In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled B...In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current（BLDC） motor. Hysteresis Current Control（HCC） is an effective method in improving the performance of current control for a BLDC motor.Nevertheless, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is realized.Simulation and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy.展开更多
针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开...针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开关频率,根据电流预测模型和电流误差最小原则,不仅减小了网侧电流谐波和直流母线侧电压纹波,而且降低了平均开关次数进而减少了器件损耗。通过建立的交流侧110 V、直流侧300 V、输出功率0.7 k W的实验平台进行了实验验证,表明该系统具有良好的稳态性能。仿真结果和实验结果验证了所提出控制方法的有效性以及理论分析的正确性。展开更多
This paper presents a new Pulse Width Modulation (PWM) controller for Unmanned Aerial Vehicle (UAV) precisionsprayer for agriculture using a TL494 fixed-frequency pulse width modulator together with a data acquisition...This paper presents a new Pulse Width Modulation (PWM) controller for Unmanned Aerial Vehicle (UAV) precisionsprayer for agriculture using a TL494 fixed-frequency pulse width modulator together with a data acquisition board and developedsoftware. An UAV can be remotely controlled or flown autonomously by pre-programmed flight plans. The PWMcontroller was implemented through the guidance system on the UAV with control commands sent between the UAV helicopterand the ground control station via a wireless telemetry system. The PWM controller was tested and validated using LabVIEW8.2. Several analyses were performed in a laboratory to test different control signals. The results show that the PWM controllerhas promise as a higher precision technique for spray applications, which will improve efficiency of pesticide application,especially in crop production areas.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51275021,61327807)
文摘In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current（BLDC） motor. Hysteresis Current Control（HCC） is an effective method in improving the performance of current control for a BLDC motor.Nevertheless, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is realized.Simulation and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy.
文摘针对三相电网不平衡故障下的电压型PWM整流器的直流电压二次纹波和网侧电流谐波,研究了一种纹波抑制方法。基于传统的双闭环控制结构,提出电网不对称故障下参考电流计算方法。利用模型预测控制取代电流环PI控制,结合PWM调制环节固定开关频率,根据电流预测模型和电流误差最小原则,不仅减小了网侧电流谐波和直流母线侧电压纹波,而且降低了平均开关次数进而减少了器件损耗。通过建立的交流侧110 V、直流侧300 V、输出功率0.7 k W的实验平台进行了实验验证,表明该系统具有良好的稳态性能。仿真结果和实验结果验证了所提出控制方法的有效性以及理论分析的正确性。
文摘This paper presents a new Pulse Width Modulation (PWM) controller for Unmanned Aerial Vehicle (UAV) precisionsprayer for agriculture using a TL494 fixed-frequency pulse width modulator together with a data acquisition board and developedsoftware. An UAV can be remotely controlled or flown autonomously by pre-programmed flight plans. The PWMcontroller was implemented through the guidance system on the UAV with control commands sent between the UAV helicopterand the ground control station via a wireless telemetry system. The PWM controller was tested and validated using LabVIEW8.2. Several analyses were performed in a laboratory to test different control signals. The results show that the PWM controllerhas promise as a higher precision technique for spray applications, which will improve efficiency of pesticide application,especially in crop production areas.
