Grid-Connected Emergency Back-Up Power Supply
- 1 Department of Electrical Engineering, University of South Carolina, Columbia, SC, USA
- 2 Department of Electrical and Electronics Engineering, Daffodil International University, Dhaka, Bangladesh
- 3 Department of Electrical and Electronics Engineering, Daffodil International University, Dhaka, Bangladesh
Abstract
This paper documents design and modeling of a grid-connected emergency back-up power supply for medium power applications. Back-up power supplies are very important in regard to support electrical loads in the events of grid power outage. However, grid-integration of a back-up power supply substantiates continual power transfer to the loads, especially to the critical loads, which should not suffer from power interruptions. Therefore, design and circuit modeling of switching converters based reliable grid-tied emergency back-up power supply are presented in this paper. There are a rectifier-link boost derived battery charging circuit and a 4-switch push-pull power inverter circuit which are controlled by high frequency pulse width modulation (PWM) signals. This paper presents a state averaging model and Laplace domain transfer function of the charging circuit and a switching converter model of the power inverter circuit. A changeover relay based transfer switch controls the power flow towards the utility loads. During off-grid situations, loads are fed power by the proposed inverter circuit and during on-grid situations, battery is charged by an ac-link rectifier-fed boost converter. However, there is a relay switching circuit to control the charging phenomenon of the battery. The proposed design is simulated in PLECS and the simulation results corroborate the reliability of the presented framework.
- [1] Choi, J. and Kang, F. (2015) Seven-Level PWM Inverter Employing Series-Connected Capacitors Paralleled to a Single DC Voltage Source. IEEE Transactions on Industrial Electronics, 62, 3448-3459.
- Botterón, F., Carballo, R.E., Núñez, R.O., Quintana, A.P. and Fernández, G.A. (2013) High Reliability and Performance PWM Inverter for Standalone Microgrids. IEEE Latin America Transactions, 11, 505-511. https://doi.org/10.1109/TLA.2013.6502853
- Pan, C., Lai, C. and Juan, Y. (2010) Output Current Ripple-Free PWM Inverters. IEEE Transactions on Circuits and Systems II: Express Briefs, 57, 823-827. https://doi.org/10.1109/TCSII.2010.2058596
- Mezaroba, M., Martins, D.C. and Barbi, I. (2007) A ZVS PWM Half-Bridge Voltage Source Inverter with Active Clamping. IEEE Transactions on Industrial Electronics, 54, 2665-2672. https://doi.org/10.1109/TIE.2007.901361
- Chen, D., Qiu, Y., Chen, Y. and He, Y. (2017) Nonlinear PWM-Controlled Single-Phase Boost Mode Grid-Connected Photovoltaic Inverter with Limited Storage Inductance Current. IEEE Transactions on Power Electronics, 32, 2717-2727. https://doi.org/10.1109/TPEL.2016.2571725
- Kim, Y., Shin, S., Lee, J., Jung, Y. and Won, C. (2014) Soft-Switching Current-Fed Push-Pull Converter for 250-W AC Module Applications. IEEE Transactions on Power Electronics, 29, 863-872. https://doi.org/10.1109/TPEL.2013.2258942
- Reznikov, B., Srndovic, M., Familiant, Y.L., Grandi, G. and Ruderman, A. (2016) Simple Time Averaging Current Quality Evaluation of a Single-Phase Multilevel PWM Inverter. IEEE Transactions on Industrial Electronics, 63, 3605-3615. https://doi.org/10.1109/TIE.2016.2541078
- Lee, J., Kwak, R. and Lee, K. (2018) Novel Discontinuous PWM Method for a Single-Phase Three-Level Neutral Point Clamped Inverter with Efficiency Improvement and Harmonic Reduction. IEEE Transactions on Power Electronics, 33, 9253-9266. https://doi.org/10.1109/TPEL.2018.2794547
- Ye, Y., Xu, G., Wu, Y. and Zhao, Q. (2018) Optimized Switching Repetitive Control of CVCF PWM Inverters. IEEE Transactions on Power Electronics, 33, 6238-6247. https://doi.org/10.1109/TPEL.2017.2740565
- Chauprade, R. (1977) Inverters for Uninterruptible Power Supplies. IEEE Transactions on Industry Applications, IA-13, 281-297. https://doi.org/10.1109/TIA.1977.4503410
- Rymarski, Z. and Bernacki, K. (2016) Different Approaches to Modelling Single-Phase Voltage Source Inverters for Uninterruptible Power Supply Systems. IET Power Electronics, 9, 1513-1520. https://doi.org/10.1049/iet-pel.2015.0142