IEEJ Journal of Industry Applications Vol.10 No.4 pp.411–416 DOI: 10.1541/ieejjia.20013024 Invited Paper NISSAN e-POWER: 100% Electric Drive and Its Powertrain Control ∗a) ∗∗ Kantaro Yoshimoto Member, Tomoyuki Hanyu Non-member (Manuscript received Jan. 5, 2021, revised Feb. 27, 2021) J-STAGE Advance published date : April 2, 2021 Nissan has developed a 100% electrified powertrain system called e-POWER, which exhibits key features such as quick response, smooth acceleration, smooth deceleration, and quietness. The quick response and smooth acceleration can be achieved owing to the 100% electric motor drive and control strategy that has been adopted from the Nissan LEAF electric vehicle and improved further. The quietness was designed and controlled using power generation con- trol and engine speed control. A driving mode called the e-POWER drive mode was developed using 100% electric deceleration to achieve smooth and efficient deceleration with linearity and controllability. Keywords: hybrid electric vehicle, electric vehicle, powertrain control, traction control, power generation control the Nissan LEAF gained popularity in the global market. 1. Introduction In 2016, Nissan launched the e-POWER system as a new “Vehicle electrification” is not only a technology of pow- hybrid system powertrain for compact cars in the Japanese ertrain, but also the key technology for a major turning point market which could provide the experience of driving an that occurs once in a hundred years. In 2010, Nissan launched EV with a smooth and quick response, as the core technol- an electric vehicle (EV) named Nissan LEAF (1),asthefirst ogy of Nissan’s vehicle electrification (3). The hybrid system mass-produced EV at a reasonable price. Nissan LEAF is configuration is a series hybrid system, that uses an electric a medium-sized hatch back vehicle that can seat five adults traction motor, inverters, and basic control software adopted comfortably. The first-generation 2011 model year Nissan from the Nissan LEAF. The 100% electric drive provides the LEAF exhibited a maximum traction power of 80 kW and a experience of driving an EV. Additionally, the control strat- driving range of 200 km under the JC08 emission test mode egy for power generation can provide EV quietness in hybrid in Japan, which could be sufficient to satisfy real-world con- electric vehicles (HEVs). This control system differentiates sumer requirements for daily use. The performance and us- the e-POWER system from conventional series hybrid sys- ability of the Nissan LEAF have been improved at the time tems. Therefore, Nissan Note became top selling-car in the of minor model change, to maintain competitiveness (2). Japanese market, owing to e-POWER system. The latest model of Nissan LEAF e+, produced in 2020, This paper introduces a system configuration and control exhibits a maximum power of 160 kW and a driving range strategy for the e-POWER system. The commonization of of 570 km in the JC08, 458 km in the worldwide-harmonized components that are modeled on Nissan LEAF exhibits the light vehicles test cycle (WLTC). One of the distinctive fea- unique strategy to provide the EV drive experience and im- tures of Nissan EVs is the smooth, responsive acceleration prove the development efficiency. Further, this paper can obtained by the use of the excellent response and controlla- provide insight into the labeling of this hybrid system as “e- bility of an electric motor. The motor and its control have POWER” and not just a series hybrid. been developed by Nissan internally and refined for over 10 2. System Configuration years as a core technology for electrification. These features can be achieved using a motor current controller (MC) and an 2.1 Line up of e-POWER In 2016, the e-POWER electric power train controller called a vehicle control module system was installed in the Nissan Note model in the (VCM). Control technologies have been enhanced to deliver Japanese market. The Nissan Note model, shown in Fig. 2, is high-power performance without sacrificing smoothness and a compact hatchback model and is the first model to use the e- quickness. This controllability of the electric powertrain pro- POWER system. The Nissan Note model also has four-wheel vides not only driving pleasure, but also driving ease in daily drive (4WD) version which uses an electric motor for the rear use, even for inexperienced drivers. This is one of the reasons axle (4). The e-POWER system has been incorporated in the Nissan Serena model, a popular minivan in the Japanese mar- JIA Cool Japan Invited Paper ket, since March 2018. In 2020, the Nissan Kicks model, a compact sports utility vehicle (SUV), adopted the e-POWER a) Correspondence to: Kantaro Yoshimoto. E-mail: kantaro@mail. system for the Japanese and Thai markets. In November dendai.ac.jp 2020, the New Nissan Note e-POWER was introduced. This ∗ Tokyo Denki University 5, Asahicho, Senju, Adachi-ku, Tokyo 120-8551, Japan paper focuses on the fundamental of the e-POWER system ∗∗ NISSAN MOTOR Co., Ltd. used for the Nissan Note model in 2016. 