Abstract: Methods and apparatus are provided for monitoring a coolant conductivity of a fuel cell supplying power via positive and negative buses. The method includes measuring a first voltage of the positive bus, measuring a second voltage of the negative bus, applying a resistance between the positive bus and a reference potential, measuring a third voltage of the positive bus after a period of applying the resistance, and determining an isolation resistance based on the measured voltages. The isolation resistance is a function of the coolant conductivity.

Abstract: Methods and apparatus are provided for monitoring a coolant conductivity of a fuel cell supplying power via positive and negative buses. The method includes measuring a first voltage of the positive bus, measuring a second voltage of the negative bus, applying a resistance between the positive bus and a reference potential, measuring a third voltage of the positive bus after a period of applying the resistance, and determining an isolation resistance based on the measured voltages. The isolation resistance is a function of the coolant conductivity.

Abstract: A method of controlling an IPM machine having a salient rotor. Stator terminal signals are measured and rotated to obtain synchronous reference frame current signals. A rotor position is estimated based on an impedance generated using the rotor and included in the current signals. The estimated rotor position is used to control the machine. An alternator-starter system in which this method is used can provide high cranking torque and generation power over a wide speed range while providing operational efficiency.

Abstract: A power steering system and induction motor load compensation algorithm or processing method for use in a vehicle. The power steering system comprises a power supply, a power steering motor, a steering subsystem, and a power steering controller coupled to the power supply. The controller processes a frequency command input corresponding to the power steering frequency requested by the steering subsystem and data contained in one or more software lookup tables to adjust the output frequency produced by the power supply to control the speed of the power steering, motor. The lookup tables are generated empirically and characterize the output power of the power supply at different system pressures over a range of motor speeds. The software lookup tables provide a power band that implements a power limiting state machine.

Abstract: An induction motor control system for use in a power steering system, comprising: a power steering induction motor coupled to a power supply and providing motive input to pressurize a hydraulic steering subsystem; a phase current sensor for sensing the phase current output by the power supply; and a power steering controller coupled to the power supply for processing a commanded frequency input, the sensed phase current, and data contained in a plurality of software lookup tables using a transfer function to adjust the motor voltage produced by the power supply to control the speed of the power steering motor.