A large amount of heat is generated during high-power charging and discharging of on-board chargers. Failure to dissipate heat in a timely manner will greatly degrade the performance and service life of internal electronic components.

Working Principle of Vehicle OBC (On-Board Charger): AC power from grid is rectified into DC power by bridge controlled rectifier circuit. After filtering, the DC power is supplied to high-frequency DC-DC power converter. The converter outputs required DC voltage via DC-DC conversion. After secondary filtering, power is supplied to charge the power battery of BEV. The on-board charger communicates and matches with public charging piles to realize communication interaction and power adjustment in accordance with national standard GB/T 20234.

We will discuss OBC and its applicable thermal materials based on three structural schemes: standalone on-board charger, OBC+DC/DC 2-in-1, and OBC+DC/DC+PDU 3-in-1.

Working principle of on-board OBC 

1. Standalone On-Board Charger

The charger is mainly composed of circuit board, die-casting shell, connectors, water-cooled cooling structure, etc., with a working temperature not exceeding 85 ℃.

The product of this scheme adopts the following thermal conductive materials:

1. EMI filter heat dissipation: It is recommended to use Haopengda Technology TC200 series ultra soft silicone gasket, with a hardness of Shore C 18 and good compressibility, which can better fit the irregular shape of the filter surface for heat transfer.

2. Heat dissipation of bus capacitor: It is recommended to use Haopeng Technology TC200 series ultra soft thermal conductive silicon film, or use TC820 two-component thermal conductive gel, which can fully contact the outer surface of the circular capacitor and transfer heat to the shell.

3. PCB board heat dissipation: It is recommended to use Haopengda Technology TC100X material to adhere to the back of the PCB. This gasket is reinforced with glass fiber cloth and processed through special technology. It is a very soft and highly compressible thermal conductive silicone gasket that can tightly contact electronic components and has strong anti puncture and anti leakage functions

4. Transformer heat dissipation: It is recommended to use the TC200 series material from Haopengda Technology, which has high thermal conductivity, breakdown voltage resistance greater than 5Kv/mm, high tear resistance, low thermal resistance under low pressure, and self-adhesive properties, making it easy to operate.

2. OBC+DC/DC 2-in-1 charger

This product is an OBC+DC/DC two in one charger with the characteristics of small size and high power. It adopts a die-casting shell and air cooling method for heat dissipation.

The product of this scheme adopts the following thermal conductive materials:

1. EMI filter heat dissipation: The TC200 series of Haopengda Technology is an ultra soft material with a hardness of Shore C 18, which has good compressibility and can better fit the irregular shape of the filter surface for heat transfer.

2. Heat dissipation of bus capacitor: Haopeng Technology TC200 series or TC820 series thermal conductive gel can fully contact the outer surface of the circular capacitor and transfer heat to the shell.

3. PCB board heat dissipation: Haopengda Technology TC100X material is used to bond the back of the PCB. The gasket is reinforced with glass fiber cloth and processed by special technology. It is a very soft and highly compressible thermal conductive silicone gasket that can be in close contact with electronic components and has strong anti puncture and anti leakage functions

4. Transformer heat dissipation: Haopengda Technology TC300 series material, this high thermal conductivity material, has a breakdown voltage resistance greater than 5Kv/mm, high tear resistance, exhibits low thermal resistance under low pressure, and has self-adhesive properties, making it easy to operate.

5. Output capacitor heat dissipation: Haopengda Technology TC200 series ultra soft thermal conductive silicone gasket

6. Rectification tube heat dissipation: Adopting Haopengda Technology TCX900S thermal insulation sheet, this material uses glass fiber cloth as reinforcement material, which has good cutting resistance and thermal conductivity of up to 1.6W/mk.

3.OBC+DC/DC+PDUThree in one product

This product is a comprehensive product, including a high-voltage box, a DC converter, and a car charger. Its main functions are as follows: the high-voltage box assembly is mainly used to place electrical components such as relays, fuses, and pre charging resistors, including fast charging relays, high-voltage accessory relays, high-voltage accessory pre charging relays, pre charging resistors, PTC relays, PTC fuses, DCDC fuses, compressor fuses, slow charging fuses, fast charging fuses, splitters, copper bars, etc.

This type of product uses TC300 series high-performance thermal conductive material to adhere to the back of the PCB board and fill the gap with the shell. Then, TC820 two-component heat conduction gel is used for overall encapsulation to meet the requirements of heat conduction of high heat generation of high power equipment such as charging, high and low voltage conversion and high voltage distribution box, and combined with water cooling for heat dissipation.

TC820 has a pressure resistance performance of>7Kv/mm, which can better protect electronic components. Low compression stress and high compression can provide shock absorption protection for components. The 2.0w thermal conductivity can quickly transfer heat and meet the internal temperature balance of the equipment. The use of automated equipment has higher dispensing efficiency.