Mitigation of electric drivetrain oscillation resulting from abrupt current derating at low coolant flow rate

Abstract

A simple adaptive linear current derating strategy for safe operation at low coolant flow rates and optimum operation at temperatures close to the allowed maximum operating junction temperature for electric drivetrain inverters is presented. An inverter junction temperature observer is implemented to calculate the maximum junction temperature which is used as an input to the derating strategy. Results of the proposed strategy are compared with those of the instantaneous derating strategy for different cooling conditions. It is observed that the proposed strategy is robust and eliminates unwanted drivetrain oscillations resulting from abrupt current reduction at low coolant flow rates using instantaneous derating.