The Lotus Evora 414E REEVolution concept showcases a plug-in, range-extended electric propulsion hybrid vehicle, with new electronic technologies to enhance driver involvement. The chassis is the same award-winning, versatile vehicle architecture used on the Lotus Evora, with an interior and exterior scheme inspired from the Lotus Evora Sport Racer.
Series hybrid electric vehicles solely utilise an electric drivetrain for propulsion. Electric power is provided by a combination of a battery pack and a range extender engine, coupled to an electric machine acting as a generator. For this reason, series hybrid vehicles are typically electric vehicles, designed for urban driving, that use the internal combustion engine to extend the range of the vehicle for extra-urban driving.
The Lotus Evora 414E REEVolution (414E) hybrid uses a series hybrid electric drivetrain, not in a vehicle designed for urban driving, but in a lightweight sports car. The project requirements for this vehicle are to match the performance of a Lotus Evora in track conditions as well as accelerate the vehicle from 0 to 60 miles per hour in 4.4 seconds. Electrical energy is provided to the battery from the Lotus range extender engine, which is capable of delivering 35 kW of continuous electrical power.
The motors, the inverters and the battery system have all been designed as part of the 414E vehicle program. As this design process has happened concurrently alongside the vehicle design, detailed simulation models of the vehicle were developed and used to drive component specifications.
For example, the simulation work showed that if the vehicle was to achieve its performance targets, then an aggressive weight down strategy was required on the battery as well as water cooling. This was to increase the continuous power capabilities of the battery. This has resulted in a battery with a class leading power to weight ratio.
The 414E vehicle has been designed to demonstrate the abilities of a range extended electric vehicle (REEV) in terms of acceleration, top speed, range, weight and CO2 emissions.
The range extender engine used in the 414E is a three cylinder, normally aspirated petrol engine, capable of producing 35 kW at 3,600 rpm.
Directly coupled to the crank shaft of the engine is a 35 kW electric generator. The generator is a permanent magnet machine based on axial flux technology.
There are two traction motors on the 414E. Each motor has a maximum power of 150 kW, a maximum torque of 500 Nm and a maximum speed of 8,000 rpm.
Each of the two motors drives a rear wheel on the car, allowing for individual torque control of the rear wheels. This controls allows for a electronic differential to be implemented meaning that torque vectoring can be implemented to aid the cornering ability of the car.
The motors are connected to a common gearbox housing, which contains two separate gear sets. Each gear set reduces the speed of the motors by 4.565:1.
Each motor is controlled by a dedicated traction inverter module (TIM). These are mounted directly on top of the motor, allowing for direct connection to the motor phases. Each TIM is rated to 150 kW and has an integrated cooling jacket, which is connected to the coolant jacket for the motor.
The generator is controlled by a generator inverter module (GIM). The GIM is located away from the generator and has a cable connection from the GIM to the generator. The GIM is rated to deliver a constant 35 kW of electrical power from the generator.
Also included in the vehicle is a high voltage fluid heater, which heats the water in the cabin heating circuit. A high voltage air conditioning compressor provides charge to the air conditioning system. Two 1.5 kW DC-DC converters provide power to the low voltage bus and charge the 12 V battery. A charger is included on the vehicle, which can charge the battery from the mains at 3.3 kW.
A HALOsonic noise management solution has been integrated onto the vehicle to both improve pedestrian safety and to enhance the driving experience of the vehicle. The system comprises a number of internal and external speakers that is able to cancel out unwanted road and engine noise, and supplement it with simulated external noises for pedestrian safety and internal noises for driver experience.
HALOsonic is a range of products, which includes: external sound synthesis, internal sound synthesis, road noise cancellation and engine order cancellation. The HALOsonic range has been designed by Lotus Engineering and HARMAN Automotive and offers a production ready technology as a stand-alone or integrated ICE system solution.
Governments around the world have acknowledged the increased risk posed by almost silent vehicles and are in the process of drawing up legislation to compel car manufacturers to equip vehicles with pedestrian warning systems like the HALOsonic system.
The vehicle incorporates two paddles, situated behind the steering wheel, to simulate the effect of engine braking. The amount of regenerative braking that is applied is varied, depending on the what ‘gear’ the driver chooses. This system allows for more precise control of the levels of regenerative braking, maximising the driver control in track situations.
The REEVolution consortium, led by Jaguar Land Rover consists of three suppliers: Axeon Technologies Ltd, EVO Electric Ltd and Xtrac Limited; and three vehicle manufacturers: Jaguar Land Rover, Lotus and Nissan Motor Company Ltd. for INFINITI brand.
Three demonstrator vehicles (414E, Emerge-E and XJ-E) showcase innovative new technologies. The cars are ‘best in class‘ and combine and build on the skills of all of the businesses involved.
The driving force behind is to build a UK supply chain for new ultra low carbon vehicle technologies and position suppliers so that they can exploit the global market. The total cost of the project including industry investment is over £20M. Just over £9M of this was grant funding from the Technology Strategy Board.
The exhibit showcased a new intelligent HALOsonic system is displayed in the cutaway hybrid Evora 414Evolution exhibit along with a supercharged version of the Lotus range extender engine.
HALOsonic: Sound Technology with Vision
A next generation intelligent pedestrian warning system, integrating the advanced HALOsonic sound synthesis system with video technology. This cutting-edge enhanced version of the HALOsonic safety system incorporates input from imaging sensors to enhance the quality of the sound synthesis system.
Using a single camera to determine the distance, trajectory and speed of pedestrians and other road users to calculate the risk of collision by comparing this information with the car’s path. The system actively control the volume of the external sound synthesis to warn pedestrians of the vehicle’s location, thereby improving pedestrian safety and reducing noise pollution. Under certain conditions the system will generate an audible and visual warning for the driver using the internal sound synthesis and instrument panel.
The system is optimised to operate in urban environments where there is the greatest risk of a collision with a pedestrian. It is calibrated to actively control the volume and pitch of the sound synthesised while the vehicle is travelling from 0-75 km/h, continually evaluating the risk of a pedestrian collision and operating in an area up to 60 metres ahead of the vehicle. All of the HALOsonic systems are designed to use low levels of power and with the new active version there will be less power consumed as the system will only increase the volume when there is a risk of an impact.
The first concept car was shown at Geneva in 2010. In addition to the hybrid drivetrain and user involvement technologies, the concept showcased a dramatic new roof system and interior concept from Lotus Design.