Why can’t the simulation produce the correct result?

程序会不会

Why can’t the simulation produce the correct result? [Copy link]

As shown in the figure: Multisim is used to simulate the voltage doubler rectifier circuit, with a transformation ratio of 20. According to the principle, if the voltage between C6 and the ground is taken as the output voltage, the voltage should be 8 times the peak voltage = 5*20*8=800V, and the voltage across C1 should be 100V. However, the simulated data shows that the voltage across C1 seems to be only 50V at most, because no matter how much I increase the primary voltage, the voltage of C1 will not change. The reverse voltage of each diode should be the peak voltage of the amplitude side, which should be 100V in the figure, and there is no reverse breakdown. Why do the voltages of C3, C2, and C6 decrease in sequence? They should be the same.

maychang

1. The voltage doubler rectifier circuit (the same applies to other rectifier circuits) needs a sufficiently long time to reach stability, and your simulation time is not long enough. 2. The voltages at both ends of each capacitor are equal, regardless of the time required, and each component must be ideal, such as the forward voltage drop of the diode is zero, the reverse resistance is infinite, the capacitor has no leakage current, the internal resistance of the voltmeter is infinite... The diode and capacitor models used in the simulation are non-ideal.

qwqwqw2088

The measurement is always step-down. Check whether the transformer is a step-up transformer and whether the positive and negative capacitors are placed in reverse. The capacitor is a little small.

qwqwqw2088

Build one in multisim, use 20x transformer, 8x transformer can't fit, build 6x transformer first to see how it goes,

qwqwqw2088

Adjust the capacitor to 120nf. According to the voltage doubling formula, Uou=Uin*√2 * N*2, where N is the voltage doubling number of the transformer. 2 times the voltage is 282, and 6 times the voltage is 848.

qwqwqw2088

Take a look at the screenshot The same circuit is also used when the voltage is increased to 8 times

程序会不会

qwqwqw2088 posted on 2018-7-6 10:05 I built one in multisim, and used a 20x transformer. The 8x one can't fit in the drawing, so I built a 6x one first to see how it goes.

Hi, what kind of transformer did you use? I don't know if I used the wrong transformer.

chunyang

The capacitance needs to be significantly increased.

qwqwqw2088

Will the program be published on 2018-7-6 12:58 Hello, may I ask what kind of transformer you are using? I wonder if I used the wrong transformer

The first transformer in the component library is fine, and the transformation ratio needs to be adjusted