Abstract
Among all vehicle classes, light duty trucks were some of the first electric vehicles commercially available on the market. Electric LDTs are viable, because the drive cycles of fleet customers are tolerant of the typical disadvantages of EVs, specifically shorter range and higher refuelling time over ICE vehicles. In many fleets, the advantages of electric LDTs heavily outweigh the disadvantages: lower running costs, maintenance costs and zero-emissions.
Building an electric vehicle from the ground-up allows optimizing all aspects regarding battery system packaging, powertrain configuration and auxiliary systems. With a new design the overall efficiency of the system can be improved. Due to the lower volume of electric vehicles produced it is still more cost-effective to electrify an existing vehicle, rather than designing a new vehicle for a fleet from scratch. Changes to the frame of commercial vehicles are expensive and limit the vehicle’s versatility as many special types of equipment are based on standard frame design.
After detailed benchmark analysis, IDIADA has electrified a light duty truck without BiW changes. Simulations using average daily cycles from fleet owners were performed to determine the specifications of the motor and the battery needed to fulfil the vehicle requirements. Since many critical components such as the heating, air conditioning, power steering, 12V supply and brake assist systems were all driven by the accessory-belt of the original internal-combustion engine, these had to be replaced with electrically-driven equivalent systems. The air conditioning and heating chosen are high voltage systems powered directly from the high-voltage battery; this allows for higher efficiency. Efficiency was a key criterion in choosing the replacements.
Extensive CAD was performed to integrate these systems with minimal impact on the frame. All control functions were integrated in the Edrive Control System, a control unit developed in-house specifically for electric vehicles. The software is developed using Simulink and makes use of automatic code generation. This allows for rapid development of new algorithm, debugging and validation as well as integration in new vehicles. All state-of-the-art HV safety concepts were implemented in the truck, such as interlocks on all high-voltage connections, isolation monitoring and service disconnect.
The vehicle range was validated on track and roller benches using different cycles such as NEDC[1], FTP-75[2] and customer cycles. Heater and air conditioning were turned on at different ambient temperatures to show the influence on the driving range.
KEYWORDS: Electric Truck; Electric Vehicle Architecture; Light duty trucks; vehicle development; powertrain