8/2/2019 05606591

1/8

Design of New Diesel-Electric Power Supply

Unit for Military VehiclesZdenk Peroutka, Tom Glasberger and Jan Molnr

University of West Bohemia in Pilsen/Dept. of Electromechanics and Power Electronics, Plze, Czech Republic,

e-mail:peroutka@ieee.org,tglasber@kev.zcu.cz,jmolnar@kev.zcu.cz

Abstract This paper introduces a new designed diesel-

electric power-supply unit developed for military purposes.

The power-supply unit is divided to two main electric parts,

(i) input part which is composed of a sensorless controlled

active voltage source rectifier supplied by a permanent

magnet synchronous generator, and (ii) output part which is

composed of a four-leg three-phase voltage source inverter

with a sinusoidal LC filter with the output voltage

controlled by a proportional-resonant controllers bank.

The proper function of both parts of the supply unit has

been verified by simulations as well as on laboratory

prototypes of the devices.

KeywordsControl of Drive, Converter control,

Modulation strategy, Permanent magnet motor, Pulse

Width Modulation (PWM), Sensorless control, Voltage

Source Inverters (VSI).

I. INTRODUCTIONDevelopment of a military application usually

represents very attractive project which however, alwaysbrings serious constraints in both electrical andmechanical design. This paper presents results of researchinto new generation of diesel-electric power supply unitswith a permanent magnet synchronous generator intended

just for military applications (power supply unit forfighting vehicle). We have proposed a new topology andcontrol of the power electronics converter. The designedconverter is configured as an indirect frequency converterwith a sinusoidal filter at its output.

The input part of the converter is composed as a voltagesource active rectifier with sensorless control of the

permanent magnet synchronous generator (PMSG). Manystrategies for rotor position estimation of PMSG aredescribed in the literature, e.g. [1] - [3]. In general, it is

possible to use the model-based techniques such as

conventional voltage model, MRAS, different kinds ofobservers (e.g. [1] [10]) or different strategies based onthe machine anisotropies (e.g. [1] [4], [9] [10]). In ourcase, the proposed control comes from model-based

principle of rotor position estimation as described in detailin section II.

The output part of the converter is conceived as a four-leg three-phase voltage source inverter with a sinusoidalLC filter because the unit must be capable to supplyarbitrary kinds of load with low voltage harmonicdistortion (three-phase symmetrical or unsymmetricalload, one-phase linear or non-linear load and theircombinations). In general, the kind of the load isunknown and the control strategy must be able to control

the output voltage independently on the load parameters.There are several papers related to control four-leg

three-phase converters creating the output part of the

designed supply unit. This converter topology brings aspecific need to a new PWM strategy as usual for standardthree-phase VSIs. There are described different PWMstrategies such as carrier-based PWM or space vectorPWM in stationary coordinate system or in abc coordinatesystem, see e.g. [11] [13]. The different types ofconverter output voltage control are introduced in [14] [17]. The presented control systems are based on eitherPI-controllers (control in the rotating frame) or on

PR-controllers (control in the stationary frame).The challenge for military applications is to design

control system and power electronics converter with veryhigh reliability, robustness, simple implementation andeasy (automatic) parameters tuning. This paper presentsthe complex solution which we have proposed anddeveloped for the described diesel-electric power supplyunit for the fighting vehicle. The paper describes the

proposed power supply unit configuration and designedcontrol for both the input voltage source active rectifierand the output four-leg three-phase voltage source inverterwith the sinusoidal filter.

II. PROPOSED CONTROL OF VOLTAGE SOURCE ACTIVERECTIFIERFED BY PMSG

A. Control system for input part of power supply unitThe configuration of designed control system is shown

in Fig. 1. The proposed control of voltage source activerectifier is based on the hysteresis control of PMSG statorcurrents. The controller of dc-link voltage (Uc) commandsthe magnitude of the PMSG stator currents (Im). Thedemanded stator phase currents (isaw, isbw, iscw) arecalculated using the position of back EMF vector (Uind).We measure only two stator currents (isa, isb); the thirdstator current (isc) is calculated as described in Fig. 1. Thestator phase currents of PMSG are controlled using

hysteresis controller which commands the switching ofeach converter leg.

