Quasi Cascaded H-Bridge Five-Level Boost Inverter

ABSTRACT

Latterly, multilevel inverters have become more attractive for researchers due to low total harmonic distortion (THD) in the output voltage and low electromagnetic interference (EMI). This paper proposes a novel single-stage quasi-cascaded H-bridge five-level boost inverter (qCHB-FLBI). The proposed five-level inverter has the advantages over the cascaded H-bridge quasi-Z-source inverter (CHB-qZSI) in cutting down passive components. Consequently, size, cost, and weight of the proposed inverter are reduced. Additionally, the proposed qCHB-FLBI can work in the shoot-though state. A capacitor with low voltage rating is added to the proposed topology to remove an offset voltage of the output AC voltage when the input voltages of two modules are unbalanced. Besides, a simple PID controller is used to control the capacitor voltage of each module. This paper presents circuit analysis, the operating principles, and simulation results of the proposed qCHB-FLBI. A 1.2-Kva laboratory prototype was constructed based on a DSP TMS320F28335 to validate the operating principle of the proposed inverter.

INDEX TERMS

Cascaded H-bridge inverter, five-level inverter, quasi-Z-source inverter, boost inverter, shoot-through state

CONVENTIONAL DIAGRAM:

Fig. 1. Conventional CHB five-level inverters based on (a) DC-DC boost converter

EXPECTED SIMULATION RESULTS:

 

Fig. 2. Simulation results when Vdc1 = Vdc2 = 50 V. From top to bottom: (a) five-level output voltage, load and inductor currents, VC1, VC2, Vdc1 and Vdc2, (b) inductor currents, capacitor voltages, DC-link and diode Da1 voltages of module 1, DC-link and diode Da2 voltages of module 2, (c) harmonic spectrum of five-level output voltage, and (d) harmonic spectrum of load current

Fig. 3. Simulation results when Vdc1 = 50 V and Vdc2 = 60 V. From top to bottom: (a) five-level output voltage, load and inductor currents, VC1, VC2, Vdc1, Vdc2 and VCd, (b) five-level output voltage, inductor currents, capacitor voltages, DC-link and diode Da1 voltages of module 1, DC-link and diode Da2 voltages of module 2, (c) harmonic spectrum of five-level output voltage, and (d) harmonic spectrum of load current.

CONCLUSION

A New Single-Phase Single-Stage CHB Five-Level Inverter With Boost Voltage Ability Has Been Proposed In This Paper. The Proposed Inverter Has The Following Main Features As: Five-Level Output Voltage, Reduction In Number Of Passive Components And Shoot-Through Immunity. With The Simple PID Controller, A Constant Capacitor Voltage Can Be Achieved With An Excellent Transient Performance Which Enhances The Rejection Of Disturbance, Including The Input Voltage And Load Current Variations. Also, Circuit Analysis And PWM Control Strategy For The Proposed System Are Shown. Simulation And Experimental Results Are Shown To Verify The Validity Of The Proposed Qchb-FLBI.

REFERENCES

[1] S. Kouro, M. Malinowski, K. Gopakumar, J. Pou, L. G. Franquelo, B. Wu, J. Rodriguez, M. A. Pérez, and J. I. Leon, “Recent advances and industrial applications of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8, pp. 2553– 2580, Aug. 2010.

[2] M. Malinowski, K. Gopakumar, J. Rodriguez, and M. A. Pérez, “A survey on cascaded multilevel inverters,” IEEE Trans. Ind. Electron., vol. 57, no. 7, pp. 2197– 2206, July 2010.

[3] G. Farivar, B. Hredzak, and V. G. Agelidis, “A DC-side sensorless cascaded H-bridge multilevel converter-based photovoltaic system,” IEEE Trans. Ind. Electron., vol. 63, no. 7, pp. 4233–4241, July 2016.

[4] J. Chavarría, D. Biel, F. Guinjoan, C. Meza, and J. J. Negroni, “Energy-balance control of PV cascaded multilevel grid-connected inverters under level-shifted and phase-shifted PWMs,” IEEE Trans. Ind. Electron., vol. 60, no. 1, pp. 98–111, Jan. 2013.

[5] M. Coppola, F. D. Napoli, P. Guerriero, D. Iannuzzi, S. Daliento, and A. D. Pizzo, “An FPGA-based advanced control strategy of a grid-tied PV CHB inverter,” IEEE Trans. Power Electron, vol. 31, no. 1, pp. 806–816, Jan. 2016.

