Hybrid Cascaded H-Bridge Multilevel Inverter Motor Drive DTC Control for Electric Vehicles.

Transcription

1 Hybrid Cacaded H-Bridge Multilevel Inverter Motor Drive DTC Control for Electric Vehicle Farid Khoucha, Soumia Mouna Lagoun, Khoudir Marouani, Abdelaziz Kheloui, Mohamed Benbouzid To cite thi verion: Farid Khoucha, Soumia Mouna Lagoun, Khoudir Marouani, Abdelaziz Kheloui, Mohamed Benbouzid. Hybrid Cacaded H-Bridge Multilevel Inverter Motor Drive DTC Control for Electric Vehicle. ICEM 8, Sep 28, Vilamoura, Turkey. pp.id 1433, 28. <hal-53133> HAL Id: hal Submitted on 2 Nov 21 HAL i a multi-diciplinary open acce archive for the depoit and diemination of cientific reearch document, whether they are publihed or not. The document may come from teaching and reearch intitution in France or abroad, or from public or private reearch center. L archive ouverte pluridiciplinaire HAL, et detinée au dépôt et à la diffuion de document cientifique de niveau recherche, publié ou non, émanant de établiement d eneignement et de recherche françai ou étranger, de laboratoire public ou privé.

2 Proceeding of the 28 International Conference on Electrical Machine Paper ID 1433 Hybrid Cacaded H-Bridge Multilevel Inverter Motor Drive DTC Control for Electric Vehicle F. Khoucha 1,2, S.M. Lagoun 2, K. Marouani 2, A. Kheloui 2 and M.E.H. Benbouzid 1 1 Laboratoire Bretoi de Mécanique et de Sytème (LBMS EA 4325), Univerity of Bret IUT of Bret Rue de Kergoat CS 93837, Bret Cedex 3, France m.benbouzid@ieee.org 2 Electrical Engineering Department, Polytechnic Military Academy, Algier, Algeria. Abtract Thi paper preent a hybrid cacaded H-bridge multilevel motor drive DTC control cheme for Electric (EV) or Hybrid Electric Vehicle (HEV). The control method i baed on Direct Torque Control operating principle. The tator voltage vector reference i computed from the tator flux and torque error impoed by the flux and torque controller. Thi voltage reference i then generated uing a hybrid cacaded H-bridge multilevel inverter, where each phae of the inverter can be implemented uing a DC ource, which would be available from fuel cell, batterie, or ultracapacitor. Thi inverter provide nearly inuoidal voltage with very low ditortion, uing le witching device. Due to the mall dv/dt, torque ripple i greatly reduced. In addition, the multilevel inverter can generate a high and fixed witching frequency output voltage with le witching loe, ince only the mall power cell of the inverter operate at high witching rate. Therefore a high performance and alo efficient torque and flux controller i obtained, enabling a DTC olution for multilevel inverter powered motor drive. Index Term AC drive, Direct Torque Control (DTC), multilevel inverter. I. INTRODUCTION Multilevel voltage-ource inverter are intenively tudied for high-power application [1-2], and tandard drive for medium-voltage indutrial application have become available [3-4]. Solution with a higher number of output voltage level have the ability to yntheize waveform with a better harmonic pectrum and to limit the motor-winding inulation tre. However, their increaing number of device tend to reduce the overall reliability and efficiency of the power converter. On the other hand, olution with a low number of level either need a rather large and expenive LC output filter to limit the motor-winding inulation tre or can only be ued with motor that do withtand uch tre. Mot invetigation concerned topologie with the ame voltage rating for all device. Advantage of uch ymmetric multilevel converter are modularity and control implicity. Hybrid multilevel inverter ue different intermediate circuit capacitor voltage in variou part of the inverter. By addition and ubtraction of thee voltage, more different output voltage level can be generated with the ame number of component, compared to a ymmetric multilevel inverter [5-8]. Higher output quality can be obtained with maller circuit and control complexity, and output filter can be remarkably hrunk or even eliminated. One of the method that have been ued by one major manufacturer in multilevel-level inverter i DTC, which i recognized today a a high-performance control trategy for AC drive [9-15]. Several author have addreed the problem of improving the behavior of DTC AC motor, epecially by reducing the torque ripple. Different approache have been propoed [9]: improving the look-up table; varying the hyterei bandwidth of the torque controller, uing flux, torque and peed oberver. Although thee approache are well uitable for the claical two level inverter, their extenion to a greater number of level i not eay. Throughout thi paper, a theoretical background i ued to deign a trategy compatible with hybrid cacaded H- bridge multilevel inverter. It