【作者】 陈伟；

【导师】 徐殿国；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2012， 博士

【摘要】 节约能源是当今社会可持续发展的一个永恒的主题。异步电机调速系统的应用对节约能源有着举足轻重的作用。然而，随着我国现代化进程的不断发展，对异步电机调速系统的性能指标要求越来越高。如何进一步提高异步电机无速度传感器调速系统的低速性能是亟待解决的关键技术之一。在异步电机无速度传感器控制算法中，应用较为广泛的主要有开环V/f控制算法和无速度传感器矢量控制算法两种。其中，开环V/f控制算法具有鲁棒性好和可靠性高的特点，但其低速性能差，且在空载和轻载时系统在某一频段存在持续振荡问题。而无速度传感器矢量控制算法具有很好的动、静态性能，低速性能较好，然而此系统在低速发电状态下的稳定性有待提高。对异步电机无速度传感器算法进行深入研究，并解决其核心技术难点，这对拓宽异步电机调速技术在工业控制中的应用场合具有重要意义。本文主要研究异步电机的无速度传感器控制算法，包括开环V/f控制算法和无速度传感器矢量控制算法，着重解决此算法中的核心技术难点。具体内容包括以下几个方面：针对异步电机开环V/f控制系统在空载或轻载时存在一个持续振荡的稳定性问题，提出了一种抑制异步电机开环V/f控制系统轻载振荡的方法。首先，通过仿真建模详细分析了系统出现持续振荡时的不稳定现象。然后，通过理论推导，对系统轻载振荡的原因进行了研究，并分析了系统中各参数对此振荡的影响。最后根据系统振荡与无功电流波动之间的关系，并基于定子电压定向对电流进行分解，通过控制无功电流分量恒定，调节电机定子电压的幅值来抑制电机振荡。该方法不依赖电机参数，鲁棒性高。采用该方法，系统在电机额定频率以下的工作范围内都能平稳运行，电机的振荡得到了抑制，有效地提高了系统在轻载下的稳定性。基于电机理想模型，转子转速在极低速下具有不可观测性。为了实现极低速下带载调速，在开环V/f控制算法的基础上结合矢量控制的思想，根据异步电机状态方程推导出一种新型电压矢量控制策略。该策略采用一种新颖的电压提升方法对电机定子电阻压降进行补偿，使电机磁链幅值保持恒定。在极低速情况下，通过对电机转矩进行提升以及对滑差频率进行补偿，使系统的低速性能和转速精度得到明显改善。与无速度传感器矢量控制算法不同的是，该控制算法是根据定子电压矢量定向对电流进行解耦，其不需要复杂的磁链观测运算，容易实现，参数鲁棒性高。实验结果表明，采用此方法在0.1Hz满载情况下，电机能平稳运行。系统的低速性能和转速精度得到了明显提升，并且系统的轻载振荡得到了抑制，在基频以下的工作范围内都能平稳运行。基于转速自适应磁链观测器的异步电机无速度传感器矢量控制算法，针对其低速发电状态下不稳定的问题，根据异步电机小信号线性化模型，推导出转速自适应观测系统的传递函数，并采用劳斯－赫尔维茨稳定性判据，提出一种基于观测器的转速自适应观测方法。该方法通过在传统的转速观测自适应律中加入励磁电流观测误差项，使转速的观测精度得到大幅提高，并通过在线调节励磁电流观测误差项的比例系数，可使系统在低速发电状态下稳定运行。考虑到电机参数误差的影响，对此算法的参数鲁棒性进行了分析。通过7.5kW异步电机对拖实验平台对此算法的有效性进行了验证。从实验结果可知，此新型速度自适应观测方法明显提高了低速下的速度观测精度，改善了系统的低速性能，并有效解决了低速发电状态下系统不稳定的问题。在异步电机调速系统中，无论是开环V/f控制算法中的定子电阻压降和滑差补偿，还是矢量控制算法中各控制器参数设计以及磁链观测都依赖于电机参数。电机参数的精度直接影响着系统的控制性能。为获得准确的电机参数，提出了一种异步电机在静止状态下的参数辨识方法。采用了一种自适应的方法对器件的非线性进行补偿，从而提高了算法的辨识精度和适应性。同时考虑到电机的磁滞效应对电机互感辨识的影响，通过在传统单相交流实验的基础上叠加一个直流电流，利用此直流电流先将电机磁场激励起来，从而准确地辨识出电机在额定励磁情况下的互感值。最后通过实验证明了此方法可以准确辨识出电机T型等效电路中的全部参数。更多还原

