- Email: [email protected]
Control algorithm of an active rectifier
Copyright © IFAC Automatic Systems for Building the Infrastructure in Developing Countries, Istanbul, Republic of Thrkey, 2003
ELSEVIER
IFAC PUBLICATIONS www.elsevier.comllocateJifac
CONTROL ALGORITHM OF AN ACTIVE RECTIFIER
u. Rechkoska-Shikoska 1, E. Lazarevska 1, V. Katic 2, J. Shikoski3 J"Sv. Kiril i Metodij" University ofSkopje, Karposh III b.b. 1000 Skopje, Macedonia 2Faculty of Technical Science, University ofNo vi Sad, 2 J 000 Novi Sad, Serbia and Montenegro A.D., Electrical Industry & Engineering, 6000 Ohrid, Macedonia E-mail: [email protected]
3EMO-Ohrid
Abstract. The control algorithm of an active rectifier is presented in this paper. This kind of an active rectifier, produced by A.D. EMO - Ohrid, R. Macedonia, is used as a battery in all substations. The control algorithm contains main program, several subprograms and three interrupt routines. Also, the active rectifier, as an industrial product is presented, as well as the innovations, in comparison to the Siemens one. This algorithm has been tested in a laboratory and the results show its efficiency. Copyright © 2003 IFA C Keywords: Control algorithm; active rectifier; power systems; PWM.
In this paper, battery charger with new type of rectifier is presented; its work doesn't lay on the phase regulation principles. Direct connection of IGBT transistors and powerful diodes are used as full-managing switch. This kind of rectifier is managed by Pulse Width Modulation (PWM). This type of management is successfully applied on invertors and it has showt;d exceptional advantages for easy, simple and cheap maintaining of wave forms, with low harmonic distortion. Rectifier like this, keeps good characteristics of the classic ones and at the same time, enables harmonic filtering.
I. INTRODUCTION The most common rectifier application is the charging or recharging the batteries at the power network substations, regulated activating of motors, etc. But the growth of real-world applications of rectifier devices is coming in the near future, when electric powered cars will become in wide use. Classic solutions of electrical power deceivers for batteries loading depend on realizations, and they are, more or less, complex, with some charging quality. Chargers, with controlled output, besides their advantages, have common shortages - they generate harmonics in the network and they reduce the electric power quality. But putting filters is justified for low power. Lately, s.c. active filters are used in order to eliminate the harmonics. The only shortage is the price of an additive deceiver in the filter's construction.
The focus of this paper will be put on the control algorithm of the rectifier, the microcontroller's software. The rectifier's work quality depends on the microcontroller's software accuracy and the speedy convergence. The control algorithm is described in details. The work simulation is made
217
Depending on the wave form of the carrier and referent signal, there're several types of PWM. In this work, PWM with triangular carrier is used. But, the management solution doesn't depend on PWM type. The separate auxiliary functions are gained by the cross section of the referent and phase voltage (Uref) and the triangular carrier.
under different conditions. The model quality is tested on a laboratory prototype and the simulation results are verified.
2. THE ACrrVE RECTIFIER The active rectifier contents a direct connection of a transistor and a diode. The management principle is produced by PWM inverter, with some modification, necessary for rectifier's work. It's convenient to use transfer function in a matrix form, by purpose of PWM rectifier management, and it's called switching function matrix.
The principle of gaining the auxiliary switching functions is presented on the Figure 1. The voltage value, at the rectifier's output is found like:
u)at) =[Pl} !fua(at)] = .., ~
Depending on selected methods, there're switching functions of the switch, switching functions of the branches, which are used here:
=[PJ]. Ifu..14
T
Uoc1. U.J
(3)
40'
where: h is a number of the harmonic; [uac{wt)J is the input voltage matrix of the h-th harmonic. PTi 4 switching function of the i-th branch PTi = 1 4 meaning the first transistor is leading PTi = -1 4 meaning the second transistor IS leading PTi =0 4 meaning none of them are leading The switching functions are generated by the auxiliary switching functions, which are outgoing signals of the PWM generator.
M ·IUre! 1 > Unos
I
M ·IUre! < Unos
~ P =1
The PWM rectifier frequency is determined by the carrier signal frequency and it's limited by the switching components work speed. The management variable of the PWM rectifier, which defines the outgoing voltage amplitude, is the amplitude modulating index, defined by:
U re!
