基于预测控制的矩阵变换器开关开路故障诊断方法Matrix converter open-circuit fault diagnosis method based on predictive control
技术领域Technical field
本发明涉及电路故障诊断领域,尤其涉及基于预测控制的矩阵变换器开关开路故障诊断方法。The invention relates to the field of circuit fault diagnosis, in particular to a matrix converter open-circuit fault diagnosis method based on predictive control.
背景技术Background technique
近年来,随着电力电子技术的迅猛发展,出现了许多新型的电源转换器,在诸多交-交变换器中,矩阵变换器可以实现所有交流参数(相数、相位、振幅、频率)的变换,并以其特有的优势吸引了大批学者的关注。与传统的变换器相比,矩阵变换器具有以下的优点:不需要中间直流储能环节、能够四象限运行、电源设计紧凑、具有优良的输入电流波形和输出电压波形、能量可双向流动、体积小、重量轻以及可自由控制输入功率因数等。另外,由于矩阵变换器没有电解电容器,所以寿命较长,可以广泛地应用于航空航天、军事和医疗等对体积、重量有较高要求的领域。In recent years, with the rapid development of power electronics technology, many new power converters have appeared. In many AC-DC converters, the matrix converter can realize the transformation of all AC parameters (phase number, phase, amplitude, frequency). And with its unique advantages, it has attracted the attention of a large number of scholars. Compared with the traditional converter, the matrix converter has the following advantages: no intermediate DC energy storage, four-quadrant operation, compact power supply design, excellent input current waveform and output voltage waveform, energy bidirectional flow, volume Small, lightweight and free to control the input power factor. In addition, since the matrix converter has no electrolytic capacitor, it has a long life and can be widely applied to fields requiring high volume and weight, such as aerospace, military, and medical.
然而,矩阵变换器***的开关器件长期处于高频调制下,发热较为严重,开关损耗较大,也极易发生故障。当某个开关器件出现开路故障时,如不能及时发现并进行处理,很容易损坏整个矩阵变换器***。特别是长时间运行后,会严重影响***的运行性能和设备使用寿命。因此,对矩阵变换器***进行故障诊断与容错至关重要。However, the switching device of the matrix converter system is under high-frequency modulation for a long time, the heat is more serious, the switching loss is large, and it is also prone to failure. When an open circuit fault occurs in a switching device, if it cannot be found and processed in time, it is easy to damage the entire matrix converter system. Especially after long-term operation, it will seriously affect the running performance of the system and the service life of the equipment. Therefore, fault diagnosis and fault tolerance for matrix converter systems are essential.
预测控制近年来被应用于电力电子变换器,因为该方法具有诸多优点,比如动态响应快速、思路清晰和约束简单等,可灵活地应用于诸多***。然而目前尚未见到用预测控制的思想进行矩阵变换器故障诊断与容错的对策。因此,需设计一种基于预测控制的矩阵变换器开关开路故障诊断方法,及时诊断***故障的发生并采取相应的容错措施,以提高矩阵变换器***的可靠性及使用寿命。Predictive control has been applied to power electronic converters in recent years because it has many advantages, such as fast dynamic response, clear thinking, and simple constraints, which can be flexibly applied to many systems. However, the idea of predictive control for matrix converter fault diagnosis and fault tolerance has not been seen yet. Therefore, it is necessary to design a matrix converter open-circuit fault diagnosis method based on predictive control, timely diagnose the occurrence of system faults and take corresponding fault-tolerant measures to improve the reliability and service life of the matrix converter system.
发明内容Summary of the invention
本发明目的在于提供一种基于预测控制的矩阵变换器开关开路故障诊断方法,以解决矩阵变换器的开关器件出现开路故障时无法及时发现的技术问题。The object of the present invention is to provide a matrix converter open-circuit fault diagnosis method based on predictive control, which solves the technical problem that the switching device of the matrix converter cannot be found in time when an open circuit fault occurs.
为实现上述目的,本发明提供了一种基于预测控制的矩阵变换器开关开路故障诊断方法,包括以下步骤:To achieve the above object, the present invention provides a matrix converter switch open circuit fault diagnosis method based on predictive control, comprising the following steps:
S1:在矩阵变换器正常工作的情况下,依据采样周期采集矩阵变换器的输出电压、输入电压、输入电流与负载电流,建立输出电压与输入电压、输入电流与负载电流之间的关系模型;S1: in the case that the matrix converter works normally, the output voltage, the input voltage, the input current and the load current of the matrix converter are collected according to the sampling period, and a relationship model between the output voltage and the input voltage, the input current and the load current is established;
S2:在满足约束条件的情况下,确定矩阵变换器的所有开关组合状态的数目;
S2: determining the number of all switch combination states of the matrix converter if the constraint is satisfied;
S3:建立矩阵变换器负载端状态空间模型,获得负载电流在下一采样周期的预测值;S3: establishing a state space model of the load transformer load end, and obtaining a predicted value of the load current in the next sampling period;
S4:建立矩阵变换器输入端滤波器状态空间模型,离散化后,获得下一采样周期输入电流与输入电压的预测值;S4: establishing a state space model of the input filter of the matrix converter, and discretizing, obtaining a predicted value of the input current and the input voltage of the next sampling period;
S5:确定评价函数;S5: determining an evaluation function;
S6:采用有限集模型预测控制策略,在每一采样周期,在所有开关组合状态中选择使评价函数值最小的开关状态,作为下一采样周期的开关状态;S6: using a finite set model predictive control strategy, in each sampling period, selecting a switch state that minimizes the evaluation function value in all switch combination states as a switch state of the next sampling period;
S7:建立开关开路故障条件下的等效电路的状态空间模型,得到故障相负载电流在开关开路故障后的变化规律;S7: Establish a state space model of the equivalent circuit under the open circuit fault condition, and obtain the change law of the fault phase load current after the open circuit fault of the switch;
S8:对负载电流进行在线监测,当负载电流持续为零时,根据有限集模型预测控制选择的开关状态进行故障诊断,识别故障开关的位置。S8: On-line monitoring of the load current. When the load current continues to be zero, the fault state is determined according to the finite set model prediction control switch state, and the position of the fault switch is identified.
作为本发明的进一步改进:As a further improvement of the invention:
优选地,步骤S8完成后,方法还包括:Preferably, after the step S8 is completed, the method further includes:
S9:在识别故障开关的位置后,将所有开关组合状态中与故障开关的动作有关的开关状态去除,确定余下所有开关组合状态的数目;S9: after identifying the position of the fault switch, remove the switch state related to the action of the fault switch in all switch combination states, and determine the number of all remaining switch combination states;
S10:在余下的所有开关组合状态中,重新确定具体故障下的评价函数;S10: re-determining the evaluation function under the specific fault in all the remaining switch combination states;
S11:采用有限集模型预测控制策略,在每一采样周期,在余下的所有开关组合状态中选择使评价函数值最小的开关组合状态,作为下一采样周期的开关状态。S11: Using a finite set model predictive control strategy, in each sampling period, a switch combination state that minimizes the evaluation function value is selected among all remaining switch combination states as a switch state of the next sampling period.