The hysteresis control of PMSG stator currents hasbeen selected due to its simplicity and robustness. In themaximum speed of PMSG, the voltage source activerectifier operates in the overmodulation area. Theemployed hysteresis control ensures troublefree, naturaltransition into the overmodulation area and is able to

provide the operation in the six-step mode.

B. Estimation of PMSG rotor position without eitherrotor speed or position sensor

As has been mentioned in section I, utilized sensorlessestimation of PMSG rotor position is based on model-

based principle. Regarding the operated speed range ofPMSG (stator frequency in the range of 50 300Hz) andextreme requirements for robustness and simplicity of

14th International Power Electronics and Motion Control Conference, EPE-PEMC 2010

978-1-4244-7855-2/10/$26.00 2010 IEEE T6-101

8/2/2019 05606591

2/8

employed sensorless approach, there has been a deal withtwo possible solutions for estimation of PMSG rotor

position, respectively required position of the back EMFvector:1) Direct model-based estimation of the back EMF vector,2) Estimation of the rotor position using compensatedconventional voltage model.

The designed prototype employs the estimation of thePMSG rotor position using the compensated voltagemodel in the stationary reference frame:

( )

=

=

=

r

rr

sssr

sssss

arctg

iL

dtiRu

, (1)

where

su is stator voltage vector,

si is stator current vector,

s is stator flux vector,

r is rotor flux vector,

sR is stator resistance,

sL is stator inductance,

r is rotor position electrical angle,

is damping factor.

The stator voltage vector is reconstructed based on themeasured dc-link voltage and the known states of powerelectronics switches. In the given speed range, the

Fig. 1. Proposed control of voltage source active rectifier fed by PMSG.

Fig. 2. Proposed control of output voltage source inverter.

T6-102

8/2/2019 05606591

3/8

operation of the presented voltage model is troublefree. Inorder to be able to estimate the position of the back EMFvector, we have to know the rotation direction. However,it is easy in this application, because the rotation directionis a priori known and fixed.

It can be concluded that proposed control system

requires only three sensors to measure the converterdc-link voltage and two phase currents of PMSG.

III. PROPOSED CONTROL OF OUTPUT THREE-PHASEFOUR-LEG VOLTAGE SOURCE INVERTER

The proposed power converter topology of the power

supply unit output part is shown in Fig. 3. The converterconsists of four-leg three-phase voltage source inverter

and the sinusoidal LC-filter, where L=6mH and C=20Ffor the laboratory prototype. This LC filter is needed to

obtain sinusoidal voltages at the output of the converter.

The voltage source inverter employs an untypical three-

dimensional space-vector PWM (3D-SVPWM) in abc

system coordinates.The most known SVPWM strategy in (dq0)

coordinate system must use the transformation from phasecoordinates to the given coordinate system and theswitching times calculation is thereafter quite difficult touse in a real system. Further, the transformation to therotating coordinate system or to the stationary coordinatesystem is not convenient for the proposed control, whichuses proportional-resonant controllers. The abovementioned coordinate transformation is profitable forcontrol systems using the control of output voltages inrotating reference frame with conventional PI controllers.This SVPWM strategy is described e.g. in [16].

A. Control system for output part of power supply unitThe proposed converter control is shown in Fig. 2. The

main request for the designed supply unit is to createsinusoidal symmetrical output voltages under arbitraryload condition (three-phase symmetrical or unsymmetricalload, one-phase linear or nonlinear load etc.). By thisreason, it is necessary to measure the output capacitorvoltages in all phases (uca, ucb, ucc). The capacitor currentsare measured in order to provide better dynamic responseof the control system (ica, icb, icc). The measured voltagesand demanded phase voltages uaw, ubw, ucw are subtracted

and the results represent the input quantities for the PRcontrollers. The control system contains a bank of three

proportional-resonant controllers. Each of them controlsindependently the voltage on the output capacitor in theinvolved phase. PR-controllers must usually be supported

by some correcting signal in this case represented bysignals uaw, ubw, ucw. The dynamic properties of the

converter are improved using the feedback from the filtercapacitor currents [18].