M=-
(4)
Unos
(2)
~P=0
The modulating index is formed like a regulation circuits output, whose inputs are: instantaneous wanted charging current, as well as values of actual current and battery voltage. PI current controller is needed for a qualitative regulation, constructed by some of the well known methods, with addition offeed-forward compensators.
P is auxiliary switching function; M is the modulating index; Uref is referent voltage and Unos is carrier voltage.
It should be noted that obtaining the desired form of an outgoing current is based on the charging characteristics, time measuring battery voltage and temperature. 3. CONTROL ALGORITHM The control algorithm is presented by software application, through main program, several subprograms and three interrupt routines.
3.1 Control Algorithm ofthe Main Program 0455
046
0465
047
0475
048
0485
This algorithm is presented on the Figure 2. In the main program, the variables are initialized and work of peripheral units of the equipment is defined.
Figure 1. The principle of gaining the auxiliary switching functions
218
Main Program
Initialization of variables and SFR
In the main program, all the interrupts are enabled, the timer TIMER2 is started as auto-reload timer, and comparison is done. As a matter of fact, in this part, the tester begins to work. The main loop is a jump to the line with a label INTPROV, by which, interrupt is waited. Also, messages are written on the display. Auxiliary switching functions are generated by the rnicrocontroller uC80535 by the peripheral unit, which contents the timer T2 and several registers, with a special usage, adapted for PWM signals generating. 3.2 Control algorithm ofthe network interrupt
Call on subroutine for work with LCD display
The network interrupt INT_FA is generated at the moment of the input altemating voltage, passing through zero, by ascending order. The blockdiagram of the network interrupt is presented in the Figure 3. The network interrupt synchronizes the referent signal of the network voltage at the moment of its forming. The regulation of the outgoing magnitudes is done according to their measured values (by the peripheral unit of the In this paperwork, for the microcontroller). regulation aims, position PI controller in the current loop is applied, and also incremental PI controller in the voltage loop is put. As a controller output, the modulating index is gained, by the comparison of the moment current and voltage values Uref and Iref, and measured values Iiz and Uiz, by the controller (by AID converter.)
Inputting the work parameters
Main loop
Figure 2. Block-diagram of the main program algorithm
The control rule is given by: Also, the main program leads the user through the procedure of inputting charging parameters, writing of messages on the display, as well as receiving information from the tester, until the charging process is started. During the process, main program informs the user about the given and instantaneous values of the voltage, current and charging time.
where u(k) is management magnitude, Iiz is measured current magnitude, ki e the constant of proportional influence, and TlTi = 24 is a constant of integral influence. The regulation loop of the charging current Iiz is presented by the Figure 4, where: D(z) is a digital controller; Gobj(z) is the transfer function of the continual system part; Iref(k) is a given value of the regulated magnitude at kTmoment; Iiz(k) is the moment value of the regulated value at kT moment; e(k) is an error signal; u(k) is the management magnitude value at kT moment; T is selecting period.The management rule, applied in the regulation part of the control software for the active rectifier is given by:
In the main loop of the program, instantaneous values of the current (Iiz) and the voltage (Uiz) at the rectifier output, also the passed charging time are tested, and after that the program is executed. The main loop contains several parts: • writing of instantaneous current, voltage and battery charging time values; • testing the active push button condition; • sending messages about the computer loading process, using direct communication; • informing the user about the situation, and after that, entering the procedure of restarting or shutting down.
T
U(Ic) =U(Ic_I)
+K; .(-Iu(lc) + [;z(Ic-I) +( TJ-e(Ic)) (6) I
219
Network interrupt INf_FA 101....,.."1"'-1)
. . . . -..
.....-pc:riocI
. . . . . . hDlIltpreYiaa
RESET
ell)
= 1~(l) -110(0)
Testers
Regulated MagnitUdes Measuring
T P = K , .(-I",t, + l.t _lI +tI(lI'-)
INITIALIZAnON of the TABSTN index
1;
REGULATION U 1._ I )
+- ufO)
1"(0_1)
+- I"'(OJ
Reading from TABP and writing into CCR Fig. 5. Algorithmic block diagram of regulatory control The interrupt signals are generated by the peripheral unit, which contains the timer n, and also several registers: CC (compare-capture) and CRC (compare-reload-capture). The CRC register determines the PWM signal frequency. In the CC register, the referent signal value is written and its determined by some parts of the software.
