Corresponding to regenerated energy such as wind energy and solar energy, as a conventional energy, oil still plays an important part in modern industrial society, neglecting negative effect of deep well flowing production. Considering ESM works in the oil well which depth of l.0 to 3.0 kilometers in [1] , it's difficult to directly measure and monitor its temperature due to the influence of high temperature and high pressure of the oil well in [2] . Study show it necessary to study a sensor-less method in order to obtain ESM parameters on line due to the influences of long cable on signal transmission in [3] . How to obtain the temperature of industrial motor is followed by many scholars. One of the main contributions of team of Habetler is sensor-less identification method. It has taken the place of monitor the temperature of traditional motors in [4]-[6] . However, almost all study is bounded by motors that work on the ground in [7]-[8] . Current research shows the proposed DIM method is an efficient technique for identifying the temperature of low power motor in [9]. There still is a negative effect such as surge current and chaos oscillation of torque shock when the DIM is used to identify the temperature of the high power ESM that works in DIM. It's necessary to explore a method to identify the temperature of high power ESM by suppressing the chaos shock of DIM.
synchronizing control, linear feedback control method and etc. In particular, pseudo-Poisson manifold is used to solve smooth feedback stabilization of a Hamiltonian system. Common examples of this study manifest dual linear system and critical system that consists of Chen system, Lti system, fuzzy hyperbola system and dynamic feedback system in [10]-[15]. It denotes mechanism of chaos oscillation of the ESM torque can be analyzed by nonlinear controlling chaos method. By suppressing nonlinear chaos oscillation of electromagnetic torque of high power ESM induced by DIM, the Wish out-filter state feedback control method is used to identify the temperature of 12kW ESM. The sensor-less temperature identification algorithm has been studied based on analyzing dynamic behavior of ESM. Design rules of series impedance between power system and ESM, the negative effect consists of chaos oscillation and surge current is studied by proposed method. By controlling instable limit cycles of electromagnetic torque to stator current of the ESM, this method can be used to stabilize chaos oscillation when identifying temperature of ESM in DIM on line. Actual measure results of designed experiment system consists of DSP2812, MOSFET driver circuit and data collection card show that, proposed method is an effective path to indentify the temperature by eliminating nonlinear chaos oscillation and surge current of the ESM.
II. WTSHOUT -FTL TER S TATE FEEDBACK
CONTROL METHOD
For two-dimensional control system in [16]:
Xl = .f; ( Xl ' Xz ; f1 ) + u
x2 = 12 (XpX2;f1)
(la)
(1 b)
Where, Xl and x2 are the system state variables, f1 is a real parameter, u is the control input variable. It and 12 are the first order continuously differentiable functions, which satisfy the following relationship:
In order to control variable Xz , the Washout-filter state feedback control method is used to analyze (1). Based on Washout-filter state feedback control method, controlling variable x2 is given as follows:
(3)
The nonlinear control function of the two-dimensional controlled system is:
(4)
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In (3) and (4), d and K are time constant and gain of Washout-filter controller respectively. According to theory of Hopf bifurcation, at the equilibrium point (x;,X:;u') gl can be written as follows:
In (8), p; and p� are the bifurcation coefficients,
.; is constant. Based on above discussion, following definitions are given:
.; = 3dhl (d -hi -.fzJ UIJ'21 -IllhJ 1 ml
ml = 4 [ -.t;� -dt; 2h [ + 3 h� ( d -122 ) ] +
(d-hS h[ (-3d2 +7d122 -312;)
(9)
(10)
In this paper, we shall use Wishout-filter state feedback control method to suppress the chaos motion of nonlinear dynamic system.
TIT. STRATEGY OF SUPPRESSING
NONLINEAR CHAOS
In order to analyze negative effect of DIM two states of ESM that consists of DIM and NM need to consider. How to understand there are DC components in the stator of ESM, but there isn't any DC current injected into ESM in fact. As shown in Fig.l, a circuit consists of MOSFET and sample impedance (Rex!) connected in parallel between power side and the stator of ESM is given.
