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Honda's technology applied to CR-Z HEV propulsion system. Presenter Takeo Nishibori, Honda R&D Co., Ltd.

This paper proposes a new motor design procedure for reducing motor loss in hybrid vehicles (HEV) and electric vehicles (EV). To find an optimum design in a short time, a non-linear magnetic circuit model was developed for interior permanent magnet synchronous motors (IPMSM). Speed-torque curves and motor losses were calculated based on this model. Combined with Energy Management Simulation, this model makes it possible to find an optimum motor design with minimum loss.

Honda has been proposing and developing a Transverse Flux Motor (T.F. motor) in order to shorten axial length of the motor for hybrid electric vehicles (HEVs). In contrast to conventional motors that are composed of a stator core (made from magnetic steel sheet) and winding wires, the T.F. motor is a new type of three-dimensional magnetic circuit motor composed of a soft magnetic composites (SMC) core and a coil. While reducing axial length and achieving a simple stator architecture comprised of just five parts, the new motor raises issues including the need to improve motor efficiency and the development of techniques for the manufacture of rectangular wave-shaped coils. To improve motor efficiency, we conducted a parameter study of the SMC core material and manufacturing conditions to establish the optimum required specifications for reducing iron loss.

The mounting of lithium-ion batteries (LIB) in hybrid electric vehicles (HEV) calls for the configuration of highly robust control systems. When mounting LIBs in the vehicle, it is important to accurately ascertain and precisely control the state of the battery. In order to achieve high durability, it is important to configure highly reliable systems capable of dependably preventing overcharging as well as to have control technology based on software that can contribute to extended battery life. The system configuration applies an overcharge prevention system that uses voltage detection with an emphasis on reliability. Furthermore, a method for varying the range of state of charge (SOC) control in the vehicle according to the battery state is implemented to assure durability. In order to achieve this, battery-state detection technology was developed for the purpose of correctly detecting and judging the battery state.

Honda has developed the 2018 model CLARITY PLUG-IN HYBRID. Honda’s new plug-in hybrid is a midsize sedan and shares a body platform with the CLARITY FUEL CELL and the CLARITY ELECTRIC. The vehicle’s electric powertrain boosts driving performance as an electric vehicle (EV) over Honda’s previous plug-in hybrid. The CLARITY PLUG-IN HYBRID’s electric powertrain consists of a traction motor and generator built into the transmission, a Power Control Unit (PCU) positioned above the transmission, an Intelligent Power Unit (IPU) fitted under the floor, and an onboard charger fitted below the rear trunk. The PCU integrates an inverter that drives the traction motor, an inverter that drives the generator, and a DC-DC converter to boost battery voltage (referred to as a “Voltage Control Unit (VCU)” below).

A hybrid simulation model in the transient bench was developed to realize the characteristics of the transient behavior and the fuel economy equivalent to that of a real vehicle. The motors and the batteries that were main components of the hybrid vehicle system were simulated as constructive modules, the functions of which have the integrated control and the input/output (I/O) function with real components. This model enabled us to accommodate a variety of auxiliary (AUX) I/O flexibly. The accuracy of the model was verified by the transient characteristics of the engine and the fuel economy result through correlation with a mass-produced vehicle. Furthermore, the flexibility of the model to a variety of AUX I/O was examined from the simulation test of the vehicle equipped with the waste heat recovery (WHR) system.

Size reduction is a significant requirement for hybrid vehicle motors. To meet this requirement, a small new-structure transverse flux (T.F.) motor has been developed, with efforts focused on coil end elimination and a higher motor torque density. The new structure is characterized by a stator core with a three-dimensional flux path configuration. A prototype motor was also designed and produced using ring coils and stator cores made of soft magnetic composites (SMC). The prototype performance was tested to verify the validity of the new magnetic circuit configuration.

An electric servo brake system applied for use on electric vehicles was applied for use on plug-in hybrid vehicles in order to achieve fuel-savings together with good brake feel and enhanced operability for plug-in hybrid vehicles. The electric servo brake system is made up of highly accurate braking pressure control that functions cooperatively with regenerative brakes together with a structure in which pedal force is not influenced by braking pressure control. The configuration of these components enabled good braking feel even when the power train was being switched from one drive mode to another. Automated pressurization functions that are intended for plug-in hybrid vehicles and that operate with electric servo brake systems were also developed. These developed functions include stall cooperative control that functions cooperatively with the power train, regenerative coordinate adaptive cruise control, and hill-start assist.