TESTERS RESTARTING
PREPARATION for the 1Interrupt testers
3.3 The control algorithm ofthe testers interrupt
The testers interrupt is generated by the timer T2, after passing of the carrier signal period (testers). Block-diagram of this algorithm is presented by Figure 6.
Fig. 3. Tester interrupt block-diagram
In this part of the program, writing of accepted values is done in the POMH/L register in CCH/L. The table TABSIN index, INDEKSa is increased by one, until 41, and after that it is taken back to zero, and values of the table are read and are prepared for writing into the CCH/L registers, in the next INT- n routine. By this, the program deletion is minimized.
e(k) ~~ ~ '{~ .···~uw::
Fig. 4. Block diagram ofthe digital regulatory loop The block-diagram of the regulatory control part is presented on the Figure 5.
The third interrupt is serial communication interrupt (SER_COM). Its task is to enable
220
4. RESULTS
communication between the computer, switched to the equipment, for accepting the data. In this routine, the data, which had arrived to the controller serial port , is written into the registers and it's processed during the main program and previous interrupt routines.
This charger is manufactured at A.D. EMO-Ohrid, DOOEL "Automation and electronics" in Skopje, R. Macedonia. The results justify the selection of the PWM rectifier as a battery charger. As an experimental result, the configuration of full equipment is presented by the Figure 7. The synchronization circuit is linked to the microcontroller, on which the display and commands are linked, for the communication to the user. The microcontroller is also linked to the decoder, for decoding the signals, the decoder is linked to the drivers, which carry the P signals to the PWM rectifier's input. The microcontroller is linked to the current and voltage sensors, too.
Interrupt tester
INT_T2
Writing the additive registers into the CCH/L
The battery is charged by constant current, until the battery voltage reaches the value which is close to the nominal loading voltage value. Then, there is a charging by constant voltage. The Figure 8 below shows the charging characteristic.
Increasing the INDEKSa index by one
Preparation for the next interrupt TESTER
C
RETI
This figure, which is an experimentally verified result, is a rather successful outcome. It justified all the design requirements, and shows the best battery charging performances so far achieved.
~
Fig. 6. Testers interrupt block-diagram
R
N
R
N
PWM RECTIFIER NO
Protectio
CURRENT
___~~~~Sl~ __ I---_....J
l.----------------------i
VOLTAGE 1 - - - - - - - - ' L:S:::EN~SO~RJ_--------'
~r------....,h
~-i
SUPPLY
r
Figure 7. The overall battery charger design
221
(AI
M
Id
10
120
l 75
Ua
(ESM). It finds application in electricity supply substations within power distribution networks.
110
~
100
Acknowledgement. Authors would like to thank Prof. G. M. Dimirovski for his constructive advice in the course of the project and in writing up this paper.
90
5
80
70 60
25
50
0
0
01
0.2
(h)
0.3
04
05
REFERENCES Figure 8. The battery charging characteristic
Bose, B. K., Microcomputer Control of Power Electronics and Drivers, IEEE press, New York, 1987. Depenbrock, M., D. A. Marshall, J. D. Van Wyk (1994), "Formulating Requirements for a Universally Applicable Power Theory as Control Algorithm in Power Compensators". ETEP, vol. 4, n. 6, pp. 445-456. D'Hondt M. (2002), "Making software knowledgeable", IEEE 24th International Conference on Software Engineering, 19-25 May 2002, Orlando, FL, USA, pp. 735-741. Katic, V., V. D. Vasic, Graovac (1995), "The Methods of Electrical Energy Converters Mode1ing", Monograph Contemporary Problems in Power Engineering, Edited by D. Gvozdenac, 1. Xypteras, M. Dimic, Faculty of Technical Sciences / School of Technology, Novi Sad (Yugoslavia) / Thessaloniki (Greece), pp.169-179. Katic, V., U. Rechkoska, S. Grabich, Z. Mladenoski, M. Kostic (2000), "Aktiven ispravuvac so faktor na moknost edinica i eliminiranje na harmoniskata zagadenost," R&D research project for technological development. Ministry of Science, Rep. of Macedonia, No. 09-2906/1, July. Kwon, B. and Min B. (1993), "A fully softwarecontrolled PWM rectifier", IEEE Transactions on Industry Applications, Vol. 40, Issue 3, June, pp. 355-363. Rechkoska, U., E. Lazarevska, V. Katic, S. Grabic (2002), "Softwerski Algoritam Aktivnog ispravljacha", In: HEPP 2002 - 2nd International Symposium, Electrotechnical Society Zagreb and Generation Division HPP Department, Croatia, Sibenik, 3-4 June: pp. 142-148. Software Support/DeveIopment Tools for the SAB-51 Family, Siemens Components, Inc.
