Frequency transformer is commonly known as low-frequency transformers, switching power supply in order to show the difference between the high-frequency transformer, frequency transformer widely used in the past, the traditional power supply, and stable way these power supplies is the use of a linear regulator, so those traditional Power has been called a linear power supply.

Frequency transformer principle is very simple, theoretically relevant formula is not complicated, so we formed the view: too simple, it is that three or four formulas, nothing to study. Just based on those simple formula, immediately successful design.

I think the understanding of both the above merits, but also a place worth studying. Merit: According to the calculation formula, you can quickly calculate the results, to solve the problem; the place is worth studying: do you know your own design product performance optimized design designed it yet how the economy????

To give an example, according to the problem of power selected core specification is a very complicated, because the factors involved more. Some books recommend using the following semi-empirical formula to select:

S = K · Sqrt (P) (1)

After the set S, and perform other calculations. This is indeed a practical way, but also recognize that this is a simplified design methods, in most cases there is a waste. This design approach for amateurs need not discuss (only occasionally to design a transformer own use), but for businesses, it is worth discussing, high-volume products with this design, reflecting reduced economic efficiency.

Then, in professional situations, such as transformer manufacturers, how they approach?

In principle, according to the wire in the window to select the core specifications occupancy factor, but this calculation is very complicated, but the relationship is not simple, such as correlation calculation formula is:

P = 0.0222 · f · B · J · Sc · Sm (2)

When the current density is determined by the voltage adjustment rate, calculated as:

P = 0.0555 (f · f) (B · B) (Sc · Sc) · Sm · ΔU / (Z · Lm) (3)

Such complex relationships, to come up with a design manual is very troublesome, so, experts on the actual situation, these relationships will combine data compiled into a series of tables, depending on the design engineers to design specifications to check the corresponding table, it You can get a set of useful data, such as power and other indicators according to the table, get the core specifications.

This method brings convenience is so large, so you can quickly come up with some solutions, combined with the accumulation of experience, the program can make the appropriate judgment before making optimization. Even so, this method there are two major shortcomings, first, the experts can not make all of the series table, two engineers to come up with a more complete product design parameters, you have to spend a lot of time to go one by one calculation, first day out several programs to engage engineers certainly big. Fortunately, the current popularity of computer applications, specialized software has also been, you can let the computer do the calculations dull, engineers only concerned with the design and optimization programs.

As another example, the selection of the current density, a simple design is generally recommended as 2.5A ~ 3A / (mm · mm), but according to (3), the small power adjustment rate is large, the current density can be taken large, to achieve 8 ~ 9A / (mm · mm) [? See column "?? ?? benches Anhui lEI type Ni Hao M astatine bag saddle blanket Huan quot;? stickers, I was there to give the landlord provides six programs], when the temperature still modest, transformers can safely work, the design premise of ensuring safety in general can reduce the amount of copper in the case of high copper prices, reducing costs; and power adjustment rate limited, the current density may be less than 2A / (mm · mm), it may make the transformer burned transformer temperature is too high. It should be emphasized noted that not just the current density can be increased, and it is linked to indicators designed to calculate given casually improve performance often leads to deterioration, and even burned transformer.

Some people may think: why did I do not think so preoccupied with, say economic growth abroad how how to save energy, conservation of raw materials, is not that a little bit not to pull out the efficiency of switching power supply comes from, is not also a?? point a little research out of it? Now the truth of this, if you really engage frequency transformer production and design, it is necessary to do a good job their bank, find out their own work-related content. Imagine, a company product requires various types of transformers, want recruit engineers engaged in a design, to make the spot a few examples of design, A and B are the result of two design engineers to meet the requirements, but the A's average cost 10% lower than B, Who said that companies will hire you?

From the perspective of saving energy and raw materials, here to share with you:

1. to reduce the amount of copper, there are two aspects can be achieved, which means that one is to reduce the diameter copper resistance increases, the loss will increase copper loss. Second is to reduce the number of turns, it will make no-load current increases, the same no-load losses will increase, if the transformer is energized long standby, wasting power resources is very large. Waste of electricity each year because of long-term household appliances in standby power is due to several billion dollars.

2. the transformer should be designed so that the copper loss and iron loss equal to the lowest loss this transformer, working most stable, if a transformer design finished, due to save copper, and take small wire diameter and number of turns reduction method so there is a lot of space core window margin, so it shows the selected core size is too large, resulting in a waste core, due to the large core size, average perimeter wire is also large, it will also cause copper increase the amount. According to current prices, the cost of the core is higher than the cost of copper.

So in the design, to ensure the performance to meet the customer's requirement, should try to choose a small core, can be 41, 48, would never use. About load current, saving standby losses from the consideration, or as low as possible is good.