Inverter cooling

High Frequency Solar Inverter

Inverter as a power electronic equipment, and all electronic products are facing the same challenge of temperature. Especially in summer, the outdoor temperature is too high,inverter surface structure is hot, touch will have a hot feeling, face this problem combined with the cooling design of the inverter to do some analysis and answer.

I. Why does it heat up

The rated operating temperature of the components in the inverter is closely related to the thermal conductivity. The more balanced the temperature inside and outside the inverter thermal conductivity is, the better the heat conduction performance is. If the inverter is cold on the outside and hot on the inside, it means the heat dissipation performance is not good. This is similar to the principle of thermal insulation cup and ordinary water cup, the existence of vacuum layer makes the temperature of the outer wall of the thermal insulation cup low, and the internal heat can not be dissipated to achieve the effect of heat preservation; the wall of the ordinary cup can transfer the internal heat well, so the outer wall is hot, but the cooling is faster than the thermal insulation cup. The heat dissipation principle of the inverter is the same as that of an ordinary water cup, the shell becomes part of the system heat sink and can share part of the heat of the components. The use of thermally conductive materials can transfer the heat from the internal components of the inverter quickly to achieve the purpose of rapidly reducing the temperature of the internal components of the inverter, thus improving the work and service life of the inverter.

2. why the inverter needs heat dissipation

1)the components in the inverter have rated working temperature, if the inverter heat dissipation performance is relatively poor, when the inverter continues to work, the heat of the components has been in the cavity of the internal collection, its temperature will become higher and higher. The high temperature will reduce the performance and life of the components, and the machine is prone to failure.

2)the inverter work heat, generate power loss can not be avoided, for example, 5kW one of the inverter, its system heat loss is about 75-125W, affecting the power generation. It is necessary to optimize the heat dissipation design, which can reduce the heat dissipation loss.

3.several ways of inverter heat dissipation

At present, the heat dissipation technology of inverter includes natural cooling, air cooling, liquid cooling and so on. The main application forms are natural cooling and forced air cooling.

1)Natural cooling: natural cooling refers to not using any external auxiliary energy, so that the local heating device dissipates heat to the surrounding environment, thus realizing temperature control. natural cooling is suitable for low-power devices that do not have high requirements for temperature control.

2)Air cooling: air cooling method is mainly with the help of a fan, so that the device emits heat away from a method. At present, the heat sink material is mainly used aluminum or copper.

4.the inverter cooling design

In the circuit, the components will generate heat as long as the current is passed. Therefore, in order to ensure that the components can work under the rated temperature, the heat dissipation capability of the system is very important.

To make the heat dissipation performance excellent, it can be realized by the following points:

① The larger the heat dissipation area, the better the result

For example, the heating power of 1kW inverter is about 25W, according to the maximum heat flow density of 0.01W/cm2 that needs to be borne by natural cooling at 60℃, the heat dissipation area is calculated as 0.5m2. In order to keep the volume of the inverter unchanged, DEET adopts the pleated design and multi-heat dissipation teeth to increase the contact area between air and heat sink, which can dissipate the heat better and faster.

②Housing-radiator tightly butted structure

The inverter shell is made of aluminum alloy, which has good thermal conductivity. With the integral shell structure, the heat sink and the shell are closely connected, so that the heat of the components can be directly transferred to the shell. At the same time, the heat from the components can also be conducted to the housing through the internal air and then dissipated to the external air, forming two heat dissipation paths. The non-integral shell needs to be connected twice, the contact is not close, resulting in a significant reduction in the overall thermal performance. Therefore, the use of integral shell structure is conducive to heat dissipation, reducing the internal temperature of the inverter and the temperature of components to ensure a longer service life.

③Inductor external design

The inductor can be externalized, and the inductor can dissipate heat independently to reduce the temperature of the machine cavity.

5. Summary

The shell, as part of the system radiator parts, can effectively share some of the heat from the components. In summer hot weather, the outside temperature may reach 38℃, the temperature of the inverter shell stays around 60℃ in most cases (in line with the safety standard). However, the temperature of the components inside the inverter will decrease much more and much faster. Therefore, when touching the inverter case, you may feel hot, but this is normal. Even if heat generation occurs, it will not cause burns.

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