Abstract: A method and system for determining a torque current in an electric machine coupled to a polyphase bus. The method comprises: detecting a rotational position of the electric machine with a position encoder; controlling an inverter comprising a plurality of switching devices, the inverter having an input coupled to a direct current bus, and an output coupled to the polyphase bus. Where the inverter is responsive to commands from a controller coupled to the inverter and to the position encoder. The method also includes measuring a current from the direct current bus; and capturing the current at a predefined interval of time.

Abstract: A method for updating a sensor offset and a medium encoded with a machine-readable computer program code for updating a sensor using a robust sensor learning algorithm wherein the method includes obtaining vehicle data signals, obtaining a position sensor data signal, the position sensor data signal being responsive to a stored positional offset data signal, determining whether algorithm initial conditions are satisfied, formulating a new positional offset data signal conditioned on satisfaction of the initial conditions, and storing said new positional offset data signal so as to combine said new positional offset data signal with said stored positional offset data signal and replace said stored positional offset data signal.

Abstract: An absolute hand-wheel position tracking system for an electric power steering system having a hand-wheel, an assist motor for providing an assist torque disposed relative to the hand-wheel, and a motor position sensor responsive to the assist motor, includes a hand-wheel position initialization function responsive to the hand-wheel; a motor position correction and scaling function responsive to the motor position sensor and responsive to the assist torque; an enable function responsive to the assist torque and responsive to the hand-wheel position initialization function; and an absolute hand-wheel position generation function in signal communication with the hand-wheel position initialization function, the motor position correction and scaling function, and the enable function.

Abstract: A method of estimating the angular velocity of an electric power steering motor for an automobile is disclosed. The method comprises estimating an average angular velocity of the motor; estimating an instantaneous angular velocity of the motor; weighting the estimated average angular velocity of the motor; weighting the estimated instantaneous angular velocity of the motor; and combining the weighted estimated average angular velocity of the motor and the weighted estimated instantaneous angular velocity of the motor.

Abstract: A method for updating a sensor offset and a medium encoded with a machine-readable computer program code for updating a sensor using a robust sensor learning algorithm wherein the method includes obtaining vehicle data signals, obtaining a position sensor data signal, the position sensor data signal being responsive to a stored positional offset data signal, determining whether algorithm initial conditions are satisfied, formulating a new positional offset data signal conditioned on satisfaction of the initial conditions, and storing said new positional offset data signal so as to combine said new positional offset data signal with said stored positional offset data signal and replace said stored positional offset data signal.

Abstract: An absolute hand-wheel position tracking system for an electric power steering system having a hand-wheel, an assist motor for providing an assist torque disposed relative to the hand-wheel, and a motor position sensor responsive to the assist motor, includes a hand-wheel position initialization function responsive to the hand-wheel; a motor position correction and scaling function responsive to the motor position sensor and responsive to the assist torque; an enable function responsive to the assist torque and responsive to the hand-wheel position initialization function; and an absolute hand-wheel position generation function in signal communication with the hand-wheel position initialization function, the motor position correction and scaling function, and the enable function.

Abstract: A method of compensating for errors in the measurement of the kinematic properties of an electric power steering motor for an automobile is disclosed. The method comprises generating a set of M-ary signals; measuring the pulse width of the set of M-ary signals; and measuring the time between the edges of the set of M-ary signals. The motor velocity may be directly measured by a tachometer or other such device. The motor position signal can be used to estimate the angular velocity of the motor, by determining the change in angular position of the motor divided by the change in time.

Abstract: Disclosed herein is a method for determining a torque current in an electric machine coupled to a polyphase bus. The method comprises: detecting a rotational position of the electric machine with a position encoder; controlling an inverter comprising a plurality of switching devices, the inverter having an input coupled to a direct current bus, and an output coupled to the polyphase bus. Where the inverter is responsive to commands from a controller coupled to the inverter and to the position encoder. The method also includes measuring a current from the direct current bus; and capturing the current at a predefined interval of time. Also disclosed is a system for determining a current in an electric machine coupled to a polyphase bus, the system comprising: a position encoder coupled to the electric machine to detect rotational position; an inverter having an input coupled to a direct current bus, and an output coupled to the polyphase bus.

Abstract: A method of minimizing the torque ripple produced by unbalanced phase currents in a sinusoidally excited motor is disclosed. The method comprises measuring the position of the motor; sampling the phase currents of the motor generating thereby at least one phase current; synchronizing the at least one phase current of the motor with the position of the motor; determining the imbalance in the magnitudes of the at least one phase current of the motor; generating a set of modulation index terms for reducing the imbalance in the magnitudes of the at least one phase current to ensure acceptable torque ripple characteristics over the operating velocity of the motor; and generating a set of minimized line-to-ground voltage commands.

Abstract: A method and system for diagnostics and ascertaining status of an electric machine coupled to a polyphase bus. The method and system include: detecting a rotational position with a position encoder coupled to the electric machine; controlling an inverter having an input coupled to a direct current bus and an output coupled to the polyphase bus, where the inverter is responsive to commands from a controller coupled to the inverter and to the position encoder. The method and system further include measuring a current from the direct current bus; capturing a torque current; calculating a current error; establishing a bound limit for the torque current; comparing the current error to the bound limit. The method and system also include: determining whether a fault exists by evaluating if the bound limit has been exceeded; incrementing a fault counter if a fault exists; decrementing a fault counter if no fault exists; and indicating a failure if the fault counter exceeds a predetermined limit.

Abstract: A system and method of discriminating faults in an error signal, such as that from a control input sensor, comprises a system for and method of determining allowable limits of an error signal versus time, passing the error signal through a low-pass filter, comparing output of the low-pass filter with a threshold and outputting a fault condition when the output of the low-pass filter exceeds the threshold. The time constant or constants of the low-pass filter and the threshold are selected so that a fault condition is detected when the error signal approaches the allowable limits before exceeding them.

Abstract: A vehicle with an electric power steering system has a steering shaft with a resonant frequency of free rotational oscillation and a control which derives a driver assist torque signal, a return to center torque signal and an active damping torque signal and sums these signals to provide a motor command signal to the electric motor. The active damping torque signal is derived by filtering a generated steering shaft position signal in a filter having amplitude and phase characteristics of a differentiator from zero Hertz only through the resonant frequency of free rotational oscillation of the steering shaft and multiplying the filtered steering shaft position signal by a vehicle velocity factor derived from sensed vehicle velocity. Preferably, the electric motor is provided with one or more rotor position sensors used in the control thereof and rotor position signals from the rotor position sensors are provided as the steering shaft position signal.