Do you understand busbars in the new energy industry? Copper bars, aluminum bars, copper-aluminum composite bars; hard bars, soft bars, soft-hard overlapping bars; soft-hard copper busbar overlap welding, etc.

1. What is a Busbar?

What exactly is a Busbar?

Busbar is to realize the electrical connection between batteries, realize the series and parallel structure of batteries, and take on the sampling of voltage and temperature at the same time, which plays an important role in the safety of power batteries.

Busbar, a new energy vehicle, is a multi-layer composite structure connecting bar;

1) Connection mode: busbarconnection connects battery terminals or module poles in series or parallel by welding or bolt fastening.

2) Application: The composite bus is not only used in new energy vehicles, but also widely used in power and hybrid traction equipment, electric traction equipment, cellular communication, base stations, telephone switching systems, large-scale network equipment, large and medium-sized computers, power switching systems, welding systems, military equipment systems, power generation systems, power conversion modules of electric equipment, etc.

2. the classification of 2.Busbar

What are the types of Busbar?

New energy vehicle battery pack, energy storage battery system Busbar, copper-aluminum structural parts.

According to the material classification, there are ① copper bar, ② aluminum bar and ③ copper-aluminum composite bar;

According to the processing properties, there are ① hard bar, ② soft bar and ③ soft-hard lap bar.

Remarks: Ba comes from English bar, which is an English foreign word in Chaozhou. In particular to a battery module and a connection method of a copper bar assembly.

3. Welding equipment needed for the production of Busbar.

The production of busbar involves the whole process of the whole line, including blanking, pre-pointing (partially needed), diffusion welding, stamping, polishing, bending, thermal shrinkage (partially needed), inspection, packaging and delivery.

Among them, the most important part is welding. Haifei can provide you with a single machine that can meet all kinds of busbar welding: polymer diffusion welding machine, copper foil soft connection diffusion welding machine and aluminum foil soft connection diffusion welding machine.

Copper bus generally refers to copper bus, also known as bus or current-carrying bus. It not only has a beautiful metallic luster in appearance, but also has a strong internal strength!

It has many advantages, such as high mechanical properties, good electrical conductivity, thermal conductivity, corrosion resistance, electroplating, brazing, easy formability and so on, which make it be made into various power transmission and transformation equipment and widely used in the electric power field.

Types of copper bars

1) according to the section points

According to the section, it can be divided into rectangular, circular, D-shaped, U-shaped, etc. Among them, rectangular copper bars with the same section are the most widely used in the voltage class of 40.5kV and below because of their lower resistance, larger heat dissipation surface and higher current carrying capacity.

picture

Circular and D-shaped copper bars have good skin effect and corona prevention effect, but their connection is complicated.

U-shaped copper bars are generally used in equipment with high current and high force effect requirements, such as generator export switchgear. Its rated current is large, generally above 5000A, and its rated peak withstand current (IP) is large, generally above 50KA.

2) according to the natural state

According to the natural state, it can be divided into hard copper bar (TMY) and soft copper bar (TMR). Soft copper bar is mainly used in places where the connection is inconvenient and can absorb some force effects, such as the inside of circuit breakers.

What affects the current carrying capacity of copper bars?

First of all, we should understand that the factors that affect the current carrying capacity are not only the size of the cross section of the copper bar, but also the environmental temperature and placement mode.

1) Ambient temperature

The ambient temperature is mainly divided into 25℃, 30℃, 35℃ and 40℃, and the ambient temperature is selected based on the average maximum temperature of the hottest month in the laying place. Because the resistance of conventional conductors is proportional to the temperature, the higher the temperature, the greater the conductor resistance, and its current carrying capacity will inevitably decrease, so the current carrying capacity will inevitably be different at different temperatures, so it is best to choose a place with good ventilation when laying.

picture

2) Placement method

The current carrying capacity of a single busbar is indeed higher at the same ambient temperature when it is placed vertically than when it is placed horizontally. Data show that when the width of a single copper bar is less than or equal to 63 mm, the horizontal placement is 0.95 times that of the vertical placement, and when the width of a single copper bar is more than 63 mm, the horizontal placement is 0.92 times that of the vertical placement.

Because the vertical copper bars accelerate the air convection, so that the heat of the copper bars can be dissipated as soon as possible, while the horizontal copper bars are relatively slow in air convection, so that the heat can be dissipated slowly, thus affecting the current carrying capacity.

In order to facilitate heat dissipation, when two or more rectangular copper bars are connected in parallel, the gap between the parallel copper bars must not be less than the thickness.

Estimation method of copper busbar current capacity

Many friends have a headache when it comes to the current carrying capacity of copper bars, and it is also very troublesome to always check the manual. Today, Xiaonan will arrange an efficient and simple estimation method for the current carrying capacity of copper bars, and the estimation formula will be given first:

//

Single row = width (mm) × thickness coefficient

Double row/three row/four row = width (mm) × thickness coefficient × experience coefficient.

But it usually reaches four rows, so this kind of choice is not recommended here in Xiaonan. It is best to replace it with a special-shaped bus bar.

Next, let's take the copper bar with a width of 100mm × 10mm in the rigid copper bar (TMY) at 40℃ and stand upright as an example:

Single row =100×18.5=1850(A) [refer to the manual for 1870A]

Double row =(100×18.5)×1.58=2923(A) [refer to the manual for 2970A].

Three rows =(100×18.5)×2=3700(A) [refer to the manual for 3750A]

In addition, there is a very simple formula for calculating the current carrying capacity of copper bars at 40℃:

Current carrying capacity of a single rectangular copper bus = bus width × (bus thickness+8.5) A

For example:

15×3 ampacity = =15×11.5=172.5A

100×8 ampacity =100×16.5=1650A.

Double-layer current carrying capacity = 1.5 times single-layer current carrying capacity

Three-layer current carrying capacity = 2.0 times of single-layer current carrying capacity