A highly efficient two-motor plug-in hybrid system is developed to satisfy the global demands of CO2 reduction. This system switches three operation modes, what is called “EV Drive”, “Hybrid Drive” and “Engine Drive”, to maximize fuel efficiency according to the driving condition of the vehicle. Practical plug-in EV (Electric Vehicle) capability is also realized by adding a high-power on-board charger and a high capacity Li-ion battery to the original system. The outlines of the system components including a newly developed Atkinson cycle engine, a highly efficient electric coupled CVT (Continuously Variable Transmission) with built-in motor and generator, an integrated PCU (Power Control Unit) and an exclusive battery for plug-in HEV (Hybrid Electric Vehicle) are described in this paper. In addition to the switching of three driving modes and the efficiency improvement of each device, cooperative control of the hybrid system is introduced.

A new brake system, able to make efficient use of regenerative braking while maintaining excellent brake feel, has been developed to increase the fuel economy of hybrid vehicles. A hydraulic servo was used as a base to enable mechanical operation of the service brakes; solenoid valves and brake fluid pressure sensors were added to this base to make it possible to control brake line pressure as demanded. The use of a stroke simulator in the hydraulic servo prevents brake feel from being affected by the control of the brake pressure. In addition, high-accuracy brake pressure control that functions cooperatively with the regenerative brakes is enabled, resulting in stable braking effectiveness.

In order to reduce CO2 emissions from automobiles, a highly fuel-efficient hybrid vehicle, the “Insight”, has been developed at Honda. Life cycle CO2 emissions are compared for the aluminum-bodied Insight, a simulated steel-bodied Insight, and a conventional gasoline vehicle. Life cycle CO2 emission is still dominated by the in-use fuel consumption. However, the contribution of CO2 emission from material use and processing could increase when the vehicle fuel consumption is greatly reduced. The use of recycled aluminum reduces CO2 emission from the aluminum-bodied Insight.

The subject is technology for damping forced vibration in the multiplate wet clutches used in hybrid vehicle transmissions. As a predictive technique for forced vibration caused by the structure of the clutch, three-dimensional simulation was used in the present study to anticipate the modes of vibration that occur. Next, a one-dimensional simulation was created as a predictive technique for drivetrain torsional vibration from the engine to the driveshaft. The one-dimensional simulation created was used to extract the modes of operation that are severe with regard to forced vibration from target values for vibration anticipated from the vehicle body. The results obtained were used with three-dimensional simulation to change the clutch structure to provide greater latitude with regard to the target for forced vibration.

The traction and power generation motors of hybrid electric vehicles need to provide greater output densities. This can be achieved by increasing output and reducing the physical size and weight of the motors. However, there are limits on how much a motor’s output can be increased while simultaneously shrinking the motor’s size, as it is conventionally structured. To address this issue, the authors developed a stator with a new structure to increase motor output and reduce motor size. By simultaneously optimizing magnetic circuit design, they increased maximum torque by 2.6% and maximum output by 8.9% and reduced volume by 23% and weight by 23% compared to motors of conventional structure, all while maintaining the same level of efficiency. The result was top-of-class output and compactness.

A battery module structure and a battery management system that is optimal for the structure were developed, in order to facilitate the work of equipping hybrid cars with lithium-ion batteries (LIBs) that are expected to improve vehicle performance. This paper describes the structure of the LIB and the battery management system that is optimal for it. The battery module structure has cells with a sturdy holding structure and a highly efficient cooling system. The structure has enabled the improvement of battery pack system power output by 80% per unit weight and by 20% per unit volume compared to the previous model. The optimal management system prevents battery overcharge by detecting and controlling the state of charge (SOC) of each cell with a high degree of accuracy.