allow not only controlling the electromagnetic tate of the motor with improved performance (minimization of the torque ripple), but alo to control the witching frequency and flying capacitor voltage. II. CASCADED H-BRIDGES STRUCTURE AND OPERATION The hybrid cacaded H-bridge inverter power circuit i illutrated in Fig. 1. The inverter i compoed of three leg, in each one a erie connection of two H-bridge inverter fed by independent DC ource that are not equal (V 1 < V 2 ). Indeed, it may be obtained from batterie, fuel cell, or ultracapacitor in EV or HEV [16-18]. The ue of aymmetric input voltage can reduce, or when properly choen, eliminate redundant output level, maximizing the number of different level generated by the inverter. Therefore thi topology can achieve the ame output voltage quality with le number of emiconductor. Thi alo reduce volume, cot, and loe and improve reliability. When cacading two level inverter like H-bridge, the optimal aymmetry i obtained by uing voltage ource proportionally caled to the two H-bridge power. Particular cell i can generate three level (+V i,, V i ). The total inverter output voltage for a particular phae j i defined by m ( 1 2), {,, } jn ji i i i i= 1 i= 1 m v = v = V S S j a b c (1) Where v ij i the i cell output voltage, m i the number of cell per phae, and (S i1, S i2 ) the witching tate aociated to the i cell. Equation (1) explicitly how how the output voltage of one cell i defined by one of the four binary combination of witching tate, with 1 and repreenting the ON and OFF tate of the correponding witch, repectively /8/$ IEEE 1 Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.

3 Proceeding of the 28 International Conference on Electrical Machine A2 A1 Rectifier DC-Link H-Inverter a b c B1 B2 N Induction Motor C1 C2 Fig. 1. Aymmetric cacaded H-bridge multilevel inverter. The optimal aymmetry i obtained with DC link caled in power of two or three, generating 7 (Fig. 2) or 9 (Fig. 3) different output level. 9 different output level can be generated uing only two cell (8 witche) while four cell (16 witche) are neceary to achieve the ame amount of level with ymmetric fed inverter. V an (V) V a2 (V) V a1 (V) (S) Fig. 2. Aymmetric multilevel inverter with 7-level output voltage ynthei. V an (V) V a2 (V) V a1 (V) Fig. 3. Aymmetric multilevel inverter with 9-level output voltage ynthei. III. INDUCTION MOTOR DTC DTC i an alternative method to flux oriented control [1]. The baic principle i the direct election of a pace vector and correponding control ignal, in order to intantaneouly regulate the electromagnetic torque and tator flux magnitude. Several advantage may be conidered: higher robutne regarding motor parameter variation, higher torque dynamic, eaier flux and peed etimator implementation ince no rotational tranformation are required. However, in the tandard verion, important torque ripple i obtained even at high ampling frequencie. Moreover, the converter witching frequency i inherently variable and very dependent on torque and haft peed. Thi produce torque harmonic with variable frequencie and an acoutic noie with diturbance intenitie very dependent on thee mechanical variable and particularly grating at low peed. The additional degree of freedom (pace vector, phae configuration, etc.) provided by the multilevel inverter hould therefore be exploited by the control trategy in order to reduce thee drawback. A. Nomenclature v = Stator voltage vector; φ (φ r ) = Stator (rotor) flux vector; T e = Electromagnetic torque; R = Stator reitance; L (L r ) = Stator (rotor) inductance; L m = Magnetizing inductance; σ = Total leakage coefficient, σ = 1 L 2 m /L L r ; θ r = Angle between tator and rotor flux vector; p = pole pair number. A. Torque and Flux Etimation The tator flux vector an induction motor i related to the tator voltage and current vector by dφ dt ( t) () () = v t R i t ( 2) Maintaining v contant over a ample time interval and neglecting the tator reitance, the integration of (2) yield () () ( ) t Δφ t = φ t φ t Δ t = vδt (3) t Δt Equation (3) reveal that the tator flux vector i directly affected by variation on the tator voltage vector. On the contrary, the influence of v over the rotor flux i filtered by the rotor and tator leakage inductance [19], and i, therefore, not relevant over a hort-time horizon. Since the tator flux can be changed quickly while the rotor flux rotate lower, the angle between both vector θ r can be controlled directly by v. A graphical repreentation of the tator and rotor flux dynamic behavior i illutrated in Fig. 4. The exact relationhip between tator and rotor flux how that keeping the amplitude of φ contant will produce a contant flux φ r [2]. 2 Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.

