Rethinking component design for electric vehicles
Despite being first invented in the 1830s, Electric Vehicles (EVs) have only become commercially viable in the last decade. Steve Hughes, Managing Director of REO UK, explains the challenges faced by automotive companies designing the next generation of EVs.
The global effort to reduce carbon emissions and improve air quality is increasing pressure on car manufacturers to transform their portfolios. Swedish manufacturer, Volvo became the first major automaker to announce a move to an all-electric range by 2019, which has since been followed by Mercedes-Benz and the Volkswagen group.
EV sales reached over 750,000 worldwide in 2016 and, as new legislation is introduced to limit the types of vehicles that are allowed into major cities, this figure is forecasted to increase. For example, France, Germany and the UK have all announced plans to ban the sale of diesel and petrol vehicles from 2040 because of concerns with the rising levels of nitrogen oxide (NOx) emissions and the resulting risk to public health.
While EVs pose substantial benefits to the environment in comparison to internal combustion vehicles, one of the biggest challenges for EVs is the design of the individual components.
According to Toyota, the average car is made up of 30,000 parts and each component must be able to withstand repeated bouts of acceleration and braking. This is in addition to being able to perform in varying weather conditions and low and high-speed driving over smooth and rough terrain.
With so many electrical and electronic components working in such close proximity to each other, EVs run a greater risk of experiencing power quality issues. The reason for this is that, while EV components provide a much more efficient way of transferring energy, the process of power conversion used by these electronics can result in electromagnetic interference (EMI).
EVs are designed so that the same lines that deliver power to the vehicle are also used to provide information like the charge status, temperature and voltage to the battery management control system. EMI issues, if left unaddressed, can result in efficiency losses, the vehicle overheating and interference with the vehicle’s data communication systems, jeopardising the accuracy of the data.
The components used in EVs can be both inductive and resistive, such as Radio Frequency Interference (RFI) filters, chokes and dynamic braking resistors. Together, these components ensure that drive energy is stored, delivered and regenerated to provide the highest efficiency.
At REO, we have used our experience of dealing with these types of components in railway traction applications to develop and integrate EV technology into production vehicles for some German automakers. To put the components through their paces, REO has their own employee e-cars and e-station.
The REO PFC Choke (CHI 412), for example, has been designed to limit the mains harmonic currents that are generated by non-linear AC power supplies, while the REO common mode choke (CHI 131) features a high performance impulse filter, which eliminates noise in the inverter that occurs due to high frequency switching.
As EVs become increasingly mainstream, it’s important that design engineers and automotive companies understand the importance of assembling their latest models with components that address power quality issues.
The components used in internal combustion vehicles have undergone a century and a half of design refinement. It is only when we have resolved the issues concerning component design that EVs will be positioned as a more sustainable alternative to petrol and diesel cars.