STUDY OF THE PRINCIPLE OF A NOVEL HYBRID DC COMPARATOR

Transcription

1 TANBL NVERTY JORNAL OF ELECTRCAL & ELECTRONC ENGNEERNG YEAR VOLME NMBER : 008 : 8 : (6-6) TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR National Key Laboratory for Veel ntegrated ower ytem Technology Naval Engineering niverity, Wuhan, 400, China hutlwb@hotmail.com ABTRACT The traditional controllable aturation reactor (CR) conit of ingle toroidal core, DC (direct current) controlled loop (including DC controlled winding and DC biaing ource) and AC (alternating current) excitation loop (including excitation winding and AC ource). A detection winding and econdary winding are added up to the CR configuration and form a hybrid DC comparator. Reearch how the terminal voltage of the detection winding i aymmetric waveform when the econdary winding of the comparator i open and the CR core i timulated both by AC and DC biaed ource. Both theory analyi and experiment verify the feaibility of the differential RM (root-mean-quare) between poitive and negative half wave of the terminal voltage from the detection winding fitted for the feedback variance to balance DC biaing magnetic potential and form a elf-balancing comparator. The zero-flux technique that the primary ampere-turn i equal to the econdary i the function bae for the comparator. The operation detail of the comparator including the control characteritic both of open-loop and cloe loop, the atiability judgment criterion, tatic error property and tet range are introduced. The experimental reult tetify to the truth of the principle of the propoed DC comparator. Key word Controllable aturation Reactor, DC Comparator, enor.. NTRODCTON The controllable aturation reactor (CR) i device with magnetic nonlinearity and widely ued in uch a the power tranmiion line, DC comparator, table ource and o on, ee []. The configuration of the CR include ingle toroidal core, DC controlled loop compoed of DC ource and DC winding (alo called primary winding, W ) and AC excitation loop made of AC ource and excitation winding (W ). The operation principle of the CR i expreed a follow: the ampere-turn combined by AC and DC can be increaed directly if the current through CR i increaing; at ome point, thi caue a decreae in the permeability of the core; with the permeability of the core decreaed, the inductance of the winding decreae; a decreae in the inductance caue an increae in power through the load. Changing the permeability of the core control the reactance of CR. Varying the flux in one direction through the core when the CR i timulated by AC voltage ource change the permeability of the core. Depending on aturation principle they can be divided on DC controllable reactor (DCCR) or AC (alternating current) controllable reactor (ACCR) [, ]. Received Date: Accepted Date:

2 6 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR Conventional DC comparator uch a magnetic modulator comparator (MMC) and magnetic amplifier comparator (MAC) are applied widely to meaure DC. They adopt two ymmetric ferromagnetic core, four winding (i.e. primary winding W, econdary winding W, excitation winding W and detection winding W M ) and peripheral circuit. The meaurement goal i accomplihed by way of the zero-flux technique that the primary ampere-turn W i equal to the econdary ampere-turn W (i.e. W = W ). A a reult, they have high accuracy. And their important difference can be generalized a follow: they have their own method for acquiring the feedback variance. With concrete analyi, the double frequency ignal of the induced voltage of the detection winding i adopted a the feedback variance for MMC when the two core are excited both by the auxiliary AC voltage ource and DC biaing ource. The odd harmonic component of the auxiliary AC current ource ued to excite the two core for MAC are adopted a the feedback variance. MMC ha the characteritic of high enitivity to the weak current and low drift and MAC ha the characteritic of no fale-balancing point and high linearity. However, they have uch diadvantage that MMC ha unatifactory output characteritic that zero output point not only at the operating point correponding to zero ampere-turn but alo at the fale-balance point. Reearch indicate the o-called fale-balance point affect not only the current ratio, but alo the tability and reliability of the comparator. And the uual MAC ha too large an electrical inertia to follow the mall value of direct current [5-8]. A novel hybrid DC comparator for overcoming the defect of the available two comparator above i preented in the paper. And it i centered on the configuration of the CR with ome proper modification, which i a neceary condition for the propoed comparator. The added two winding that are repectively called detection winding W M and econdary winding W (alo called feedback winding) are wound around the CR core. And the hybrid comparator i made of four winding like the available DC comparator above (i.e. primary, econdary, detection, and excitation winding, a toroidal core and peripheral circuit that compoed of AC excitation ource, DC biaing ource, the feedback loop, and the diplay loop. The chematic diagram of the propoed DC comparator i demontrated in Fig.. The winding on the left upper part i called primary winding with W -turn and i connected to a reactor L functioning a a ripple filter and a rheotat R including wire and winding reitance. The winding on the left lower part called excitation winding with W -turn i connected a current-limiting reitor R. The CR core i timulated both by AC ource (u ) and DC biaing ource. The winding on the right lower part i called econdary winding with W -turn and i connected to a current-limiting reitor R and a ripple filter reactor L. The winding on the right upper part i called detection winding with W M -turn and i connected to a terminal reitor R M. The increment of the controlled biaing current will caue the amount of magnetim in the aturation core to increae and the inductance of the winding in the load circuit to decreae (becaue the toroidal core i common to four winding. The detection winding can dicloure the alternation of the flux of the core baed on the law of electromagnetic induction.

