A Coordinated Boost Control in a Twincharged Spark Ignition Engine With High External Dilution

Abstract

This paper proposes a novel master-slave control strategy for coordination of throttle, wastegate and supercharger actuators in an electrically twincharged engine in order to guarantee efficient boost control during transients, while at steady state a throttle-wastegate coordination provides minimum engine backpressure hence engine efficiency elevation. The benefits and challenges associated with Low Pressure Exhaust Gas Recirculation (LP-EGR) in a baseline turbocharged engine, including improved engine efficiency, mainly due to better combustion phasing, and sluggish engine response to a torque demand due to slowed down air path dynamics were studied and quantified in [1]. Hence in this paper an electrical Eaton TVS roots type supercharger at high pressure side of the turbocharger compressor (TC compressor) is added to the baseline turbocharged engine and the performance of the proposed controller in the presence of LP-EGR, which is a more demanding condition, is evaluated and compared to the turbocharged engine. One dimensional (1D) crankangle resolved engine simulations show that the proposed master-slave control strategy can effectively improve the transient response of the twincharged engine, making it comparable to naturally aspirated engines, while the consumed electrical energy during transients can be recovered from the decreased fuel consumption due to LP-EGR conditions at steady state in approximately 1 second. Finally, a simple controller is developed to bypass the TC compressor and maximize the engine feeding charge during the transients in order to avoid TC compressor choking and achieve faster response.

Numerical Investigation on the Effects of the Setting of the Load Control System of a Formula SAE Single-Cylinder Turbocharged Engine on Fuel Efficiency and Performance

“…In view of the future FSAE competitions, the combined adoption of a BPV with an efficiencybased schedule (EBS-BPV system) was proposed to contemporarily improve transient response and efficiency. In fact, despite the higher complexity requiring a different sensors positioning [8], the recirculation of compressed air due to the BPV can reduce the energy exchanged between blades and airflow, thus maintaining the turbocharger at high speed and reducing turbo-lag intensity. Moreover, the design of a smart EBS aimed at reducing fuel usage is well-suited to improve the final score.…”

Control of hybrid boosting in highly diluted internal combustion engines

“…3,4 The planetary gear set and the motor in the PSS decouple the supercharger (SC) boost from the engine speed, creating a high-bandwidth high-stroke boost actuator similar to electric boosting systems. 5,6 This benefit comes at the expense of an extra fuel penalty compared to a traditional turbocharger, which takes advantage of waste energy recovery but has a lower bandwidth. The control design of such system is critical to the engine fuel consumption.…”

“…Although engine air path hybridization can also be achieved through electrically assisting the turbocharger, 9 or electric supercharging, 5,10 the PSS is only partially powered by the electric motor, thus can maintain a near charge sustaining operation. 11 In addition, this system can further increase the vehicle fuel economy through start–stop and regenerative braking.…”