Quadratic boost converter with low-output voltage ripple

Abstract

This study proposes a non-isolated quadratic boost converter (QBC) that features a low-output-voltage ripple with respect to traditional QBCs. This advantage is in contrast with other topologies that require a higher amount of stored energy by capacitors to achieve the same output-voltage ripple specification. This benefit permits to design a compact converter, since the size of capacitors is proportional to their energy storage rating. Moreover, the proposed transformerless topology is suitable for applications that require high-voltage gains as in the case of renewable energy applications. The main properties of the converter are corroborated as well as its advantages by providing mathematical models, analytical waveforms and experiments.

Block Diagram:

 

Fig. 1  Traditional QBC

(a) Single switch QBC, quadratic boost converter [8–12], (b) Emerging QBC with

reduced energy stored, reduced energy-stored quadratic boost converter in [14, 15]

 

Expected Simulation Results:

Fig. 2  Experimental waveforms

(a) Currents through inductors and voltages across switches S1 and S2, (b) Output voltage and voltages across capacitors C1 and C2 with respect to the PWM signal, (c) Output voltage and voltages across capacitors C1 and C2 in AC mode, with respect to the PWM signal of switch with Vg = 90 V and D = 0.4

Fig. 3  Experimental waveforms

(a) Currents through inductors and voltages across switches S1 and S2, (b) Output voltage and voltages across capacitors C1 and C2 with respect to the PWM signal, (c) Output voltage and voltages across capacitors C1 and C2 in AC mode, with respect to the PWM signal of switch with Vg = 62 V and D = 0.5

 

Fig. 4  Experimental waveforms

(a)     Currents through inductors and voltages across switches S1 and S2, (b) Output voltage and voltages across capacitors C1 and C2 with respect to the PWM signal, (c) Output voltage and voltages across capacitors C1 and C2 in AC mode, with respect to the PWM signal of switch with Vg = 40 V and D = 0.6

Conclusions

 

In this paper, a novel quadratic dc–dc converter topology is presented. The main advantages of the proposed topology are: (i) the voltage gain is quadratic type, which enables the converter to work in a wide input voltage range within a reduced range of duty cycle. (ii) A voltage ripple cancelling technique can be applied to the output voltage, and then for the same energy stored in capacitors, the output-voltage ripple is smaller than existing topologies; this allows using smaller capacitors for the same voltage ripple specification. Several tests were performed over the full operation range, defined with a realistic example. Experimental results showed that the proposed converter produces a lower voltage ripple in the full operation range compared with traditional topologies. The previous propositions are demonstrated using analytical formulations and waveforms as well as by experimental results.

References

 

[1] Lessa Tofoli, F., de Castro Pereira, D., de Paula, W.J., et al.: ‘Survey on nonisolated high-voltage step-up dc–dc topologies based on the boost converter’, IET Power Electron, 2015, 8, (10), pp. 2044–2057

 

	[2] Erickson, R.W., Maksimovic, D.: ‘Fundamentals of power electronics’ (Springer, New York, USA, 2001, 2nd edn.) [3] Rosas-Caro, J.C., Ramirez, J.M., Peng, F.Z., et al.: ‘A DC–DC multilevel boost converter’, IET Power Electron, 2010, 3, (1), pp. 129–137 [4] Gandomkar, A., Parastar, A., Seok, J.: ‘High-power multilevel step-up DC/DC converter for offshore wind energy systems’, IEEE Trans. Ind. Electron., 2016, 63, (12), pp. 7574–7585 [5] Rosas-Caro, J.C., Mancilla-David, F., Mayo-Maldonado, J.C., et al.: ‘A                   transformerless high-gain boost converter with input current ripple cancelation at a selectable duty cycle’, IEEE Trans. Ind. Electron., 2013, 60, (10), pp. 4492–4499

 

Power Factor Improvement in Modified Bridgeless Landsman Converter Fed EV Battery Charger

Abstract

 This work deals with the design and implementation of a new charger for battery operated electric vehicle (BEV) with power factor improvement at the frontend. In the proposed configuration, the conventional diode converter at the source end of existing electric vehicle (EV) battery charger, is eliminated with modified Landsman power factor correction (PFC) converter. The PFC converter is cascaded to a flyback isolated converter, which yields the EV battery control to charge it, first in constant current mode then switching to constant voltage mode. The proposed PFC converter is controlled using single sensed entity to achieve the robust regulation of DC-link voltage as well as to ensure the unity power factor operation. The proposed topology offers improved power quality, low device stress, low input and output current ripple with low input current harmonics when compared to the conventional one. Moreover, to demonstrate the conformity of proposed charger to an IEC 61000-3-2 standard, a prototype is built and tested to charge a 48V EV battery of 100Ah capacity, under transients in input voltage. The performance of the charger is found satisfactory for all the cases.

