中国铁道科学 第29卷 t s (a)电机励磁给定电流 , 乏 t s (b)直流母线输入功率 , t/s (c)电机转矩给定电流 l 000 f 900 lI 800 700 600 500 4.5 5.0 5.5 6.0 6.5 7.0 t/s (d)电机转速 t}s (e)电机输出转矩 图6 FLSC过程中的动态响应 4.5 5.0 5.5 6.0 65 7.0 t/s (a)电机励磁给定电流产 图7转子电阻降低50%对应FLSC效率寻优控制 图8所示为转子电阻升高50 的FI SC效率 寻优仿真结果。当 由额定值9 A变为5.8 A, 由820 W变为690 W时,系统最优效率为 68.3 。 t/s (a)电机励磁给定电流r , s (b)直流母线输入功率 图8转子电阻升高5O%对应FLSC效率寻优控制 由此可以发现,转子电阻变化将会影响电机额 定励磁控制工况时的直流母线输入功率和最终的最 优励磁给定电流数值;但是经过FLSC效率寻优 后,电机系统在最优点的运行效率基本上没有发生 变化。 3实验结果 基于对FLSC算法的理论分析及计算机仿真, 进行了小功率异步电机系统轻载台架FLSC效率寻 优的实验研究,实验系统框图参见图1。逆变器选 用IGBT为开关器件,开关频率为10 kHz;选用 TI公司的定点DSPTMs320LF2407A为控制芯片; 图形数据经由CAN总线输入,然后在上位机由 VB程序测绘得到。实验选取负载丁lJ为1.4 N・m (0.1 pu),电机转速为750 r・min_。,输出功率为 109.9 W。 图9为电机系统由额定励磁控制状态向FLSC 效率寻优控制状态的转变过程。当电机的初始励磁 给定电流 为额定值9 A、直流母线输入功率约为 400 W时,电机系统效率为27.5 ;当电机运行 至稳态后,在15.5 S时间点系统进入第1次FLSC 效率寻优,经过4步模糊寻优, 降至4 A,直流 母线输入功率降至250 W,电机系统效率为 44.0 。 在图中横坐标为19.2 S处,进行了电机带载 状态下的暂态响应实验。诌被瞬间拉起并重新设定 为9 A,直流母线输入功率迅速升至400 W;在图 中横坐标为20.8 s处系统进入稳态运行,此时系统 : 维普资讯 http://www.cqvip.com 第1期 异步电机效率优化算法设计 87 f『 ≤8 0 4 O l 16 18 12 , ; [ . 一.^ ._ . 2O t . _1一 ... 22 24 4结语 (a)电机励磁给定电流i 500 本文简要总结了异步电机效率优化的主要控制 算法的优缺点,提出了一种混合在线式直流输入功 400 芝 300 200 . ===.=: 18 16 二二 二=: 20 22 24 20 22 24 率最小模糊搜索控制算法(FLSC)。算法采用了在 线模糊推理,因此运算量较大;但是通过新型比例 因子的设计,以及对模糊集合及其隶属度函数所做 的系统化设计,使前期控制器的设计过程相对简 单,并能够很好地解决传统搜索控制算法速度慢、 以及在效率最优点处容易出现振荡的问题,使系统 的鲁棒性有了明显的提高。 理论分析及仿真结果表明,FLSC算法综合了 LMC算法速度快、SC算法鲁棒性好的优点,能够 t/s ,、 Co)直流母线输入功率 .量 800 晕 400 O 16 18 t/s (C)电机转矩给定电流, 图9电机转速为750 r・min、负载n为0.1 pu时 FLSC控制曲线图 适应电机的各种稳态工况;FLSC算法在反复进行 的电机实验过程中也表现出可靠性高、运行稳定、 抗外界扰动能力强等突出优点。 进入第2次FLSC效率寻优,控制进程重现第1次 寻优进程。在整个控制过程中电机转速保持不变。 参 [1]Bonet 考 文 献 Understanding Efficiency in Squirrel Cage Induction Motors I-J].IEEE Transactions on Industry Applica— tions,1980,16(4):476—483. 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Design for the Efficiency Optimization Algorithm of Induction Motors ZHANG Liwei ,HU Guangyan , WEN Xuhui .ZHENG Qionglin Jiaotong University,Beijing 100044,China; (1.School of Electrical Engineering,Beijing 2.Institute of Electrical Engineering,Chinese Academy of Sciences,Beijing 100080,China) Abstract:Based on Loss Model Control(I.MC)and Search Control(SC)strategies appearing in recent years,this paper proposes a new fuzzy logic based hybrid on-line minimum input power search control (FI SC)strategy for the efficiency optimization of induction motor.Unlike other fuzzy methods that need simulation calculations to get the coefficients of the scaling factors,the gains derivative method of this strategy utilizes the research results of I MC to do on—line scaling factor calculation。which can mark out the optimization course in advance and ensure the convergence.According to the characteristics of induc— tion motor and the comprehensive analysis of the previous test data,the systematic design is carried out for new fuzzy sets and its affliliation level functions used for fuzzy contro1.Scaling affiliation level functions design is conducted for ZE fuzzy set with input variables,and positive and negative asymmetric affiliation level function design for output variables,which can make the control system converge fast with avoiding the oscillation around the optimal flux.The simulation of low power induction motor system and stand tests show that FI SC algorithm can remarkably improve the control performance of induction motor sys— tem under light load operation,and have good robustness for rotor resistance parameter change condition of induction motor. Key words:Induction motor;Efficiency optimization;Loss model control;Search control;Fuzzy logic based search control (责任编辑刘卫华)
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