Coordinated control of electronic throttle and variable geometry turbocharger in boosted stoichiometric spark ignition engines

A method for operating an engine control system, such engine system having an intake manifold and an exhaust manifold, exhaust gas in such exhaust manifold fed to a variable geometry turbine, such turbine being connected to a compressor, such compressor feeding air to the intake manifold through an electronically controlled throttle, such variable geometry turbine being controlled by a variable geometry turbine control signal, such electronically variable throttle being controlled by a throttle control signal, such method comprising:

• determining engine torque demand and engine speed;
• determining from the determined torque demand and engine speed a desired intake manifold pressure pintake,desired and a desired exhaust manifold pressure pexhaust,desired;
• determining a feed forward throttle signal uthrottle,desired and a feed forward VGT signal uvgt,desired in accordance with the measured engine speed and determined desired intake manifold pressure pintake,desired;
• measuring engine intake manifold pressure pintake and engine exhaust manifold pressure pexhaust;
• forming a first error signal pintake−pintake,desired between measured and the desired intake pressure and a second error signal pexhaust−pexhaust,desired;
• forming a weighted sum signal evgt as:
• evgt=w·(pintake−pintake,desired)+(1−w)·(pexhaust−pexhaust,desired)
• where w is a number between 0 and 1;
• combining the determined feed forward throttle signal uthrottle,desired, with the formed first error signal pintake−pintake,desired multiplied by a gain kp,throttle and the integral state of the formed first error signal pintake−pintake,desired multiplied by a gain ki,throttle to produce a signal e′throttle(t);
• combining the determined feed forward VGT signal uvgt,desired with a signal e′vgt(t) where e′vgt(t) is the formed signal evgt multiplied by a gain kp,vgt and the integral state of the formed signal evgt multiplied by ki,vgt;
• adding the signal e′throttle(t) to the determined feed forward signal uthrottle,desired to produce a first composite signal uthrottle;
• feeding such first composite signal to the throttle;
• adding the signal e′vgt(t) to the signal uvgt(t) to produce a second composite signal uvgt(t);
• feeding such second composite signal uvgt(t) to the VGT.

An article of manufacture, comprising:

• a computer storage medium having a computer program encoded therein for executing a method for operating a engine control system, such engine system having an intake manifold and an exhaust manifold, exhaust gas in such exhaust manifold fed to a variable geometry turbine, such turbine being connected to a compressor, such compressor feeding air to the intake manifold through an electronically controlled throttle, such variable geometry turbine being controlled by a variable geometry turbine control signal, such electronically variable throttle being controlled by a throttle control signal, such storage medium comprising:
• code for determining engine torque demand and engine speed;
• code for determining from the determined torque demand and engine speed a desired intake manifold pressure pintake,desired and a desired exhaust manifold pressure pexhaust,desired;
• code for determining a feed forward throttle signal uthrottle,desired and a feed forward VGT signal uvgt,desired in accordance with the measured engine speed and determined desired intake manifold pressure pintake,desired;
• code for measuring engine intake manifold pressure pintake and engine exhaust manifold pressure pexhaust;
• code for forming a first error signal pintake−pintake,desired between measured and the desired intake pressure and a second error signal pexhaust−pexhaust,desired;
• code for forming a weighted sum signal evgt as:
• evgt=w·(pintake−pintake,desired)+(1−w)·(pexhaust−pexhaust,desired),
• where w is a number between 0 and 1;
• code for combining the determined feed forward throttle signal uthrottle,desired, with the formed first error signal pintake−pintake,desired multiplied by a gain kp,throttle and the integral state of the formed first error signal pintake−pintake,desired multiplied by a gain ki,throttle to produce a signal e′throttle(t);
• code for combining the determined feed forward VGT signal uvgt,desired with a signal e′vgt(t) where e′vgt(t) is the formed signal evgt multiplied by a gain kp,vgtand the integral state of the formed signal evgt multiplied by ki,vgt;
• code for adding the signal e′throttle(t) to the determined feed forward signal uthrottle,desired to produce a first composite signal uthrottle;
• code for feeding such first composite signal to the throttle;
• code for adding the signal e′vgt(t) to the signal uvgt(t) to produce a second composite signal uvgt(t);
• code for feeding such second composite signal uvgt(t) to the VGT.

An engine control system comprising:

• an engine having:
• an intake manifold;
• an exhaust manifold;
• a compressor;
• an electronically controllable throttle;
• a variable geometry turbine fed by exhaust in such exhaust manifold, such turbine being connected to the compressor;
• wherein the compressor feeds air to the intake manifold through an electronically controlled throttle, such variable geometry turbine being controlled by a variable geometry turbine control signal, such electronically variable throttle being controlled by a throttle control signal
• a processor for combining a difference between an actual intake manifold pressure and a desired intake manifold pressure and a difference between an actual exhaust manifold pressure and a desired exhaust gas pressure into a composite signal to provide the variable geometry turbine control signal and the difference between the actual intake manifold pressure and the desired intake manifold pressure to produce the throttle control signal.