Keywords

1.      Battery Operated Electric Vehicle

2.      Battery Charger

3.      Power Factor Improvement

4.      Modified Landsman Converter

5.      Power Quality

Conclusion

An improved EV charger with modified BL Landsman converter followed by a flyback converter has been proposed, analyzed, and validated in this work to charge an EV battery with inherent PF Correction. The design and control of the proposed EV charger in DCM mode have offered the advantage of reduced number of sensors at the output. Moreover, the proposed BL converter has reduced the input and output current ripples due to inductors both in input and output of the converter. A prototype has been developed and operation of the charger has been verified by the experimental results under steady state and sudden fluctuations in input voltage. The results from the hardware validation show that the performance of proposed charger is found satisfactory for improved power quality based charging of EV battery. Moreover, the input current THD is reduced as low as 4.3% to meet the recommended IEC 61000-3-2 standard guidelines for power quality. Therefore, proposed BL converter fed charger aims at cost effective, reliable and suitable option to replace the conventional lossy and inefficient EV battery charger

References

[1] Wencong Su, Habiballah Eichi, Wente Zeng and Mo-Yuen Chow, “A survey on the electrification of transportation in a smart grid environment,” IEEE Transactions Industrial Informatics, vol. 8, no. 1, pp. 1-10, Feb. 2012.

[2] Ching Chuen Chan, “The state of the art of electric, hybrid, and fuel cell vehicles,” Proc. IEEE, vol. 95, no. 4, pp. 704–718, Apr. 2007

[3] Kaushik Rajashekara, “Present status and future trends in electric vehicle propulsion technologies,” IEEE J. Emerg. Sel. Topics Power Electronics., vol. 1, no. 1, pp. 3–10, Mar. 2013.

[4] Juan C. Gomez and Medhat M. Morcos, “Impact of EV battery chargers on the power quality of distribution systems,” IEEE Transactions Power Del., vol. 18, no. 3, pp. 975–981, Jul. 2003.

[5] Luca Solero, “Nonconventional on-board charger for electric vehicle propulsion batteries,” IEEE Transactions Vehicular Technology, vol. 50, no. 1, pp. 144-149, Jan 2001

 

 

Off-board electric vehicle battery charger using PV array

ABSTRACT

During the recent decade, the automobile industry is booming with the evolution of electric vehicle (EV). Battery charging system plays a major role in the development of EVs. Charging of EV battery from the grid increases its load demand. This leads to propose a photovoltaic (PV) array-based off-board EV battery charging system in this study. Irrespective of solar irradiations, the EV battery is to be charged constantly which is achieved by employing a backup battery bank in addition to the PV array. Using the sepic converter and three-phase bidirectional DC–DC converter, the proposed system is capable of charging the EV battery during both sunshine hours and non-sunshine hours. During peak sunshine hours, the backup battery gets charged along with the EV battery and during non-sunshine hours, the backup battery supports the charging of EV battery. The proposed charging system is simulated using Simulink in the MATLAB software and an experimental prototype is fabricated and tested in the laboratory and the results are furnished in this study.

BLOCK DIAGRAM:

Fig. 1  Block diagram of the EV battery charger

 EXPECTED SIMULATION RESULTS:

Fig. 2  Waveforms of PV array irradiation and gate pulses to the auxiliary switches

Fig. 3  Waveforms of

(a) PV array voltage, VPV & PV array current, IPV, (b) DC link voltage, Vdc, & current, Idc, (c) EV battery SOC, EV battery current, IBatt & EV battery voltage, VBatt, (d) Backup battery SOC, backup battery current, IBackup Batt & backup battery voltage, VBackup Batt

CONCLUSION

 

In this paper, an off-board EV battery charging system fed from PV array is proposed. This paper discusses the flexibility of the system to charge the EV battery constantly irrespective of the irradiation conditions. The system is designed and simulated in Simulink environment of the MATLAB software. The hardware prototype is fabricated and tested in laboratory for the three modes of operation of the proposed charging system separately and the results are furnished. In OPAL-RT Real time simulator OP4500, experimental investigation is carried out in RCP methodology and the dynamic response of the system is furnished both in simulation and experimental investigation. Correlation between the simulation and experimental results emphasise the effectiveness of the proposed charger.

