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VITESCO TECHNOLOGIES Romania uses Ansys for automotive applications

Vitesco Technologies brings together the full expertise of drive technologies. The company’s aim is to develop innovative, efficient electrification technologies for all types of vehicles. Portfolio includes 48-volt electrification solutions, electric drives, and power electronics for hybrid and battery-electric vehicles. Furthermore, the product range counts electronic controls, sensors and actuators as well as solutions for exhaust after-treatment. With each and every solution, Vitesco Technologies consistently pursues its mission: POWERING CLEAN MOBILITY.

Summary - wireless Battery Management System (wBMS)

  • Task

The BMS is the brain of any electric vehicle’s battery pack. Its purpose is to evaluate the overall functionality and safety of the battery. The general functions are data acquisition; storage and processing; electrical and thermal management; voltage & current protection; safety management and cell balancing & communication.

The primary module (BMS) requires a communication link from each battery module. The last, are monitored via a Cell Supervising Circuit (CSC), individually mounted for each module. Vitesco Technologies Battery Management Systems can be used for a wide range of plug-in hybrid vehicles (PHEV) as well as for battery electric vehicles (BEV).

  • Solution

In order to evaluate the possibility of migrating from a physical wired communication link between the BMS-CSC, to a wireless solution based on Inverted F-type Antennas (IFAs), a thorough 3-D electromagnetic (EM) simulation needs to be performed. This is done by using the ANSYS HFSS simulation software. In our analysis the complex environment of a generic battery is used, in order to evaluate the efficiency of the transmitted RF power.

  • Customes benefits

By shifting from a conventional cable communication system to a wireless antenna-based solution, important gains can be obtained by the exclusion of cables and connectors (reducing the bill of materials); the increase of energy density of the battery pack; the flexibility in adaptation of modules and the diminishing of recall/ repair time intervals of EV batteries.

Project details

  • Task

Vitesco Technologies integrates innovative and efficient powertrain system solutions for vehicles, such as battery electric (EV), hybrid (HEV), and fuel cell electric (FCEV). For evaluation of the feasibility for a wBMS system, EM simulations need to be performed for the PCBs with the integrated antenna solution. As the performance of the IFA is very susceptible to the PCB stackup, epoxy-resin used and RF environment, two distinct cases will be investigated: the free-air scenario (PCBs with/ without plastic housings) and the final fixture, in which the wireless modules are included inside the battery.

As the project presents demonstrative purposes, non-commercial generic geometries will be used. The PCBs present a 4-layer stackup, epoxy FR4 resin (εR=4.4 and tan(δ)=0.02) and copper traces. Return & insertion losses, radiation efficiency and 3-D profiles, as well as field propagation in space will be computed via ANSYS HFSS. Based on simulations, the feasibility of this technology is evaluated for the next generation of BMS developed by Vitesco Technologies Engineering.

Top view of PCBs with antennas for wBMS (left) and wCSC (right) with no plastic housing

Trimetric view of PCBs with antennas for wBMS (left) and wCSC (right) presenting their plastic housings

Trimetric view of the battery box with RF units mounted on the top of the cells (left) and in the middle channel of cells (right)

  • Solution

To study the RF performance of this arrangement, a driven modal solution is implemented within ANSYS HFSS. The aim is to use the existing Bluetooth bandwidth, hence a 2.44 GHz analysis is conducted. A frequency sweep from 2 up to 3 GHz is carried in order to observe the performance of the system outside its frequency spectrum. An optimization function is imposed, by using algorithms from ANSYS HFSS, to further improve the original antenna geometry. Thus, the overall performance of the wireless modules is increased. Last, a matching circuit is imposed via the Circuit simulation tool, integrated inside ANSYS HFSS.

3D view of EM radiation profiles for wBMS (left) and wCSC (right) in free air

Return losses for wBMS (red) and wCSC (green) and insertion loss (blue). Results are shown before antenna optimization (left) and after (right) for the free air scenario

Side view of E-fields inside battery pack at phase = 0° (upper) and phase = 90° (down)

Insertion loss for wCMUs mounted on top of channels (left) and wCMUs mounted in the mid side channel (right)

  • Customer benefits

By creating a virtual fixture of a wireless BMS-CSC for EV batteries, and running detailed simulations via ANSYS HFSS, the following can be done:

- Investigate EM field propagation inside a battery box and push forward this emerging technology
- Further study and improve existing antenna design for such applications
- Increase the efficiency of transmitted RF power
- Perform virtual prototyping for existing solutions
- Reduce bill of materials and costs
- Create a strong feedback loop with existing customers