A dc voltage regulator power module consists of four parts, respectively is the transformer, rectification, filtering and voltage regulator, about the transformer, rectification, filtering, in the previous article has been roughly introduced, also a voltage regulator, this paper focuses on the regulator circuit.
The circuit through the voltage regulator, the output waveform can be basically constant, which is in line with our expectations, the realization of voltage regulator, is determined by the characteristics of the regulator element.
A voltage regulator generally refers to a voltage regulator diode and, in particular, to an integrated voltage regulator circuit.
Zener diode, also known as the voltage regulator diode, belongs to a surface contact, high current transistor. Due to the large current allowed through, under normal circumstances, it will not cause heating of the pipe fittings. The graphic symbol is similar to that of a normal diode, but with an extra ear at the bottom.
As mentioned earlier, the realization of the voltage regulator is determined by the characteristics of the regulator element, which is the voltammetric characteristic curve of the regulator tube.
When the voltage is positive, the regulator is no different from the ordinary diode, the difference lies in its reverse characteristics.
In the reverse characteristic interval, OB segment, with the increase of voltage, the current is basically unchanged, called reverse cut-off zone; At point B, the corresponding voltage, Uz, the reverse current starts to increase, but the voltage basically stays at Uz, with little change. Uz is its breakdown voltage. As long as the current is within the range of Izmin and Izmax, the voltage is basically constant, which is called the reverse stability zone. Therefore, in the circuit, it is necessary to use current limiting resistance to control the reverse current of the regulator.
If there is such a circuit, the breakdown voltage of Dz is 5V
If Ui were an intersection variable, Ui =10sinωt, what would the output waveform of Uo look like?
We know from UI =10sinωt that the voltage will be greater than 5V, less than 5V, and over 0, plus and minus half axis changes, so we have to consider separately.
The voltage regulator works in the reverse cut-off zone, so the output voltage is still 10sinωt; In the range of 5-10V, the regulator works in the reverse regulator area, the output voltage is 5V; When the half-axis is negative, the regulator tube is positively biased, which is equivalent to the short-circuit state. At this time, the output voltage is 0V.
In the analysis of regulated circuit, the most important is its application. As mentioned at the beginning, dc regulated power supply module includes four parts: transformer, rectifier, filter and voltage regulator. It can be seen that DC regulated power supply is its most typical application. The DC power module we use on the scene, no matter how the circuit changes, there are always these four parts, it can be said that these four parts constitute the prototype of dc regulated power supply.