The fuel cell hybrid test train requires methods to control fuel cell output power. The acceleration and regenerative-brake performance of the train varies with the SOC of the battery. And the energy consumption also varies with the passenger occupancy and the ambient temperature. Therefore, we studied the traction performance and fuel consumption depending on the difference of the control methods and the number of parameters to be considered with using a driving energy simulator.

We developed a driving energy simulator to study fuel cell output control of a hybrid test train. The simulator takes into account that the powering and regenerating performance of the test train depends on the SOC of the battery. The simulator was validated by confirming that it matched the driving test data. And the running simulation was carried out on a 15 km virtual route to show the efficiency and fuel consumption of the fuel cell.

In this study, we focused on the eco-driving of electric heavy-duty vehicles. The target vehicle is an electric truck developed by our research team. Using the parameters of the truck and developed speed pattern optimization simulator, we derived EV eco-driving speed change patterns. Compared to eco-driving of diesel vehicles, we found several different characteristics. Specifically, we examined the details of the result “acceleration interval with allowed strong acceleration,” which was significantly different from that of diesel vehicles. We confirmed with chassis dynamometer measured data that the strong acceleration of EV will not cause significant deterioration in vehicle efficiency.

In this study, we focused on the eco-driving of electric vehicles (EVs). The target vehicle is an electric bus developed by our research team. Using the parameters of the bus and speed pattern optimization algorithm, we derived the EV’s eco-driving speed pattern. Compared to the eco-driving of internal combustion engine vehicles (ICVs), we found several different characteristics. We verified these characteristics with actual vehicle driving test data of the target bus, and the results confirmed its rationality. The EV’s eco-driving method can improve electricity consumption by about 10–20% under the same average speed.

Our research group designed two electric buses, a small-sized bus for driving on ordinary roads, and a medium-sized bus for driving on expressways. Analyzing the data obtained from verification test, we found a characteristic phenomenon related to regenerative energy on the expressway. In this paper, analysis of evaluation related to this phenomenon by simulating three different driving routes with the medium-sized electric bus is summarized.

In this paper, a series-type plug-in hybrid vehicle simulator is used to validate the distance traveled dependence of environmental performance of the plug-in hybrid vehicles proposed in our previous paper is established. First, the characteristics of the distance traveled dependence such as cross-point and the difference of CO2 emissions between AE and BLD controls are confirmed. Also, the appropriateness and usefulness of the propositions, including the CD mode control selection policy, the optimal BLD control, and the indicator BCPI (blended control performance indicator), which can simply evaluate the effect of BLD control, are valid.

Our research group designed and made a trial creation of a medium-sized electric bus for expressways and conducted a demonstration test on Metropolitan Expressway Bay Shore Route for approximately one year. In this paper, analyzed results focused on the regenerative energy made by electric heavy-duty vehicles running on the expressway will be summarized.

Plug-in hybrid vehicles (PHVs) have two driving modes, which are known as charge-depleting (CD) mode and charge-sustaining (CS) mode. The environmental performance of a PHV differs greatly based on the travel distance when the PHV switches from the CD mode to the CS mode. This paper focuses on the low-carbon effect and energy cost reduction effect of PHVs and numerically describes the dependence of the effects on the distance traveled. It also accounts new knowledge obtained through a detailed analysis and examination of the mathematical equations.

Wireless charging technology for heavy-duty vehicles has been investigated for eco-friendly transportation. We present a new wireless power transfer system for 44 kW rapid charging of electric buses. The transmission distance between the charging pads is from 10 to 13 cm. The large air gap can be fulfilled by the ordinary kneeling function, equipped on most low-floor buses. Dual-block parallel transmission with opposite-phase-current-feeding suppresses magnetic radiation. The system operates in the common 85 kHz band with the light-duty vehicle system. The result of the field test and the public road operation of two electric buses confirm the CO2 reduction effect described.

The two opposite concepts of BE bus (battery-electric bus) which were 'Short-range Frequent-charging-type' and 'Night-charging-type' low-floor buses, were designed and evaluated. Firstly, the current technical level of battery and charging equipment had taken into account to conduct the vehicle design of both BE buses. In additional, the ideal performances of battery and charging equipment for fully substituting the highly used diesel buses in the very densely packed city transportation routes would be clarified in the paper.

A long-term operation test in cold region of electric buses on public roads was performed in Nagano prefecture as a project of the Japan Ministry of the Environment from 2011 to 2014. For this project, the short-range frequent charging type electric buses, "Waseda Electric Buses (WEBs)" were developed. WEB-3, one of the test vehicles, was driven for 42,114 km over 902 days and charged 4,298 times. In this paper, the following was obtained. (1) The battery performance deterioration is measured and proofed to be predictable. (2) One strategy is advised for expanding battery lifetime. (3) Even started the operation at sub-zero environment, the performance of vehicle was not affected.

A long-term operation test of electric buses on public roads was performed in Nagano as part of a project of the Japan Ministry of the Environment from 2011 to 2014. For this project the short-range frequent-charging type electric buses, "Waseda Electric Buses (WEBs)" were developed. WEB-3, one of the test vehicles, was driven for 41,724 km without any major problems and had advantages to reduce 28-42% of CO2 emissions and 57-64% of energy costs, compared to conventional diesel buses. The battery performance deterioration is also confirmed to be predictable, therefore two suitable strategies is advised for expanding battery lifetime.

Various studies were conducted from the aspects of both the battery cells and the module with the aim of making more effective use of the battery capacity. As a result, after 77 cycles of driving and rapid charging, the capacity degradation of the battery module as a whole was 7.7 % and it was determined that the cause of this additional 0.7 % degradation of the capacity was the loss of cell balance. In addition, by adopting module balance coefficient (a) that was proposed as an indicator to show the available percentage of the lowest capacity cell in the module, new cell balancing rules were created that do not significantly affect the convenience of vehicle operation.

This paper addresses the method of detailing the motor system including the inverter and the boost converter of plug-in hybrid vehicles (PHVs). In the past, we had to use the actual measurement data such as efficiency map to calculate the loss of a motor system. However, by estimating the output current of the motor system, allows us to separate the one loss into losses caused by the inverter, the boost converter and the motor. Based on the separation of the losses, we can then build a multi-voltage motor system or estimate the losses of the different ranks of vehicles.