While it is said that the global popularity of electric vehicles (BEVs) has reached a plateau, conventional hybrid vehicles (HEVs) are attracting more attention.
Eventually, BEVs and fuel cell electric vehicles (FCEVs), which can run without the use of fossil fuels, may become more widespread, but in the transitional period, HEVs are expected to occupy a certain market as a means of reducing CO2 emissions in an economical manner.
In this context, I would like to explain the differences between Honda’s e:HEV and Nissan’s e-POWER.
Please note that this comparison is based solely on publicly available information and may differ from the actual situation.
Product Overview
Honda launched its first HEV, the Insight, in 1999 (the Toyota Prius was launched in 1997).
Since then, Honda has launched various types of HEVs (one-motor IMA, i-DCD, two-motor i-MMD, and three-motor SH-AWD), and starting in 2020, the two-motor hybrid system is being developed into a series as e:HEV.
The latest version of this system is used in the Odyssey, Fit, Vezel, Step Wagon, Civic, ZR-V, and Accord, and has become Honda’s flagship system. The system is also available in the U.S. and other overseas markets.
On December 18, the company also announced Honda S+ Shift, a new function that pursues “joy of driving” by highlighting the sense of oneness between driver and car while utilizing the characteristics of e:HEV, an electric AWD unit, and a next-generation medium-sized platform, and the scope of application is expected to expand in the future.
Nissan launched the Tino Hybrid in limited numbers in 1997, the Altima Hybrid with Toyota’s THS for the US market in 2007, and the FR Hybrid for the Fuga and Skyline since 2010.
None of these models have been continuously supplied to date, but in 2016 the e-POWER, a series HEV, was launched for the Japanese domestic market.
Starting with the current Note, which went on sale in 2020, the e-POWER is in its second generation, with an updated motor, inverter, and road The motor and inverter have been redesigned, and improvements have been made to improve quietness by actively running the engine when road noise is high.
The latest version of e-POWER is mounted on the Extrale, Serena, KIX, Note Aura, and Note, with the exception of the Serena, all of which are e-POWER-only models. It is also available in Europe from 2022 on the Qashqai and Extrale.
Functional and Technical Features
e:HEV is a hybrid system with both motor and engine driving methods.
The car runs on the motor at low and medium speeds, where the motor excels, and at high speed cruising, where the engine excels, the car runs primarily on the engine directly connected to the tires.
As with conventional series-parallel hybrids, motor drive and engine drive cannot be used together, but electricity generated by the engine can be supplied directly to the motor when battery capacity is insufficient but motor driving is advantageous.
The main components of the system are an “electric CVT with two motors built-in” that incorporates two motors for driving and power generation and a clutch directly connected to the engine, an “Atkinson-cycle DOHC engine,” a “power control unit” and a “lithium-ion battery pack.
In the electric CVT with two built-in motors, the driving motor not only converts electric energy into driving force, but also performs regeneration during deceleration.
The motor for power generation converts energy from the engine into electrical energy.
In the past, the gears used for engine and motor driving were shared, but the electric CVT with two built-in motors in a parallel shaft arrangement used in the mid-sized models has achieved improved driving power and quietness by setting each gear separately.
There are three types of Atkinson-cycle DOHC engines depending on the model: 1.5L Atkinson-cycle DOHC, 2.0L Atkinson-cycle DOHC, and 2.0L direct-injection Atkinson-cycle DOHC.
To improve combustion efficiency and fuel economy, Honda’s proprietary VTEC (variable valve timing lift mechanism) and electric VTC (continuously variable valve timing control mechanism) are used.
Nissan’s e-POWER is a series hybrid system that runs on a motor alone, with the engine used exclusively for power generation.
Unlike conventional hybrid systems, the engine does not directly drive the tires and is always dedicated to generating electricity.
The main components of the system are an “engine dedicated to power generation,” a “generator,” an “inverter,” a “running motor,” a “control unit,” and a “lithium-ion battery pack.
There are three main types of engines used.
The compact car uses an inline 3-cylinder 1.2L engine, the minivan uses an inline 3-cylinder 1.4L direct injection engine that is exclusive to e-POWER, and the SUV uses an inline 3-cylinder 1.5L variable compression ratio engine (VC turbo engine).
Since the e-POWER engine is dedicated to power generation, it can operate in a more thermally efficient area.
The inverter is responsible for converting DC power into AC power that can be used by the running motor.
The running motor generates driving force by using electric energy from the engine dedicated to power generation and from the battery.
Regeneration is also performed during deceleration.
Starting with the second-generation e-POWER, the motor and inverter have been integrated to make the system more compact and to increase output.
The e-POWER system controls to make engine noise less noticeable by actively running the engine when driving on highways or rough surfaces, maximizing the amount of energy recovered on downhill slopes by consuming the battery before the downhill slopes based on navigation information, and controlling recharging to enable EV driving around the destination. The system also maximizes the amount of energy recovered on downhill slopes by consuming the battery before the downhill slopes based on navigation information, and performs charging control to enable EV driving around the destination.
| feature | Honda e:HEV | Nissan e-POWER |
| Driving method | Motorized and Engine Driving | Runs on motor alone |
| Main Components | Engine for driving and power generation Electric CVT with 2 built-in motors (for power generation and driving) Inverter Control unit Lithium-ion battery pack | Generation-only engine Generator Inverter Running motor Control unit Lithium-ion battery pack |
| engine usage area | Direct engine-directed driving at high speeds, etc. Battery recharging by power generation and direct power supply to motor | Battery recharging by electricity generation and direct power supply to the motor |
summary
Honda e:HEV and Nissan e-POWER are the main electric vehicle technologies of both companies, but there is a major difference: e:HEV can run on both engine and motor, while e-POWER can only run on motor.
Since engine driving is more efficient in many cases, such as at high speeds, it is likely to have a wider range of applications as a car, including the market, while it may be simpler system-wise to concentrate on motor driving.
Both systems are highly regarded by the market, and we will keep an eye on their further evolution.
We will continue to publish commentary articles on electric vehicles and electrification from an objective perspective that is easy to understand for as many people as possible.
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This article was written by.
YAJIMA Kazuo
President, Blue Sky Technology Inc.
