Real-world testing of the cooling solution for the 22KW AC charging pile's mainboard!

The heat dissipation of the 22kW AC charging pile's mainboard primarily addresses the triple overlapping issues of high three-phase 32A current, relay heating, and outdoor enclosed conditions.

Actual measurement of heat source:

• Relays/contactors are larger heat sources, with a three-phase power consumption of 45-90W and a contact temperature of 85-110℃. Derating is required if the temperature exceeds 105℃.

• Electrolytic capacitors generate ripple heat, and their lifespan is halved for every 10°C increase, so they must be controlled within 75°C.

• When copper bar terminals are crimped poorly, the local temperature rise can exceed 40℃, posing a hidden fire risk.

Natural heat dissipation:

• The aluminum alloy casing is passively cooled. After operating at full load for 2 hours in a 35℃ environment, the relay approaches its limit at 98-105℃, and the capacitor slightly exceeds its limit at 78-82℃.

• Only applicable to underground parking lots or derated to 16A.

• After adding 20mm cooling fins, the temperature of the relay dropped to 92-98℃, barely meeting the standard. However, the efficiency plummeted after dust accumulation.

Forced air cooling:

• 8025/9225 axial fan + chimney duct with bottom inlet and top outlet, 40℃ full load for 4 hours, relay 72-78℃, capacitor 58-62℃, noise 42-48dB.

• The key is to separate the power area from the signal area, with cold air blowing first through the relays and then towards the MCU; add a dustproof net at the air inlet, and if the air volume decreases by 30% after 3 months, quick disassembly maintenance is required; dual fans provide redundancy, and operate at half speed to reduce noise when below 11 kW.

• The fan is selected as the ball bearing IP55 model, with a lifespan of 3-5 years and a 50% increase in cost.

Thermal conductive material:

• Silicone grease has good thermal conductivity but it will dry and crack after 2-3 years at high temperatures; the thermal pad has a lifespan of over 10 years, and the temperature drop is 2-3℃ more, making it reliable and worthwhile to replace.

• The thermal resistance of phase change materials decreases by 20%, but their cost is 10 times higher, making them only suitable for high-end applications.

• The soaking plate can reduce the temperature of the housing beneath the relay from 105℃ to 88℃, and a fanless silent solution can be considered.

Liquid cooling:

• Cold plate + ethylene glycol circulation, with the relay temperature stabilized at 45-50℃ and noise level below 30dB.

• Suitable for extremely cold regions (with heating function to prevent adhesion), high dust and high altitude areas (with IP67 sealing), and noise-sensitive areas.

• However, the system is complex and costs 500-800 yuan more, and it requires leak detection and power cut-off measures.

Verification method:

• Thermocouple accuracy ±1℃ for attaching key components, infrared thermal imager for locating hot spots and detecting solder defects, and NTC for real-time feedback and overtemperature protection.

• The national standard requires that the device should not be derated under full load in a 40℃ environment.

Selection suggestions:

• Indoor use with natural heat dissipation + fins;

• Outdoor operation piles are equipped with mandatory air cooling, dust prevention, and speed regulation, featuring a 3-year maintenance-free design;

• For high-end communities, use shims, a heat spreader, and a low-speed fan to control noise below 35dB; for extremely cold and high dust environments, use liquid cooling or heat pipes.

The essence of heat dissipation lies in optimizing the heat transfer path. Budget should be prioritized on low on-resistance contactors, high-quality thermal interfaces, and reasonable air ducts. Actual measurements have proven that good air cooling can improve reliability by 3 times compared to extensive natural heat dissipation, with a cost increase of only 15-20%.

The AC charging pile mainboard produced by XinCheng Technology is of high quality and competitive price. Welcome to inquire and purchase!