REFERENCES

[1] Santhosh, T.K., Govindaraju, C.: ‘Dual input dual output power converter with one-step-ahead control for hybrid electric vehicle applications’, IET Electr. Syst. Transp., 2017, 7, (3), pp. 190–200

[2] Shukla, A., Verma, K., Kumar, R.: ‘Voltage-dependent modelling of fast charging electric

vehicle load considering battery characteristics’, IET Electr. Syst. Transp., 2018, 8, (4), pp. 221–230

[3] Wirasingha, S.G., Emadi, A.: ‘Pihef: plug-in hybrid electric factor’, IEEE Trans. Veh. Technol., 2011, 60, pp. 1279–1284

[4] Kirthiga, S., Jothi Swaroopan, N.M.: ‘Highly reliable inverter topology with a novel soft computing technique to eliminate leakage current in grid-connected transformerless photovoltaic systems’, Comput. Electr. Eng., 2018, 68, pp. 192–203

 [5] Badawy, M.O., Sozer, Y.: ‘Power flow management of a grid tied PV-battery system for electric vehicles charging’, IEEE Trans. Ind. Appl., 2017, 53, pp. 1347–1357

Solar Optiverter – A Novel Hybrid Approach to the Photovoltaic Module Level Power Electronics

ABSTRACT

 In this paper the concept of an Optiverter is proposed as a novel class of photovoltaic (PV) module level power electronics systems. Functionally, the Optiverter is a hybrid technology that combines the ultrawide maximum power point tracking (MPPT) voltage window of the PV power optimizers with the direct AC connectivity and inherent safety of the PV microinverters. Thanks to the advanced multimode control with variable DC-link and the shade-tolerant MPPT algorithm, the proposed Optiverter ensures efficient energy harvest from the PV module in different shading scenarios. To justify the superiority of the concept, the performance of a 300 W prototype of the PV Optiverter was experimentally compared to that of the industrial microinverters in different operation conditions, including an extreme case with opaque shading of two out of three substrings of the PV module.

INDEX TERMS

1.      Photovoltaic systems

2.      Module-level power electronics

3.      Microinverter

4.      Power optimizer

5.      Maximum power point tracking

6.      Partial shading

7.      Efficiency

BLOCK DIAGRAM:

Fig. 1. Generalized schematics of MLPE based grid-connected PV systems: with PVPOs (a) and with PVMICs (b)

EXPECTED SIMULATION RESULTS:

Fig. 2. Voltage and current waveforms of the Optiverter operating with JinkoSolar JKM300M-60 PV module under uniform irradiance of 800 W/m2 and nominal cell temperature of 45 °C: input voltage and current (a), DC-link voltage and current (b), and grid voltage and current (c).

Fig. 3. Electromagnetic compatibility test results: conducted emission in the range of 0.15 MHz to 30 MHz (a) and radiated emission in the range of 30 MHz to 1000 MHz (b).

CONCLUSIONS

 The novel concept of the PV Optiverter with an ultra-wide input voltage range was proposed and justified as a shadetolerant solution for residential and small commercial PV installations, which is compatible with a wide variety of modern residential PV modules. It outperforms conventional microinverters under partial shading due to the implementation of the shade tolerant MPPT and can deliver power under severe opaque shading conditions, when the microinverters fail to capture any power due to their limited input voltage regulation range. Moreover, it is compatible with emerging high power PV modules due to increased power rating for avoiding the power clipping. These features result from the application of the galvanically isolated ultra-wide range buck-boost dc-dc converter and the novel control principle with the variable DC-link voltage that optimizes efficiency in the most probable input voltage operating range. This enables the shade tolerant MPPT through P-V curve scanning. Hence, the PV Optiverter can be used as a versatile solution for residential and small commercial PV installations. Using single stock keeping unit for different PV modules decreases installation and shipping costs as well as staff training expenses. The qZSSRC topology is not the only possible option to be used in the Optiverter and other DC-DC converter topologies with comparable performance could be applied. Also, Optiverter design for a wide input voltage range could impose limitations on the efficiency. However, improvements are possible at light load with cycle skipping modulation, and by use of reconfigurable rectifiers at high DC voltage gain.

