Working waveform problem of single-phase bridge uncontrolled rectifier circuit with capacitor filtering

西里古1992

Working waveform problem of single-phase bridge uncontrolled rectifier circuit with capacitor filtering [Copy link]

 

In the working waveform b) of the capacitor-filtered single-phase bridge uncontrolled rectifier circuit, is i2 the input current? Or the charging current of the capacitor? And why are there two sine waves with a phase difference of 180°?

maychang

[In the working waveform b) of the capacitor-filtered single-phase bridge uncontrolled rectifier circuit, is i2 the input current? Or is it the charging current of the capacitor? ]

The current waveform in this figure is wrong, so there is no need to look at it again.

maychang

I have posted eight posts on rectification in this forum. The second post contains the voltage and current waveforms of capacitor filtering, which you can refer to.

Rectification

davidzhu210

The current i in Figure b is i2 in Figure a , which is the current on the secondary side of the transformer (in the positive half cycle). In the negative half cycle, i2 is reversed, which is the pink part in the figure. The voltage on the capacitor is wavy (excluding the black cross part). The sine wave is drawn for easy understanding.

jiangbianyeren

Study, MARK it, just passing by, just to gain experience, hehe

maychang

davidzhu210 posted on 2022-11-4 19:49 The current i in Figure b is i2 in Figure a, which is the current on the secondary side of the transformer (in the positive half cycle). In the negative half cycle, i2 is reversed, which is the pink in the figure...

How do you explain the waveform in the first post that is zero current and then rises sharply? At this moment, the instantaneous value of the transformer secondary AC voltage is equal to the voltage across the capacitor.

davidzhu210

maychang posted on 2022-11-4 22:21 Then how do you explain the waveform in the first post where the current rises sharply at the moment of zero current? At this moment, the instantaneous value of the transformer secondary AC voltage is equal to the voltage across the capacitor.

At that moment, the instantaneous value of the transformer secondary AC voltage is not strictly equal to the voltage across the capacitor, and there is a diode forward voltage drop. The moment the diode is turned on, the current rises sharply.

maychang

davidzhu210 posted on 2022-11-4 22:59 At that moment, the instantaneous value of the transformer secondary AC voltage is not strictly equal to the voltage across the capacitor. There is a diode forward voltage drop. At the moment the diode is turned on, the current...

Yes, the previous discussion did not take into account the forward voltage drop of the diode. Only when the forward voltage drop of the diode is taken into account can the two voltages be equal.

However, the two voltages are equal, which means the current is zero! The greater the transformer winding voltage (instantaneous value) is than the voltage across the capacitor, the greater the current through the diode (or winding).

maychang

davidzhu210 posted on 2022-11-4 22:59 At that moment, the instantaneous value of the transformer secondary AC voltage is not strictly equal to the voltage across the capacitor. There is a diode forward voltage drop. At the moment the diode is turned on, the current...

"Current surge" can only occur when the voltage surges and the capacitive load is present. In the picture in the first post, it is impossible for the current to surge.

maychang

davidzhu210 posted on 2022-11-4 22:59 At that moment, the instantaneous value of the transformer secondary AC voltage is not strictly equal to the voltage across the capacitor. There is a diode forward voltage drop. At the moment the diode is turned on, the current...

If you read the second article in the link I provided on the 3rd floor carefully, all the above problems will be solved.

davidzhu210

maychang posted on 2022-11-5 08:34 Take a closer look at the second article in the link I provided on the third floor, and all the above problems will be solved.

Just read it, very well written and detailed!

西里古1992

maychang posted on 2022-11-4 19:12 I have posted eight posts on rectification in this forum. The second post contains the voltage and current waveforms of capacitor filtering, which can be used as a reference. Miscellaneous talks on rectification

OK, thanks

chunyang

Go and read maychang's excellent post on rectification and filtering. The "information" the poster read was wrong from the name to the content.

西里古1992

chunyang posted on 2022-11-5 19:57 Go to read the excellent post written by maychang on rectifier and filtering. The "information" you read is wrong from the name to the content.

Can