3 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR 6 peak) and called knee of the curve. The knee of the curve i the point of maximum curvature. CR and magnetic amplifier hould be operated on the knee of the magnetization curve. The prerequiite i a good knowledge of the following fundamental of the propoed comparator. Fig. chematic diagram of the hybrid DC comparator centered on CR configuration n the following dicuion we aume the primary current be poitive (i.e. >0) marked in Fig.. Thu, equation of the electric and magnetic circuit are expreed a The feedback loop include V/ converter, (proportional integral) controller, power amplifier and feedback winding. The feedback loop function to provide feedback variance for the comparator and track the meaured current,, in real time. The precondition circuit, amplifier circuit and diplay circuit form the diplay loop, whoe function i to acquire and deal with econdary current data for calculating and diplaying the meaured current (alo called primary current).. Operation principle of the hybrid dc comparator. Fundamental of the comparator centered on CR Auming that B-H curve of the CR i the ideal three-fold line, which mean magnetization and permeability curve for a CR i the ideal operating point. The idea operating point i the place in which a mall increae in biaing DC will caue a large increae in output power and a mall decreae in biaing DC will caue a large decreae in output power. Thi point i on the flattet portion of the permeability curve (after it u db = Ri W () dt + i + ' = i () B = f (H ) () where i cro-area of the aturation core. i i AC excitation current paing along the excitation winding. B and H are magnetic induction and intenity. i i called the equivalent excitation current for timulating magneto-motive force (MMF). Voltage u can be expreed a u = inωt, where m i the peak value. The angular frequency i expreed a ω = πf, where f i the frequency of the AC excitation ource. ' and i can be repectively determined by / ' = W W (4) i = Hl / (5) W where l i the average length of the core. i called the meaured current (alo called biaing DC) paing along the DC winding. A premie i given that the magnetic property of the core i in the critical ituation between aturation and under-aturation tate when the core i timulated only by AC ource. A a m

4 64 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR reult, m equal m = = W ωb = πfw B (6) at where at i peak value of the critical ituation of the AC ource. B i the aturation magnetic induction. Gueing the initial value of the magnetic tate i B when ω t=0. During the duration of 0 ω t π + β, the magnetic ituation of the core i in the aturation tate. Auming that excitation winding i independent of the primary winding, hence, i and i can be deduced a i = u / R = inωt / R (7) m i = ω / W (8) m in t / R + W Aω t = π + β, i=0, angle β equal β = arcin[ R W /( mw )] (9) and angle β i limited a 0 β π / (0) Analyi of the equation (6), (9) and (0) enable u to conclude that the range ability of meaured current can be limited a W m /( RW ) = πfw B /( RW ) () Equation () indicate that the maximum range ability of current i dependent on uch parameter a B, W, R, W, and f. During the duration of 0 ω t π + β, the terminal voltage of the detection winding i zero and hown a u = 0 () M During the duration of π + β ωt π + α, the magnetic property i in the under-aturation tate. Thu, i=0, H=0. α i called aturation angle. AC excitation current equal ' i = () During the duration of π + β ωt π β, the magnetic induction B i decreaed from B to minimum B min. During the duration of π β ωt π + α, the magnetic induction B i increaed from minimum B min to B. The magnetic induction of the core can be deduced a R W B = ( coωt + ωt) W mω ωw + (4) When ω t= π, the minimum magnetic induction equal πr W B = ( + ) W m W + min ω ω B B (5) During the duration of π + β ωt π + α, the total maximum increment of the magnetic induction i zero and an important equation can be deduced ( co β coα ) = ( π + α β ) in β + (6) t follow that angel α can be olved by ubtituting olution of angle β into Eqn. (6). During duration of π + β ωt π β or π β ωt π + α, the terminal voltage of the detection winding both equal WM RW u M = ( m in ω t + ) (7) W W During the duration of π + α < ωt π + β, the magnetic tate of the core i in the aturation tate (i.e. B=B ), o that the terminal voltage of the detection winding i zero. The analyi detail are the ame to the duration of 0 ω t π + β. When ω t = π + β, i=0, H=0. Then next analyi period i retarted.