4 Proceeding of the 28 International Conference on Electrical Machine v Δ(t) V 3 V 2 φ (t) φ (t-δt) θ r φ r (t) = φ r (t-δt) Fig. 4. Influence of v over φ during a imple interval Δt. V V44 Sector 3 Sector 4 Sector 5 Sector 2 Sector 1 v k Sector 6 V 1 Since the electromagnetic torque developed by an induction motor can be expreed by [2] V 5 V 6 Fig. 5. Poible voltage change Δv k that can be applied from certain v k. T 3 L m e = p φφr in θ r 2 σllr (4) V 3 V 2 It follow that change in θ r due to the action of v allow for direct and fat change in the developed torque. DTC ue thi principle to achieve the induction motor deired torque repone, by applying the appropriate tator voltage vector to correct the flux trajectory. V 4 φ (t) V 5 V 6 Sector 2 V 1 B. Voltage Vector Selection Figure 5 illutrate one of th e 127 voltage vector generated by the inverter at intant t = k, denoted by v k (central dot). The next voltage vector to be applied to the load v k+1, can be expreed by v v v k + 1 k k = +Δ (5) where Δv k = { v i i = 1,, 6}. Each vector v i correpond to one corner of the elemental hexagon illutrated in gray and by k+1 the dahed line in Fig. 5. The tak i to determine which v will correct the torque and flux repone, knowing the actual voltage vector v k, the torque and flux error e k φ and e k T and the tator flux vector poition (ector determined by angle θ ). Note that the next voltage vector v k+1 applied to the load will alway be one of the ix cloet vector to the previou v k, thi will often the actuation effort and reduce high dynamic in torque repone due to poible large change in the reference. Uing (4) and (5), and analyzing, for example, ector (2) illutrated in Fig. 6; the application of v 1 increae the tator flux amplitude but reduce θ r leading to a torque reduction. Converely, v 4 reduce the flux magnitude, while it increae θ r and thu the torque. If v 3 i applied to the load, both torque and flux increae, and it i clear that v 6 produce the invere effect. Table 1 ummarize vector election according to the above criterion, for the different ector and comparator output (deired φ and T e correction). To implement the DTC of the induction motor fed by an hybrid H-bridge multilevel inverter, one hould determine at each ampling period the logic tate of the inverter witche a a function of intantaneou value of torque and flux for the election of the pace vector, in the - frame. θ r φ r (t) Fig. 6. Voltage election Δv k in ecto r 2. Table 1. Voltage vector election lookup table. Sector ign(eφ k,e k ) (+,+) (+, ) (,+) (, ) 1 V2 V6 V3 V5 2 V 3 V 1 V 4 V 6 3 V 4 V 2 V 5 V 1 4 V 5 V 3 V 6 V 2 5 V 6 V 4 V 1 V 3 6 V 1 V 5 V 2 V 4 Once the pace i choen, the equence of phae level can be elected. To enure thi tak, one hould detect the poition of the pace vector in - frame ( k at ampling time t k ). The propoed algorithm mut then elect the next poition k+1 to be achieved before next ampling intant t k+1 (Fig. 7) in order to reduce voltage tep magnitude. Thi tak allow the commutation number reduction in the ame phae order to minimize loe and conequently the torque ripple. Finally, the configuration of each phae will be elected and mut be able to generate the phae level. T 3 Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.

