Electric turbocompound control system

A method of controlling an engine having a turbo-compound system having a first electric machine generating electrical power in response to engine exhaust flow, a second electric machine driving the engine in response to electrical power from the first electric machine, and an electrical bus connecting the first and second electric machines, comprising the steps of:

• having a control variable for the engine;
• presenting optimum operating values for the control variable at operating conditions for the engine;
• identifying a difference in a measured value representing the control variable from a comparable optimum value for the control variable at certain engine operating conditions;
• controlling the demand for electrical power of the second electric machine power in response to the difference identified;
• identifying one of the electrical current and voltage values present on the electrical bus taking into account the demand of the second electric machine;
• controlling the supply of electrical power by the first electric machine based upon one of the desired current and voltage of the electrical bus;
• and
• regulating the electrical power on the electrical bus to meet the demand on the bus for the one of the current and voltage.

A turbo-compound system for an engine, comprising:

• a first electric machine capable of operating as a generator;
• a supply sub-system having a generator controller capable of regulating the electrical power generated by the first electric machine based upon operating conditions of the engine;
• a second electric machine capable of operating as a motor;
• a demand sub-system having a motor controller capable of setting a desirable electrical demand for the second electric machine based upon operating conditions of the engine;
• a control sub-system having a controller capable of providing operating conditions of the engine to control the amount of electrical power recovered through the turbo-compound system;
• and
• an electrical circuit connecting the sub-systems.

A turbocompound system for an engine, comprising:

• a turbocharger;
• a first electric machine capable of acting alternatively as one of a generator and motor in response to certain engine conditions and being driven by the turbocharger when acting as a generator;
• a second electric machine capable of acting alternatively as one of a motor and a generator in response to certain engine conditions, driving the engine when acting as a motor and driving the turbocharger when acting as a generator;
• at least one sensor that is capable of providing a signal indicative of an out of parameter condition for the engine as it operates;
• a set point generator that is capable of determining desired operating points for given operating conditions of the engine and having first and second maps, the first map being used to determine desired operating points for engine conditions other than those associated with the out of parameter condition and the second map being used to determine desired operating points for engine conditions associated with the out of parameter condition;
• a comparator that compares one of the desired operating points and a measured operating point of the engine based at least in part on the signal indicative of when the engine is operating in the out of parameter condition;
• and
• a control that regulates the second electric machine to act as a generator providing a desired amount of electrical power in response to comparison of the desired and measured operating points.