How to analyze which solution is better when two rectifier bridges are connected together?

灞波儿奔

How to analyze which solution is better when two rectifier bridges are connected together? [Copy link]

 

Which solution is better for two rectifier bridges? How to analyze it? I feel like I don't know where to start

maychang

The two connection methods are actually the same. The latter method is slightly simpler to wire.

Why do we need two rectifier bridges? Can't we use a rectifier bridge with a larger current capacity?

灞波儿奔

maychang posted on 2022-4-18 16:45 The two connection methods are actually the same. The latter method is slightly simpler to wire. Why use two rectifier bridges? The current capacity is larger...

I have made power supplies before, and I feel that the power of the rectifier bridge is small. Suddenly I have this idea. The teachers have suggested using it this way. I don’t know if it is feasible.

I'm worried about the problem of heating up the two together.

呜呼哀哉

In fact, the second one is better. The parameters of the same package tube are more consistent and the current is evenly distributed. The first one outputs in parallel, and the parameters of the diodes of different components are less consistent than the second one.

chunyang

Whether you buy a ready-made bridge stack or build it yourself with diodes, you should not connect them in parallel. Instead, you should directly use a larger bridge stack or diode. The cost of parallel connection will be higher, and there will also be current sharing issues.

maychang

Alas, published on 2022-4-18 18:41 In fact, the second one is better. The parameters of the same package tube will be more consistent and the current will be even. The first one outputs in parallel, and the parameters of the diodes of different components are consistent...

The second connection method cannot avoid uneven current distribution.

It is better to choose a rectifier bridge with larger current capacity or an independently packaged diode.

不亦心

If you have to play it this way, choose the second one.

This is how fast charging heads work.

PowerAnts

Bu Yixin posted on 2022-4-18 21:40 If you have to play this way, choose the second one. This is how fast charging heads are played.

Now PDs are probably all playing ACF! EMI lineup is still so spectacular

不亦心

PowerAnts posted on 2022-4-18 22:29 Now PD probably plays ACF! EMI lineup is still so spectacular

This is a 100W fast charging head of a certain brand, PFC+LLC architecture

不亦心

ACF is used for around 65W, and PFC+AHB, PFC+LLC is basically used for above

PowerAnts

Bu Yixin published on 2022-4-18 22:35 ACF is used for around 65W, and PFC+AHB, PFC+LLC is basically used for above

AHB is still easier to handle than ACF

PowerAnts

ACF high voltage light load efficiency is not very good

PowerAnts

A few years ago, Chen Yongzhen was optimistic about AHB, and Li Longwen told me that since two MOSFETs were consumed, it would be better to do LLC. Now I guess Mr. Li's glasses are broken all over the floor, haha

不亦心

PowerAnts posted on 2022-4-18 22:58 A few years ago, Chen Yongzhen was optimistic about AHB, and Li Longwen told me that since two MOSFETs were consumed, it would be better to do LLC. Now I guess Mr. Li’s glasses are broken all over the floor, haha

Haha, the times are progressing, technology is developing,

A few years ago, people were still playing with hard switch charging heads. Who would have thought that accessory manufacturers would fight for the current power density and spare no cost?

灞波儿奔

Alas, published on 2022-4-18 18:41 In fact, the second one is better. The parameters of the same package tube will be more consistent and the current will be even. The first one outputs in parallel, and the parameters of the diodes of different components are consistent...

This can be calculated and analyzed from that aspect, such as current sharing

How to consider the power if connected in parallel?

灞波儿奔

chunyang posted on 2022-4-18 18:43 Whether you buy a finished bridge stack or build it yourself with diodes, you should not connect them in parallel. Just use a larger bridge stack or diode. The cost of parallel connection will increase...

I originally wanted to buy a high-power rectifier bridge.

But the changes to the old power supply are a bit big

Suddenly I thought of this method, which was also suggested by the teacher, and I am also curious about this solution.

This can be calculated and analyzed from that aspect, such as current sharing

If two rectifier bridges are connected, how to consider the power when using the second one

灞波儿奔

Bu Yixin posted on 2022-4-18 21:40 If you have to play this way, choose the second one. This is how fast charging heads are played.

It seems that there is such a use in actual power supplies.

Please advise, if two rectifier bridges are connected, how can this be calculated and analyzed, such as current sharing, whether heat is generated, etc.

If the second method is adopted, how should the parameters be considered for power and what is the calculation formula? It seems like I have no idea where to start. What aspects should be considered?

PowerAnts

When people analyze problems, they always stay at the ideal device state. However, what does the VI characteristic curve of the real device imply?

Taking 1N4007 as an example, the curve tells us that in addition to the PN junction, this diode also has a resistance component of about 35mR. The actual current sharing of parallel diodes mainly depends on it! ! !

What will happen if two 1N4007s are connected in parallel and the device temperatures are different?

A pulse current of 4A amplitude flows through them together, the temperature difference is 10 degrees, the high temperature tube is 2.1A, and the low temperature tube is 1.9A, which is not a big problem.

If two PN junctions are sealed together, the temperature difference will be smaller, which will make you feel more at ease.

se7ens

The second one doesn't feel good. If it's connected in parallel, it always feels like it will break down quickly.

chunyang

灞波儿奔 posted on 2022-4-19 08:46 I originally wanted to buy a high-power rectifier bridge, but the changes to the old power supply were a bit big. Suddenly I thought of this method, which was also the teacher's suggestion. I also want to...

If you connect in parallel, the change is big, and the PCB is different. If you only use a larger bridge rectifier, it is possible that there are the same packages, and if you use discrete diodes, it goes without saying.