5 Proceeding of the 28 International Conference on Electrical Machine.9 Trajectory direction.8 k+2 k+3 k+4 k +1 k k+1 k Trajectory correction k+1 Etimated flux (Wb) k+5 Fig. 7. Optimal pace vector tracking and trajectory correction in the tationary frame. IV. SIMULAT ION AND EXPERIMENTAL RESULTS For the validation of the above dicued control approach, imulation and experiment have been carried out. Figure 8 how imulation reult for a 7-level cacaded H-bridge inverter. For further verification, a three-phae DSP (TMS32LF247A) controlled 7-level cacaded H-bridge multilevel DTC induction motor drive ytem prototype wa built and teted (Fig. 9). The induction motor wa rated at 1- kw / 38V / 5.2 A / 142 rpm. The control cycle i 12 μ. It hould be noted, a illutrated by Fig. 9a, that the experimental etup wa built to lightly emulate an EV. Figure 1 illutrate experimental reult of the 7-level inverter realized in the laboratory (Fig. 9). The output voltage form with 7-level tepped multilevel waveform can be clearly appreciated; the motor current complete the overview of the performance of the drive. They appear completely inuoidal, ince the low pa nature of the load ha filtered the high frequency content of the applied voltage. The tator flux with contant amplitude impoed by the flux controller confirm the good dynamic performance of the drive. The mot important reult i that torque ripple ha been almot eliminated in comparion to two level claic DTC [21]. Stator current (A) (b) Stator flux waveform (c) Output current waveform Torque (Nm) (a) Etimated torque waveform. Phae current pectrum Frequency (Hz) (d) Phae current FFT analyi. 4 Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.

6 Proceeding of the 28 International Conference on Electrical Machine 2 15 Gearbox Phae voltage (V) (e) Phae voltage waveform (7 level). Induction S a,s b,s c Motor Control Unit Scope Power Control Senor Interface Interface Analog Digital Output Output TMS32F247 DSP Development Board (b) Fig. 9. The experimental etup. Wheel.9 Phae voltage pectru m Etimated torque Reference torque Frequency (Hz) (f) Phae voltage FFT analyi. Fig level cacaded H-bridge inverter imulation reult. (a) Reference and etimated torque waveform. (a) (b) - flux component waveform. 5 Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.