Corrected signals uaref, ubref, ucref are taken as PWMmodulation commands into the 3D space vector PWMmodulator to control the voltage source inverter. Veryimportant advantage of the using of PR controllers in thissystem is that the output frequency is always constant(either fout=50 or 60Hz).

B. Output voltage source inverter modulation strategyThe SVPWM in abc coordinates does not use any

transformations; the output voltage vector is createddirectly from the phase voltages values. The

3-dimensional ordering of basic voltage output vectors ofthe four-leg inverter is shown in Fig. 4. There are 16voltage vectors in the inverter, 14 of them are the activeand two are the zero vectors. The demanded output vectoris created as a combination of three selected adjacent

basic vectors (and the zero vector eventually) as usually.The exact description of this modulation strategy can befound in [12] or [14].

C. Proportional-Resonant ControllersThe control system of the designed power supply unit

uses a set of three proportional-resonant controllers. ThePR controller transfer function is described in (1):

22

2)(+

+=s

sKKsF rpPR , (1)

where Kp is the proportional gain and Kr is the resonantgain, is the angular frequency of the output signal thePR controller works as a filter with infinite gain for thesignal of frequency and with zero gain for signals ofother frequencies. The PR controller is eligible componentfor tracking sinusoidal signals. The detailed description ofPR controllers theory can be found e.g. in [19].

The time domain representation of the Laplaces form

Fig. 3. Configuration of output part of designed power supply unit. Fig. 4. Ordering of inverter output vectors in abc coordinate system.

T6-103

8/2/2019 05606591

4/8

(1) must be calculated in order to implement the regulatorin the microcontroller:

)(.)(1 tyKtu p= , (2a)

dt

tdy

Krudt

tdu )(

..2

)( 2222

2

2

=+

, (2b)

)()()( 21 tututu += , (2c)

where u1(t) and u2(t) is the time domain function of thefirst and second part of (1), respectively, u(t) is thecontroller output,y(t) is the controller input signal (controlerror). The equations (2) are more suitable forimplementation to a DSP instead of equations derived e.g.in [4]. The main advantage of PR controllers is that theoutput and input signals can be alternating. In AC systemsthe PR controller based system works as a PI controller

based system in revolving (synchronous) coordinatesystem, but no transformation of controlled quantities tothe rotating coordinate system is required.

IV. SIMULATION RESULTSA. Input part of power supply unit

Behaviour of proposed prototype of voltage sourceactive rectifier fed from PMSG is analyzed in followingsimulation results. The employed simulation modelrespects as close as possible the properties of the realapplication including rated power of 100kW (dead-timesof 3s, nonlinear voltage drops on the power electronicdevices, etc.) and microprocessor-based controller. The

control algorithms implemented in the microprocessor aresimulated in the fixed-point arithmetic. The sampling

period of the controllers and the voltage model is the sameand equal to 25s. The average switching frequencydetermined by the hysteresis band of the currentcontrollers is 5kHz. The load of the investigated voltagesource active rectifier is replaced in simulations by theequivalent current source (Iload).

Fig. 5 shows response of designed converter on the stepchange of the load (Iload = 50A 100A). The transienteffect occurring due to the step change of the dc-linkvoltage command (Ucw = 700V 600V) is depicted inFig. 6. Under conventional operating conditions, thedc-link voltage is controlled on the fixed value of 700V.

However, the behaviour of the designed converter understep change of the demanded dc-link voltage is presentedin order to illustrate dynamic properties of proposedcontrol. The special attention has been paid to the rectifierstart-up. Fig. 6 verifies successful solution of this problem

there is employed the zero voltage vector in order toreduce the dc-link voltage drop at the converter startup.

B. Output part of the supply unitSimulations of the output converter of the supply unit

have been taken to verify that the designed control systemfor the small scale prototype of 18kVA works properlyunder arbitrary conditions different kinds of the load,different transient phenomena, etc. The most importanttransient phenomenon is the start up of the converter withzero voltage on the output capacitors. There can appear

dangerous voltage oscillations. It is a hard condition forthe control system to suppress those oscillations.

The simulations have been taken under the followingparameters: dc-link voltage Udc=600V, switchingfrequency fpwm=7000Hz, output frequency fout=50Hz.

