New energy grid needs DC contactor, new energy equipment equipment need DC contactor to control. In recent years, with the rapid development of new energy vehicles charging facilities, the market capacity of DC contactor, one of the key electrical components, has been expanded. In view of the special needs of this emerging industry, how to the appropriate DC contactor products for the automotive design, charging pile other DC electrical equipment design engineers? What are the key points to focus on? In this paper, the application adaptability of products are discussed.

1、 Electric vehicle charging equipment [4.4 of GB / T 18487.1]:

Electric vehicle power supply equipment is classified according to output voltage:

AC: single phase 220 V, three phase 380 V;

DC: 200V ‐ 500V, 350V ‐ 700V, 500V ‐ 950v.

The preferred value of DC charging current: 80A, 100A, 125A, 160A, 200A, 250A.

Note: power supply equipment higher than 950v shall be decided by vehicle manufacturer power supply equipment manufacturer through negotiation.

As shown in the above, high voltage high reliability are required for commercial electric contactors. Different ordinary industrial contactor products, its manufacturing also requires professional manufacturing processes such as vacuum pumping, gas filling, pressure sealing, intelligent control, etc., has high requirements for design technology manufacturing technology.

2、 Application of DC contactor in new energy vehicle charging pile (machine)

1. Application in charging pile (machine)

It is used for DC charging pile, DC output side of charging station output side of vehicle charger. When the contactor is closed, it can connect the charging pile with the vehicle; when it is disconnected, it can isolate the connection between the charging pile the outside, which plays a role of safety protection.

Application of DC contactor in new energy vehicle charging pile (machine)

2. Application in electric vehicles

DC contactor is set between battery system inverter of electric vehicle. When the system stops running, it can isolate connect when the system is running. When the vehicle is shut down fails, the energy storage system can be safely separated the electrical system of the vehicle to break the circuit. It is used as power control device in other auxiliary circuits. As shown in Figure 2

Application of DC contactor in electric vehicle

Important technical indicators:

a) After the system stops running, it can isolate the power supply end the load end; (important technical index: rated insulation voltage UI)

b) When the system is running, it is used to connect the power supply end the load end; (important technical index: agreed heating current ith)

c) When the fault occurs, it can break the circuit. (important technical index: operating voltage U)

3、 Adaptive design of products

1. Environmental adaptability design:

Different the general industrial contactor products, the use of environmental conditions for electric vehicle contactors more stringent requirements, while meeting the wide temperature range, high protection level, high vibration resistance other basic conditions.

1) High low temperature design: to meet the temperature requirements of electric vehicles charging piles (machines) in extreme weather. The storage environment temperature of the product is - 55 ~ + 125 ℃, the normal working environment temperature is - 25 ~ + 40 ℃, the ambient temperature under the limit condition is - 40 ~ + 85 ℃,

2) Protection grade design: it is required to meet the requirements of normal operation under harsh environmental conditions normal use in rain dust environment. The product can completely prevent dust entering meet the requirements of short-term immersion. The protection grade can reach IP67.

3) Anti vibration performance design: products need to have strong anti vibration impact resistance. It can meet the special requirements of bumpy vibration of vehicles in various road conditions.

2. Safety reliability design

Safety reliability is the key factor to measure the DC contactor of electric vehicle, which is mainly reflected in arc extinguishing ability insulation voltage.

The DC arc has no zero crossing point it is difficult to extinguish the arc after arcing. The structure of the product is designed as double break point direct motion. The technology of filling compressed gas into sealed arc extinguishing chamber can achieve good arc extinguishing ability. The main principle is: after the arc is heated, it forms high-pressure gas with the filled gas, the increase of gas pressure makes the thermal dissociation decrease greatly, the pressure difference between the arc gap the arc extinguishing chamber accelerates the gas movement, intensifies the cooling effect extinguishes the arc rapidly.

4、 Special materials key processes

The R & D design of any product must rely on appropriate raw material selection, advanced process measures, stable parts tooling, perfect manufacturing process before it can be completely transformed into products. Raw materials, manufacturing technology production line are the key elements of design transformation.