优选地,输出电压与输入电压、输入电流与负载电流之间的关系模型如下:Preferably, the relationship between the output voltage and the input voltage, input current and load current is as follows:
其中,uoA、uoB和uoC分别为A、B和C三相的输出电压;uea、ueb和uec分别为A、B和C三相的输入电压;iea、ieb和iec分别为A、B和C三相的输入电流;ioA、ioB和ioC分别为A、
B和C三相的负载电流;S为开关状态矩阵;S中的元素SXY(X∈{A,B,C},Y∈{a,b,c})表示该开关的开关状态,SXY=1表示开关SXY为闭合状态,SXY=0表示开关SXY为断开状态。Where u oA , u oB and u oC are the output voltages of the three phases A, B and C respectively; u ea , u eb and u ec are the input voltages of the three phases A, B and C respectively; i ea , i eb and i ec is the input current of three phases A, B and C respectively; i oA , i oB and i oC are the load currents of three phases A, B and C respectively; S is the switching state matrix; the element S XY in S (X ∈{A, B, C}, Y∈{a, b, c}) indicates the switching state of the switch, S XY =1 indicates that the switch S XY is closed, and S XY =0 indicates that the switch S XY is off. .
优选地,约束条件包括:Preferably, the constraints include:
S201:输入端不短路,输出端不断路;S201: the input end is not short-circuited, and the output end is continuous;
S202:在任意时刻,连接到同一相输出的三个双向开关中,有且仅有一个开关导通,另外两个开关关断;S202: at any time, among the three bidirectional switches connected to the same phase output, one and only one switch is turned on, and the other two switches are turned off;
S203:满足各个开关占空比的非负性;S203: satisfying non-negativeity of duty ratios of the respective switches;
在上述约束条件下,开关状态矩阵S中的每个元素满足:Under the above constraints, each element in the switch state matrix S satisfies:
可得矩阵变换器正常工作时的所有开关组合状态有3*3*3=27种。The state of all switch combinations in the normal operation of the matrix converter is 3*3*3=27.
优选地,步骤S3,包括以下步骤:Preferably, step S3 comprises the following steps:
S301:建立矩阵变换器负载端状态空间模型如下:S301: Establish a state space model of the matrix converter load end as follows:
其中,io和uo分别为负载电流与输出电压;L和R分别表示负载的电感和电阻;Where i o and u o are the load current and the output voltage, respectively; L and R represent the inductance and resistance of the load, respectively;
S302:定义一个开关周期Ts,根据向前欧拉公式得到负载电流在下一采样周期的预测值io
k+1为:S302: Define a switching period T s , and obtain a predicted value i o k+1 of the load current in the next sampling period according to the forward Euler's formula:
其中,io
k和uo
k分别为当前采样时刻的负载电流值和输出电压值;系数F1和F2分别为:Where i o k and u o k are the load current value and the output voltage value at the current sampling time, respectively; the coefficients F 1 and F 2 are:
优选地,步骤S4,包括以下步骤:Preferably, step S4 comprises the following steps:
S401:建立矩阵变换器输入端滤波器状态空间模型如下:S401: Establish a filter state space model at the input end of the matrix converter as follows:
其中us、ue、is和ie分别表示电源电压、滤波电容电压、电源电流和输入电流;Ri、Li和Ci分别表示滤波电阻、电源和滤波电感以及滤波电容;Where u s , u e , i s and i e represent the supply voltage, the filter capacitor voltage, the supply current and the input current, respectively; R i , L i and C i represent the filter resistor, the power supply and the filter inductor, and the filter capacitor, respectively;
S402:结合(9)式和(10)式得到:S402: Combining (9) and (10) to obtain:
其中:among them:
S403:将(11)式离散化,得到:S403: discretizing (11) to obtain:
式中和分别表示在下一采样周期的滤波电容电压和电源电流值;和分别表示在当前采样时刻的电源电压、滤波电容电压、电源电流和输入电流值;且有:In the middle with Representing the filter capacitor voltage and the supply current value in the next sampling period; with The power supply voltage, filter capacitor voltage, power supply current, and input current value at the current sampling time are respectively indicated; and:
S404:将(15)式代入(14)式,得到下一采样周期的输入电流以及滤波电容电压:S404: Substituting (15) into equation (14) to obtain an input current and a filter capacitor voltage for the next sampling period:
其中,E2、E3、D2和D3均为矩阵G的元素,E1、E4、D1和D4均为矩阵H的元素,由Ri、Li、Ci和采样周期Ts决定。Where E 2 , E 3 , D 2 and D 3 are elements of the matrix G, and E 1 , E 4 , D 1 and D 4 are elements of the matrix H, by R i , L i , C i and the sampling period T s decided.
优选地,步骤S5,包括以下步骤:Preferably, step S5 includes the following steps:
S501:确定与矩阵变换器的输入电流相关的评价函数;S501: determining an evaluation function related to an input current of the matrix converter;
矩阵变换器输入电流的参考值为:
The reference value of the matrix converter input current is:
其中φ是输入电压的相角,为参考输入电流的幅值,并且有:Where φ is the phase angle of the input voltage, Reference input current The magnitude and have:
其中Usm为电源电压us的幅值;η为矩阵变换器的效率,由如下公式获得:Where U sm is the magnitude of the supply voltage u s ; η is the efficiency of the matrix converter, obtained by the following formula:
其中的Po和Pin分别表示输出功率和输入功率,分别由如下公式得到:P o and P in represent the output power and input power, respectively, which are obtained by the following formula:
其中I*
om表示参考负载电流i*
o的幅值;期望输入电流is功率因数为1,所以式中θ为0;Where I * om represents the magnitude of the reference load current i * o ; the expected input current i s has a power factor of 1, so θ is 0;
S502:确定预测控制中关于输入电流is期望达到单位输入功率因数性能的评价函数g1为:S502: determining the predictive control on the input current i s reaches unity input power factor is desirable to evaluate the performance as a function of g 1:
式中,Δisα和Δisβ分别表示两相静止坐标系下的输入电流在下一采样周期预测值is
p与参考值is
*偏差的α和β分量,由如下公式得到: Wherein, Δi sα and Δi sβ represent the input current two-phase stationary coordinate system in the next sampling period of a predicted value with a reference value i s p i α and β components s * deviation, obtained by the following equation:
式中,Tabctoαβ是三相静止坐标系转换为两相旋转坐标系的变换矩阵,由下式得到:In the formula, T abctoαβ is a transformation matrix of a three-phase stationary coordinate system converted into a two-phase rotating coordinate system, which is obtained by:
S503:确定预测控制中与矩阵变换器负载电流相关的评价函数:S503: Determine an evaluation function related to the matrix converter load current in the predictive control:
定义关于负载电流预测值期望达到跟踪参考负载电流性能的评价函数g2为:The evaluation function g 2 defining the expected value of the load current predicted to achieve the tracking reference load current is:
式中,Δioα和Δioβ分别表示两相静止坐标系下的负载电流在下一采样周期预测值io
p与参考值io
*偏差的α和β分量,由如下公式得到: Wherein, Δi oα and Δi oβ represent load current two-phase stationary coordinate system in the next sampling period of a predicted value with a reference value i o p i o * deviation α and β components, obtained by the following formula:
S504:定义总评价函数为:S504: Define the total evaluation function as:
g=λ*g1+g2 (28)g=λ*g 1 +g 2 (28)
其中,λ是权重因子,表示输入电流的性能指标在整个矩阵变换器***的控制中的重要程度;Where λ is a weighting factor, indicating the importance of the performance index of the input current in the control of the entire matrix converter system;
则,步骤S6,具体为:在矩阵变换器运行过程中,采用有限集模型预测控制策略,即在每个采样周期计算所有开关组合状态的总评价函数的g值,选择其中能使g值最小的一种开关状态,作为下一采样周期的开关状态,实现达到***期望的动态性能和稳态性能指标的运行。Then, in step S6, specifically: during the operation of the matrix converter, the finite set model prediction control strategy is adopted, that is, the g value of the total evaluation function of all switch combination states is calculated in each sampling period, and the g value is selected to be minimized. A switching state, as the switching state of the next sampling period, achieves the operation of achieving the desired dynamic performance and steady state performance specifications of the system.
