Relay is a necessary and core electronic control basic component in the complete machine circuit control system, widely used in home appliances, industrial control, automobile, communications, electric power, energy, security, aerospace and other fields, the main role is to achieve "automatic, remote" control.

I. technical principle

In the field of traditional automobile, relay is mainly applied in circuit opening and closing control, including wipers, Windows, lights and other electrical appliances. Traditional automobile relay is applied in low-voltage products with a voltage range of 12-48v.

Figure 1 basic structure of relay

The voltage of the main circuit of new energy vehicles is generally greater than 200V, far higher than 12-48v of traditional vehicles. In addition to the low-voltage relay required by traditional cars, new energy vehicles also need to be equipped with special high-voltage dc relay.The HVDC relay is mainly configured between the battery system and the motor controller of the electric vehicle.

Figure 2 application of HVDC relay in new energy vehicles

In terms of application types, the most commonly used HVDC relays for new energy vehicles are vacuum and gas-filled relays.

Vacuum is an ideal insulation.Since the high voltage arc is generated by ionization of the dielectric, and the vacuum itself has no dielectric, there is a good isolation between the contacts.The complete vacuum state is only an ideal state. In fact, there will be some residual oxygen, which generates copper oxide with the copper electrode in the case of arc. The contact resistance increases, and the relay has the risk of failure.

At present, gas-filled relay is mainly applied, and gas-filled relay's main arc extinguishing solution is hydrogen and nitrogen.Filling pure hydrogen with deflecting magnet to assist arc extinguishing is better than vacuum pumping and nitrogen charging. Hydrogen has good insulation performance and is hard to ionize.

Figure 3 comparison of arc extinguishing gas types of HVDC relays

2. Basic functions and development trend

As a key safety device in new energy vehicles, HVDC relay should have the basic functions of high voltage resistance, load resistance, impact resistance, arc extinguishing ability and breaking ability.The specific content is as follows:

Figure 4 basic functions of HVDC relay for new energy vehicles

In addition to the basic functions of high pressure resistance, load resistance, impact resistance, strong arc extinguishing capability and strong breaking capability, new energy vehicles will also put forward more requirements on the technical improvement and cost reduction of the products.Generally speaking, HVDC relay will develop towards lightweight, energy-saving, intelligent and low-cost.

Figure 5 development trend of HVDC relay technology for new energy vehicles

3. Market status and trend

HVDC relay is the core part of new energy vehicles, is forming a new automotive relay market.The demand for HVDC relays generated by new energy vehicles is characterized by high individual value, rapid and sustained market growth, low price and high quality of domestic products, and the formation of domestic substitution trend.

Depending on the type of vehicle and the power system, the number and scale of relays used in automobiles are also quite poor.On average, each new energy vehicle should be equipped with 5-8 HVDC relays -- 2 main relays, 1 pre-charger, 2 quick chargers, 2 ordinary charging relays and 1 auxiliary machine relay of high voltage system.

The development of HVDC relay industry for new energy vehicles is mainly affected by the sales volume of new energy vehicles. It is estimated by public consultation that the market size of HVDC relay for new energy vehicles in 2018 will exceed 2 billion yuan.

HVDC relays have higher added value than traditional relays.Generally, each car USES 20 relay products, and the price of each relay varies from 3 to 10 yuan. Based on this calculation, the value of traditional relay for a single car is 60-200 yuan.In the new energy vehicles, the HVDC relay, the price of a single vehicle is about 2000-3400 yuan, more than 10 times the traditional car.

The rapid growth of production and sales of new energy vehicles will support the broad market of HVDC relays for new energy vehicles.It is estimated that the market size of high-voltage relay for new energy vehicles will exceed 4 billion yuan by 2020.(for more information, please refer to the "report on the market prospect and investment of China's high-voltage relay for new energy vehicles in 2018-2022")

The rapid development of "quality" and "quantity".In the application field of HVDC relay, except for new energy vehicles, there is a large demand space in charging equipment, high-pressure plug-ins and other fields, and the market potential will be gradually released with the development of the industry.After the rapid development in 2017, 2018-2020 is a stage of rapid increase in new energy vehicle products and rapid development of the market, and the performance and quality requirements on components will also be improved.Therefore, in the next few years, the HVDC relay market for new energy vehicles will show a rapid development trend in both "quality" and "quantity".

4.The pattern and trend of enterprise competition

Compared with traditional relays, HVDC relays for new energy vehicles have high technical content and complex production process. From the perspective of global market pattern, HVDC relays have a high concentration of brands.The production and r&d of products in this field are mainly concentrated in foreign enterprises, including tyco, panasonic, omron and Bosch.Domestic brands such as hongfa and other enterprises have entered the new energy vehicle HVDC relay market.

In recent years, it shows the rising trend of domestic brands.Among the foreign brands, omron, tyco and panasonic have the manufacturing capacity of HVDC relay, but the investment in large-scale construction is weakened, and the product cost and technical iteration are weakened.China's leading enterprises continue to expand the market with the advantage of quality and low price. In 2013, jac HVDC relay supplier was replaced by panasonic as hongfa stock. In 2017, ningde times signed a cooperation agreement with hongfa to replace panasonic products.In addition, China's HVDC relay has also entered the tesla industrial chain, which will further expand the market share at home and abroad in the future.