In 2002, to address environmental and energy issues, Honda began to deliver a fuel cell vehicle, the FCX. Now, Honda has developed a new model FCX, which is able to operate in cold regions with significantly enhanced driving performance, in an attempt to increase the popularity of fuel cell vehicles in the world. The new vehicle employs Hondas next-generation fuel cell stack which enables start-up and allows for power generation at - 20 ° C, and Honda has delivered new FCXs to customers where winter temperatures fall to -20 ° C--in New York state, US and Hokkaido, Japan-leading the world. As the motor power-output has been increased to 80kW increases in both the power-output of the fuel cell stack and the energy capacity of the ultra-capacitors have enabled an increased supply of power to ° the motor, resulting in significant enhancement of both initial and overtake acceleration performance.

This paper presents a power train developed for a 2011-model compact sporty hybrid vehicle. The power train, developed based on existing mass-produced car components such as an engine, transmission, and Integrated Motor Assist (IMA) system, takes advantage of the IMA system to strike a good balance of driving performance, fuel economy, and low exhaust gas emissions. The conventional concept behind a hybrid design was to use motor output to compensate for a power reduction caused by smaller engine displacement. For the development of this power train, a new approach was taken to utilize the motor output to create a better driving feel. Making full use of a good motor response and directness, the power train realized this sporty driving feel, unlike anything offered by conventional cars.

This paper clarifies influence rate of traffic-flow and eco-driving factors that have effect on on-road fuel economy and a case study was conducted to estimate the CO₂ reduction potential due to traffic-flow smoothing and eco-driving promotion by analyzing floating car data from throughout Japan. The data employed in the study was obtained from hybrid vehicles equipped with an Eco Assist system. Previous research has reported that repeated use of these vehicles enhances fuel economy by approximately 10%. First, multiple regression analysis was performed on the subject floating car data to obtain a polynomial with fuel economy as the explained variable and items related to traffic flow and eco-driving as the explanatory variables. Average travel speed was found to have the greatest effect on fuel economy.

Ultra-low energy consumption and ultra-low emission vehicle technologies have been developed by combining petroleum-alternative clean energy with a hybrid electric vehicle (HEV) system. Their component technologies cover a wide range of vehicle types, such as passenger cars, delivery trucks, and city buses, adsorbed natural gas (ANG), compressed natural gas (CNG), and dimethyl ether (DME) as fuels, series (S-HEV) and series/parallel (SP-HEV) for hybrid types, and as energy storage systems (ESSs), flywheel batteries (FWBs), capacitors, and lithium-ion (Li-ion) batteries. Evaluation tests confirmed that the energy consumption of the developed vehicles is 1/2 of that of conventional diesel vehicles, and the exhaust emission levels are comparable to Japan's ultra-low emission vehicle (J-ULEV) level.

Two of the goals of the Penn State FutureTruck project were to reduce the emissions of the hybrid electric Ford Explorer to ULEV or lower, and improve the fuel economy by 25% over the stock vehicle. The hybrid electric vehicle system is powered with a 103kW 2.5L Detroit Diesel engine which operates with a fuel blend consisting of ultra-low-sulfur diesel and biodiesel (35%). Lower emissions are inherently achieved by the use of biodiesel. Additionally, the engine was fitted with a series of aftertreatment devices in an effort to achieve the low emissions standards. Vehicle testing has shown a gasoline-equivalent fuel economy improvement of approximately 22%, a reduction in greenhouse gas emissions by approximately 38%, and meeting or exceeding stock emissions numbers in all other categories through the use of an advanced catalyst and control strategy.

The Integrated Motor Assist (IMA) Hybrid Electric Vehicle (HEV) technology used in Civic Hybrid or Insight is developed originally by Honda, and is mounted in a V6 Accord with the aim of enhancing fuel economy of a mid-size passenger car. The development goal was to realize a mid-size passenger car that provides acceleration performance superior to a V6 Accord and the fuel economy of a compact class vehicle. Various means are employed to achieve high torque and high efficiency simultaneously, including an Interior Permanent Magnet (IPM) type rotor, low-loss electrical steel sheets as the stator material, and high maximum energy product magnets. These technologies increase the maximum power of the newly developed motor by approximately 20%, the maximum torque by 26% and motor efficiency over all ranges by approximately 1% to 3% compared to the current Civic Hybrid motor. Consequently, the maximum motor power of 14 kW and maximum motor torque of 136 Nm are achieved.