Torque oscillation compensation using torque emulator/observer feedback

Abstract

A torque oscillation compensation system and torque estimator that uses torque emulator/observer feedback derived from an electric vehicle motor drive train. The present torque oscillation compensation system is adapted for use with an electric vehicle comprising a source of torque command signals and an electric motor that is controlled by a power switching circuit. The power switching circuit is responsive to the torque command signals and provides pulse width modulated signals for driving the motor. The system comprises a torque estimator that is coupled to received pulse width modulated signals provided by the power switching circuit, and motor currents and speed, for providing estimated torque feedback signals derived therefrom. A summing device coupled to the source of of torque commands, the torque estimator, and to the power switching circuit, for combining the torque command signals with the estimated torque feedback signals to provide compensated input signals to the power switching circuit that control the motor torque and speed. The present invention provides a calculated estimate of motor power and torque in an electric drive train system. The power and torque are calculated by utilizing pulse width modulated signals of a motor controller and scaling the result according to the value of the battery voltage/power supply. This provides accurate operation over the entire battery voltage range without requiring voltage measurement at the motor terminals. The present technique provides for smooth vehicle handling over a broad range of speeds for every mode of propulsion operation. Single phase and three phase embodiments of the invention are disclosed.