The first simulation result (Fig. 7) presents behaviour of

the system under symmetrical load condition (a three-phase RL load; where R=150, L=4mH) in the steady-state. The figure shows the phase voltages in all three

phases and the current in phase a. The demanded voltageamplitude has been of 260V.

In Fig. 8, there is analyzed behaviour of the systemunder no-load condition the inverter supplies only thesinusoidal LC filter.

The simulation result shown in Fig. 9 exploresbehaviour of the system under unsymmetrical three-phaseload condition different resistances in all phases(Ra=150, Rb=150, Rc=100 and the same inductances(La=Lb=Lc=4mH). There are shown all three phasevoltages and currents in phases ia and ic, respectively.

Fig. 10 presents the behaviour of the converter feedinga one-phase nonlinear load. The load is presented as aone-phase diode bridge rectifier which supplies RC load,where Rz=250 and Cz= 40F.

V. EXPERIMENTAL RESULTS:DEVELOPED SMALL SCALE PROTOTYPES

Proposed control systems of both the input voltagesource active rectifier and output three-phase four-legvoltage source inverter have been implemented in fixed-

point digital signal processor Texas InstrumentsTMS320F2812. Parameters of the microprocessor controlsystem (sampling times, dead-times, etc.) have been set

exactly as for the target prototype of 100kW.

A. Input part of power supply unitIn the laboratory prototype, the PMSG is driven by

variable-speed induction machine drive which simulatesthe diesel engine. Fig. 11 Fig. 13 present selectedexperiments made on developed small scaled prototype ofthe input part of the power supply unit. In Fig. 11a, thereis displayed startup of the converter using proposedsensorless control. Fig. 11b analyzes behaviour of theinput converter employing a PMSG rotor position sensor.From these figures is obvious that employed startup

procedure avoids overcurrents during the converterstartup. A steady state with demanded output voltage

Uc=600V is shown in Fig. 12. Verification of the properfunction of the sensorless position estimation is shownFig. 13 where sensorless position estimation is comparedwith the information from rotor position sensor.

B. Output part of power supply unitThis section presents experimental results, which have

been taken on the developed prototype of output part ofpower supply unit. The experiments have been made forseveral kinds of load under both steady-state and transientconditions. The dc-link voltage has been set Udc=600V,the demanded output voltage amplitude has beenu*=260V, the switching frequency has been fpwm=7000Hzand the output frequency has been fout=50Hz.

The behaviour of the control system under arbitraryload conditions is shown in Fig. 14 Fig. 17.

T6-104

8/2/2019 05606591

5/8

Fig. 5. Prototype of 100kW: Step change of the load of PMSG fed

voltage source active rectifier: Iload = 50A 100A, Ucw = 700V,el. rotor speed of 200Hz.

Fig. 6. Prototype of 100kW: Startup of developed PMSG fed voltagesource active rectifier: Ucw = 700V, Iload=0A, el. rotor speed of 50Hz.

Fig. 7. Behaviour of output voltage source converter under

symmetrical three-phase load (Udc=600V, fout=50Hz).Fig. 8. Behaviour of output voltage source converter under no-load

conditions (Udc=600V, fout=50Hz).

T6-105

8/2/2019 05606591

6/8

Fig. 9. Behaviour of output voltage source converter under

unsymmetrical three-phase load, (Udc=600V, fout=50Hz). Fig. 10. Behaviour of output voltage source converter under non-linear

one-phase load conditions, (Udc=600V, fout=50Hz).

a) Proposed sensorless control

b) Control employing PMSG rotor position sensor

Fig. 11. Startup of developed PMSG fed VSAR:

Ucw = 600V, el. rotor speed of 80Hz, load represented by Rload = 660

connected in parallel with dc-link capacitors;ch1: Uc [V], ch2: Isq (13.6A/V), ch3: Isd (13.6A/V), ch4: Isa (13.6A/V).