5. CONCLUSION The proposed solution for the battery charger, as a PWM rectifier, keeps good characteristics of a standard solution, from the charging characteristics point of view, enables harmonic minimization by simple capacitive filter. Also, it's characterized by the power factor almost equal to one.The management concept and the control algorithm are chosen and created correctly and effectively, which is proved by the results. Another advantage, beside the ones mentioned previously, is that the microprocessor management enables inflected and open realization access. More charging processes are possible to program, adapted to different types of batteries, different indications and checking, battery condition monitoring, etc. Comparing the harmonic values after filtering, to the IEC J000-3-2 standard, it c~ be concluded that rectifier's work satisfies the standard and by future algorithm and PWM techniques improvement, the spectrum can be improved and the filter's price can be reduced. An innovation, and also advantage, of this type of rectifier EMOSTAT-BAT-RTDZ which works on the PWM principle, comparing to the classic ones is ~ fact that it works on high switching frequency: whIch enables filtering the harmonics by LC filters. By filtering the network current harmonics it's shape becomes almost sinusoidal, and th~ power factor is almost one. This fact makes this type of rectifier most suitable for application. This type of battery charger, as PWM rectifier, with power factor equal to one, as a prototype of full equipment including the microcontroller card for the energetic converter and original control and management software, is manufactured for the Electricity Power Company ofthe R. Macedonia
222
ELSEVIER
IFAC PUBLICATIONS www.elsevier.comllocateJifac
CONTROL ALGORITHM OF AN ACTIVE RECTIFIER
u. Rechkoska-Shikoska 1, E. Lazarevska 1, V. Katic 2, J. Shikoski3 J"Sv. Kiril i Metodij" University ofSkopje, Karposh III b.b. 1000 Skopje, Macedonia 2Faculty of Technical Science, University ofNo vi Sad, 2 J 000 Novi Sad, Serbia and Montenegro A.D., Electrical Industry & Engineering, 6000 Ohrid, Macedonia E-mail: [email protected]
3EMO-Ohrid
Abstract. The control algorithm of an active rectifier is presented in this paper. This kind of an active rectifier, produced by A.D. EMO - Ohrid, R. Macedonia, is used as a battery in all substations. The control algorithm contains main program, several subprograms and three interrupt routines. Also, the active rectifier, as an industrial product is presented, as well as the innovations, in comparison to the Siemens one. This algorithm has been tested in a laboratory and the results show its efficiency. Copyright © 2003 IFA C Keywords: Control algorithm; active rectifier; power systems; PWM.
In this paper, battery charger with new type of rectifier is presented; its work doesn't lay on the phase regulation principles. Direct connection of IGBT transistors and powerful diodes are used as full-managing switch. This kind of rectifier is managed by Pulse Width Modulation (PWM). This type of management is successfully applied on invertors and it has showt;d exceptional advantages for easy, simple and cheap maintaining of wave forms, with low harmonic distortion. Rectifier like this, keeps good characteristics of the classic ones and at the same time, enables harmonic filtering.
I. INTRODUCTION The most common rectifier application is the charging or recharging the batteries at the power network substations, regulated activating of motors, etc. But the growth of real-world applications of rectifier devices is coming in the near future, when electric powered cars will become in wide use. Classic solutions of electrical power deceivers for batteries loading depend on realizations, and they are, more or less, complex, with some charging quality. Chargers, with controlled output, besides their advantages, have common shortages - they generate harmonics in the network and they reduce the electric power quality. But putting filters is justified for low power. Lately, s.c. active filters are used in order to eliminate the harmonics. The only shortage is the price of an additive deceiver in the filter's construction.
