A physics-based approach to the control of homogeneous charge compression ignition engines with variable valve actuation

Abstract

Homogeneous charge compression ignition (HCCI) is a promising low-temperature combustion strategy for reducing NOx emissions and increasing efficiency in internal combustion engines. However, HCCI has no direct combustion initiator and, when achieved by reinducting or trapping residual exhaust gas with a variable valve actuation (VVA) system, becomes a dynamic process as the temperature of the residual gas couples one cycle to the next. These characteristics of residual-affected HCCI present a challenge for control engineers and a barrier to implementing HCCI in a production engine. In order to address these challenges, this paper outlines physics-based control strategies for both the VVA system and the HCCI combustion process. The results show that VVA system control can provide arbitrary valve timings on a cycle-to-cycle basis, enabling tight control of HCCI. By abstracting these valve timings further into an inducted gas composition and an effective compression ratio, model-based controllers can be developed to control simultaneously load and combustion timing in an HCCI engine.

The effects of key parameters on the transition from SI combustion to HCCI combustion in a two-stroke free piston linear engine

“…(26) [20,34,[40][41][42][43][44]. The heat release and heat transfer are calculated similarly, as shown in Eqs.…”

A University Consortium on Homogeneous Charge Compression Ignition Engine Research

“…Using a model-based LQR control scheme, control of peak pressure has been previously demonstrated (Shaver et al, 2005a(Shaver et al, , 2005b. Peak pressure scales closely with load, therefore, current control efforts have focused on peak pressure as a reasonable surrogate for load.…”

An analytical method for reducing combustion instability in homogeneous charge compression ignition engines through cycle-to-cycle control

“…12 One way to develop a controller from one of these actuation strategies is to use a simple, physics-based analytical model. [13][14][15][16][17][18] The key advantage of using such a model is that it gives physical insight into the in-cylinder dynamics; this physical intuition leads to control intuition about the system that can then be used to design an appropriate controller.…”

“…By substituting equations (13) and (14) into equation (12) and combining common terms, the first law can now be rewritten as in equation (15) …”