High impedance AC coupling method for quick command response in torque compensation systems

摘要

A high impedance AC coupling arrangement that processes a transducer feedback signal derived from an output shaft of an electric vehicle motor to compensate for electrical motor pulsations. The high impedance AC coupling arrangement is coupled between the transducer and a summing device and generates a feedback compensation signal that is combined with an input signal to compensate for output shaft oscillations. The high impedance AC coupling arrangement includes a loop amplifier having a predetermined transfer function that is coupled to the transducer, and AC coupling circuitry, typically including a plurality of coupling capacitors, that is coupled between the loop amplifier and the summing device. A limiter circuit having first and second oppositely coupled diodes is coupled between a voltage source and a point between the AC coupling capacitors. A cascode amplifier is coupled to the AC coupling circuitry. Compensation for the pulsations is provided by utilizing the AC component of the signal derived from the transducer as a feedback signal from which compensation commands are derived. This AC-coupled signal is fed back with proper amplitude and phase shift to modulate and compensate the motor current and/or slip and/or speed and/or commutating angle and/or field current to eliminate torque fluctuations of the drive train of the vehicle. The present invention eliminates these unwanted pulsations over all modes of propulsion operation.