农业履带车驱动电机零低速控制与死区补偿

    Research on Zero Low-Speed Control and Dead Zone Compensation of Drive Motor for Agricultural Tracked Vehicle

    • 摘要: 永磁同步电机在零低速区间控制性能欠佳,导致农业履带车在丘陵山区难以实现精准作业。针对该问题,结合现有基础和丘陵山区的实际作业工况特征,研究提出一种融合高频注入法与非线性观测器的复合控制策略。通过系统分析逆变器死区时间和非线性因素对电机运行特性的影响,设计对应的补偿方案,有效削弱上述因素带来的不利影响。建立永磁同步电机(PMSM)数学模型,对比无补偿方案与死区时间-非线性因素复合补偿策略下的电机三相电流波形,结果表明:经补偿后电机电流中的死区效应与抖振现象得到显著抑制,电流波形稳定性大幅提升。搭建试验平台并在设定负载条件下开展电机启动与工况切换试验,试验结果验证了所提复合控制策略的有效性,即使在高频注入法与磁链观测器的切换过程中,系统仍可维持稳定运行。数据对比显示:相较于无补偿控制,采用复合补偿策略后空载工况下电机电流总谐波畸变率(THD)降低 6.34%,负载工况下 THD 降低 5.26%。同时,超扭滑模自抗扰控制对比试验表明,该控制策略可基本消除电机运行时的转速超调,进一步提高系统控制精度。研究结果表明,所提方法对于改善农业履带车运行性能具有重要价值,可为提升丘陵山区农业机械化水平提供理论依据与技术支撑。

       

      Abstract: Hilly and mountainous areas serve as important production bases for grain, oil, sugar and distinctive agricultural products in China. However, restricted by complex topography and landforms, the level of agricultural mechanization in these regions is roughly 20% lower than the national average, posing a huge challenge to the promotion of agricultural mechanization. At present, agricultural production in hilly and mountainous areas still relies mainly on manual labor, which is inconsistent with the actual demand due to population aging and the loss of young and middle-aged labor force. As a power platform in hilly and mountainous areas, electric tracked vehicles feature excellent trafficability and environmental friendliness. Nevertheless, the existing motor control theories are difficult to meet the operational requirements of tracked vehicles in such scenarios. Specifically, permanent magnet synchronous motors (PMSM), which is viewed as power core of agricultural tracked vehicle, exhibit unsatisfactory control performance in the zero and low-speed range, making it difficult for agricultural tracked vehicles to achieve precise operation in hilly and mountainous areas. To address this issue, a hybrid control strategy combining the high-frequency signal injection method and a nonlinear observer is proposed based on existing research foundations and the actual operating conditions of hilly and mountainous regions. Through a systematic analysis of the impacts of inverter dead time and nonlinear factors on the motor operating characteristics, a corresponding compensation scheme is designed to effectively attenuate the adverse effects caused by the aforementioned factors. The mathematical model of a PMSM is established, and the three-phase current waveforms of the motor under the non-compensation scheme and the hybrid compensation strategy for dead time and nonlinear factors are compared. The results demonstrate that the dead-time effect and chattering phenomenon in the motor current are significantly suppressed after compensation, and the stability of the current waveform is greatly improved. An experimental platform is built, and motor starting and operating condition switching tests are carried out under set load conditions. The experimental results verify the effectiveness of the proposed hybrid control strategy; the system can maintain stable operation even during the switching process between the high-frequency signal injection method and the flux observer. Data comparison reveals that compared with non-compensation control, the total harmonic distortion (THD) of the motor current is reduced by 6.34% under no-load conditions and by 5.26% under load conditions after adopting the hybrid compensation strategy. Meanwhile, a comparative test of super-twisting sliding mode active disturbance rejection control shows that the control strategy can basically eliminate the speed overshoot during motor operation and further enhance the control precision of the system. It should be acknowledged that satisfactory progress has been made in the present research. However, limited by experimental conditions, only simulations and tests under partial operating conditions have been completed. Further optimization of the switching strategy and improvement of the field test scheme are required in future work, so as to fully verify the robustness of the hybrid algorithm.

       

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