Tal'
1,()!(/(,,, If 1(,,)
a) equivalent topology b) current direction
Fig.l Equivalent topology of DIM
To control the MOSFET when ias <0 or ias >0 respectively, unbalanced phase current will occur between phases of the stator of ESM. Given the on-impedance of MOSFET is small, correct series impedance plays an important part for decreasing torque impact. Rs and T, can be written as follows:
To analyze the negative effect of proposed method, the simulation model of 12kW ESM is given. As shown in Fig.2, in order to analyze the influence of series impedance Rex! on the stator current and output torque of ESM, different situation models are given.
a) Rext = 0.10 b) Rex! = 0.50
c) Rext=I.OO d) Rext = 1.50
Fig.3 Analysis of stator current of ESM in DIM
As shown in Fig.3 and Tab. 1 , at a time interval [0.1l7s, 0.1l9s] due to there are terrible instant surge currents of ESM that exceed rated current of the stator. It denotes that when 0.10 < Ret! :s; 1.00, the smaller
173
series impedance Rex, is the greater surge current of
the stator of ESM. But when Re" > 1.00 , the surge
current of stator decreases with impedance Rex, increases in same condition. The stator current becomes smoother and smoother since 0.20s past.
TABLE 1. MAXIMUM ELECTROMAGNETIC TORQUE OF ESM
R",(Q) DIM torque(Nm) 0.1 0.5 1.0 1.5
electromagnetic torque (Nm) 1372 1343 1335 1395
stator current(A) -962 -1015 -1190 -1030
Fig.4 and TABLE 1. show that there is chaotic oscillation of motor torque at the time interval [0.117s,0.119s] when 0.10< Rex1::; 1.00. It denotes that
the smaller value of Rex' is, the greater impact of chaotic oscillation is.
,,--�------�--� E ;;
clnentolseriesimpedance (A) CllTent 01 series impedance (A)
a) Rex' = 0.10 b) Rex' =0.50
current 01 series impedance (A) cutTen! 01 series impedaoce (A)
c) Rex, = 1.00 d) Rex, = 1.50
Fig.4 Electromagnetic torque of ESM in DIM
Fig.4 d) shows when Re." > 1.00 the motor torque
decreases with impedance Rex, increases in similar above condition. The chaos oscillation of torque of ESM need to consider due to the rated current of the stator is 18A only, although the electromagnetic torque of ESM becomes smoother and smoother when stator current ias > 100A .Fig.S shows the flowchart of proposed method which essential question is how to combine Wishout-filter state feedback control method with nonlinear dynamic theory for identifying the temperature of ESM. The negative effect that induced by DIM is suppressed by analyzing the influence of the series impedance Rex' on the stator current distortion and torque shock of ESM.
The chaotic oscillation of torque of ESM in DIM is a deterministic nonlinear motion which trajectory is complicated but not completely random. Tn order to analyze the sensitivity of chaotic motion to small perturbation of the series impedance, the dynamic theory is used to analyze ESM. For obtaining main reason induced the chaotic oscillation of torque of ESM, the state equations that describe dynamic behavior of ESM can be written as follows:
diA / dt U A - ( Rs + Rex{ ) i A diB / dt UR - Rs iR die / dt
= A-I Uc - Rsic ( 16) dia / dt ua - Rria
dib / dt uh - Rrih die / dt Ue - Rrie
Where un and in (n=A,B,C) are the three-phase
stator voltage and current, Uk and ik (k = a,b,c) are three-phase rotor voltage and current. Coefficient matrix A can be expressed as:
LAA LAR LAC LAa LAh LAc LRA LRR LRC LRa LRh L&
A= LCA LCR Lcc LCa LCh LCe
(17) LaA LaR LaC Laa Lah Lac LhA LhR LhC Lha Lhh Lhe LeA LeR LeC Lea Leh Lee
Where LAA ,LBB and Lcc are the self-inductance of
stator windings of three phases respectively, Laa , Lbb and Lee are the self-inductance of rotor windings of
three phases, Lmn (m = A,B,C;n = A,B,C,a,b,c;m::f. n) and
L,/i =a,b,c,n =a,b,c,A,B,C;i::f. j) are mutual inductance.
Define Lll and LI2 are the leakage inductance of
stator and rotor respectively, Lml and Lm2 are mutual inductance between the stator and rotor respectively, Lml = Lm2. Following expressions can be given.
Fig.6 Limit cycle between stator current and series impedance Rex! of ESM in DIM
For analyzing the influence of Rex! on output torque of ESM, corresponding solutions of manifolds of (16)-(21) are obtained by numerical iterate algorithm which are shown in Fig.6-Fig.9. Comparing FigA to Fig.6 indicates that the relationship between the stator current of three phases with respect to perturbation of series impedance Rex!. It denotes when Rex! changes between 00 to 0.50, the stator current appears a closed limit cycle curve that may induce self-oscillation of the stator current. In order to avoid above oscillation occurs, the series impedance should satisfy Rex! ;::: 0.50 in condition of perturbation of unbalance three voltages. This conclusion can also be illustrated by the limit cycle of electromagnetic torque to series impedance Rex! of ESM in Fig.7.
