Investigating Converter Options for Automotive Grade Permanent Magnet Sychronous Generators

Transcription

1 Investigating Converter Options for Automotive Grae Permanent Magnet Sychronous Generators Erkan MESE *, Yusuf YAŞA *, Hakan AKÇA *, Mustafa G. AYDENIZ *, Murat AYAZ **, Murat TEZCAN * ( * )Yiliz Technical University, Electrical Engineering Department ( ** )Kocaeli University, Technical Eucation Faculty emese@yiliz.eu.tr, yasa@yiliz.eu.tr, hakca@yiliz.eu.tr, ayeniz@yiliz.eu.tr, murat.ayaz@kocaeli.eu.tr, mutezcan@yiliz.eu.tr Abstract In this paper, converter options for an automotive class permanent magnet synchronous generator (PMSG) are investigate. There are two options to rectify an regulate voltage from AC to DC. These are uncontrolle rectifier/cc converter an controlle rectifier. Each converter topologies are explaine an their comparison is performe. The comparison consiers generator apparent power, efficiency, power flow a cost. As far as converter effects on the generator apparent power rating an system efficiency are concerne, uncontrolle rectifier/cc converter seems to be superior. On the other han, controlle rectifier option has cost avantage over uncontrolle rectifier/cc converter topology. A traeoff exists between converter cost an PMSG utilization while making ecision between two topologies. Keywors Permanent magnet synchronous generator, hybri electric vehicle, uncontrolle rectifier, cc converter, controle rectifier. I. INTRODUCTION Electrical accessories in a conventional vehicle are supplie by a Lunell alternator an battery combination. In hybri electric vehicles (HEV), converter is use for the same purpose [1]. Another cost effective solution for HEVs so calle electric accessory rive system (EADS) has single electric motor an this motor rives all accessory loas through a belt [2]. A separate Lunell alternator is riven by EADS motor. Furthermore, another propose solution is permanent magnet ualwining electric machine as EADS prime mover which consists of motor an generator parts. Winings of the machine are concentrate. Motor an generator winings are electrically an magnetically isolate [3]. When the traction motors of the vehicle shut own, the motor part of the ualwining electric machine runs an rives mechanical accessory loas. Generator part in the machine runs an provies electric power to electrical accessories. With this technique, both motoring an generating operations can be implemente in a single housing of electric machine. The system offers packaging avantages for HEVs. Above iscussion inicates that, both conventional vehicles an some HEVs are using an alternator for lowvoltage electric power generation. Lunell alternators in these applications are suffering from problems such as power an packaging limitations [4]. One solution is to replace Lunell alternator with PMSG. Automotive is not the only area where PMSG is consiere. Other prospective areas have been seen in the horizon such as aviation, efense, marine, renewable energy an etc. This paper iscusses PMSG operation for automotive applications where generator operation occurs over much wier spee range because of the spee range of the vehicle s crankshaft. In this stuy generator spee is boune between 1500 rpm an 6000 rpm. This suggests that AC to DC conversion shoul take place in the face of very wie range of AC input voltage. II. GENERATOR SIDE CONVERTER OPTIONS Two AC to DC conversion options are investigate as shown in Fig 1. In the first option, an uncontrolle rectifier an a buck type DC to DC converter is stuie. In the secon option, a controlle rectifier is stuie. For both options, simulation an experimental results will be given in the following sections. Impacts on PMSG as well as cost breakown of two converters will be iscusse. D2 D4 D6 VUO8016NO1 1 2 D1 D3 D5 DWPMSM Generator Winings 220UF 450V DC L1 50UH Q1 IXFK48N50 D7 RHRG75N60 C UF 50V DC 3 Phase Uncontrolle Rectifier Buck Type DCDC Chopper Loa TR1 TR3 TR5 TR2 TR4 TR6 MCC7212IO1B 3300UF 350V DC 3 Phase Controlle Rectifier Loa Figure 1. Voltage regulation options of PMSG.