优选地,步骤S7,包括以下步骤:Preferably, step S7 includes the following steps:
S701:假设如下条件S7011至S7013成立:S701: It is assumed that the following conditions S7011 to S7013 are established:
S7011:采样周期为Ts;S7011: The sampling period is T s ;
S7012:将输入电压周期分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ顺序排列的六个扇区,输入电压相角在扇区Ⅴ并且即将进入扇区Ⅵ;A输出相的参考电流值i*
oA和实际值ioA都是正值;S7012: The input voltage period is divided into six sectors in which I, II, III, IV, V and VI are sequentially arranged, the input voltage phase angle is in the sector V and is about to enter the sector VI; the reference current value i of the A output phase * oA and the actual value i oA are positive values;
S7013:SAa发生开路故障,在kth个采样周期Ts
k的时间内,预测控制器为了缩小A输出相电流的实际值与参考值的偏差,始终给SAa导通信号;S7013: S Aa has an open circuit fault. During the k th sampling period T s k , the predictive controller always turns on the S Aa turn-on signal in order to reduce the deviation between the actual value of the A output phase current and the reference value;
则有,A输出相开路,A相负载电流ioA会流经箝位电路,其电路状态空间模型描述如下:Then, the A output phase is open, and the A phase load current i oA flows through the clamp circuit. The circuit state space model is described as follows:
式中,uN是负载中性点与电源接地点之间的电压;Where u N is the voltage between the load neutral point and the power ground point;
输出相的电压表示如下:
The voltage of the output phase is expressed as follows:
其中,Ucp是箝位电路的电容电压,umax为输入三相电压的最大值;Where U cp is the capacitance voltage of the clamp circuit, and u max is the maximum value of the input three-phase voltage;
由于A相负载电流流过箝位电路,所以Ucp远大于umax,表示为:Since the phase A load current flows through the clamp circuit, U cp is much larger than u max , which is expressed as:
其中,umin表示输入三相电压的最小值;Where u min represents the minimum value of the input three-phase voltage;
根据(29)式和(30)式,得到A相负载电流ioA的变化率为:According to the equations (29) and (30), the rate of change of the phase A load current i oA is obtained as follows:
由(31)可得:Available from (31):
将(33)代入(32),得到:Substituting (33) into (32) gives:
当ioA>0时 (34) When i oA >0 (34)
S703:构造能量函数v:S703: Construct energy function v:
其变化率表示为:The rate of change is expressed as:
于是,得到:So, get:
当ioA<0时 (37)
When i oA <0 (37)
由(34)式和(37)式可知:当故障开关满足SAa=1时,A相负载电流的幅值会越来越小,从而使其实际值与参考值之间的偏差越来越大;因为SAa在扇区VI和I连通A输出相对应的最大输入电压,预测控制器始终给开关SAa导通信号,然而,SAa因为故障无法导通,结果就是A相负载电流幅值减小并且连续几个采样周期内SAa=1;在一定时间内,A相负载电流的幅值逐渐减小到零;It can be known from equations (34) and (37) that when the fault switch satisfies S Aa =1, the amplitude of the phase A load current will become smaller and smaller, so that the deviation between the actual value and the reference value becomes more and more Large; because S Aa is in the sector VI and I connected to the A corresponding output of the maximum input voltage, the predictive controller always turns on the switch S Aa , however, S Aa cannot be turned on because of the fault, the result is the A phase load current amplitude The value decreases and S Aa =1 for several consecutive sampling periods; the amplitude of the phase A load current gradually decreases to zero within a certain period of time;
S704:当输入电压相角落在扇区III和IV时,A输出相的参考电流值i*
oA和实际值ioA都是负值,此时的能量函数变化率表示为:S704: When the input voltage phase is in the sectors III and IV, the reference current value i * oA and the actual value ioA of the A output phase are both negative values, and the energy function change rate at this time is expressed as:
在一定的时间内,A相负载电流的幅值也会减小到零。The amplitude of the phase A load current will also decrease to zero for a certain period of time.