E z
0.' series impedance R",
Fig.7 Limit cycle between the torque and series impedance R"X! of ESM in DIM
Fig.8 shows that when Rex! = 0.50 , the relationship of electromagnetic torques to the stator current appears entire limit cycles. It denotes the chaotic oscillation of T;, to stator current may occur in condition of the perturbation of stator current. Considering stable current of stator is about 18A that attributed to range of -lOA to 20A illustrate by Fig.9.
a) Phase A b) Phase B c) Phase C
Fig.S Limit cycle between the torque and stator current of ESM in DIM
Fig.9 Limit cycle between stator current ia and ib of ESM in DIM
Considering self excitation vibration may be induced by instable limit cycle, we focus on study how to avoid or suppress the chaos motion of electromagnetic torque occurs by adjusting control parameters of ESM. For this purpose, control limit cycle such as in Fig.6-Fig.9 appear stable period motion is core work of this study.
Such as in Fig.2, considering the torque oscillation is induced by the impedance which is in series between power supply and stator of ESM, the Wishout-filter state feedback control method is used to control current ia. The sample period of stator current is 30s that separates into 29.75s and 0.25s, which denote the response period of NM and DIM respectively. In order to control the current of stator ia, following expression is given:
m= ia -d]OJ= Y]
UI = glYI + g3Y;
(22a)
(22b)
Where, g] and g3 denote the controller gain, d., denotes the Washout-filter time constant. Based on above analysis (16) can be expressed as follows:
diA / dt diR / dt die / dt
UA -(Rs + Rext)iA UB -RsiB
= A-I Uc -Rsic + 0 � /� �-�� 0 � /� �-�� 0
� /� �-�� 0
(23)
According to the experimental analysis, equilibrium pointof ESM can be given as follows:
(t ,i* ,t ; R* ,R* ) = (18,18,18;OA35,0.5) .,1 H C s
(24)
In order to suppress chaotic oscillation of torque of ESM that described by (20), following parameters such as gl = 0.002 , g3 = 8.005 and dl = 1.5 are given and substituted into (5)-(10). Through making limit cycles of Fig.6-Fig.9 to converge by Washout-filter method, the chaotic oscillation can be avoided when ESM works in DIM. This work lays a basic foundation of sensor-less identification technology for identifying the temperature of ESM.
V. EXPERIMENTAL STUDY
As shown in Fig.l0, the proposed experiment system consists of host computer and slave computer. The host computer includes industrial PC and data collection card with sample frequency of 5kHz. The core of slave computer is DSP2812 and MOSFET driver circuit. The stator impedance of 12kW ESM is OA35H, self-inductance and mutual inductance are I O.OmH and 69.30mH respectively.
a) actual device b) physical connection
175
ESM DC genearator
c) electrical schematics
Fig.IO Experiment system of ESM Tek JL I!:!lAOJ1(, M Po�: o,ooo� SAVE_REC
M�+ A�:��N
FOR1vIAT BMF
D+ ABOUT SAVE
SELECT FOLDER
. "\ SAVE of
M 10.0ms CH1 ./"·O�O�l.BMP
Fig. II Actual stator current of ESM
When power supply voltage is 380Y, rated speed of ESM is 2900r/min. Load of this system is ISkW DC motor that is connected in coaxial with the rotor of ESM. The type, rated current and rated voltage are IXTQ16N10T, 160A and 100Y respectively. Based on TABLE I. and (I), following parameters are given as Rext =l.OQ , T,o =22SC and a =0.011(1IC) 0
Considering oscillation of electromagnetic torque that induced by surge current of stator when ESM works in DIM, based on Wish-out idea an algorithm that can suppress surge current is proposed and realized by designed TMS2812 digital signal processor system. Contribution of this study is how to reduce the surge current to the lowest extent within 0.2Ss that is period of DIM. As shown in Fig.ll, there isn't almost any surge of the actual stator current of ESM by using proposed method.
voltage of series impedance MOSFET drive
Fig.12 Experimental waveforms in DIM
��:::�:::::::: �::::: ::::: :::::� :::: current of stator A
Fig.13 Experimental waveforms in NM
Moreover, Fig.12 and Fig.13 show the experimental waveforms of ESM in DIM and NM respectively. The blue line denotes drive signal of MOSFET whose turn on and turn off voltage are + lSY and -lOY respectively. The red line denotes voltage of series impedance. It indicates when turn off the MOFET the voltage of impedance is greater than that when turn on the MOFET. This conclusion can be illustrated by comparing Fig.12 to Fig.l3. There is significant negative DC offset of current that denotes by green line. It indicates that the surge current becomes so small as not to do observe almost.Corresponding to Fig.12 and Fig.13, the electromagnetic torque of ESM in DIM is illustrated by Fig.14 that obtained by data collection card. It denotes that there isn't any chaotic motion of the torque comparing to Fig.4 due to the Wish-out method.