7 Proceeding of the 28 International Conference on Electrical Machine Input current 3A/div (c) Output current waveform. Input voltage 1V/div (d) Multilevel inverter output voltage during DTC. Fig level cacaded H-bridge inverter experimental reult. V. CONCLUSION Thi paper dealt with a hybrid cacaded H-bridge multilevel motor drive DTC control cheme that ha big potential for Electric (EV) or Hybrid Electric Vehicle (HEV). The main achievement of the propoed control method are: ignificant reduction in the torque ripple, inuoidal output voltage and current, lower witching loe and a high-performance torque and flux regulation. The hybrid multilevel inverter enable a DTC olution for high-power motor drive, not only due to the higher voltage capability provided by multilevel inverter, but mainly due to the reduced witching loe and the improved output voltage quality, which provide inuoidal current without output filter. R EFERENCES [1] L. G. Franquelo et al., The age of multilevel converter arrive, IEEE Indutrial Electronic Magazine, vol. 2, n 2, pp , June 28. [2] J. Rodriguez et al., Multilevel inverter: A urvey of topologie, control and application, IEEE Tran. Indutrial Electronic, vol. 49, n 4, pp , Augut 22. [3] M. Ecalante et al., Flying capacitor multilevel inverter and DTC motor drive application, IEEE Tran. Indutrial Electronic, vol. 49, n 4, pp , Augut 22. [4] T. Ihida et al., Fundamental characteritic of five-level double converter with adjutable DC voltage for induction motor drive, IEEE Tran. Indutrial Electronic, vol. 49, n 4, pp , Augut 22. [5] C. Rech et al., Hybrid multilevel converter: Unified analyi and deign conideration, IEEE Tran. Indutrial Electronic, vol. 54, n 2, pp , April 27. [6] M. Veentra et al., Control of a hybrid aymmetric multilevel inverter for competitive medium-voltage indutrial drive, IEEE Tran. Indutry Application, vol. 41, n 2, pp , March-April 25. [7] P.C. Loh et al., Modular hyterei current control of hybrid multilevel inverter, IEE Proc. Electric Power Application, vol. 152, n 1, pp. 1-8, January 25. [8] Y.S. Lai et al., Topology for hybrid multilevel inverter, IEE Proc. Electric Power Application, vol. 149, n 6, pp , November 22. [9] G.S. Buga et al., Direct torque control of PWM inverter-fed AC motor - A urvey, IEEE Tran. Indutrial Electronic, vol. 51, n 4, pp , Augut 24. [1] D. Caadei et al., FOC and DTC: two viable cheme for induction motor torque control, IEEE Tran. Power Electronic, vol. 17, n 5, pp , September 22. [11] M.E.H. Benbouzid et al., A lo-minimization DTC cheme for EV induction motor, IEEE Tran. Vehicular Technology, vol. 56, n 1, pp , January 27. [12] J. Faiz et al., Senorle direct torque control of induction motor ued in electric vehicle, IEEE Tran. Energy Converion, vol. 18, n 1, pp. 1-1, March 23. [13] X. del Toro Garcia et al., Direct torque control of induction motor utilizing three-level voltage ource inverter, IEEE Tran. Indutrial Electronic, vol. 55, n 2, pp , February 28. [14] J. Rodriguez et al., Direct torque control with impoed witching frequency in an 11-level cacaded inverter, IEEE Tran. Indutrial Electronic, vol. 51, n 4, pp , Augut 28. [15] S. Kouro et al., High-performance torque and flux control for multilevel inverter fed induction motor, IEEE Tran. Power Electronic, vol. 22, n 6, pp , November 27. [16] M. Carpita et al., Multilevel converter for traction application: Smallcale prototype tet reult, IEEE Tran. Indutrial Electronic, vol. 55, n 5, pp , May 28. [17] S. Lu et al., A unique ultracapacitor direct integration cheme in multilevel motor drive for large vehicle propulion, IEEE Tran. Vehicular Technology, vol. 56, n 4, Part 1, pp , July 27. [18] S. Dieckerhoff et al., Power lo-oriented evaluation of high voltage IGBT and multilevel converter in tranformerle traction application, IEEE Tran. Power Electronic, vol. 2, n 6, pp , November 25. [19] D. Caadei et al., DTC drive for wide peed range application uing a robut flux-weakening algorithm, IEEE Tran. Indutrial Electronic, vol. 54, n 5, pp , October 27. [2] M. Ecalante et al., Flying capacitor multilevel inverter and DTC motor drive application, IEEE Tran. Indutrial Electronic, vol. 49, n 4, pp , Augut 22. [21] F. Khoucha et al., An improved enorle DTC cheme for EV induction motor, in Proceeding of the IEEE IEMDC'7, Antalya (Turkey), vol. 2, pp , May 27. [22] F. Khoucha et al., A minimization of peed ripple of enorle DTC for controlled induction motor ued in electric vehicle, in Proceeding of the IEEE IECON'6, Pari (France), pp , November Authorized licened ue limited to: Univerite de Bretagne Occidentale. Downloaded on April 3, 29 at 7:12 from IEEE Xplore. Retriction apply.