Using known approaches to describe the reaction kinetics of soot, simple models are formulated to calculate regeneration limits and describe the interaction between engine and filter. - Insulation of exhaust ports and manifold reduces the lower limit of automatic filter regeneration by approx. 0.5 bar bmep. - Intake throttling extends the range of automatic regeneration to within medium load. - The combination of intake throttling with a small constant output burner enables regeneration for all engine operating conditions. - Fuel additives can lower the limit for filter regeneration through lowering the activation energy to within the lower part load without additional measures.