analyze the working principle of the voltage regulation when the output voltage UO is reduced. In fact, the working principle of the voltage regulation in other cases such as the reduction of the input voltage UI is similar to this. In the end, it is reflected in the reduction of the output voltage UO, so the working principle is roughly same.
It can be seen from the working principle of the circuit that there are two key points for voltage regulation: one is that the voltage regulation value UD1 of the voltage regulator tube D1 must remain stable; the other is that the regulator tube T1 must work in the amplification area and have good working characteristics.