优选地,步骤S8,包括以下步骤:Preferably, step S8 includes the following steps:
S801:当负载电流保持为零的持续时间Tzero达到故障诊断所需时间时,再根据有限集模型预测控制选择的开关状态进行故障诊断,识别故障开关的位置,故障情况与输入电压周期和负载电流基波周期To有关,将故障持续时间表示为:S801: When the duration T zero of the load current remains zero reaches the time required for fault diagnosis, the fault state is determined according to the finite set model prediction control switch state, the fault switch position, the fault condition and the input voltage period and the load are identified. The current fundamental period is related to T o and the duration of the fault is expressed as:
其中,Tin和To分别表示输入电压基波周期和负载电流基波周期;Wherein T in and T o represent the input voltage fundamental period and the load current fundamental period, respectively;
定义故障相的负载电流通过箝位电路变到零所需的时间Tdischarge,故障相电流保持为零的时间Tzero表示为:The time T discharge required to define the load current of the fault phase to zero by the clamp circuit, and the time T zero at which the fault phase current remains zero is expressed as:
Tzero=Tfault-Tdischarge (39)T zero =T fault -T discharge (39)
故障诊断时间需要满足:The troubleshooting time needs to be met:
kfTs>Tε (40)k f T s >T ε (40)
其中,kf是故障诊断的敏感系数;Ts是正常运行情况下输出相的参考电流的过零(输出相的参考电流小于阈值ε)时间;阈值ε是为了减少故障诊断的误报率而设置的一个小的正值;Where k f is the sensitivity coefficient of fault diagnosis; T s is the zero-crossing of the reference current of the output phase under normal operation (the reference current of the output phase is less than the threshold ε); the threshold ε is to reduce the false alarm rate of the fault diagnosis. a small positive value set;
综合(38)~(40)式,故障诊断所需时间应该满足:Comprehensive (38) ~ (40), the time required for fault diagnosis should meet:
S802:根据有限集模型预测控制选择的开关状态进行故障诊断,识别故障开关位置,假
设SAa发生开路故障,故障开关定位的逻辑可以表示为:S802: Perform fault diagnosis according to the limited set model predictive control switch state, identify the fault switch position, and assume that the open fault of the SA Aa , the logic of the fault switch positioning may be expressed as:
如果几个连续的采样周期内,满足|ioA|≤ε且SAa=1,那么SAa发生开路故障,即:If |i oA | ≤ ε and S Aa =1 are satisfied in several consecutive sampling periods, then S Aa has an open circuit fault, namely:
优选地,步骤S9中当SAa开路时,矩阵变换器的运行的约束条件为:Preferably, when S Aa is open in step S9, the constraint of the operation of the matrix converter is:
从而余下的开关组合状态共有2*3*3=18种;其余开关开路时,依此类推;Therefore, the remaining switch combination states are 2*3*3=18; when the other switches are open, and so on;
步骤S10中,在余下的所有开关组合状态中,不考虑与矩阵变换器输入电流相关的评价函数,即(28)式总评价函数中的λ取零值,重新确定具体故障下的评价函数为:In step S10, in all the remaining switch combination states, the evaluation function related to the input current of the matrix converter is not considered, that is, the value of λ in the total evaluation function of (28) is zero, and the evaluation function under the specific fault is re-determined as :
gF=g2 (44)g F = g 2 (44)
步骤S11中,在矩阵变换器带故障运行过程中,采用有限集模型预测控制方法,即在每个采样周期计算余下的所有开关组合状态下的gF值,选择其中使gF最小值的开关组合状态作为下一采样周期的开关状态;实现故障后的满足***动、稳态性能指标的容错运行。In step S11, the matrix converter with fault during operation, the finite set of model predictive control method, i.e., calculated at each sampling period g F values for all remaining combinations of state switches, selecting the minimum value which the switching g F The combined state is used as the switching state of the next sampling period; the fault-tolerant operation that satisfies the dynamic and steady-state performance indexes of the system after the fault is realized.
本发明具有以下有益效果:The invention has the following beneficial effects:
1、本发明的基于预测控制的矩阵变换器开关开路故障诊断方法,实时监测三相负载电流,通过判断输出相电流保持为零,检测矩阵变换器***是否有故障发生,并且根据当时预测控制器的开关状态定位故障开关。本发明能及时诊断开路故障,以便控制器及时进行处理,从而延长使用寿命。1. The predictive control based matrix converter open-circuit fault diagnosis method of the present invention monitors the three-phase load current in real time, and determines whether the output of the matrix converter system is faulty by judging that the output phase current remains zero, and predicts the controller according to the time. The switch state locates the fault switch. The invention can diagnose the open circuit fault in time, so that the controller can process in time, thereby prolonging the service life.
2、本发明的基于预测控制的矩阵变换器开关开路故障诊断方法,进一步还能对故障进行容错处理,当矩阵变换器的一个开关发生开路故障时,利用剩余的正常开关组成新的开关状态组合,然后继续使用预测控制思想选择最合适的开关状态,使矩阵变换器***在单开关开路故障的情况下继续运行。本发明可以避免因开路故障造成的器件损坏,进一步延长了器件的使用寿命。2. The predictive control based matrix converter open-circuit fault diagnosis method of the present invention can further perform fault-tolerant processing on faults. When an open-circuit fault occurs in a switch of the matrix converter, a new switch state combination is formed by using the remaining normal switches. Then, continue to use the predictive control idea to select the most appropriate switch state, so that the matrix converter system continues to operate in the case of a single switch open fault. The invention can avoid device damage caused by open circuit failure and further prolong the service life of the device.
除了上面所描述的目的、特征和优点之外,本发明还有其它的目的、特征和优点。下面将参照附图,对本发明作进一步详细的说明。In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. The invention will now be described in further detail with reference to the accompanying drawings.
附图说明DRAWINGS
构成本申请的一部分的附图用来提供对本发明的进一步理解,本发明的示意性实施例及其说明用于解释本发明,并不构成对本发明的不当限定。在附图中:
The accompanying drawings, which are incorporated in the claims In the drawing:
图1是本发明优选实施例的基于预测控制的矩阵变换器开关开路故障诊断方法的流程示意图;1 is a flow chart showing a method for predicting open-circuit fault of a matrix converter based on predictive control according to a preferred embodiment of the present invention;
图2是本发明优选实施例的矩阵变换器的拓扑结构图;2 is a topological structural view of a matrix converter in accordance with a preferred embodiment of the present invention;
图3是本发明优选实施例的矩阵变换器的模型预测控制策略的流程示意图;3 is a flow chart showing a model predictive control strategy of a matrix converter in accordance with a preferred embodiment of the present invention;
图4是本发明优选实施例的矩阵变换器在正常工作条件下的输入/输出电压以及输入/负载电流实验波形图;4 is an experimental waveform diagram of input/output voltage and input/load current of a matrix converter under normal operating conditions in accordance with a preferred embodiment of the present invention;
图5是本发明优选实施例的矩阵变换器的输入电压基波周期分扇区示意图;其中,Voltage为电压;Sector为扇区;5 is a schematic diagram showing a period of a fundamental voltage period of an input voltage of a matrix converter according to a preferred embodiment of the present invention; wherein, Voltage is a voltage; and Sector is a sector;
图6是本发明优选实施例的矩阵变换器开关SAa故障条件下的等效电路示意图;6 is a schematic diagram showing an equivalent circuit of a matrix converter switch SAa under a fault condition according to a preferred embodiment of the present invention;
图7是本发明优选实施例的矩阵变换器开关开路故障诊断的流程图;7 is a flow chart of the open circuit fault diagnosis of the matrix converter of the preferred embodiment of the present invention;
图8是本发明优选实施例的矩阵变换器开关开路故障容错策略的流程图;8 is a flow chart of a matrix converter switch open fault fault tolerant strategy in accordance with a preferred embodiment of the present invention;
图9是发明优选实施例的矩阵变换器发生开路故障的条件下加入诊断与容错措施前后的负载电流波形对比示意图。9 is a schematic diagram showing a comparison of load current waveforms before and after adding diagnostic and fault-tolerant measures under the condition that an open circuit fault occurs in a matrix converter of a preferred embodiment of the present invention.
具体实施方式detailed description
以下结合附图对本发明的实施例进行详细说明,但是本发明可以由权利要求限定和覆盖的多种不同方式实施。The embodiments of the present invention are described in detail below with reference to the accompanying drawings.
