Method and apparatus for controlling a high-voltage electrical system for a multi-mode transmission

A method for controlling torque machines of a multi-mode transmission, said torque machines electrically coupled via a power inverter to a high-voltage electric bus, the method comprising:

• monitoring voltage and current on a high-voltage electric bus electrically coupled to a high-voltage battery and a power inverter configured to transfer electric power to the torque machines and providing the monitored voltage and current as feedback to a control module including a feed-forward electric power model;
• iteratively estimating electric power limits for the high-voltage electric bus using the feed-forward electric power model, the electric power limits including a constrained battery power command based upon a total motor torque electrical power for the torque machines, wherein the feed-forward electric power model estimation of the constrained battery power command comprises:
• developing a relationship of the power of the high-voltage battery to the monitored voltage and current on the high-voltage bus;
• and
• executing a local expansion about one of the voltage and current on the high-voltage electric bus using the developed relationship of the power of the high-voltage battery and the monitored voltage and current on the high-voltage bus to determine the constrained battery power command that will place said one of the voltage and current on the high-voltage bus at a corresponding limit;
• determining torque commands for the torque machines that are constrained in response to the estimated electric power limits for the high-voltage electric bus, including the constrained battery power command;
• determining a battery power demand for a high-voltage battery electrically coupled to the high-voltage electric bus based upon the constrained torque commands;
• determining a battery pack voltage for the high-voltage battery, said battery pack voltage corresponding to the battery power demand for the high-voltage battery;
• and
• controlling operation of the torque machines of the multi-mode transmission in response to the torque commands for the torque machines.