5 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR 65 Typical waveform of u, B,, i, i and u M are repectively demontrated in Fig. (a) ~ (f). ' = k MRM 0 = π u ( α + β ) k π + α M π β k (in α + in β ) + k (co β coα) dωt () = k MRMN 0 = u π ( π β ) k π β M π + β + k dωt in β k coβ () = k MRM 0 = MRM + MRMN ( π + α β ) k + k (in β in α ) k (co β + coα ) () Fig. Typical waveform u, B, ( >0) ', i, i and u M where k0 = W M /( π W ), k = m / 4 k = m / + ( R W / W ), k = mr W / W. Hence, the differential RM value, MdiffRM, equal During duration of π + β < ωt π + β, though the average value of the terminal voltage u M i zero, upon analyzing above Eqn. (7), we got the following et of equation of the minimum, maximum, and peak-peak value of the terminal voltage: MN WM W = ( R m ) (8) W W W M W ( in α M = R + m ) (9) W W M M = = W ( + in α ) / W MN (0) Hence, RM value of the poitive half-wave, negative half-wave, and full-wave of the voltage (u M ) are repectively deduced a m M MdiffRM = (4) MRM MRMN From equation (8) ~ (4) it can be concluded that the minimum, maximum, peak-peak, differential RM value of the terminal voltage (u M ) ha relation to the DC biaing ampere-turn, W (or the primary ampere-turn). When the direction i negative (i.e. <0), analyi method for the negative current are the ame to the poitive current (i.e. >0) and more detailed decription are omitted.. Cloe-loop principle of the hybrid DC comparator The fundamental of the propoed comparator are the aturation property of the CR. And the aturation phenomenon of the core might

6 66 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR occur everely when the AC excitation current (i ) and DC biaing current ( ) are too large. The terminal voltage (u M ) ha ome high-frequency component (i.e. rd, 5 th order harmonic component, et. al.) due to the aturation property of the core, which i particularly diturbing the waveform of the terminal voltage (u M ) and will give evere influence to the computation accuracy of the minimum MN, maximum ( M ), and peak-peak ( M ). With the differential RM MdiffRM, thing are different. The RM theory emphaize the comprehenive impact induced by all component of the terminal voltage. Thu the differential RM MdiffRM will give few conideration of the odd harmonic or even harmonic component of the terminal voltage, which can guarantee the high enitivity of the comparator. One of the greatet advantage of thi method i it great imple peripheral circuit in repect that the adoption of RM C (e.g. AD76/AD77) and an adder circuit can eaily accomplih the function of the method and acquire the differential RM ignal. Conequently, by referring to the implified chematic diagram of Fig., the cloe-loop operation principle of the propoed comparator i decribed a follow: Firtly, the terminal voltage (u M ) i acquired and preconditioned. econdly, reorting to the RM C (e.g. AD76/AD77) and an adder circuit, the differential RM voltage ( MdiffRM ) i obtained and turned into the current by the V/ converter circuit. Thirdly, the current i amplified by the power amplifier and regulated by the controller. And the amplified current i pecially called the econdary current. Fourthly, the econdary current flow into the econdary winding and produce a revered magnetic potential (i.e. W, alo called econdary number-turn) with regard to the primary one for balancing the DC biaing magnetic potential in the core. When the total DC biaing magnetic potential i zero, an important equation that W = W i obtained. Hence the meaured current can be determined by = W /W. Furthermore the econdary current can be determined by the current hunt and hown a =u /R. A a reult, current can be determined by =W u /W R.. Tranfer function of the enor head F( n Figure, the enor head i compoed of a toroidal core, AC excitation loop (including AC excitation ource and excitation winding), and detection loop (made of detection winding, terminal reitor R M, precondition circuit, differential RM circuit for acquiring the differential RM of the terminal voltage from the detection winding). The tranfer function of the enor head, F(, can be defined a MdiffRM ( F( = (5) W ( ) where MdiffRM ( and W ( are Laplace tranformation of differential RM MdiffRM and primary ampere-turn W. A direct quantitative analyi of the tranfer function F( i rather involved according to the Laplace tranformation of equation (4) and (5) whoe Laplace tranformation are very complex. Thi complicated tranfer function F( can be repreented graphically. And the practical method of obtaining the tranfer function F( i generalized a follow:

7 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR 67 At firt, let the feedback loop i in open circuit and the core i timulated both by DC and AC ource. DC biaing ampere-turn, W /A, denote abcia x-axi, i.e. x= W. Differential RM value of the terminal voltage of the detection winding, MdiffRM /V, denote vertical y-axi, i.e. y= MdiffRM. The plot of W /A a a function of MdiffRM /V i defined a the output characteritic graph of W veru MdiffRM of the enor head of the propoed DC comparator. Thi i written ymbolically a MdiffRM =f( W ) or y= f(x). econdly, we will acquire the experimental data both of W /A and MdiffRM /V and plot the characteritic curve of W /A v. MdiffRM /V. ome parameter of the prototype comparator are preented in Table, where D, d and h D are the outide diameter, inide diameter and thickne of the toroidal core tacked by ermalloy 80 iron ring. And the characteritic curve of MdiffRM /V v. W /A can be acquired and plotted in Fig.. Table imulation and experimental parameter of the comparator L =L mh m 9.7V W Turn f 0.8Hz W 00 Turn R 5 Ω W M 90 Turn R M 0k Ω W 400 Turn B 0.78 T R 00 Ω R 00 Ω K p T 4.7m h D 0mm K D undetermined D 50mm d 0mm nitial >80000(G/Oe) Curie permeability Tem. 400 C Max. 600,000(G/Oe) Coercive<(A/m) ermeability force Fig. Experimental relation curve: MdiffRM /V v. W /A Thirdly, gue the maximum fitting error ξ max i le than a given tolerance value T E (e.g. T E =0-5 ). Reorting to a leat quare etimator, we can fit the characteritic curve function, i.e. ˆ MdiffRM = yˆ = f ( W ) = f ( ˆ). When primary ) x ampere-turn W >0 (i.e. i poitive current), the fitting polynomial i expreed a follow: yˆ = (6) x x x +. 0 When primary ampere-turn W <0 (i.e. i negative current), the fitting polynomial i expreed a follow: ˆ y =.6 0 x x (7). 0 x.7 0 x Fig. plot the characteritic that MdiffRM varie with the bia number-turn W when CR i timulated both by AC voltage ource and direct current. Analyi of Fig.4 indicate MdiffRM varie increaingly at firt and then varie decreaingly with increaing number-turn W. When the CR core i in deeply aturation ituation, MdiffRM i very mall but in t zero. By varying MdiffRM only x