参见图1,本发明实施例的基于预测控制的矩阵变换器开关开路故障诊断方法,包括以下步骤:Referring to FIG. 1, a method for predicting open-circuit fault of a matrix converter based on predictive control according to an embodiment of the present invention includes the following steps:
S1:在矩阵变换器正常工作的情况下,依据采样周期采集矩阵变换器的输出电压、输入电压、输入电流与负载电流,建立输出电压与输入电压、输入电流与负载电流之间的关系模型;S1: in the case that the matrix converter works normally, the output voltage, the input voltage, the input current and the load current of the matrix converter are collected according to the sampling period, and a relationship model between the output voltage and the input voltage, the input current and the load current is established;
S2:在满足约束条件的情况下,确定矩阵变换器的所有开关组合状态的数目;S2: determining the number of all switch combination states of the matrix converter if the constraint is satisfied;
S3:建立矩阵变换器负载端状态空间模型,获得负载电流在下一采样周期的预测值;S3: establishing a state space model of the load transformer load end, and obtaining a predicted value of the load current in the next sampling period;
S4:建立矩阵变换器输入端滤波器状态空间模型,离散化后,获得下一采样周期输入电流与输入电压的预测值;S4: establishing a state space model of the input filter of the matrix converter, and discretizing, obtaining a predicted value of the input current and the input voltage of the next sampling period;
S5:确定评价函数;S5: determining an evaluation function;
S6:采用有限集模型预测控制策略,在每一采样周期,在所有开关组合状态中选择使评价函数值最小的开关状态,作为下一采样周期的开关状态;S6: using a finite set model predictive control strategy, in each sampling period, selecting a switch state that minimizes the evaluation function value in all switch combination states as a switch state of the next sampling period;
S7:建立开关开路故障条件下的等效电路的状态空间模型,得到故障相负载电流在开关开路故障后的变化规律;S7: Establish a state space model of the equivalent circuit under the open circuit fault condition, and obtain the change law of the fault phase load current after the open circuit fault of the switch;
S8:对负载电流进行在线监测,当负载电流持续为零时,根据有限集模型预测控制选择
的开关状态进行故障诊断,识别故障开关的位置。S8: On-line monitoring of load current, predictive control selection based on finite set model when load current continues to zero
The switch status is diagnosed and the position of the fault switch is identified.
以上步骤,通过实时监测三相负载电流,判断输出相电流保持为零(实际应用中,保持为零可以采用其持续时间是否超过阈值来判断),检测矩阵变换器***是否有故障发生,并且根据当时预测控制器的开关状态定位故障开关,能及时诊断开路故障。In the above steps, by monitoring the three-phase load current in real time, it is judged that the output phase current remains zero (in practical applications, keeping zero can be judged by whether its duration exceeds the threshold), detecting whether the matrix converter system has a fault, and according to At that time, the controller's switch state was positioned to locate the fault switch, which can diagnose the open circuit fault in time.
在实际应用中,在上述步骤的基础上,本发明另一优选实施例的基于预测控制的矩阵变换器开关开路故障诊断方法,增加容错运行步骤进行优化:In practical applications, based on the above steps, the predictive control based matrix converter open-circuit fault diagnosis method according to another preferred embodiment of the present invention increases the fault-tolerant operation steps for optimization:
即在上述的步骤S8完成后,进行以下步骤:That is, after the above step S8 is completed, the following steps are performed:
S9:在识别故障开关的位置后,将所有开关组合状态中与故障开关的动作有关的开关状态去除,确定余下所有开关组合状态的数目;S9: after identifying the position of the fault switch, remove the switch state related to the action of the fault switch in all switch combination states, and determine the number of all remaining switch combination states;
S10:在余下的所有开关组合状态中,重新确定具体故障下的评价函数;S10: re-determining the evaluation function under the specific fault in all the remaining switch combination states;
S11:采用有限集模型预测控制策略,在每一采样周期,在余下的所有开关组合状态中选择使评价函数值最小的开关组合状态,作为下一采样周期的开关状态。S11: Using a finite set model predictive control strategy, in each sampling period, a switch combination state that minimizes the evaluation function value is selected among all remaining switch combination states as a switch state of the next sampling period.
这一优选实施例能进一步对故障进行容错处理,当矩阵变换器的一个开关发生开路故障时,利用剩余的正常开关组成新的开关状态组合,然后继续使用预测控制思想选择最合适的开关状态,使矩阵变换器***在单开关开路故障的情况下继续运行。本发明实施例可以避免因开路故障造成的器件损坏,进一步延长了器件的使用寿命。The preferred embodiment can further perform fault tolerance processing on the fault. When an open circuit fault occurs in a switch of the matrix converter, the remaining normal switch is used to form a new switch state combination, and then the predictive control idea is used to select the most suitable switch state. The matrix converter system continues to operate in the event of a single switch open circuit failure. The embodiment of the invention can avoid device damage caused by open circuit failure and further prolong the service life of the device.
下面将上述实施例应用到如图2所示的拓扑结构的矩阵变换器上,且以矩阵变换器的开关SAa发生开路故障为例,对本发明进行进一步分析:The above embodiment is applied to the matrix converter of the topology shown in FIG. 2, and the open-circuit fault of the switch S Aa of the matrix converter is taken as an example to further analyze the present invention:
矩阵变换器正常运行时,其主电路拓扑结构如图2所示;矩阵变换器有限集模型预测控制选择开关状态的过程如图3所示;实验参数如表1所示。When the matrix converter is in normal operation, its main circuit topology is shown in Figure 2. The process of predicting the control switch state by the matrix converter finite set model is shown in Figure 3. The experimental parameters are shown in Table 1.
表1.实验参数表Table 1. Experimental parameter table
本发明实施例的基于预测控制的矩阵变换器开关开路故障诊断方法,包括以下步骤:The predictive control based matrix converter open-circuit fault diagnosis method according to the embodiment of the invention comprises the following steps:
S1:在矩阵变换器正常工作的情况下,依据采样周期采集矩阵变换器的输出电压、输入电压、输入电流与负载电流,建立输出电压与输入电压、输入电流与负载电流之间的关系模
型如下:S1: In the case of normal operation of the matrix converter, the output voltage, the input voltage, the input current and the load current of the matrix converter are collected according to the sampling period, and the relationship between the output voltage and the input voltage, the input current and the load current is established.
The type is as follows:
其中,uoA、uoB和uoC分别为A、B和C三相的输出电压;uea、ueb和uec分别为A、B和C三相的输入电压;iea、ieb和iec分别为A、B和C三相的输入电流;ioA、ioB和ioC分别为A、B和C三相的负载电流;S为开关状态矩阵;S中的元素SXY(X∈{A,B,C},Y∈{a,b,c})表示该开关的开关状态,SXY=1表示开关SXY为闭合状态,SXY=0表示开关SXY为断开状态。Where u oA , u oB and u oC are the output voltages of the three phases A, B and C respectively; u ea , u eb and u ec are the input voltages of the three phases A, B and C respectively; i ea , i eb and i ec is the input current of three phases A, B and C respectively; i oA , i oB and i oC are the load currents of three phases A, B and C respectively; S is the switching state matrix; the element S XY in S (X ∈{A, B, C}, Y∈{a, b, c}) indicates the switching state of the switch, S XY =1 indicates that the switch S XY is closed, and S XY =0 indicates that the switch S XY is off. .