The base of identification temperature of ESM has been established by proposed method.
Fig.14 Electromagnetic torque of ESM in DIM
Fig.IS Actual temperature of surface of ESM
Fig.1S shows that at 17:S2:1S the measure temperature is II O.S n by TMP-A. At this time stator voltage and current is measured by the data collection card which sample frequency is SkHz. Fig.16 shows the off-line identification temperature of stator and rotor of ESM in DIM based on sample data of Fig.IS.
rotor temperature (OC)
Fig.16 Relationship of stator current to rotor temperature of ESM
In Fig.16-Fig.18, there is a small temperature coefficient a . The perturbation of the stator impedance of ESM is small too. According to the identification results, the temperature of ESM rises from ambient temperature 22.S'C to liS -. The variation of stator impedance is O.ISQ, i.e. it varies between 0.43S and 0.S80.
g 10,85
" $ -8. 10.8
" C :!' 10.75
B i
120 125 130 stator temperature (OG)
Fig.17 Relationship of stator current to its temperature of ESM
i: I I I I I I I <{ 10.85 -1- - -I- ---t - -I- ---t - -1-- 1'1 � -
114.00'C I I � .. "'� !vl� �;', j, � I 1 10.8 --Q}: - -.. �- --t _ l,� -i --tl--r.'\;�--t --is I"� � I 1 \ I ) I � II �_� I - I 1 10.75 -:- -\� � 1' �\' - � - ���:- - � --� � -� -- � - � -- � - � --� - � --� I I -I I I I I
Fig.IS Relationship of stator current to its impedance of ESM
stator impedance ( )
Fig.19 Identification temperature of stator and rotor of ESM
176
In Fig.15, the measure temperature is 110.5_ at 17:52: 15, the identification temperature of the stator and rotor are 114.88Uand 123.22U respectively. As shown in Fig.19, after 17:52: 15 the temperature trends of the stator and rotor are identified by DIM. It denotes when stator impedance increases to O.S4Q, the stator and rotor temperature may reach equilibrium points, close to 135 n . In this experiment, the temperature of ESM monotonically increased to 110.5°C at about 17:52:15 with the stator current of ESM obtained by TPS2024 oscilloscope in Fig. 11 , which the amplitude of stator current is about 18A.
As shown in TABLE II, the absolute and relative error of identification temperature of stator and rotor to measure temperature of ESM surface are 4.0% and 11.5% respectively. Considering only the temperature of the surface of ESM is measured by TMP-A, inner temperature of stator and rotor is identified by proposed method, it is sometimes impossible to keep clear of errors. These results may serve as correction standard of identifying temperature of ESM. It denotes that study on suppressing nonlinear chaos of the electromagnetic torque play an important part for indentifying temperature of ESM.
TABLE II. ANALYSTS OF THE ERROR OF TEMPERATURE
Table Head Stator Actual Temperature ('C) llO.5
Identification Temperature ( C) 114.88
Absolute Error (%) 4.38
Relative Error (%) 4.0
VI. CONCLUSIONS
Rotor llO.5
123.22
12.72
11.5
In order to increase calculation precision and decrease negative effect of DIM idea that combine Wishout-filter state feedback control method with nonlinear dynamic theory is used to identify the temperature of ESM. Service life and system maintenance cycle of ESM has been extended effectively by proposed method. The identification results of 12kW ESM show that not only the surge current is suppressed, but also the chaotic distortion of electromagnetic torque of ESM which induced by DIM can be eliminated by proposed method. Especially, the relative error of identification temperature of stator of ESM reached to 4.0%. Although there is relatively high error of rotor of ESM, it can be decreased by improving proposed method. This study overcomes the limit of application of DIM in identifYing the temperature of high power AC motor, due to the nonlinear chaos oscillation induced by DIM can be eliminated by Wishout-filter state feedback control method. Study show that the proposed method is an effective path to identify the temperature of ESM based on nonlinear dynamics analysis. This work provides the theoretical and engineering basis for sensor-less identifying the temperature of higher power AC motor by DC Injection Method.
ACKNOWLEDGMENT
The authors would like to thank the support from "National Natural Science Foundation (50877016, 51177028) ".
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