8 68 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR a few tenth of a volt will how the bia number-turn W in t zero, i.e., W i either very mall or very large. On the bai of thee data plotted in Fig.4 it can be concluded that the output characteritic graph of the enor head ha no fale-balance point, which guarantee the tability and reliability of the cloe-loop operation of the propoed comparator. A comparion of the output characteritic graph of MMC with the propoed comparator indicate that the latter can overcome the problem of the intability of the cloe-loop control operation. When current i poitive, the tranfer function of the enor head, F(, can be hown a 4 MdiffRM ( F ( = = W ( (8) When current i negative, the tranfer function of the enor head, F(, can be hown a.4 0 (9) MdiffRM ( F ( = = 5 4 W ( Tranfer function analyi of the comparator ytem The main component of the hybrid comparator conit of enor head F(, power amplifier K D, controller T ( and feedback winding T F (. The control diagram of the preented comparator i hown in Fig.4, where Δ W i the net number-turn and defined a Δ W = W - W. ower amplifier will amplify the nonzero deviation voltage MdiffRM that reflect the net number-turn Δ W. Then the deviation voltage MdiffRM (i.e. MdiffRM 0 ) i regulated by controller and follow into the feedback winding forming a revere biaing magnetic potential relative to the primary one. imultaneouly the total biaing magnetic potential in core decreae. Hence the deviation voltage MdiffRM decreae. Once the biaing magnetic potential i balanced, the deviation voltage MdiffRM doe not exit and the zero-flux tate i gained, i.e. Δ W = W - W. Thu, an important equation that W = W can alo be obtained from the homeotai of the comparator. The comparator can readily perform the DC meaurement operation. Tranfer function of the controller T ( and feedback winding T F ( are repectively expreed a T ( = K ( / T (0) + T F ( = W () where K p i proportion factor, T i integration time, ee Table. The tranfer function of the whole comparator enor ytem, T(, can be deduced a follow: Fig.4 Control block diagram of the hybrid DC comparator T( = () F( K DK ( + T = W T + W F( K K ( + T D

9 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR 69 where K D tand for power amplifier parameter and i undetermined variable..5 tability analyi of the DC comparator The characteritic equation of T( can be expreed a ( = T + WF( K DK ( + T () 0. < 5 K << 6. 0 (5) D WK Thu, the unit-tep repone of the comparator enor ytem can be deduced a follow: F( K DK ( + T = T ( = W T + W F( K K ( + T (6) D The tability of the whole meaurement enor ytem i of great importance to the normal operation for the comparator. To atify the meauring requet, ome conideration of the tatic error and dynamic characteritic of the comparator enor ytem mut be emphaized. Eqn. () indicate that the whole comparator belong to a high-order ytem. The tability can conveniently be judged and controlled by the Routh criterion. Of the three parameter K D, K, T, only parameter K D, the power amplifier multiple i unknown and function for regulating the tability of the comparator ytem. Hence, other two parameter can be dipoed of rather quickly. Auming characteritic equation i zero and hown by ( = T + W F( K DK ( + T = 0 (4) The neceary and ufficient precondition of the tability of the meauring ytem i that all of the real part of the characteritic root of ( are negative. t i neceary for u to olve the characteritic equation for K D. n our dicuion of dynamic property of the whole comparator, we hall retrict our attention to the poitive cae ( >0). Analyzing method for the negative cae ( <0) i the ame to the poitive and omitted in the paper. A a reult, ubtituting known parameter K, T, and Eqn. () into the characteritic Eqn. (4), K D may be limited by - K D =0 --- K D =50 K D =00 Fig.5 nit-tep p repone of the hybrid elf-balancing DC comparator The dynamic propertie of the comparator are o important that uch dynamic qualification indexe centered on the Eqn. (5) a overhoot (le than 50%), rie time, table time and governing time, mut be taken into account. thu, parameter K D mut be limited by K 000 (7) D Baed on the imulation tool of the MATLAB MLNK environment (ee [0]), the unit-tep repone with the change of the parameter K D of the hybrid comparator i plotted in Fig.5. Analyi of Fig.5 how the overhoot and table time will increae obviouly with K D enhancement. Thu, parameter K D mut be properly elected for the comprehenive conideration of the tability,

10 60 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR overhoot, rie time, table time and governing time of the comparator ytem..6 tatic error analyi of the whole DC comparator The amplifier multiple of the open-loop of the comparator, K O, i defined a the product of each component amplifier multiple and hown a follow: K = W W K K (8) O D Experimental point Fitting curve Fig.6 Experimental reult of the propoed elf-balancing DC comparator And the tatic error of the comparator i determined a σ =/ K O (9) The foregoing provide a bai for thi propoed comparator, although it cannot be conidered a a precie proof.. Experemental reult The CR core i a toroidal core tacked by ermalloy 80 iron ring. ermalloy 80 i an ideal material for CR application. quarene coefficient i almot a high a the cobalt baed amorphou material and flux denity i higher. ome important parameter of the experimental prototype comparator baed on Fig. are lited in the Table. Thu, in the above prototype comparator analyi, K D =00. The experimental point are plotted and joined, thu forming the curve repreent the enor function for the comparator and illutrate a Fig.6, where vertical y-axi tand for the meaured current /A, and abcia x-axi denote the econdary current /A. The characteritic graph of againt can be determined by = + (40) K KDB where K DB i offet value of the comparator. K i the ratio of meaured current /A to the econdary current /A and alo i called the ratio of the output tatic curve of the propoed comparator and expreed a K = / (4) ince the output tatic curve of the comparator i linear, the enitivity of the comparator i equal to the lope ratio of the experimental curve, and determined by = K W G (4) = /W where G i the total gain of the feedback loop (uually G ). The experimental value K, and K DB are lited a follow:

