Patent ID: 7174714

Claim:
A method of controlling an engine in 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 machines, and an electrical bus connecting the first and second electric machines, comprising: 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.