By Vijayagopal Panchangam
The world population is expected to hit 10 billion by mid-century and 15 billion by the end of this century. ~60 percent of the oil produced is consumed for transportation, while vehicular emissions stand 4th among the largest polluters, motorization rate (number of cars per 1000 people) is expected to grow multifold, thus there is an imminent need to control both the use of oil and CO2 concentrations.
Could we believe the first electric vehicle to be commercialized was in 1884, more than a century and three decades ago? Between 1900 – 1920 in the USA, electric vehicles were in mainstream mobility. After that, electric vehicles took a standstill with the resurgence of IC engines and mass production, electric vehicles remained off-guard till the 1970s. There was a short-lived revival between 1975 to 1998, and the resurgence took place in 2007.
Since the resurgence, hybrid and fully electric vehicle development has rapidly progressed; however, not until 2010 that an automobile could have a full range of operation in complete electric mode with less than 3 kms range. Since then, numerous innovations have been made in the electric vehicle and battery storage space. While the adoption of electric vehicles is picking up; there are still numerous barriers to adopting electric vehicles in mainstream transportation.
I believe the adaption is driven by one faster charging times to replenish the batteries and secondly, larger capacity batteries to increase the range, apart from the policy and socio-economic barriers (or) enablers and most importantly the safety of EVs.
Both these will remove the anxiety amongst users to adopt electric vehicles and allow manufacturers to offer a wider choice of models in the market. For a pure electric vehicle, the battery storage has a direct impact on the range. The solution to overcome this would be high voltage batteries for fast charging utilizing lower current for the same power.
High voltage (typically 525V and high) systems have faster DC charging, lower current for the same power, smaller motors and conductors, increased vehicle performance, and reduced vehicle weight. However, with high voltage systems, there are a few drawbacks, components are less common, higher cost, creepage and clearance issues, and risks of high voltage arc and fault currents lead to safety concerns.
Illustrated above is the simple electric vehicle architecture; as close as possible to the battery, a power distribution unit (PDU) manages the power that goes through the circuit.
The power distribution system essentially consists of a fuse that melts in case of overload, or a short circuit protects the circuit. Contactors switch on and off the power at the rated current.
In today’s electric vehicles, the number one challenge is the coordination between fuse and contactors; this can lead to dramatic situations: Fuses are like a steady flow of current, it ages when extreme fluctuation of currents which is normal for EVs (i.e., start, acceleration, braking) and may start to deteriorate and may not function as desired, and contractors can have a tendency to arc flash during short circuit and high voltage spikes during switchovers, the fuse can react ten times slower.
Coordination between these two is a challenge. Both the aging of the fuse as well as poor coordination of fuse and contactors can cause a fire or explosion hazard inside the vehicle.
At the core of Eaton, smart power management and advanced circuit protection are our mission. To overcome the challenges with high voltage and current systems, need to achieve a balance on 3 requirements, number one is the safety of the occupants, environment, and the asset, number two is to manage the high voltage and increasing current levels, and number three being able to seamlessly integrate into the systems and operate at flash speeds in the vehicle.
Through extensive research and technology development, Eaton has developed an innovative device with a combination of circuit breaker and contactor.
It sits inside the Power Distribution Unit and replaces the fuse and contactors, has many advantages over conventional protection, improves vehicle safety and protects components from the high level of overcurrent conditions, lightning-fast response, safe actuation at higher voltage and current levels, resettable like a circuit breaker, enables reactivation of the device following a functionality check, current limiting in the event of a short circuit, independent of the current direction in the circuit, offers active and passive safety and last but not least available in multiple configurations including voltage levels and multi-pole configurations. With these features and functionality, it would help manufacturers to adopt this in the system safely and push the envelope toward higher system voltage architectures.
The future is electric mobility, and it’s not far away to reach the masses; I believe with the advent of innovations in power electronics, battery technology, motors, system safety, and infrastructure development, electric vehicles will take a leapfrog in the not-so-distant future.
The author is Vijayagopal Panchangam, Head-eMobility, Eaton India Innovation Center, Pune.
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