In the future, environment-friendly automobiles such as electric vehicles (EV) and plug-in hybrid vehicles (PHEV) are expected to become increasingly popular.
Securing the safety of the new vehicles is an important issue.
In Fuji Electric FA Components & Systems, we developed our original "Sealed type High Voltage Contactor" with the world's highest overcurrent withstand capability.
It is compatible with high-performance, high-voltage batteries which have been developed in recent years and contributes to securing the safety of the environment-friendly automobiles.

- Since the EV and PHEV have become popular, we heard that the demand for vehicle contactors is on the rise. First of all, what is a contactor?

Hayama

The operation of electronic device and electric circuit can be controlled by the connecting point that utilizes electromagnetic power to connect and disconnect. More than 60 years ago, Fuji FA Components & Systems released the plunger-type industrial contactor for the first time in Japan. Utilizing this technology, we have newly developed a sealed type high voltage contactor (HVC).

- How can we utilize the HVC?

Suzuki

It is being used for environmentally compatible vehicles such as EV and PHEV that are expected to expand in the future. For EV and PHEV, the contactor opens and closes the electric circuit connecting to the battery, the inverter and the motor. In recent years, batteries mounted on environment-friendly automobiles require high performance, high voltage and large capacity; therefore, it is mandatory for the contactor to meet these requirements.

- Please tell us about the characteristics of HVC.

Hayama

A concern with the battery performance improvement is that in an event of a unforseeable accident, damage caused by over current called "short circuit current" may happen. Since the high voltage battery capacity is getting bigger, the risk of the short circuit current also tends to become higher. As a solution, we developed HVC.

Suzuki

When the short circuit current occurs, a large amount of current flows through the contactor generating electromagnetic repulsive force and disconnects the connection point. Next, it will be followed by a discharge phenomenon called "arc" which may cause the contactor to ignite or rupture. The "overcurrent withstand capability" indicates how large current the contactor can withstand. By researching on the structure of the contactor, we realized the world's highest overcurrent withstand capability of 20,000 amps.

- It means that it holds a structure that can reduce the possibility of accident.

Suzuki

Yes. Furthermore, one feature of HVC is the identical cutoff performance both in the forward and reverse directions. There are two types of EV charging methods: "regular charging" and "quick charging". The charged electricity can be transferred from the car to an external equipment such as the charging system for home. In this case, electrical current will flow through the circuit in the opposite direction which it flowed from when it was charged. General contactor has a polarity against elimination of the arc; the issue was the difference in cutoff performance between charging and discharging. We researched the arrangement of permanent magnets and developed HVC to have identical blocking performance for both directions. With this advantage, we were able to design while eliminating the polarity concern and prevent accident that was caused by using wrong polarity.

Hayama

Also, another feature of HVC is its strength against shock. Generally speaking, contactor has a weakness that it can not properly function when the shock happens to the direction where contact point is moving. By incorporating a permanent magnet into the electromagnet circuit, HVC can withstand a large shock of 50G from all directions.

Suzuki

Many of the high voltage contactors are large-sized, but HVC realized a compact size by shortening the distance required for electricity interruption with the gas sealed in the capsule at the contact point. By tightly closing the contacts, it prevents poor contact with foreign substances such as dust and oil; it achieved higher level of reliability and safety.

- What challenges did you have when you were developing the vehicle contactors?

Hayama

Car is a product that can change our life when it is not properly used. In the same vain, all parts should meet the requirements to be able to prevent any damage in the case of accident. Our customers in automobile manufacturers require zero defects and thorough care of quality control. HVC enables to trace all the operational processes; including manufacturing process and shipment inspection.

Suzuki

Choosing the right gas for sealing the contact point and the method of sealing the gas was especially troublesome. You repeat a number of elemental and environmental tests. The most important thing for a car is the safety. To achieve the safety, verification tests are mandatory. In Japan, there are only a few test facilities. One of the facilities is within our company that can facilitate a large current to the contactor. I was quite nervous when I carried out the first evaluation test. The test was sending a large electric current to the prototype of this product.

Hayama

All automobile parts should have the same quality. It was hard for me to understand various qualities in the manufacturing process and consolidate.

- Please tell us about the future deployment of HVC.

Suzuki

Since 2017, our HVC has been employed by the real field EV. We expect to see the increase in the demand for HVC as the number of environment-friendly cars expands. Of course, the competition of HVC will become intense and I want to carry out product development by working closely with our customers to take advantage of our accumulated industrial contactor and breaker technology.

Hayama

Industrial contactors of Fuji Electric FA Components & Systems occupies 50% of domestic market share; yet our automotive contactor is not widely known. In the future, we will expand the application of HVC not only to the environment-friendly automobiles, but also to the high voltage applications such as hybrid forklifts, construction equipment and uninterruptible power supply (UPS).