EFI AUTOMOTIVE develops a new generation of current sensors

Olivier Brunel, is in charge of Marketing for the e-mobility product families.
Here is his analysis on current sensors and their application in the fast-growing e-mobility market.


Before explaining what a current sensor is, it’s interesting to do a little history… EFI Automotive is a specialist in electromagnetic sensors and actuators. “Originally, more than 10 years ago, we worked on a current sensor installed on lead batteries” says Olivier. When a vehicle stopped at a red light or at a stop sign, as part of vehicle management, the sensor mounted on the lead battery would give an indication of its status to check that it would have enough energy to restart the engine. At the time, the solution proposed by EFI Automotive was chosen by Mercedes for a truck application. Despite the interest of the collaboration, for strategic reasons, it was decided to withdraw from the project.

The magnetic and electronic technology used on these products is at the heart of our know-how and is adjacent to our product families (these are onboard solutions in the powertrain part). We have continued to develop our skills in this field over the years for other applications.
Thus, with the arrival of hybrid and electric vehicles on the market, we naturally returned to the market of current sensors in order to provide solutions adapted to this new type of motorization.

The current sensor project relaunched with the electrification of the automotive market

A current sensor is a sensor that will measure the intensity of the current flowing in electrical conductors.
In a vehicle in general, there are about 20 current sensors. In the case of an engine is electric, it is supplied with voltage and current. The current must therefore be monitored to ensure its proper operation and the movement of the actuator.

For example, all window lifters are controlled by a current sensor to prevent fingers from being pinched. If you put your finger towards the window and the window is moving upwards, a resistance will be created that requires more current. This resistance will be identified by the sensor, which will then command the window to stop.
Another example is the Start & Stop function: if the current sensor detects that the battery is no longer powerful enough, it will not stop the engine at a red light to prevent the vehicle from being unable to restart.

There are therefore several types of current sensors (low current and high current). EFI Automotive, for its part, has decided to specialise in current sensors dedicated to power electronics that operate in very harsh environments, 400 or 800 volts with enormous insulation constraints. This power electronics, composed of three to four current sensors, is the one that powers the electric motor and passes between the battery and the engine.
The solution offered by the torque is what is known as a “packaged” sensor, i.e. a current sensor with a connector and a housing, integrated into a finished product, which will then be sold either to OEMs or directly to manufacturers.

A new generation of components

Sensors currently used in power electronics use magnetic circuits of significant size and weight, adding to the complexity of the sensor. With the new magnetic technologies of the future (currently under development at EFI Automotive), it will be possible to do without these magnetic circuits and simplify the sensor and its integration into power electronics at more attractive prices.
However, these new generation solutions do not yet exist on the market as they are currently in the development phase. However, they are already being promoted to our various customers around the world.

These current sensors can work in synergy with our position sensors for electric motors (e-mobility family) which measure the angular position of the motor. These are the two sensors that are truly vital for the proper control of the electric drive train. Together, they enable the ECU to precisely control the electric motor, its power supply, acceleration and continuous rpm phases.

Our expertise of more than 10 years on this type of sensor now enables EFI Automotive to be a partner of the Volkswagen Group in this type of application.
We also have other developments in progress that will go into series production in 2022 and as a developer of electric Powertrain (GMP), we have already identified other applications on which we can collaborate in the future.

Bringing value to the market with breakthrough innovation

EFI Automotive is positioning itself on electric and hybrid vehicles with the ambition to bring breakthrough innovations that offer a perceptible benefit to the customer. Next, the Group’s strategy will be to broaden the offer, to become a significant market player with a wide range. EFI Automotive is already planning to work on other functions…

For example, in our collaboration with the Volkswagen Group, we are working on the version according to the ID3. The process of prospecting customers and presenting our solution takes time. After all, it takes at least two years from the time the product is presented to the customer until it is put into operation. On this project, the team is in the technology validation phase with the customer. The objectives for the start of series production are for 2023 – 2024.