【Abstract】 Energy saving is an eternal theme for a sustainable development in present society.Induction motor (IM) drive system plays an important role in the energy saving.However, with the continuous development of the modernization process in our country,the performance requirements for the IM drive system becomes higher and higher. Howto further improve the low speed performance of the IM drive system is one of the mostarduous technologies to be solved. Open loop variable voltage and variable frequency(V/f) control method and close loop speed sensorless vector control (SLVC) method aretwo popular methods for IM speed sensorless control. V/f control method possessesgood robustness and high reliability. However this method has poor low speedperformance and suffers from sustained oscillations under the light load conditions. Inaddition, the SLVC method is specialized by the good dynamic and static performanceand good low speed performance. But the drive systems controlled by this methodencounter instability in the regenerating mode at low speeds. Thorough study in IMspeed sensorless control algorithms and research on the solution for the core technologyis important for improving the applications of IM speed control technology in powerdrive systems.This thesis mainly studies the IM speed sensorless control methods, including theopen-loop V/f control method and speed sensorless vector control method, and focuseson solving the core technologies that involved in these methods. The contents includeseveral aspects as follows:In order to improve the stability of V/f controlled IM drive system in light loadconditions, a stabilizing control method is presented. Through simulation modeling, thesystem instability is analyzed in detail based on the simulation results. Then bytheoretical derivation, the reasons that result in the instability under light load conditionare studied, and the influences on system stability of various parameters are alsoanalyzed. Based on the relationship between the system oscillations and the fluctuationof reactive current the stabilizing method is implemented by adjusting the stator voltageamplitude according to the fluctuation of reactive current which is decoupled throughstator voltage oriented synchronous rotation frame transformation. The proposedmethod is parameter independent and robust. Experiments have proven that the systemhas a very stable operation over the whole speed range from0to50Hz with theproposed method. The oscillations have been suppressed effectively, and the systemstability in light load conditions is much improved.Based on the ideal model of IM, the motor speed is unobservable when the IM is operating in a very low speed range. In order to achieve speed control with load inextremely low speed range, on the basis of open loop V/f control method combing withthe vector control theory, a novel voltage vector control strategy is derived according tothe state equations of IM. The control scheme adopts a novel voltage boost method tocompensate the stator resistor voltage drop keeping the magnitude of the stator fluxconstant. The performance under very low speed conditions is greatly improved byboosting the torque and compensating the motor slip frequency. Different from speedsensorless vector control methods, all the compensation and regulation are based onstator voltage oriented synchronous rotation frame transformation, which avoidscomplicated flux linkage vector estimation, and is easy to implement, and has goodparameters robustness. The experimental results show that, by adopting the proposedmethod, the speed can be accurately controlled down to0.1Hz with rated load torque.The low speed performance and speed accuracy are much improved, and the systemunder no load condition is stabilized at the speed range from0to50Hz.In the speed-sensorless IM drive system adopting the speed adaptive flux observermethod, there exists an unstable region in the regenerating mode at low speeds. In orderto solve this problem, a novel speed estimation method is presented. Based on the smallsignal linearized model of IM, the transfer function of the speed adaptive estimationsystem is deduced, and a novel speed adaptive estimation method is developed byapplying Routh-Hurwitz criteria. The speed accuracy could be greatly improved byadding the magnetizing current estimation error to the general speed estimation law, andthe instability behavior in the low speed regenerating mode could be remedied byadjusting the adaptation gain on-line. Concerning the motor parameters error, therobustness of the proposed method is analyzed as well. The feasibility of the proposedscheme is verified by the experimental results of speed sensorless field-oriented vectorcontrolled7.5kW IM platform. Experimental results show that the speed estimationaccuracy and the low speed performance are greatly improved, and also a stableoperation is acquired in a very wide speed range.In the IM drive system, both the stator resistance voltage drop and slipcompensation in open loop V/f control algorithm, or the parameters design of variouscontrollers and flux observations in vector control algorithm, depend on motorparameters. The control performance is highly dependent on the accuracy of theparameters of IM. In order to obtain the parameters of IM accurately, a parameteridentification method at standstill is proposed. The nonlinearity of the inverter is takeninto account and compensated adaptively to improve the estimation precision. Inaddition, the influence due to the magnetic hysteresis phenomenon when calculating themutual inductance is also considered. The mutual inductance is estimated at the rated magnetizing level by superimposing a direct current into the traditional single phasealternating current. The feasibility of the proposed scheme is verified by theexperimental results which show a high estimation accuracy of IM parameters.更多还原