Fig. 12. Steady-state behaviour of PMSG fed VSAR:

Ucw = 600V, Iload = 2A, el. rotor speed of 80Hz; ch1: Uc [V],ch2: Isq (13.6A/V), ch3: Isd (13.6A/V), ch4: Isa (6.8A/V)

Fig. 13. Verification of proper function of employed sensorless

estimation of position of back EMF vector:Ucw = 600V, el. rotor speed of 120Hz, Iload 2A;

ch1: Uc [V], ch2: Uind model (72/V),

T6-106

8/2/2019 05606591

7/8

The behaviour of designed output voltage sourceconverter with symmetrical three-phase load is analyzedin Fig. 14. The load parameters have been set according tothe simulation resistors Ra = Rb =Rc = 150 andinductances La = Lb = Lc = 4mH. It can be seen that theconverter works without problems, the output voltages aresinusoidal without any visible distortions (THDu has been

demanded lower than 5%).Fig. 15 shows converter behaviour in steady-state under

unsymmetrical three-phase load condition

(Ra=Rb=150, Rc=100, La=Lb=Lc=4mH). The powersupply unit works without problems in this case as well.Fig. 16 presents the start-up and the steady-state behaviourof the converter under no-load conditions. The start-up ofthe non-loaded LC filter is very hard condition for thecontrol system, but the oscillations of the output voltageare damped very fast in several milliseconds.

Fig. 17 illustrates behaviour of the converter supplyinga one-phase diode bridge rectifier, which feeds the RCload (parameters are the same as in the simulation:

Rz=250, Cz=40F). There can be seen that the rectifierinput current is distorted by thin pulses.

VI. CONCLUSIONSThis paper introduces a new design of the diesel-

electric power supply unit for military vehicles. From themilitary demand results that the power supply unit must bedesigned with very high reliability and robustness (shockendurance 9G, THDu < 5%, wide temperature range, highoverload endurance). Developed supply unit resolved as

indirect frequency converter is composed of two mainparts, the input one is created as the voltage source activerectifier and the output one is created as the three-phasefour-leg voltage source inverter with sinusoidal LC filter.

The designed control of the voltage source activerectifier is based on the hysteresis control of the PMSGstator currents, which is simple and robust. The PMSG isoperated without the rotor position sensor; the required

position of the back EMF vector is estimated using thecompensated voltage model of PMSG. The employedsensorless strategy is under given operating conditionstroublefree and simple for implementation.

The output part of developed power supply unit iscomposed of the four-leg three-phase voltage sourceinverter with sinusoidal LC filter to create symmetricalsinusoidal output voltage. The designed control system

Fig. 14. Behaviour of the laboratory prototype under symmetrical

three-phase load condition start up and steady state;ch1-ch3: phase voltages, ch4: phase current.

Fig. 16. Behaviour of the laboratory prototype under no-load condition

start up and steady state;ch1-ch3: phase voltages, ch4: phase current.

Fig. 15. Behaviour of the laboratory prototype under unsymmetrical

three-phase load condition steady state;ch1-ch3: phase voltages, ch4: phase current.

Fig. 17. Behaviour of the laboratory prototype under non-linear

one-phase load - start up and steady state;

ch1-ch3: phase voltages, ch4: phase current.

T6-107

8/2/2019 05606591

8/8

uses 3 proportional-resonant controllers; each of themcontrols the output voltage in one of three phases to createsymmetrical three-phase voltage. Used modulationstrategy of the converter does not require anytransformation into specific reference system. Hence,

proposed control system of output voltage source inverteris robust and simple for implementation,

The proper function of developed power supply unit hasbeen verified by simulations of the target prototype of100kW as well as by simulations and experimental tests ofdeveloped small scale prototype of 18 kVA.

ACKNOWLEDGMENT

This research has been funded by the Czech Science

Foundation under project GA R 102/09/1164.

REFERENCES

[1] Vas, P., Sensorless Vector and Direct Torque Control, OxfordUniversity Press. New York, USA, 1998.

[2] Holtz, J., Sensorless Control of Induction Motors and PMSynchronous Machines, Tutorial. In: IEEE InternationalSymposium on Industrial Electronics (ISIE) 2005. Dubrovnik,Croatia, 2005.

[3] Schroedl, M., Sensorless Control of Permanent MagnetSynchronous Machines: An Overview, In: EPE-PEMC 2004.Riga, Latvia, 2004.

[4] Lorenz, R.D., Future Motor Drive Technology Issues and TheirEvolution, In: EPE-PEMC 2006. Portoroz, Slovenia, 2006.

