− 42 − Honda R&D Technical Review October 2013 Development of Motor and PCU for a SPORT HYBRID i-MMD System Jiro KUROKI* Hiroshi OTSUKA* ABSTRACT A highly efficient SPORT HYBRID Intelligent Multi-Mode Drive system was developed in order to achieve a balance between the joy of driving and measures to address climate change and energy issues. The developed power train is composed of the engine, an electric coupled CVT with a built-in motor and generator, a Power Control Unit, and an Integrated Power Unit. The built-in motor was given higher torque, higher output, and higher efficiency by using reluctance torque and raising the voltage. The Power Control Unit was made more compact and power was increased by enhancing the unit’s heat dissipation performance, and it was made more efficient by using a low-loss chip. As a result, the motor achieves maximum torque of 307 Nm and maximum output of 124 kW, while the Power Control Unit achieves a voltage increase of 700 V and total output of 400 kVA. The Power Control Unit including the motor achieved a maximum efficiency of 96%. 1. Introduction In order to address climate change and energy issues, there is demand for motor vehicles with lower emissions and better fuel economy. Honda has responded to these expectations by developing the Integrated Motor Assist (IMA) system (1) installed in models such as the INSIGHT, CR-Z, FREED HYBRID, and FIT HYBRID, and by taking steps to reduce fuel consumption. Honda has also been developing fuel cell electric vehicles (2) and battery electric vehicles (EV) as highly advanced zero emission vehicles. A fuel cell EV uses hydrogen as fuel, causing it to react with oxygen in the air to generate electricity and provide driving power. A battery EV uses electricity stored in batteries for driving power. It has the advantage of not emitting exhaust gases when operating, but one issue faced by the battery EV is that it has a limited driving range compared to an Internal Combustion Engine Vehicle (ICEV). At present, there are also not many hydrogen stations or charging facilities, and more widespread use will be limited until the infrastructure is developed. A 2014 model year Accord Plug-in Hybrid was developed in order to resolve these issues. The batteries can be charged from household power or other such sources, enabling EV operation for commuting, shopping, and other such everyday short-range uses. When the remaining battery capacity diminishes, the vehicle can use the energy in gasoline to operate in hybrid mode, so the driving range is not limited by battery capacity. The developed vehicle described here is equipped with the newly developed SPORT HYBRID Intelligent Multi-Mode Drive (SPORT HYBRID i-MMD) system (3), which has a higher electric transmission ratio. The motor and Power Control Unit (PCU) were given enhanced performance and efficiency to achieve higher dynamic performance as well as fuel consumption of 115 MPGe (Charge Depleting mode: CD) and 46 mpg (Charge Sustaining mode: CS) and EV range of 13 miles. This Paper will describe the technology of the newly developed motor and PCU. 2. SPORT HYBRID i-MMD System Figure 1 shows the SPORT HYBRID i-MMD system power train. The motor and generator are built into the case of the electric coupled CVT. The PCU is located above it. The engine is a 2.0 L Atkinson cycle engine developed for hybrid electric vehicle use. Figure 2 shows the three operating modes of the SPORT HYBRID i-MMD system, namely (1) EV drive mode, in which the vehicle is driven by the motor * Automobile R&D CenterIntroduction of new technologies− 43 −Development of Motor and PCU for a SPORT HYBRID i-MMD System using battery energy; (2) hybrid drive mode, in which the mechanical energy of the engine is converted into electrical energy to drive the vehicle using the motor; and (3) engine drive mode, in which the vehicle is driven using the engine. Figure 3 shows a section view of the electric coupled CVT and the transf