S2:在满足约束条件的情况下,确定矩阵变换器的所有开关组合状态的数目。设立约束条件是为了确保矩阵变换器的安全运行。约束条件包括以下几个:S2: Determine the number of all switch combination states of the matrix converter if the constraints are met. The constraints are set up to ensure the safe operation of the matrix converter. Constraints include the following:
S201:输入端不短路,输出端不断路;S201: the input end is not short-circuited, and the output end is continuous;
S202:在任意时刻,连接到同一相输出的三个双向开关中,有且仅有一个开关导通,另外两个开关关断;S202: at any time, among the three bidirectional switches connected to the same phase output, one and only one switch is turned on, and the other two switches are turned off;
S203:满足各个开关占空比的非负性;S203: satisfying non-negativeity of duty ratios of the respective switches;
在上述约束条件下,开关状态矩阵S中的每个元素满足:Under the above constraints, each element in the switch state matrix S satisfies:
可得矩阵变换器正常工作时的所有开关组合状态有3*3*3=27种。The state of all switch combinations in the normal operation of the matrix converter is 3*3*3=27.
S3:建立矩阵变换器负载端状态空间模型,获得负载电流在下一采样周期的预测值。具体包括以下步骤:S3: Establish a state space model of the load transformer load end to obtain a predicted value of the load current in the next sampling period. Specifically, the following steps are included:
S301:建立矩阵变换器负载端状态空间模型如下:
S301: Establish a state space model of the matrix converter load end as follows:
其中,io和uo分别为负载电流与输出电压;L和R分别表示负载的电感和电阻;Where i o and u o are the load current and the output voltage, respectively; L and R represent the inductance and resistance of the load, respectively;
S302:定义一个开关周期Ts,根据向前欧拉公式得到负载电流在下一采样周期的预测值io
k+1为:S302: Define a switching period T s , and obtain a predicted value i o k+1 of the load current in the next sampling period according to the forward Euler's formula:
其中,io
k和uo
k分别为当前采样时刻的负载电流值和输出电压值;系数F1和F2分别为:Where i o k and u o k are the load current value and the output voltage value at the current sampling time, respectively; the coefficients F 1 and F 2 are:
S4:建立矩阵变换器输入端滤波器状态空间模型,离散化后,获得下一采样周期输入电流与输入电压的预测值。包括以下步骤:S4: Establish a state space model of the input filter of the matrix converter. After discretization, obtain the predicted value of the input current and the input voltage for the next sampling period. Includes the following steps:
S401:建立矩阵变换器输入端滤波器状态空间模型如下:S401: Establish a filter state space model at the input end of the matrix converter as follows:
其中us、ue、is和ie分别表示电源电压、滤波电容电压、电源电流和输入电流;Ri、Li和Ci分别表示滤波电阻、电源和滤波电感以及滤波电容;Where u s , u e , i s and i e represent the supply voltage, the filter capacitor voltage, the supply current and the input current, respectively; R i , L i and C i represent the filter resistor, the power supply and the filter inductor, and the filter capacitor, respectively;
S402:结合(9)式和(10)式得到:S402: Combining (9) and (10) to obtain:
其中:among them:
S403:将(11)式离散化,得到:
S403: discretizing (11) to obtain:
式中和分别表示在下一采样周期的滤波电容电压和电源电流值;和分别表示在当前采样时刻的电源电压、滤波电容电压、电源电流和输入电流值;且有:In the middle with Representing the filter capacitor voltage and the supply current value in the next sampling period; with The power supply voltage, filter capacitor voltage, power supply current, and input current value at the current sampling time are respectively indicated; and:
S404:将(15)式代入(14)式,得到下一采样周期的输入电流以及滤波电容电压:S404: Substituting (15) into equation (14) to obtain an input current and a filter capacitor voltage for the next sampling period:
其中,E2、E3、D2和D3均为矩阵G的元素,E1、E4、D1和D4均为矩阵H的元素,由Ri、Li、Ci和采样周期Ts决定。Where E 2 , E 3 , D 2 and D 3 are elements of the matrix G, and E 1 , E 4 , D 1 and D 4 are elements of the matrix H, by R i , L i , C i and the sampling period T s decided.
S5:确定评价函数,具体包括以下步骤:S5: Determine the evaluation function, which specifically includes the following steps:
S501:确定与矩阵变换器的输入电流相关的评价函数。S501: Determine an evaluation function related to an input current of the matrix converter.
矩阵变换器输入电流的参考值为:The reference value of the matrix converter input current is:
其中φ是输入电压的相角,为参考输入电流的幅值,并且有:Where φ is the phase angle of the input voltage, Reference input current The magnitude and have:
其中Usm为电源电压us的幅值;η为矩阵变换器的效率,由如下公式获得:Where U sm is the magnitude of the supply voltage u s ; η is the efficiency of the matrix converter, obtained by the following formula:
其中的Po和Pin分别表示输出功率和输入功率,分别由如下公式得到:P o and P in represent the output power and input power, respectively, which are obtained by the following formula:
其中I*
om表示参考负载电流i*
o的幅值;期望输入电流is功率因数为1,所以式中θ为0;Where I * om represents the magnitude of the reference load current i * o ; the expected input current i s has a power factor of 1, so θ is 0;
S502:确定预测控制中关于输入电流is期望达到单位输入功率因数性能的评价函数g1
为:S502: determining the predictive control on the input current i s reaches unity input power factor is desirable to evaluate the performance as a function of g 1:
式中,Δisα和Δisβ分别表示两相静止坐标系下的输入电流在下一采样周期预测值is
p与参考值is
*偏差的α和β分量,由如下公式得到: Wherein, Δi sα and Δi sβ represent the input current two-phase stationary coordinate system in the next sampling period of a predicted value with a reference value i s p i α and β components s * deviation, obtained by the following equation:
式中,Tabctoαβ是三相静止坐标系转换为两相旋转坐标系的变换矩阵,由下式得到:In the formula, T abctoαβ is a transformation matrix of a three-phase stationary coordinate system converted into a two-phase rotating coordinate system, which is obtained by:
S503:确定预测控制中与矩阵变换器负载电流相关的评价函数:S503: Determine an evaluation function related to the matrix converter load current in the predictive control:
定义关于负载电流预测值期望达到跟踪参考负载电流性能的评价函数g2为:The evaluation function g 2 defining the expected value of the load current predicted to achieve the tracking reference load current is:
式中,Δioα和Δioβ分别表示两相静止坐标系下的负载电流在下一采样周期预测值io
p与参考值io
*偏差的α和β分量,由如下公式得到: Wherein, Δi oα and Δi oβ represent load current two-phase stationary coordinate system in the next sampling period of a predicted value with a reference value i o p i o * deviation α and β components, obtained by the following formula:
S504:定义总评价函数为:S504: Define the total evaluation function as:
g=λ*g1+g2 (28)g=λ*g 1 +g 2 (28)
其中,λ是权重因子,表示输入电流的性能指标在整个矩阵变换器***的控制中的重要程度。Where λ is the weighting factor, indicating the importance of the performance index of the input current in the control of the entire matrix converter system.
