US Patent 7127892 Techniques for determining turbocharger speed

One embodiment of the present invention includes an internal combustion engine with a turbocharger. The turbocharger includes a compressor with an outlet coupled to an intake of the engine and a turbine coupled to an exhaust manifold of the engine. A a turbocharger speed estimate is determined from engine speed and a ratio between inlet and boost pressure for the compressor. The turbocharger speed estimate is further adjusted as a function of compressor boost pressure variation with time.