560-2, Okatsukoku, Atsugi, Kanagawa 243-0192, Japan 2.2 System Configuration The e-POWER hardware c 2021 The Institute of Electrical Engineers of Japan. 411 NISSAN e-POWER 100% Electric Drive and Its Control（Kantaro Yoshimoto et al.） Table 1. Specifications of the e-POWER system used for the Nissan Note (2016) model Fig. 1. Nissan LEAF EV output of 55 kW. The transaxle incorporates two functions in a single housing unit. One is a speed- reducing function for connecting the motor and the drive-shaft, and the other is a speed increasing function for connecting the generator and the ICE. The Li-ion battery is capable of producing a high rate of discharge and charge power, and can deliver a quick acceleration response similar to that of EVs. The water- cooling system for the electric motor, generator and invert- ers is dedicated cooling circuit that is not connected to the ICE cooling system. There is a dedicated forced-air cooling system for the Li-ion battery pack. The e-POWER system is controlled by a VCM that communicates with an MC, a gen- erator controller (GC), a battery management system (BMS) Fig. 2. Nissan Note e-POWER and an engine control module (ECM). The function of the GC is similar to that of the MC, which controls the motor current and generates pulse width modulated (PWM) signals for the gate drives of the switching device. The ECM controls and directs the ICE torque to follow the torque command of the VCM. The rotational speed of the ICE is controlled by the GC and the generator to follow the rotational speed com- mand of the VCM. The major specifications of the e-POWER system for the Nissan Note model, which is the first applica- tion of the e-POWER system, are listed in Table 1. For other vehicles, the system power and motor torque are designed to satisfy the requirements of a minivan and an SUV. Fig. 3. System configuration of the e-POWER 2.3 Package on a Vehicle Figure 4 shows the in- vehicle layout of the e-POWER including the battery used for configuration is categorized as a series-hybrid system. The Nissan Note model. The drive and power generating systems distinctive feature of this configuration is that the power are integrally assembled. Additionally, the drive and generat- generation system is mechanically separated from the trac- ing systems are functionally separated. As a result, this sub- tion system. This means that an internal combustion engine assembly ensures mountability on compact platforms, such (ICE) is connected to the generator through the transaxle and as those of B-segment vehicles. The battery was designed in is not connected to the traction drive-shaft. Owing to this a compact package, enabling it to be located below the front feature, the traction drive system can be adopted from the seats. Positioning the battery pack in the dead space below technology and components used for EVs, and the vehicle is the front seats enables the possibility of achieving virtually propelled by the electric motor only. The operational torque the same cabin space and luggage area as those in an ICE and speed of the ICE can be set flexibly, and is not dependent vehicle without affecting occupant comfort. In addition, this on the vehicle traction conditions. battery pack is located around the center of the gravity of the Figure 3 shows the system configuration of the e-POWER. vehicle. Thus, it can contribute to better handling and stabil- The powertrain system consists mainly of a traction motor ity of the vehicle. (e-Motor), generator, inverters, ICE, and a Li-ion battery. 2.4 Electric Powertrain of e-POWER The configu- The traction motor and its inverter which are used in the ration of the e-POWER unit is shown in Fig. 5. The electric Nissan LEAF, were adopted. The power generating sys- traction motor was developed by Nissan, and was adopted tem incorporates a 3-cylinder, 1.2 L gasoline-powered ICE from Nissan LEAF. In the Nissan LEAF, these components (HR12DE), which is also used for B-segment ICE vehicles, are connected by three-phase busbars. However, the connec- in combination with a generator with a maximum power tion between the inverter and the electric traction motor is 412 IEEJ Journal IA, Vol.10, No.4, 2021 NISSAN e-POWER 100% Electric Drive and Its Control（Kantaro Yoshimoto et al.） Table 2. Specifications of the traction motor, generator and inverter Fig. 4. In-vehicle layout of the e-POWER used for the Nissan Note model Fig.