Modeling and Control of Co-Surge in Bi-Turbo Engines*

Abstract

Abstract:Using a bi-turbocharged configuration makes for better utilization of the exhaust energy and a faster torque response in V-type engines. A special surge phenomenon that should be avoided in bi-turbocharged engines is co-surge, which is when the two interconnected compressors alternately go into flow reversals. If co-surge should occur, the control system must be able to quell the oscillations with as little disturbance in torque as possible. This paper presents a model of a bi-turbocharged engine based on a Mean Value Engine Model that includes a MoreGreizer compressor model for surge. The model is validated against measured data showing that it captures the frequency and amplitude of the co-surge oscillation. The effect of momentum conservation in the pipes is investigated by adding this feature to the control volumes before and after the compressor. This gives a slightly better mass flow shape with the drawback of increased simulation time, due to more states and a higher frequency content in the model. A sensitivity analysis is performed to investigate which model parameters have most influence on the co-surge behavior. It is shown that the largest influence comes from the turbocharger inertia, the volumes after the compressor and the "zero mass flow pressure ratio" during flow reversal in the compressor. The model is used to investigate principles for control strategies to detect and quell co-surge. The detection algorithm is evaluated on measured data.

Co-Surge Detection and Control for Bi-Turbo Engines with Experimental Evaluation

“…Studies of surge in bi-turbocharged engines are even scarcer, although the problem of one compressor pushing another into surge, when connected to a common intake, was pointed out by Watson and Janota (1982). The main contributions of this paper is an extension and experimental evaluation of the detection and control strategy for co-surge presented in Thomasson and Eriksson (2011). The paper strengthen the model validation from that paper with measurements from a vehicle dynamometer.…”

“…To do this a model that can capture the most important system properties, in this case cosurge, is needed. The model was outlined in Thomasson and Eriksson (2011) and in this paper the model validation is strengthened with additional measurements including turbocharger speed.…”

“…The model parameters have been tuned for best fit in this region. A study of how the model parameters affect the co-surge behavior was presented in Thomasson and Eriksson (2011).…”

A surge and choke capable compressor flow model—Validation and extrapolation capability

“…Currently e.g. series sequential (Chasse et al, 2008;Galindo, Climent, Guardiola, & Domenech, 2009;Zhang, Deng, Wang, & Zhu, 2008), parallel sequential (Borila, 1988;Thomasson & Eriksson, 2011) systems or a combination of a turbo and a mechanical compressor is in production. Both more stages (Nitta, Minato, & Shimazaki, 2011) as well as the inclusion of electric machines connected to a turbo or a mechanical compressor shaft are being investigated (Eriksson, Lindell, Leufvén, & Thomasson, 2012).…”

Transient Momentum Balance—A Method for Improving the Performance of Mean-Value Engine Plant Models

“…In the publically available literature two approaches to considering the momentum equation coupled to the compressor model [20,21] and to the compressor/turbine model [22] are presented, however in both approaches momentum equation is not primarily applied to improve the stability of the model, although stability implications are addressed in [20]. In [20,21] the momentum equation is considered to evaluate the compressor's mass flow, which is needed as an input for the compressor model that relies on the independent variables of mass flow and the turbocharger's speed, and in [22] the momentum equation is considered to improve the acoustic predictions and the prediction performance under pulsed-flow conditions. In both references the momentum equation was thus applied to the elements where mechanical work is added to, or extracted from, the flow.…”