Lotus Engineering designed and integrated the complete drivetrain for the PROTON Emas a plug-in series hybrid city car, styled by Italdesign and unveiled at the Geneva Motor Show.
Our work included an electrical drive system with single-speed transmission, which delivers low emissions, optimised performance and acceptable electric-only operating range for city use. For longer journeys, when the battery charge level falls, the 3 cylinder, 1.2 litre Lotus Range Extender engine is used to replenish the charge in the battery and provide electrical power for the drive motors.
The battery can also be recharged via an AC mains domestic outlet to achieve initial electric-only operation.
The vehicle energy storage system is made up of 11.5 kWh Lithium Polymer batteries with over 100 kW discharge capability. It includes fusing, power distribution and high voltage interlock safety system hardware.
The generator converts mechanical energy to electrical energy for battery pack charge maintenance and vehicle range extension. The generator is also used as a motor for range extender engine starting. It has a power of 41 kW 280-420 VDC generator and starter motor for the range extender engine.
The high voltage inverter converts and controls the three phase voltage from the generator to DC voltage to charge the battery and run the traction motor.
The traction motor provides 75 kW peak and 45 kW continuous power with a 280-420 VDC motor. The motor converts electrical energy to provide mechanical energy to the driven wheels through the transmission.
The high voltage inverter traction motor converts DC voltage to three phase voltage.
The Proton Concept uses a single-speed transmission with an integrated differential.
The high voltage charger converts AC mains power to high voltage DC to charge the battery pack. It produces 3.3 kW, with 90-265 V AC single phase with CAN control.
The DC-DC Converter maintains charge in the 12 V vehicle battery by taking power from the high voltage battery pack. It is the electric vehicle equivalent of the alternator and converts 1.5 kW of power from 420 V to 13.8 V.
The three-cylinder 1.2 litre Range Extender engine is optimised between two power generation points, giving 15 kW of electrical power at 1,500 rpm and 35 kW at 3,500 rpm via the integrated electrical generator. Its low mass of 56 kg and compact package makes it ideal for the series hybrid drivetrain in the Proton Concept.
The vehicle controller is a microprocessor that controls the throttle, torque, power and energy management and is the same T6e engine management software as used on the Lotus Evora.