REFERENCES

[1] S. Kouro, J. I. Leon, D. Vinnikov and L. G. Franquelo, "Grid-Connected Photovoltaic Systems: An Overview of Recent Research and Emerging PV Converter Technology," IEEE Ind. Electron. Mag., vol. 9, no. 1, pp. 47-61, March 2015.

[2] M. Kasper, D. Bortis and J. W. Kolar, "Classification and Comparative Evaluation of PV Panel-Integrated DC–DC Converter Concepts," IEEE Trans. Power Electronics, vol. 29, no. 5, pp. 2511-2526, May 2014.

[3] “SolarEdge Fixed String Voltage, Concept of Operation.” [Online]. Аvailable: https://www.solaredge.com [Accessed: 28-Jan-2018]

[4] E. Liivik, A. Chub, R. Kosenko and D. Vinnikov, "Low-cost photovoltaic microinverter with ultra-wide MPPT voltage range," in Proc. 6th Int. Conf. on Clean Elect. Power, Santa Margherita Ligure, Italy, 2017, pp. 46-52.

[5] J.K. Kaldellis, et al "Temperature and wind speed impact on the efficiency of PV installations. Experience obtained from outdoor measurements in Greece," Renewable Energy, vol. 66, pp. 612-624, June 2014.

Sliding Mode Control of Single-Phase Grid Connected Quasi-Z-Source Inverter

Abstract

Quasi-Z-source inverters (qZSI) are nowadays increasingly used owing to advantages like single stage operation, lower component rating, and continuous input current, and common DC rail. These benefits lead to investigate this converter for grid connected applications. This paper presents a grid connected quasi-Z-sourceinverter (qZSI) with both AC and DC side control. Sliding Mode Control (SMC) based controller for capacitor voltage regulation has been proposed to ensure a fast and dynamic response for wide variations in input voltage, output load, and reference controlled quantity. A detailed mathematical model of the system is presented. A stable and fast response of SMC has been demonstrated using simulation and is validated by experimental results.

Index Terms

1.      Quasi-Z-Source Inverter

2.      Sliding Mode Control (SMC)

3.      Grid connected system

Schematic Diagram:

Fig. 1. Proposed grid connected quasi-Z-Source Inverter with closed loop control.

Expected Simulation Results:

Fig. 2. Simulation results for step change in input voltage from 250V to 300V (a) Input voltage (b) Capacitor voltage.

Fig. 3. Simulation results for step change in capacitor reference voltage from 400V to 500V (a) Capacitor voltage (b) Grid voltage and current..

Fig. 4. Comparison of Simulation results for step change in capacitor reference voltage (a) PI Controller (b) SM Controller.

Fig. 5. Simulation results for step change in grid feed current from 0.5A to 1.5A (a) Capacitor voltage (b) Grid voltage and current.

 

Conclusion

In this paper, SMC is used for controlling the dynamic response of the grid connected qZSI system. The detailed mathematical analysis of the SMC is done. Various aspects of the controller, are discussed in the paper, which include the selection method of the sliding surface, and the existence condition. The simulation and experimental result shows that the capacitor voltage controller gives a very fast response to a step change in reference value. Also, the controller is stable and robust for wide variations in input and output. A comparison of the proposed controller, with the PI controller, also clearly, proves the superiority, of the SMC based controller, over the classical controller.

References

[1] F. Z. Peng, ‘‘Z-source inverter,’’ IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. 504-510, 2003. [2] P. C. Loh, D. M. Vilathgamuwa, Y. S. Lai, G. T. Chua, and Y. Li, ‘‘Pulse-width modulation of Z-source inverters,” IEEE Trans. Power Electron., vol. 20, no. 6, pp. 1346-1355, Nov. 2005. [3] M. S. Shen, J. Wang, A. Joseph, F. Z. Peng, L. M. Tolbert, D. J. Adams, “Constant Boost Control of the Z-Source Inverter to Minimize Current Ripple and Voltage Stress,” IEEE Trans. on Ind. Appl., vol. 42, no. 3, pp. 770-778, 2006.

[4] V. P. Galigekere, M. K. Kazimierczuk, “Analysis of PWM Z-source DC-DC converter in CCM for steady state,” IEEE Trans. Circuits Syst. I, vol. 59, no. 4, pp. 854–863, Apr. 2012.

