2018-01-0458 Published 0 3 Apr 2018 © 2018 SAE International. All Rights Reserved.Development of High-Power-Density DC-DC Converter Using Coupled Inductors for Clarity Plug-In Hybrid Akitomo Komatsuzaki Honda R&D Co., Ltd. Satoshi Hashino Keihin Corporation Citation: Komatsuzaki, A. and Hashino, S., “Development of High-Power-Density DC-DC Converter Using Coupled Inductors for Clarity Plug-In Hybrid,” SAE Technical Paper 2018-01-0458, 2018, doi:10.4271/2018-01-0458. Abstract Honda has developed an electric powertrain for a 2017 plug-in hybrid vehicle using its second-generation SPORT HYBRID i-MMD powertrain system as a base. The application of the newly developed powertrain system realizes a long all-electric range (AER), allowing opera - tion as an EV for almost all everyday driving scenarios, with dynamic performance making it possible for the vehicle to operate as an EV across the entire speed range, up to a maximum speed of 100 mph. The amount of assist provided by power from the batteries during acceleration has been increased, helping to downsize the engine while also balancing powerful acceleration with quietness achieved by controlling racing of the engine. In order to realize this EV performance with the second-generation SPORT HYBRID i-MMD system as the base, it was necessary to increase the power output of the DC-DC converter, taking restrictions on space into consideration. An interleaved circuit design using coupled inductors was employed as the method of increasing the power density of the DC-DC converter. This circuit design reduced magnetic flux generated in the inductor cores by direct current, making it possible to reduce the size of the inductors. However, it was not possible to position electric devices such as current sensors close to the coupled inductors due to magnetic flux leakage to the exterior, making it challenging to increase the integration density of the components. In order to address this issue, a configuration of coupled inductors that reduces magnetic flux leakage was developed, making it possible to increase the integration density of the peripheral layout of the DC-DC converter. The application of the proposed coupled inductors has increased the continuous power density of the DC-DC converter approximately 2-fold in comparison with the conventional unit employed in previous Honda hybrids. Introduction Against the background of increasing concern over global warming and global-scale energy issues, the development and popularization of eco-friendly electric vehicles, as represented by electric vehicles (EVs), hybrid vehicles (HEVs), and fuel cell vehicles (FCVs), has become a responsibility for the automotive industry. Looking towards the realization of societies based on sustainable energy, Honda commenced marketing its new CLARITY FCV in 2016, and its CLARITY ELECTRIC and CLARITY PLUG-IN HYBRID vehicle in 2017. The development process for these eco-friendly electric vehicles recognized that in addition to low cost and a high level of environmental perfor - mance, the realization of dynamic performance equivalent to or greater than that of a conventional gasoline engine vehicle would be a necessary condition for promoting widespread use of the vehicles. The main focus of this paper will be the devel - opment of a new electric powertrain for the CLARITY PLUG-IN HYBRID, looking towards the fully-fledged popu - larization of PLUG-IN HYBRID vehicles (PHEV). This powertrain includes modifications of the second-generation SPORT HYBRID i-MMD powertrain system already marketed by Honda in order to optimize it for a long-range PHEV. This has made it possible to achieve a long all-electric range (AER) of 47 miles and EV operation across the full vehicle speed range up to a maximum speed of 100 mph, and to offer the comfort - able acceleration and quietness that are the advantages of EV operation in almost all everyday driving scenarios. When the battery capacity is exhausted and the vehicle swi