S6:在矩阵变换器运行过程中,采用有限集模型预测控制策略,在每个采样周期计算所有开关组合状态的总评价函数的g值,选择其中能使g值最小的一种开关状态,作为下一采样周期的开关状态,实现达到***期望的动态性能和稳态性能指标的运行。图4所示为矩阵变换器正常工作条件下的输入/输出电压以及输入/负载电流实验波形图。由图4可见,采用预测控制策略选择合适的开关状态可以使矩阵变换器的输入/负载电流正弦且很好地跟踪参考值,并且输入功率因数为1。S6: In the operation of the matrix converter, the finite set model predictive control strategy is adopted, and the g value of the total evaluation function of all switch combination states is calculated in each sampling period, and a switch state in which the g value can be minimized is selected as The switching state of the next sampling period achieves the operation of the system with the desired dynamic performance and steady state performance specifications. Figure 4 shows the input/output voltage and input/load current experimental waveforms of the matrix converter under normal operating conditions. As can be seen from Figure 4, the use of a predictive control strategy to select the appropriate switching state can sine the input/load current of the matrix converter and track the reference well well with an input power factor of one.
以下步骤为对矩阵变换器***进行实时的故障检测与诊断步骤:
The following steps are the real-time fault detection and diagnostic steps for the matrix converter system:
S7:建立开关开路故障条件下的等效电路的状态空间模型,得到故障相负载电流在开关开路故障后的变化规律,具体包括以下步骤:S7: Establish a state space model of the equivalent circuit under the open circuit fault condition, and obtain the change law of the fault phase load current after the open circuit fault of the switch, which specifically includes the following steps:
S701:假设如下条件S7011至S7013成立:S701: It is assumed that the following conditions S7011 to S7013 are established:
S7011:采样周期为Ts;S7011: The sampling period is T s ;
S7012:如图5所示,将输入电压周期分为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ顺序排列的六个扇区,输入电压相角在扇区Ⅴ并且即将进入扇区Ⅵ;A输出相的参考电流值i*
oA和实际值ioA都是正值;S7012: As shown in FIG. 5, the input voltage period is divided into six sectors in which I, II, III, IV, V, and VI are sequentially arranged, and the input voltage phase angle is in the sector V and is about to enter the sector VI; The reference current value i * oA and the actual value i oA of the phase are both positive values;
S7013:SAa发生开路故障,在kth个采样周期Ts
k的时间内,预测控制器为了缩小A输出相电流的实际值与参考值的偏差,始终给SAa导通信号。S7013: S Aa has an open circuit fault. During the k th sampling period T s k , the predictive controller always turns on the S Aa turn-on signal in order to reduce the deviation between the actual value of the A output phase current and the reference value.
则有,A输出相开路,A相负载电流ioA会流经箝位电路,电路如图6(a)所示。其电路状态空间模型描述如下:Then, the A output phase is open, and the A phase load current i oA flows through the clamp circuit, as shown in Figure 6(a). Its circuit state space model is described as follows:
式中,uN是负载中性点与电源接地点之间的电压。Where u N is the voltage between the load neutral point and the power supply ground.
输出相的电压表示如下:The voltage of the output phase is expressed as follows:
其中,Ucp是箝位电路的电容电压,umax为输入三相电压的最大值。Where U cp is the capacitance voltage of the clamp circuit, and u max is the maximum value of the input three-phase voltage.
由于A相负载电流流过箝位电路,所以Ucp远大于umax,表示为:Since the phase A load current flows through the clamp circuit, U cp is much larger than u max , which is expressed as:
其中,umin表示输入三相电压的最小值。Where u min represents the minimum value of the input three-phase voltage.
根据(29)式和(30)式,得到A相负载电流ioA的变化率为:
According to the equations (29) and (30), the rate of change of the phase A load current i oA is obtained as follows:
由(31)可得:Available from (31):
将(33)代入(32),得到:Substituting (33) into (32) gives:
当ioA>0时 (34)。 When i oA > 0 (34).
S703:构造能量函数v:S703: Construct energy function v:
其变化率表示为:The rate of change is expressed as:
于是,得到:So, get:
当ioA<0时 (37) When i oA <0 (37)
由(34)式和(37)式可知:当故障开关满足SAa=1时,A相负载电流的幅值会越来越小,从而使其实际值与参考值之间的偏差越来越大;因为SAa在扇区VI和I连通A输出相对应的最大输入电压,预测控制器始终给开关SAa导通信号,然而,SAa因为故障无法导通,结果就是A相负载电流幅值减小并且连续几个采样周期内SAa=1;在一定时间内,A相负载电流的幅值逐渐减小到零。It can be known from equations (34) and (37) that when the fault switch satisfies S Aa =1, the amplitude of the phase A load current will become smaller and smaller, so that the deviation between the actual value and the reference value becomes more and more Large; because S Aa is in the sector VI and I connected to the A corresponding output of the maximum input voltage, the predictive controller always turns on the switch S Aa , however, S Aa cannot be turned on because of the fault, the result is the A phase load current amplitude The value decreases and S Aa =1 for several consecutive sampling periods; the amplitude of the phase A load current gradually decreases to zero for a certain period of time.
S704:当输入电压相角落在扇区III和IV时,A输出相的参考电流值i*
oA和实际值ioA都是负值,等效电路如图6(b)所示,此时的能量函数变化率表示为:S704: When the input voltage phase is in the sectors III and IV, the reference current value i * oA and the actual value ioA of the A output phase are both negative values, and the equivalent circuit is as shown in FIG. 6(b). The rate of change of the energy function is expressed as:
在一定的时间内,A相负载电流的幅值也会减小到零。The amplitude of the phase A load current will also decrease to zero for a certain period of time.
步骤S8,包括以下步骤:Step S8 includes the following steps:
S801:当负载电流保持为零的持续时间Tzero达到故障诊断所需时间时,再根据有限集模型预测控制选择的开关状态进行故障诊断,识别故障开关的位置,故障情况与输入电压周期
和负载电流基波周期To有关,将故障持续时间表示为:S801: When the duration T zero of the load current remains zero reaches the time required for fault diagnosis, the fault state is determined according to the finite set model prediction control switch state, the fault switch position, the fault condition and the input voltage period and the load are identified. The current fundamental period is related to T o and the duration of the fault is expressed as:
其中,Tin和To分别表示输入电压基波周期和负载电流基波周期;Wherein T in and T o represent the input voltage fundamental period and the load current fundamental period, respectively;
定义故障相的负载电流通过箝位电路变到零所需的时间Tdischarge,故障相电流保持为零的时间Tzero表示为:The time T discharge required to define the load current of the fault phase to zero by the clamp circuit, and the time T zero at which the fault phase current remains zero is expressed as:
Tzero=Tfault-Tdischarge (39)。T zero =T fault -T discharge (39).