The focus of this paper will be put on the control algorithm of the rectifier, the microcontroller's software. The rectifier's work quality depends on the microcontroller's software accuracy and the speedy convergence. The control algorithm is described in details. The work simulation is made
217
Depending on the wave form of the carrier and referent signal, there're several types of PWM. In this work, PWM with triangular carrier is used. But, the management solution doesn't depend on PWM type. The separate auxiliary functions are gained by the cross section of the referent and phase voltage (Uref) and the triangular carrier.
under different conditions. The model quality is tested on a laboratory prototype and the simulation results are verified.
2. THE ACrrVE RECTIFIER The active rectifier contents a direct connection of a transistor and a diode. The management principle is produced by PWM inverter, with some modification, necessary for rectifier's work. It's convenient to use transfer function in a matrix form, by purpose of PWM rectifier management, and it's called switching function matrix.
The principle of gaining the auxiliary switching functions is presented on the Figure 1. The voltage value, at the rectifier's output is found like:
u)at) =[Pl} !fua(at)] = .., ~
Depending on selected methods, there're switching functions of the switch, switching functions of the branches, which are used here:
=[PJ]. Ifu..14
T
Uoc1. U.J
(3)
40'
where: h is a number of the harmonic; [uac{wt)J is the input voltage matrix of the h-th harmonic. PTi 4 switching function of the i-th branch PTi = 1 4 meaning the first transistor is leading PTi = -1 4 meaning the second transistor IS leading PTi =0 4 meaning none of them are leading The switching functions are generated by the auxiliary switching functions, which are outgoing signals of the PWM generator.
M ·IUre! 1 > Unos
I
M ·IUre! < Unos
~ P =1
The PWM rectifier frequency is determined by the carrier signal frequency and it's limited by the switching components work speed. The management variable of the PWM rectifier, which defines the outgoing voltage amplitude, is the amplitude modulating index, defined by:
U re!
M=-
(4)
Unos
(2)
~P=0
The modulating index is formed like a regulation circuits output, whose inputs are: instantaneous wanted charging current, as well as values of actual current and battery voltage. PI current controller is needed for a qualitative regulation, constructed by some of the well known methods, with addition offeed-forward compensators.
P is auxiliary switching function; M is the modulating index; Uref is referent voltage and Unos is carrier voltage.
It should be noted that obtaining the desired form of an outgoing current is based on the charging characteristics, time measuring battery voltage and temperature. 3. CONTROL ALGORITHM The control algorithm is presented by software application, through main program, several subprograms and three interrupt routines.
3.1 Control Algorithm ofthe Main Program 0455
046
0465
047
0475
048
0485
This algorithm is presented on the Figure 2. In the main program, the variables are initialized and work of peripheral units of the equipment is defined.
Figure 1. The principle of gaining the auxiliary switching functions
218
Main Program
Initialization of variables and SFR
In the main program, all the interrupts are enabled, the timer TIMER2 is started as auto-reload timer, and comparison is done. As a matter of fact, in this part, the tester begins to work. The main loop is a jump to the line with a label INTPROV, by which, interrupt is waited. Also, messages are written on the display. Auxiliary switching functions are generated by the rnicrocontroller uC80535 by the peripheral unit, which contents the timer T2 and several registers, with a special usage, adapted for PWM signals generating. 3.2 Control algorithm ofthe network interrupt
Call on subroutine for work with LCD display
The network interrupt INT_FA is generated at the moment of the input altemating voltage, passing through zero, by ascending order. The blockdiagram of the network interrupt is presented in the Figure 3. The network interrupt synchronizes the referent signal of the network voltage at the moment of its forming. The regulation of the outgoing magnitudes is done according to their measured values (by the peripheral unit of the In this paperwork, for the microcontroller). regulation aims, position PI controller in the current loop is applied, and also incremental PI controller in the voltage loop is put. As a controller output, the modulating index is gained, by the comparison of the moment current and voltage values Uref and Iref, and measured values Iiz and Uiz, by the controller (by AID converter.)