[5] Bolognani, S., Oboe, R., Zigliotto, M., Sensorless Full-DigitalPMSM Drive With EKF Estimation of Speed and Rotor Position,IEEE Trans. on Industrial Electronics, Vol. 46, No. 1, February1999. pp. 184 191.

[6] Peroutka, Z., Design Considerations for Sensorless Control ofPMSM Drive Based on Extended Kalman Filter, In: 11thEuropean Conference on Power Electronics and Applications(EPE) 2005, Dresden, Germany, 2005.

[7] Urlep, E., Jezernik, K., Kos, D., Sensorless Sliding modeControl of PM Synchronous Machine In: EPE-PEMC 2004.Riga, Latvia, 2004.

[8] Cecchini, G., Parasiliti, F., Petrella, R., Tursini, M.,SensorlessPermanent Magnet Synchronous Motor Drive for DomesticRefrigerators, In: EPE 1999, Lausanne, Switzerland, 1999.

[9] Silva, C., Asher, G.M., Sumner, M., Hybrid Rotor PositionObserver for Wide Speed-Range Sensorless PM Motor DrivesIncluding Zero Speed, IEEE Transactions on IndustrialElectronics, Vol. 53, No. 2, April 2006, pp. 373 378.

[10] Filka, R., Balazovic, P., Dobrucky, B., A Seamless Whole SpeedRange Control of Interior PM Synchronous Machine withoutPosition Transducer, In: EPE-PEMC 2006. Portoz, Slovenia,2006.

[11] Glasberger, T.; Peroutka, Z.; Molnr, J., Comparison of 3D-SVPWM and carrier-based PWM of Tthree-Phase Four-LegVoltage Source Inverter, In: EPE 2007. Brussels : EPEAssociation, 2007. pp. P.1-P.9.

[12] Glasberger, T.; Peroutka, Z.; Molnr, J., Design of Power SupplyUnit Based on Four-Leg Voltage Source Inverter with Focus onDifferent PWM Strategies, In: Electrical drives and powerelectronics. Koice : Slovensk elektrotechnick spolonos,2007. pp. 1-6.

[13] Kim, J. H., Sul, S. K., A Carrier-Based PWM Method for Three-Phase Four-Leg Voltage Source Inverters, IEEE Trans. onPower Electronics, Vol.19., No.1, January 2004, pp. 66-75.

[14] M. A. Perales, M. M. Prats, Ramn Portillo, Jos L. Mora, Jos I.Len, Leopoldo G. Franquelo, Three-Dimensional Space VectorModulation in abc Coordinates for Four-Leg Voltage SourceConverters, in:IEEE Power Electronics Letters, Vol.1, No.4, pp.104-109, December 2003.

[15] Ryan, M.J., De Doncker, R.W., Lorenz, R.D. Decoupled Controlof a Four-Leg Inverter Via a New 4 4 Transformation Matrix,IEEE Trans. on Power Electronics, Vol. 16, No. 5, September2001, pp. 694 701.

[16] Zhang, R., Prasad, W.H., Boroyevich, D., Three-DimensionalSpace Vector Modulation for Four-Leg Voltage SourceConverters, IEEE Trans. on Power Electronics, Vol. 17, No. 3,May 2002, pp. 314 326.

[17] Zhang, R., High Performance Power Converter Systems forNonlinear and Unbalanced Load/Source [Dissertation]. VirginiaPolytechnic Institute and State University. Blacksburg, Virginia,USA, 1998.

[18] Demirkutlu, E.; Cetinkaya, S.; Hava, A.M.; Output VoltageControl of A Four-Leg Inverter Based Three-Phase UPS by Meansof Stationary Frame Resonant Filter Banks, In:Electric Machinesand Drives Conference 2007 IEMDC 07, Volume 1, 3-5 May2007, pp. 880-885, Antalya, Turkey.

[19]Xiaoming Y.; Merk, W.; Stemmler, H.; Allmeling, J.; Stationary-frame generalized integrators for current control of active powerfilters with zero steady-state error for current harmonics ofconcern under unbalanced and distorted operating conditions,IEEE Transactions on Industry Applications; Volume 38, Issue 2,March-April 2002; pp. 523 --- 532.

T6-108