2 A. Uncontrolle Rectifier/ DCDC Converter Output of the generator is connecte to the uncontrolle rectifier as shown in Fig 2. Average DC output of an uncontrolle rectifier is given as in (1). D1 D3 D5 220UF 450V DC L1 50UH Q1 IXFK48N50 D7 RHRG75N60 C UF 50V DC D2 D4 D6 VUO8016NO1 3 Phase Uncontrolle Rectifier Buck Type DCDC Chopper Loa Figure 2. Schematic of uncontrolle rectifier an cc converter. Figure 3. (a) Generator voltage waveforms /6 1 3 /6 3 ll max cos( ) ll max sin( ) /6 ll (max) /3 /6 V V t t V t V (1) Where, V ll is linetoline voltage of the generator. V is the mean output voltage value of the uncontrolle rectifier. Three phase uncontrolle rectifier is connecte to a bucktype cc converter. Buck converter equations are; Ts 1/ fs (2) Ts Ton Toff (3) Ton Ts (4) T (1 ) T (5) off s Where f s an T s is the switching frequency an perio of the converter, respectively. On an off urations of switches are represente with T on an T off. is uty cycle. Following expressions show the output voltage (V out ) an current (i out ) of a buck converter. V V (6) out 1 Iout I (7) Simulation an Experimental Results Couple simulation has been performe for uncontrolle rectifier/dcdc converter options. Couple simulation is a new simulation technique which uses finite element (FE) analysis that provies more reliable results compare to others. Uncontrolle rectifier an cc converter moels are built in AnsoftSimplorer an then couple to PMSG which runs as AnsoftMaxwell FE moel. In simulation, PMSG is rotate at 2500 rpm. The simulation an experimental results of generator voltages an currents are given in Fig 3. Figure 3. (b) Generator current waveforms B. Controlle Rectifier PMSG is connecte to a controlle rectifier. The c output voltage is controlle with ajusting SCRs trigger angle. The schematic can be seen in Fig 4. Mean value of the output voltage of the controlle rectifier is given in (8). Vlmax is peak linetoline PMSG voltage. α is trigger angle of SCRs. /6 1 3 /6 l max cos( ) l max sin( ) /6 /3 /6 V V t t V t V Vl cos Vph cos 2.34V ph cos TR1 TR3 TR5 TR2 TR4 TR6 MCC7212IO1B 3300UF 350V DC 3 Phase Controlle Rectifier Loa Figure 4. The circuit scheme of controlle rectifier. Simulation an Experimental Results (8) Controlle rectifier simulation is performe with couple simulation technique. Simulation results for generator voltage an current can be seen in Fig 5. Experimental results are given in Fig 6.

3 Vas, Vbs, Vcs [V] Ias, Ibs, Ics [A] Vc [V] Ic [A] Current (A) Voltage (V) Generator Voltages Curve Info InuceVoltage(PhaseGA) InuceVoltage(PhaseGB) InuceVoltage(PhaseGC) (a) Generator Currents Time (s) x Figure 6 (a) Generator voltages Curve Info Current(PhaseGA) Current(PhaseGB) Current(PhaseGC) (b) Vc (c) Ic () Figure 5. (a) Generator voltages, (b) generator currents, (c) c output voltage an () c output current Time (s) Figure 6 (b) Generator currents III. COMPARATIVE STUDY So far, some simulation an experimental results relate to the controlle rectifier an cc converter are given. In this section, comparative analysis of two converter options is performe. These two options are compare with each other cost an electrical performance. A. Cost Analysis In cost stuy, it is assume that the circuits will be prouce in quantities of Cost stuy results are given in TableI an TableII for cc converter an controlle rectifier, respectively. The power capacity of each converter is assume to be 3 kw which correspons to generator output power capacity. TABLE I. DCDC CONVERTER COST ANALYSIS DCDC Converter No Item Number Prouct Name Qty 1 IXFN140N30P 2 VUO11016N07 3 TLP250 4 DCW08B uF/250V 6 1.5uf/1000V Power MOSFET Three Phase Rectifier Brige TOSHIBA Photocoupler Converters 8W Input an output Snubber Price Item Subtotal 3 23,8 71,4 1 51,9 51,9 1 0,87 0, V 200 A Output inuctor Total 220,17