Inputting the work parameters
Main loop
Figure 2. Block-diagram of the main program algorithm
The control rule is given by: Also, the main program leads the user through the procedure of inputting charging parameters, writing of messages on the display, as well as receiving information from the tester, until the charging process is started. During the process, main program informs the user about the given and instantaneous values of the voltage, current and charging time.
where u(k) is management magnitude, Iiz is measured current magnitude, ki e the constant of proportional influence, and TlTi = 24 is a constant of integral influence. The regulation loop of the charging current Iiz is presented by the Figure 4, where: D(z) is a digital controller; Gobj(z) is the transfer function of the continual system part; Iref(k) is a given value of the regulated magnitude at kTmoment; Iiz(k) is the moment value of the regulated value at kT moment; e(k) is an error signal; u(k) is the management magnitude value at kT moment; T is selecting period.The management rule, applied in the regulation part of the control software for the active rectifier is given by:
In the main loop of the program, instantaneous values of the current (Iiz) and the voltage (Uiz) at the rectifier output, also the passed charging time are tested, and after that the program is executed. The main loop contains several parts: • writing of instantaneous current, voltage and battery charging time values; • testing the active push button condition; • sending messages about the computer loading process, using direct communication; • informing the user about the situation, and after that, entering the procedure of restarting or shutting down.
T
U(Ic) =U(Ic_I)
+K; .(-Iu(lc) + [;z(Ic-I) +( TJ-e(Ic)) (6) I
219
Network interrupt INf_FA 101....,.."1"'-1)
. . . . -..
.....-pc:riocI
. . . . . . hDlIltpreYiaa
RESET
ell)
= 1~(l) -110(0)
Testers
Regulated MagnitUdes Measuring
T P = K , .(-I",t, + l.t _lI +tI(lI'-)
INITIALIZAnON of the TABSTN index
1;
REGULATION U 1._ I )
+- ufO)
1"(0_1)
+- I"'(OJ
Reading from TABP and writing into CCR Fig. 5. Algorithmic block diagram of regulatory control The interrupt signals are generated by the peripheral unit, which contains the timer n, and also several registers: CC (compare-capture) and CRC (compare-reload-capture). The CRC register determines the PWM signal frequency. In the CC register, the referent signal value is written and its determined by some parts of the software.
TESTERS RESTARTING
PREPARATION for the 1Interrupt testers
3.3 The control algorithm ofthe testers interrupt
The testers interrupt is generated by the timer T2, after passing of the carrier signal period (testers). Block-diagram of this algorithm is presented by Figure 6.
Fig. 3. Tester interrupt block-diagram
In this part of the program, writing of accepted values is done in the POMH/L register in CCH/L. The table TABSIN index, INDEKSa is increased by one, until 41, and after that it is taken back to zero, and values of the table are read and are prepared for writing into the CCH/L registers, in the next INT- n routine. By this, the program deletion is minimized.
e(k) ~~ ~ '{~ .···~uw::
Fig. 4. Block diagram ofthe digital regulatory loop The block-diagram of the regulatory control part is presented on the Figure 5.
The third interrupt is serial communication interrupt (SER_COM). Its task is to enable
220
4. RESULTS
communication between the computer, switched to the equipment, for accepting the data. In this routine, the data, which had arrived to the controller serial port , is written into the registers and it's processed during the main program and previous interrupt routines.
This charger is manufactured at A.D. EMO-Ohrid, DOOEL "Automation and electronics" in Skopje, R. Macedonia. The results justify the selection of the PWM rectifier as a battery charger. As an experimental result, the configuration of full equipment is presented by the Figure 7. The synchronization circuit is linked to the microcontroller, on which the display and commands are linked, for the communication to the user. The microcontroller is also linked to the decoder, for decoding the signals, the decoder is linked to the drivers, which carry the P signals to the PWM rectifier's input. The microcontroller is linked to the current and voltage sensors, too.
Interrupt tester
INT_T2
Writing the additive registers into the CCH/L
The battery is charged by constant current, until the battery voltage reaches the value which is close to the nominal loading voltage value. Then, there is a charging by constant voltage. The Figure 8 below shows the charging characteristic.