11 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR 6 K = =04, K DB =0.0A. And the linearity correlation coefficient of the fitting curve of Fig.6 baed on the experimental data i For counteracting the offet value of the comparator, ome compenation meaure are neceary (i.e. the econdary compenation meaure are uually adopted). ome detail of the econdary compenation meaure of the comparator are omitted in the paper. 4. Concluion With the incluion of detection winding and econdary winding for the conventional CR configuration, thing are different. The propoed comparator jut i centered on the above contruction of the CR. The detection-winding function a an indicator that reflect the DC biaing magnetic potential. The econdary winding act a a compenation one. The reduction of the comparator eliminate unneceary core and complicate peripheral circuit, thereby aving cot, pace and weight. And the comparator ha the characteritic of four winding wound around the toroidal core and imple peripheral circuit. The comparator i uually operated by the counterbalance of an acending and a decending DC number-turn. The differential RM of half wave of the terminal voltage from the detection winding i verified to fit for the feedback variance for the hybrid comparator. And the output characteritic curve of the enor ha no fale point, which guarantee the tability and reliability of the cloe-loop control operation of the comparator. The analyi method of the tranfer function of the enor head reorting to the curve fitting technique i ueful to determine and optimize the dynamic property of the comparator. 5. Reference [] A. Barili, A.Brambilla, G. Cottafava, et al. A imulation model for the aturable reactor, EEE Tranaction on ndutrial Electronic, vol: 5, no:, pp.0-06, May 988. [] M. MacMartin, N. Kuter. A elf-balancing direct current comparator for ampere, EEE Tranaction. on Magnetic, vol:, no: 4, pp , Dec 965. [] Li Weibo, Mao Chengxiong, Lu Jiming. tudy of the Virtual ntrumentation Applied to Meaure uled Heavy Current, EEE Tranaction on ntrumentation & Meaurement, 005, 54(): [4] Mingjun Zhu, Xu, Ken, A calibrating device for large direct current intrument up to 0 kiloampere-turn, EEE Tranaction on ntrumentation & Meaurement, vol: 47 (), pp. 7-74, June 998. [5] K. Harada, Y. hihara, T. Todaka. A novel high power factor converter uing a magnetic amplifier, EEE Tranaction on Magnetic, vol:, no: 5, pp , ept [6] E.o. The application of the current-comparator technique in intrumentation and meaurement equipment for the calibration of non-conventional intrument tranformer with non-tandard rated output, EEE Tranaction on ower Delivery, vol: 7, no:, pp. 46-5, 99. [7] Li Weibo, Mao Chengxiong, Lu Jiming. A novel fiber-optic current meaurement intrument for high-power laer ource. Journal of Electrical and Electronic

12 6 TDY OF THE RNCLE OF A NOVEL HYBRD DC COMARATOR Engineering, vol:, no:, pp.85-84, 00. [8] Li Weibo, Mao Chengxiong, Lu Jiming. ome conideration of deigning a high performance Rogowki coil for puled current meaurement, Journal of Electrical and Electronic Engineering, vol: 7, no:, pp.7-, 006. Biographie Li Weibo received hi B.. degree in mechanical engineering from ichuan niverity of cience & Technology (CT), Chengdu, in 997. And he received hi M.. degree and.h. degree in Department of Electrical Engineering from Huazhong niverity of cience & Technology (HT), Wuhan, repectively in 00 and 006. He i currently in the Naval Engineering niverity. He i a member of EEE. Now he focue all hi attention on meaurement and control technologie.