Ford Global Technolgoies, LLC

Yingfeng Ji

Michael W Degner

Jiyao Wang

Yang Xu

Jonathan Hair

Matthew Penne

Systems and methods for operating an electric drive system for an electric or hybrid vehicle is described. In one example, the drive system is operated by suppling a pulsed torque current command while supplying a zero flux current command. The torque current command and the flux current command make up winding current commands for an electric machine.

Methods and system for estimating electric machine position offset

A controller detects a rotor magnet temperature based on an actively detected back electromotive force (BEMF) voltage of the motor. The controller detects the BEMF voltage by commanding the injection of a direct-axis (d-axis) current into the motor while the motor is spinning but otherwise commanding no torque. The controller actively detects the BEMF voltage in that the controller purposely injects a known quantity of d-axis current at a chosen time during which the controller detects or is aware that the motor is commanding no torque. Using a quadrature-axis (q-axis) voltage equation, which describes the relationship between a voltage command, the current, the BEMF voltage, and reactance in the q-axis, the controller solves for the BEMF voltage with the voltage command, the current, and the q-axis reactance being known to the controller. The controller detects the rotor magnet temperature based on the BEMF voltage.

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Northville, MI, United States of America

Yingfeng Ji