4 DCDC converter prouction cost is aroun 220 $/per converter an controlle rectifier is aroun 163 $/per converter. TABLE II. CONTROLLED RECTIFIER COST ANALYSIS Controlle Rectifier No Item Number Prouct Name Qty 1 MCC7212IO1B 2 TLP250 3 DCW08B15 4 DCW03B uF/250V Thyristor/Dioe Moules TOSHIBA Photocoupler Converters 8W Converters 2W Output Price Item Subtotal 3 36,28 108,8 6 0,87 5, Total 163,02 Figure 7. Generator efficiency comparison for two converters Input capacitance an output inuctance of cc converter are the major causes of this ifference. Controlle rectifier oes not require input inuctance because it uses generator inuctance. So it gives cost avantage to the controlle rectifier. B. Effects on Generator Performance In this section, effects of the converters on generator performance are analyze. In analysis; the effects of using each option on generator, converter an system efficiency are one. In aition to that, torque ripple an voltage/current harmonic analysis are also performe. The effects of each converter on generator, converter an system efficiency for ifferent power levels can be seen in Table III an Table IV. Fig 6 shows that uncontrolle rectifier/cc converter topology an controlle rectifier topologies have aroun same converter efficiency. Figure 6. Experimental efficiency comparison between uncontrolle rectifier/cc converter an controlle rectifier Figure 8. Generator efficiency comparison for two converters The variation of generator efficiency by using ifferent topologies is given in Fig 7. In low power levels, generator efficiency levels are comparable for both converters. However with increasing power, efficiency of generator using c/c converter topology becomes better than the one with controlle rectifier. The reason is that, effective value of the current in controlle rectifier is much more than c/c converter topology because of high reactive current. Finally, the system efficiency, which combines generator an converter efficiency, can be mentione: PMSG with uncontrolle rectifier/cc converter has much higher efficiency than PMSG with controlle rectifier has. Harmonic analysis of generator phase voltage an current is performe with Fast Fourier transform (FFT) technique to see the effects of each converter on generator. Fig 9 an Fig 10 show waveforms for cc converter option an controlle rectifier option, respectively.

5 Figure 9. Experimental generator phase current (left) an voltage (right) when uncontrolle rectifier/cc converter is use. Figure 10. Experimental generator phase current (left) an voltage (right) when controlle rectifier is use. TABLE III. EXPERIMENTAL FFT RESULTS OF UNCONTROLLED RECTIFIER/DCDC CONVERTER Harmonic 5 th 7 th 11 th 13 th cosø Magnitue Current 11.52% 7.25% 0.99% 1.36% 0.92 Voltage 15.38% 13.49% 4.1% 5.35% Phase ( o ) Current Voltage TABLE IV. EXPERIMENTAL FFT RESULTS OF CONTROLLED RECTIFIER Harmonic 5 th 7 th 11 th 13 th cosø Magnitue Current 4.17% 3.39% 1.57% 1.57% 0.73 Voltage 39.5% 45.5% 30.55% 37.84% Phase( o ) Current Voltage FFT results emonstrate that both converters have common harmonics on voltages an currents which are 5 th, 7 th, 11 th an 13 th harmonics. This suggests that extra power flow woul occur ue to harmonics. Whether this is active or reactive power epens on the phase shift between associate voltage an current harmonic components. From the phase shift ata, in the uncontrolle rectifier/ DCDC converter case harmonics seem to be contributing to both active an reactive power flow. Whereas in the controlle rectifier case, harmonics are mainly contributing to reactive power flow. Current harmonic ata shows that RMS current in the controlle rectifier case is higher than its counterpart. These observations imply that PMSG with controlle rectifier has to supply higher apparent power than PMSG with uncontrolle rectifier an DCDC converter option. IV. CONCLUSION In this paper, converter options of a PMSG have been investigate. There are two options to convert an regulate voltage from ac to c which are uncontrolle rectifier/cc converter an controlle rectifier. Each converter topologies are explaine an their comparison is performe. Cost an performance are two metrics for comparison. As far as the cost is concerne, controlle rectifier has avantage on uncontrolle rectifier/cc converter topology. However, for electrical performance such as efficiency an apparent power rating, uncontrolle rectifier/cc converter is superior. ACKNOWLEDGMENT The work has been supporte uner the grant number 110E111 by the Scientific an Technological Research Council of TURKEY (TUBITAK) REFERENCES [1] N.R. Trevett, XbyWire_New Technologies for 42V Bus Automobile of Future, Msc. Thesis, The South Carolina Honors College, [2] R.K. Serrels, Accesory Drive System, US Patent Application, Patent Number , [3] E. Mese, Y. Yasa, H. Akca, M.G. Ayeniz, M. Garip, A New Electric Accessory Drive System for Hybri Electric Vehicles, ECCE 2012 IEEE Energy Conversion Congress&Exposition, pp , September 1520, 2012, Raleigh, NC, USA. [4] D.J. Perreault an V. Caliskan, Automotive Power Generation an Control IEEE Transactions on Power Electronics, vol. 19, no. 3, pp , May 2004.