Increasing the INDEKSa index by one
Preparation for the next interrupt TESTER
C
RETI
This figure, which is an experimentally verified result, is a rather successful outcome. It justified all the design requirements, and shows the best battery charging performances so far achieved.
~
Fig. 6. Testers interrupt block-diagram
R
N
R
N
PWM RECTIFIER NO
Protectio
CURRENT
___~~~~Sl~ __ I---_....J
l.----------------------i
VOLTAGE 1 - - - - - - - - ' L:S:::EN~SO~RJ_--------'
~r------....,h
~-i
SUPPLY
r
Figure 7. The overall battery charger design
221
(AI
M
Id
10
120
l 75
Ua
(ESM). It finds application in electricity supply substations within power distribution networks.
110
~
100
Acknowledgement. Authors would like to thank Prof. G. M. Dimirovski for his constructive advice in the course of the project and in writing up this paper.
90
5
80
70 60
25
50
0
0
01
0.2
(h)
0.3
04
05
REFERENCES Figure 8. The battery charging characteristic
Bose, B. K., Microcomputer Control of Power Electronics and Drivers, IEEE press, New York, 1987. Depenbrock, M., D. A. Marshall, J. D. Van Wyk (1994), "Formulating Requirements for a Universally Applicable Power Theory as Control Algorithm in Power Compensators". ETEP, vol. 4, n. 6, pp. 445-456. D'Hondt M. (2002), "Making software knowledgeable", IEEE 24th International Conference on Software Engineering, 19-25 May 2002, Orlando, FL, USA, pp. 735-741. Katic, V., V. D. Vasic, Graovac (1995), "The Methods of Electrical Energy Converters Mode1ing", Monograph Contemporary Problems in Power Engineering, Edited by D. Gvozdenac, 1. Xypteras, M. Dimic, Faculty of Technical Sciences / School of Technology, Novi Sad (Yugoslavia) / Thessaloniki (Greece), pp.169-179. Katic, V., U. Rechkoska, S. Grabich, Z. Mladenoski, M. Kostic (2000), "Aktiven ispravuvac so faktor na moknost edinica i eliminiranje na harmoniskata zagadenost," R&D research project for technological development. Ministry of Science, Rep. of Macedonia, No. 09-2906/1, July. Kwon, B. and Min B. (1993), "A fully softwarecontrolled PWM rectifier", IEEE Transactions on Industry Applications, Vol. 40, Issue 3, June, pp. 355-363. Rechkoska, U., E. Lazarevska, V. Katic, S. Grabic (2002), "Softwerski Algoritam Aktivnog ispravljacha", In: HEPP 2002 - 2nd International Symposium, Electrotechnical Society Zagreb and Generation Division HPP Department, Croatia, Sibenik, 3-4 June: pp. 142-148. Software Support/DeveIopment Tools for the SAB-51 Family, Siemens Components, Inc.
5. CONCLUSION The proposed solution for the battery charger, as a PWM rectifier, keeps good characteristics of a standard solution, from the charging characteristics point of view, enables harmonic minimization by simple capacitive filter. Also, it's characterized by the power factor almost equal to one.The management concept and the control algorithm are chosen and created correctly and effectively, which is proved by the results. Another advantage, beside the ones mentioned previously, is that the microprocessor management enables inflected and open realization access. More charging processes are possible to program, adapted to different types of batteries, different indications and checking, battery condition monitoring, etc. Comparing the harmonic values after filtering, to the IEC J000-3-2 standard, it c~ be concluded that rectifier's work satisfies the standard and by future algorithm and PWM techniques improvement, the spectrum can be improved and the filter's price can be reduced. An innovation, and also advantage, of this type of rectifier EMOSTAT-BAT-RTDZ which works on the PWM principle, comparing to the classic ones is ~ fact that it works on high switching frequency: whIch enables filtering the harmonics by LC filters. By filtering the network current harmonics it's shape becomes almost sinusoidal, and th~ power factor is almost one. This fact makes this type of rectifier most suitable for application. This type of battery charger, as PWM rectifier, with power factor equal to one, as a prototype of full equipment including the microcontroller card for the energetic converter and original control and management software, is manufactured for the Electricity Power Company ofthe R. Macedonia
222