[5] R. Badin, Y. Huang, F. Z. Peng, H. G. Kim, “Grid Interconnected ZSource PV System,” in Proc. IEEE PESC 2007, Orlando, FL, pp. 2328-2333, 2007.

A Novel Variable DC-Link Voltage Control Method for PMSM Driven by Quasi-Z-Source Inverter

Abstract

Variable dc-link voltage control methods can effectively improve the operation efficiency of the permanent magnet synchronous motor (PMSM) drive system. At present, the reported variable dc-link voltage control methods applied in the PMSM driven by quasi-Z-source inverter (qZSI) are limited to analytical calculation methods (ACMs) based on system model. The ACMs demand measurement of qZSI’s input voltage and usually need a larger margin index due to the inaccurate model to calculate the reference dc-link voltage. To overcome the restriction, this paper proposes a novel variable dc-link voltage control method which can indirectly adjust dc-link voltage with an extra PI-regulator. Basic principle of the method is introduced and two design rules of the PI-regulator are illustrated. Besides, necessary conditions which need to be met when obtaining the feedback signal of the PI-regulator are analyzed. Finally, experiments are performed to validate the feasibility and effectiveness of the proposed method. In comparison with the ACMs, the proposed method gets rid of the dependence on an extra voltage sensor to measure the input voltage and can reserve less margin for the dc-link voltage, which contributes to less cost and higher efficiency of the drive system. Besides, the proposed method is easy and convenient to apply.

Index Terms

1.      Permanent magnet synchronous motor (PMSM)

2.      Quasi-Z-source inverter (qZSI)

3.      Variable dc-link voltage control

4.      Analytical calculation method (ACM)

Schematic Diagram:

Fig. 1 Schematic diagram of ACM-based variable dc-link voltage control

Expected Simulation Results:

Fig. 2 Waveforms of on-load speed variation experiment with MDVR adopted under (a) slope speed command (b) step speed command.

 

Fig. 3 Waveforms of torque variation experiment with MDVR adopted under constant speed.

Fig. 4 Waveforms of regeneration braking experiment with MDVR adopted.

Conclusion

 

To avoid the existing problems of the ACM-based variable dc-link voltage control method in qZSI-PMSM drive system, this paper proposes an MDVR-based variable dc-link voltage control method. The novel method can indirectly adjust the dc-link voltage to its minimum which can exactly meet the PMSM’s operation demand by using an extra PI-regulator to control the minimum duty cycle of zero vector in one output electrical cycle to be a small constant. In this paper, basic operation principle of the proposed method is introduced firstly and then two design rules of the PI-regulator are illustrated with examples. Further, some conditions that need to be met when obtaining the minimum duty cycle of zero vector are also analyzed. Finally, experiments are performed to validate the feasibility and effectiveness of the proposed method. The advantages of the proposed method can be concluded as follow.

(1) It gets rid of the dependence on input voltage and thus does not need an extra voltage sensor;

(2) It does not rely on drive system’s inaccurate model and thus can reserve less margin for the dc-link voltage, which contributes to higher system efficiency;

(3) It is simple and easy to apply.

References

 

[1] W. Deng, C. Xia, Y. Yan, Q. Geng, and T. Shi, “Online multi-parameter identification of surface-mounted PMSM considering inverter disturbance voltage,” IEEE Trans. Energy Convers., vol. 32, no. 1, pp. 202–212, Mar. 2017.

[2] Z. Zhou, C. Xia, Y. Yan, Z. Wang, and T. Shi, “Disturbances attenuation of permanent magnet synchronous motor drives using cascaded predictive-integral-resonant controllers,” IEEE Trans. Power Electron., vol. 33, no. 2, pp. 1514–1527, Feb. 2018.

[3] S. Tenner, S. Gunther, and W. Hofmann, “Loss minimization of electric drive systems using a dc/dc converter and an optimized battery voltage in automotive applications,” in Proc. IEEE VPPC, 2011, pp. 1-7.

[4] S. Tenner, S. Gunther, and W. Hofmann, “Loss minimization of electric drive systems using a Z-source inverter in automotive applications,” in Proc. EPE’13-ECCE Europe, 2013, pp. 1-8.

[5] W. Deng, Y. Zhao, and J. Wu, “Energy efficiency improvement via bus voltage control of inverter for electric vehicles,” IEEE Trans. Veh. Technol., vol. 66, no. 2, pp. 1063-1073, Feb. 2017.