Abstract:Aiming at the problems of the transient jerk and low operational stability during the mode switching of electric tractors which are powered by a dual motors drive system (DMDS), a engagement/release drive mode switching control method was proposed based on the transient characteristics of DMDS. The friction torque model of the wet multi-disc electromagnetic clutch and the dynamics model of the dual motors drive system were established in the transient process of mode switching, and the model predictive control (MPC) strategy which was used in the engagement process and torque transfer control (TRC) strategy which was used in the release process were proposed to realize the coordinated control of traction motor (TM), PTO motor (PM) output torque and the friction torque of wet multidisc electromagnetic clutch. With jerk and operating speed deviation as evaluation indexes in the mode switching process of the electric tractor, DMDS mode switching bench tests were carried out. The results showed that the maximum jerk of MPC engagement strategy was 15.86m/s3, and the absolute maximum operating speed deviation was 0.17km/h, which was 56.24% and 51.42% lower than that of traditional PID control strategy, respectively. The maximum jerk of TRC release strategy was 9.06m/s3, and the absolute maximum operating speed deviation was 0.07km/h, which was 74.92% and 76.66% lower than that of traditional PID control, respectively. The proposed method took into account the action characteristics of the key components in the dual motors drive system and load time-varying characteristics in the field working environment, improved the mode switching smoothness and operation stability of DMDS, and met the requirements of tractor traction operation, which can provide a reference for the research of multi-source drive control of electric tractors.