为了区分故障相由于故障发生时电流保持为零和正常时电流过零点的情况,故障诊断时间需要满足:In order to distinguish the fault phase from the situation where the current remains at zero when the fault occurs and the current crosses zero at normal, the fault diagnosis time needs to be satisfied:
kfTs>Tε (40)k f T s >T ε (40)
其中,kf是故障诊断的敏感系数;Ts是正常运行情况下输出相的参考电流的过零(输出相的参考电流小于阈值ε)时间;阈值ε是为了减少故障诊断的误报率而设置的一个小的正值;Where k f is the sensitivity coefficient of fault diagnosis; T s is the zero-crossing of the reference current of the output phase under normal operation (the reference current of the output phase is less than the threshold ε); the threshold ε is to reduce the false alarm rate of the fault diagnosis. a small positive value set;
综合(38)~(40)式,故障诊断所需时间应该满足:Comprehensive (38) ~ (40), the time required for fault diagnosis should meet:
S802:根据有限集模型预测控制选择的开关状态进行故障诊断,识别故障开关位置,假设SAa发生开路故障,故障开关定位的逻辑可以表示为:S802: Perform fault diagnosis according to the finite set model prediction control switch state, identify the fault switch position, and assume that the open fault of the SA Aa , the logic of the fault switch positioning may be expressed as:
如果几个连续的采样周期内,满足|ioA|≤ε且SAa=1,那么SAa发生开路故障,即:If |i oA | ≤ ε and S Aa =1 are satisfied in several consecutive sampling periods, then S Aa has an open circuit fault, namely:
图7所示为以上矩阵变换器***进行实时的故障检测与诊断步骤的流程图,试验中故障诊断时间为1.4ms。Figure 7 is a flow chart showing the real-time fault detection and diagnosis steps of the above matrix converter system. The fault diagnosis time is 1.4ms.
以下为在识别故障后,执行容错运行的步骤:The following are the steps to perform a fault-tolerant operation after identifying a fault:
S9:在识别故障开关的位置后,将所有开关组合状态中与故障开关的动作有关的开关状态去除,确定余下所有开关组合状态的数目。例如当SAa开路时,矩阵变换器的运行的约束条件为:
S9: After identifying the position of the fault switch, the switch states related to the action of the fault switch in all switch combination states are removed, and the number of remaining switch combination states is determined. For example, when S Aa is open, the constraints of the operation of the matrix converter are:
从而余下的开关组合状态共有2*3*3=18种;其余开关开路时,依此类推;Therefore, the remaining switch combination states are 2*3*3=18; when the other switches are open, and so on;
S10:在余下的所有开关组合状态中,不考虑与矩阵变换器输入电流相关的评价函数,即(28)式总评价函数中的λ取零值,重新确定具体故障下的评价函数为:S10: In all the remaining switch combination states, the evaluation function related to the input current of the matrix converter is not considered, that is, the value of λ in the total evaluation function of (28) is zero, and the evaluation function under the specific fault is re-determined as:
gF=g2 (44)g F = g 2 (44)
S11:在矩阵变换器带故障运行过程中,采用有限集模型预测控制方法,参见图8,即在每个采样周期计算余下的所有开关组合状态下的gF值,选择其中使gF最小值的开关组合状态作为下一采样周期的开关状态;实现故障后的满足***动、稳态性能指标的容错运行。S11: In the course of operation with fault matrix converter using a finite set of model predictive control methods, see FIG. 8, i.e., the calculated value of F g of all the remaining switches in the combined state of each sampling period, in which a selected minimum value g F The switch combination state is used as the switch state of the next sampling period; the fault-tolerant operation that satisfies the dynamic and steady-state performance indexes of the system after the fault is realized.
图9所示为矩阵变换器发生开路故障的条件下加入诊断与容错措施前后的负载电流波形对比图。由图9(a)可见,矩阵变换器***前期正常运行时,负载电流基本正弦,谐波畸变率很低,并且很好地跟踪参考值,引入SAa开关开路故障后,负载电流ioA发生畸变并且迅速衰减为零,ioB和ioC也受到比较大的影响。如图9(b)所示,加入故障诊断措施,当引入SAa开关开路故障后,预测控制器在几个连续的采样周期内一直给SAa导通信号,然而,SAa由于故障无法导通,从而A输出相的电流会在几个连续的采样周期内保持为零,此时可诊断出SAa发生开路故障,该故障诊断过程可有图9(c)更明显地看出。在定位了故障开关后,加入容错措施,利用预测控制在剩余的开关组合状态中选择能使评价函数值最小的开关组合状态。由图可知,容错运行时,矩阵变换器的三相负载电流能基本平衡并且较好地跟踪参考正弦电流。Figure 9 shows a comparison of the load current waveforms before and after the diagnostic and fault-tolerant measures are added to the matrix converter in the event of an open-circuit fault. It can be seen from Fig. 9(a) that when the matrix converter system is in normal operation in the early stage, the load current is basically sinusoidal, the harmonic distortion rate is very low, and the reference value is well tracked. After the S Aa switch open circuit fault is introduced, the load current i oA occurs. Distortion and rapid decay to zero, i oB and i oC are also relatively large. As shown in Fig. 9(b), after the fault diagnosis is added, after the introduction of the S Aa switch open circuit fault, the predictive controller always turns on the S Aa signal for several consecutive sampling periods. However, the SA Aa cannot be guided due to the fault. Therefore, the current of the A output phase will remain at zero for several consecutive sampling periods, and an open circuit fault of S Aa can be diagnosed at this time, and the fault diagnosis process can be more clearly seen in FIG. 9(c). After the fault switch is located, fault tolerance measures are added, and the switch combination state in which the evaluation function value can be minimized is selected in the remaining switch combination states by the predictive control. As can be seen from the figure, the three-phase load current of the matrix converter can be substantially balanced and better track the reference sinusoidal current during fault-tolerant operation.
表2是矩阵变换器正常、故障以及容错运行条件下的THD比较表。Table 2 shows the THD comparison table for normal, fault, and fault tolerant operation of the matrix converter.
表2Table 2
从表2中可以看出,开关SAa发生开路故障后,矩阵变换器A相负载电流的基波分量明显减少,谐波畸变率明显上升,B和C两相的负载电流的波形质量也受到了比较大的影响。在本发明实施例的容错运行状态下,A、B和C三相的负载电流的基波分量都有所增加,谐
波畸变率都有所下降,波形质量得到提高,进一步证明了本发明的有效性。It can be seen from Table 2 that after the open circuit fault of the switch S Aa , the fundamental component of the phase load A of the matrix converter is significantly reduced, the harmonic distortion rate is significantly increased, and the waveform quality of the load current of the two phases B and C is also affected. A relatively large impact. In the fault-tolerant operation state of the embodiment of the invention, the fundamental wave components of the load currents of the three phases A, B and C are increased, the harmonic distortion rate is decreased, and the waveform quality is improved, which further proves the invention. Effectiveness.
以上所述仅为本发明的优选实施例而已,并不用于限制本发明,对于本领域的技术人员来说,本发明可以有各种更改和变化。凡在本发明的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本发明的保护范围之内。
The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.