【正文】 ontrol technology used in the Honda Insight. 4. AIM OF THE IMA SYSTEM While developing this nextgeneration IMA hybrid system, we incorporated as many currently achievable technologies and techniques as possible, in order to achieve the world39。s intent to stop, preparing for the restart, providing a smooth feeling of deceleration, and minimizing vibration of the car body when the engine stops. Figure (sec) The number of cranking in the engine start This IMA system results in the achievement of both very quick restarts and exceptionally smooth starts. 6. MOTOR ASSIST MECHANISM . DEVELOPMENT OBJECTIVES – By limiting the IMA motor functions to assistance and regeneration, development themes were established to achieve the following two points. 1. A simple and pact structure 2. A system weight of 10% (80 kg) or less of the pleted car weight . THIN PROFILE DC BRUSHLESS MOTOR – A thin and pact DC brushless motor with engine assist and energy regeneration functions was coupled to the engine crankshaft (Fig. 5). Figure 5. Section view of Motor This is a high efficiency, pact, and lightweight permanent magtype threephase synchronous electric motor with a maximum output of 10 kW. In addition to developing technologies to reduce the weight and increase efficiency, we also aimed to make the motor as thin as possible in order to achieve a pact power train. Lost wax precision casting process was used for the rotor, rotating by bending coupled to the crankshaft. This achieves high strength and lighter weight (approximately 20%) pared with normal cast products. For the rotor mags, further improvements were made to the neodymiumsintered mags used in the HONDA EV PLUS, realizing approximately 8% greater torque density and improved heat resistance. This design also results in a motor structure that does not require a cooling system. A split stator structure with salient pole centralized windings was developed and used to reduce the motor axial width. A split stator was adopted to drive the rotor. This makes it possible to use the salient pole centralized windings, which are both more pact and efficient than the conventional coil wave winding method, as shown in Fig. 6. In addition, centralized distribution bus rings (Fig. 7) formed from copper sheets were used for the harness that supplies electricity to the coils on both sides of the stator. This results in an extremely pact and simple structure. These improvements achieve an extremely thin motor with a width of only 60 mm. This represents a 40% reduction in width pared to conventional technology. Wave winding Salient pole winding Figure 6. Compare of winding Figure 7. Cut view of Motor . NICKELMETAL HYDRIDE (NIMH) BATTERY – A nickelmetal hydride battery is used to store and provide electrical energy for the motor assist. This is an advanced battery which has already achieved proven results in the high specific energy version used for the HONDA EV PLUS electric vehicle. The hybrid vehicle battery features stable output characteristics, regardless of the stateofcharge status. It is also extremely durable in this application. The battery pack has an integrated structure consisting of 20 modules, each having six Dsize cells connected in series, arranged in a lattice formation. These 120 V cells are all connected in series for a total battery pack voltage of 144 V. . POWER CONTROL UNIT (PCU) – The PCU performs precise control of motor assist/regeneration and supplies power to the 12 V power source. It has builtin cooling functions, which give it a lightweight, efficient and pact structure. Significant weight reduction was achieved by integrating an air cooling system using highly efficient cooling fins and a magnesium heat sink case. The inverter for the drive motor, which is the most important ponent within the PCU, has switching elements integrated into a single module for generating the threephase AC current. These were separate ponents on the EV PLUS. The drive circuit has been miniaturized and converted to an IC using high density integration. These improvements have resulted not only in significant weight reduction, but have also improved the power conversion efficiency. Further, using phase control to drive the motor at very high efficiencies reduces the amount of heat produced and makes it possible to use a lightweight and simple aircooling system. (Fig. 8) Figure Cut view of PCU Heat Sink case 7. ENGINE . DEVELOPMENT OBJECTIVES – The following four points were set as development themes in order to achieve low fuel consumption over a wide range of operating conditions. 1. Improvement of thermal efficiency 2. Reduction of mechanical losses (10% pared with conventional designs ) 3. Reduction of size and weight (lightest weight in its class) 4. Achievement of half the EU2021 standards . ENGINE OVERVIEW AND SPECIFICATIONS – The engine specifications are shown in Table 1 and the main new features and their pur