• • • ELECTRIC VEHICLES • • •
resulting in the extraction of electrons from the hydrogen. These electrons then create electricity, which is stored in a small battery used to power the vehicle. If the hydrogen used to power them is produced
using electricity from renewable sources, the result is a completely carbon-free transport system. The only end products of the fuel cell reaction are electricity, water and heat, and the sole exhaust emissions are water vapour and air, making them more aligned with the EV rollout. However, they do have some operational shortfalls. Fuel cells are unable to work under heavy loads
for a long time, which presents issues when rapidly accelerating or decelerating. Studies into fuel cell function have shown that, when an FCEV begins accelerating, the fuel cell’s power output increases gradually to a point, but then it begins to oscillate and drop despite velocity remaining consistent. This unreliable power output presents a challenge for automakers. The solution is to install a fuel cell for a higher
power requirement than necessary. For example, if a FCEV needs 100 kilowatts (kW) of power, installing a 120-kW fuel cell would ensure there is always at least the required 100 kW of power available, even if the fuel cell’s power output drops. Opting for this solution requires a DBR to remove the excess energy when not required, by performing a “load bank” function. By absorbing the excess energy, DBRs protect
an FCEV’s electrical system and also enabling them to be very reactive to high power demands and accelerate and decelerate rapidly without storing excess energy in a battery.
Cressall’s EV2 To meet each of these applications for DBRs in the EV space, Cressall’s EV2 DBR offers a tailored solution. When selecting a DBR for an EV application, automakers must consider a few key design factors. For all vehicles powered by electricity — be it a battery or a fuel cell — making components as lightweight and compact as possible is a top design demand. In response to these demands, Cressall’s EV2 is
the most compact and lightweight solution available to the EV market, offering ten kW of power per cubic decimetre (dm3) and 9.3 kW of power per kilogram. It’s a modular solution, meaning up to five unit can be combined in a single assembly to meet power requirements of up to 125 kW.
Being water cooled, heat can be dissipated
safely without the need for extra components, such as fans, as is the case with air-cooled resistors. This means that the EV2 is 10% of the volume and 15% of the weight of a conventional DBR, lightening the load of the vehicle itself, meaning it can travel further on the same amount of fuel. While DBRs are an essential element of an
EV braking system, selecting the right one is essential to efficient operations. Offering unrivalled compact, lightweight qualities, the EV2 Cressall allows automakers to meet their design and safety requirements without forfeiting weight or size qualities.
electricalengineeringmagazine.co.uk
ELECTRICAL ENGINEERING • NOVEMBER 2022 29
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