Improving the corrosion resistance of wind turbine controllers can be approached from the following aspects:
1、 Material selection
Shell material
Corrosion resistant metal: Choose metal materials with good corrosion resistance to make the controller housing, such as stainless steel. Stainless steel contains alloying elements such as chromium and nickel, which can form a dense oxide film on the surface of the material, preventing further erosion by oxygen and moisture.
Engineering plastics: Some high-performance engineering plastics are also good choices. For example, polycarbonate (PC) and polybutylene terephthalate (PBT) have good chemical corrosion resistance, mechanical properties, and insulation properties. Moreover, engineering plastics can further improve their weather resistance and corrosion resistance by adding additives such as anti UV agents and antioxidants.
Circuit board material
Copperplate: Choose high-quality copper-clad laminates, whose copper foil should have good antioxidant properties. For example, copper foil treated with OSP (Organic Solderability Protector) can effectively prevent oxidation during storage and use. At the same time, the substrate material should have low water absorption, such as FR-4 (epoxy glass fiber cloth board), which is a commonly used substrate material with low water absorption and can reduce corrosion caused by moisture.
Component packaging materials: The packaging materials for electronic components are also crucial. For wind turbine controllers operating in harsh environments, packaging materials with good sealing and corrosion resistance should be selected. For example, some high-precision chips use ceramic packaging, which has better corrosion resistance and sealing than ordinary plastic packaging, and can effectively prevent the invasion of water vapor and corrosive gases.
2、 Protective coating
Shell coating
Paint coating: Apply anti-corrosion paint to the controller casing. Paint can provide a physical barrier to prevent corrosive substances from coming into contact with the shell material. For example, epoxy zinc rich primer is a commonly used primer, and zinc powder can provide cathodic protection. When the coating is partially damaged, the zinc powder will be preferentially corroded, thereby protecting the underlying metal; Polyurethane paint can be chosen as the topcoat, which has good weather resistance and wear resistance, and can resist external factors such as ultraviolet rays and wind erosion. The thickness of the coating is also important. Generally, a primer thickness of 70-100 μ m and a topcoat thickness of 50-80 μ m are more suitable.
Ceramic coating: Ceramic coatings have many advantages such as high hardness, high temperature resistance, wear resistance, and corrosion resistance. Coating ceramic coatings on the surface of the controller housing through processes such as thermal spraying can effectively improve its corrosion resistance. For example, alumina ceramic coatings can resist corrosion from chemical substances such as acid and alkali, and their hardness can resist the erosion of wind and sand.
Circuit board protective coating
Conformal coating is a layer of conformal coating applied to the surface of a circuit board, such as acrylic resin coating, polyurethane coating, or silicone coating. These coatings can protect the components and circuits on the circuit board from moisture, salt spray, dust, and other factors. They can fill the tiny pores on the surface of the circuit board, forming a continuous protective film. For example, in wind farms by the sea, the concentration of salt spray is high, and silicone coatings can effectively prevent corrosion of circuit boards by salt spray. The coating thickness is generally between 25-75 μ m.
3、 Sealing design
Shell sealing
Sealing strip: Install sealing strips, such as rubber sealing strips, at the interface of the controller housing. The sealing strip should have good weather resistance, corrosion resistance, and elasticity, which can effectively prevent rainwater, dust, and corrosive gases from entering. For example, using EPDM sealing strips, it has good resistance to ultraviolet radiation, ozone, and various chemicals, and can maintain good sealing performance in environments with large temperature changes.
Sealing structure design: Optimize the sealing structure of the shell, using mortise and tenon structures, embedded structures, etc., to increase the sealing performance of the shell. For example, the upper and lower parts of the shell are designed as embedded structures with protrusions and grooves at the joint, which fit tightly during installation and are further sealed with sealing strips to effectively prevent moisture from seeping into the interface.
Internal component sealing
Encapsulation technology: For some key electronic components or modules, encapsulation technology can be used. Encapsulate components or modules with sealing materials (such as epoxy resin, silicone rubber, etc.) to isolate them from the external environment. For example, for the power module in the controller, using epoxy resin encapsulation can prevent moisture, dust, and corrosive gases from damaging its internal circuits, while also serving to fix components and improve vibration resistance.
Airtight sealing: For components that are extremely sensitive to humidity and corrosive gases, such as high-precision sensors, airtight sealing technology can be used. By using a special packaging process, the components are encapsulated in an airtight chamber to ensure a dry and pure internal environment. For example, using metal packaging combined with glass sealing technology can provide a highly reliable sealing environment for sensors.
4、 Environmental control
Temperature and humidity regulation
Heating device: Install a heating device inside the controller to prevent condensation in low temperature and high humidity environments. When the ambient temperature is low, the heating device can raise the temperature inside the controller, avoiding condensation of water vapor on the surface of the circuit board and components. For example, using small electric heating elements, heating is automatically controlled based on data from internal humidity and temperature sensors to maintain the internal temperature above the dew point temperature, which can generally be set at 5-10 ℃.
Dehumidification device: Install dehumidification devices such as adsorption dehumidifiers or condensing dehumidifiers. Adsorption dehumidifiers use desiccants (such as silica gel, molecular sieves, etc.) to adsorb moisture. When the desiccant is saturated, it can be regenerated by heating. A condensing dehumidifier uses a refrigeration system to condense water vapor into liquid water, which is then discharged. Reduce corrosion caused by humidity by controlling internal humidity.
Air filtration
Air intake filtration: Install a high-efficiency particulate air filter (HEPA) at the controller’s air intake to filter out dust, salt spray, and other corrosive particles in the air. The filtration efficiency of the filter should be selected according to the severity of the environment. Generally, for wind farm environments, the filtration efficiency of HEPA filters is required to be no less than 99.97% (for particles larger than 0.3 μ m). This can effectively reduce the entry of corrosive substances into the interior of the controller, protecting internal components and circuit boards.