Increasing the efficiency of the automotive generator due to active rectification




mild hybrid electric vehicle, start-stop system, automotive generator, active rectifier system, three-phase bridge rectifier, synchronous rectifier


Problem. Increasing fuel economy requirements for modern vehicles lead to an increase in their electrification. The rise in the number of electrical systems leads to a higher load on the electrical power supply system, with the vehicle's power load reaching 2-3 kW. Leading automobile companies have begun serial production of vehicles with the new 12/48 V power supply voltage standard. The traditional alternator used today is a synchronous alternator, and rectifier diodes are used to convert the generated AC to DC to charge the battery, which is inefficient. A study of losses in an automobile alternator shows that the diode rectifier creates a significant portion of the machine's losses at low speeds, resulting in increased fuel consumption. The solution to this problem is to use a synchronous rectifier to replace traditional rectifier diodes, thus improving the efficiency of the AC/DC rectifier. Goal: To improve the economic and environmental characteristics of a mild hybrid vehicle through the use of a synchronous two-semi-periodic rectifier with a midpoint in the car generator. Methodology: Analytical methods are used to calculate energy losses on diodes and in the phase windings of the generator when employing a two-semiperiod rectifier with a midpoint, compared to a bridge rectifier. Results: The structure, functions, and operation modes of the synchronous rectification system are considered. The effect of synchronous rectification on the generator efficiency of a mild hybrid vehicle is analyzed. It was determined which configurations of synchronous rectification are more effective from the standpoint of energy saving and under which operating conditions. It was determined that in a two-semiperiod rectifier with a midpoint, compared to a bridge rectifier, there will be the same heating of the phase windings and 2 times fewer losses on the diodes. Practical value: A version of the bridge synchronous rectification system of the 48 V generator for a mild hybrid vehicle using MOSFET transistors and specialized control IC is proposed. A synchronous rectification system and its circuit implementation for a 12 V generator based on a two-semi-periodic rectifier scheme with a midpoint is proposed, which allows increasing the energy efficiency and economy of the automobile generator.

Author Biographies

Volodymir Dvadnenko, Kharkov National Automobile and Highway University

professor, Doct. of Science, Vehicle Electronics Department

Oleksandr Dziubenko, Kharkiv National Automobile and Highway University, 25, Yaroslava Mudrogo str., Kharkiv, 61002, Ukraine

Ph.D., Assoc. Prof. Vehicle Electronics Department


Taoudi, A., Haque, M., Luo, C., Strzelec, A. et al. (2001). Design and Optimization of a Mild Hybrid Electric Vehicle with Energy-Efficient Longitudinal Control. SAE Int. J. Elec. Veh. 10 (1): 55-78, 2021.

Sarafianos, Dimitrios & Logan, Thomas & Mcmahon, Richard & Flack, T.J. & Pickering, Stephen. (2014). Alternator loss breakdown and use of alternative rectifier diodes for improvement of vehicle electrical power system efficiency. 502-507.

Mürken, Michael & Kübel, D & Kurz, A & Thanheiser, Andreas & Gratzfeld, P. (2018). Fault analysis of automotive claw pole alternator rectifier diodes.

Mild Hybrid Electric Vehicle (MHEV) – examples (2020).

Mahmood, Omar & Wan Hasan, W. & Ismail, Luthffi & Shafie, Suhaidi & Azis, Norhafiz & Norsahperi, Nor Mohd Haziq. (2022). Optimization Approaches and Techniques for Automotive Alternators: Review Study. Machines. 10. 10.3390/machines10060478.

Chen, Jyh-Wei & Tran, Thanh Nhat Trung. (2019). Design of Low-Cost Voltage Sensing Method of Three-phase Synchronous Rectifier with High-Efficiency for Automotive Alternator. 1-6.

Hidaka, Yuki. (2021). Novel coupled analysis methods of automotive alternators considering synchronous rectification circuit. COMPEL - The international journal for computation and mathematics in electrical and electronic engineering. ahead-of-print.

K. S. Kao et al. (2018). A high efficient synchronous rectifier for next generation automotive alternator applications. International Conference on Electronics Packaging and iMAPS All Asia Conference (ICEP-IAAC), Mie, Japan, 2018, pp. 391-395.

Rees, Stephan & Ammann, Ulrich. (2003). A smart synchronous rectifier for 12 V automobile alternators. 1516 - 1521 vol.4.

International Rectifier. (2018). HEXFET Power MOSFET: IRFP4468PBF.

Diodes Incorporated. (2021). Secondary side synchronous rectification controller. APR348, Document number: DS42016 Rev. 5 - 2.

International Rectifier. (2013). Advanced smartrectifierTM control IC: IR11672AS.

International Rectifier. (2011). Dual smart rectifier driver IC: IR1168S.

Adnaan Lokhandwala. (2016). Design of Secondary-Side Rectification using IR1168 Dual SmartRectifier™ Control IC. Application Note AN-1139. International Rectifier.



How to Cite

Dvadnenko, V., & Dziubenko, O. (2024). Increasing the efficiency of the automotive generator due to active rectification. Vehicle and Electronics. Innovative Technologies, (25), 6–12.