A Duster Plug-in Hybrid Electric Vehicle with Wireless Charging System

The paper presents the GASTER Electricway 4WD concept, Plug-in Hybrid Electric Vehicle (PHEV) type, in development within the Automotive Engineering Research Centre of the University of Pitesti, aiming to create a green and versatile version of Romanian Dacia Duster. The car has been built by implementing a hybrid propulsion system with electrified rear axle. This hybrid system is PHEV, parallel type with two shafts, organized in a motorized solution E4WD (Electricway 4WD). It is composed of a thermal power train with a 1.6 litre engine fuelled with Compressed Natural Gas (CNG) and a CVT (Continuously Variable Transmission), placed in the front of the vehicle. The electric powertrain, located at the rear side of the vehicle includes an electric motor coupled with a mechanical transmission. The traction battery is Lithium-ion NMC type. The charging of the traction battery can be performed with the on board charger of by cable from a Wallbox or public station, in the Standard version, and Plug-in bidirectional or Wireless from renewable sources in the Premium version.


Introduction
The paper reveals for the first time the details of the GASTER Electricway 4WD PHEV concept car project (Figure 1).The vehicle is built on the platform of the SUV Dacia DUSTER II, made by the Automobile Dacia -Group Renault at their plant located near Pitesti city, Romania.

Main project objectives
The GASTER Electricway 4WD PHEV concept has been developed aiming to create a green SUV part time all-wheel drive type.This will be used for research of the means to reduction of pollutant emissions under 100g CO2/km, using a hybrid system with engine fueled by Compressed Natural Gas (CNG) coupled by an intelligent transmission CVT and a part time all-wheel drive by rear axle electrified.

Architecture
The GASTER Electricway 4WD concept has an architecture similar with GRAND HAMSTER Electricway 4WD [1].It is realised with new components and represents a Plug-in evolved solution of, in agreement with Euro 6 pollution requirements.The architecture of the GASTER Electricway 4WD concept is presented in Figure 2. It is a parallel system type, with torque addition and with two shafts.
The organization of this hybrid propulsion equipment Plug-in type is done by dividing it in two parts, (motorized solution E-4WD): the thermal powertrain in the front side and the electric powertrain in the rear side.The thermal powertrain with engine (1) mainly fuelled by CNG (8,9) coupled by a CVT transmission (2,3,4,5) is mounted in the front side of the vehicle.The electric powertrain with electric motor (11) added is mounted in rear side.The CNG fuel tank with 2 cylinders ( 7) is located under the rear seats.
For safety, it has been provided a supplementary gasoline fuel tank (not presented in the figure), located on the rear side of the vehicle.The refill sockets of CNG and gasoline (10) are placed on the The architecture of the thermal management of vehicle includes 4 complexes hydraulic circuits for colling/heating of the components: one colling high temperature circuit of the thermic engine, one colling low temperature circuit of the electric components, one heating circuit of the CNG reducer and one climate circuit in the cabin.

Thermal powertrain
The thermal powertrain mounted in the front side is created with elements from Renault-Nissan, not yet introduced in the production of the Dacia vehicles.It includes an engine, 1,6 SCe (Figure 3, right) fuelled for the first time by Compressed Natural Gas (CNG) (Figure 4) coupled with an automatic gearbox X -Tronic CVT DK0 type, V-Belt (Figure 5).The engine of the GASTER Electricway 4WD PHEV is an 1,6 SCe, four-cylinder, H4M type, 84 kW @ 5500 rpm, liquid cooled [2] fuelled for the first time by Compressed Natural Gas (CNG) Figure 4. Considering the engine`s adaptation to CNG fueling and its integration in a PHEV, other modifications were operated, as follows:  Integration of the specific components of the LANDI RENZO OMEGAS EVO natural gas system that meets the strictest European emissions standards Euro 6.The system features OBDII connectivity via the K and CAN protocols and offers thorough diagnostics on the connection with petrol injectors and the functioning of individual gas injectors [3]. Replacement of the original AC compressor with an electro compressor, fuelled by the traction battery. Building a new exhaust gas system, adapted to the architecture of the central and rear areas under the floor. Building a new gasoline tank for stopping the gasoline vapours during the CNG and electric mode functioning. Building a ThermoSTART preheating system for reducing the CO2 emission at cold starting of the engine fuelled by CNG, powered with energy from the traction battery or from a charging point in the charging mode.
The second main novelty of the concept is the thermal engine coupling H4M type with a Nissan CVT (Continuously Variable Transmission), new X Tronic generation [4].The transmission features a ratio coverage of 7.0 using a sub planetary gear to switch between low and high ranges, allowing smaller pulleys to reach higher transmission ratio coverage.This raises responsiveness on start-ups and at low speeds while allowing lower engine rpm at high speeds, resulting in higher fuel economy.This generation X Tronic CVT model achieves an improvement in fuel economy of up to 10% compared to previous CVTs for comparable vehicles.Combined with Adaptive Shift Control (which adapts shifting patterns to match each driver's style and the road), this transmission delivers responsive and powerful acceleration.It also helps keep the engine from revving too fast at high speeds and minimize noise.

Rear axle and electric powertrain
The electric powertrain with an electric motor induction type and a reducer-differential transmission of the GASTER Electricway 4WD PHEV (figure 6, center) is mounted in the rear side in an innovative solution, with an H type axle and twisted travers (figure 6, left).This rear axle is an adapted solution of the GRAND HAMSTER Electricway 4WD [1].The electric motor, liquid cooled, has the maximum power peak 32 kW, able to achieve a maximum speed of 80 km/h with zero CO2 emissions.This electric motor also handles the harvest of energy during braking and deceleration in order to recharge the battery and increase the range for 100% electric driving.

5
In order to adapt the rear axle to the new weight distribution, the rear suspension has been revised and includes two pneumatically supplementary air suspensions (figure 6, right).

The Traction Battery
The Traction Battery System includes the battery pack, the Battery Management System and the Monitor System.The battery pack is Lithium Nickel-Manganese-Cobalt (NMC) technology 400V, 9,8 kWh from the Renault CAPTUR PHEV.It has 96 cellules, series coupled [2].This battery 1 equipped with external switch 2 is placed on the floor of the rear side of vehicle (Figure 7).The battery is controlled by an Orion 2 Li-Ion Battery Management System [5].This BMS protects and monitors the battery pack by monitoring sensors and uses several outputs to control charge and discharge into the battery.The BMS measures inputs from cell voltage taps, the total pack voltage tap, a hall effect current sensor and thermistors.Using the programmed settings, the BMS then controls the flow of current into and out of the battery pack through broadcasting charge and discharge current limits via the CANBUS.The BMS relies on the user to provide external controls that respect the current limits set by the BMS to protect the batteries as the BMS does not have integrated switches.During and immediately after charging, the BMS will balance the cells using internal shunt resistors based on the programmed settings.

The GASTER Electricway 4WD Batteries Charging Systems
The GASTER Electricway 4WD PHEV concept is equipped with two batteries: the 12 V auxiliary battery that feeds the low-voltage electrical network and the 400 V traction battery of the electric propulsion system.The 12V auxiliary battery is charged by a DC/DC converter of 1000.W TDC IT 320 -12 type, air cooling, with CAN protocol.Two types of charging systems are provided for the traction battery: The Standard system, by conduction (plug-in) and the Premium system, by induction (wireless) and plug-in (bidirectional).

The Standard charging system
The Standard type achieves plug-in charging via a 3.3 kW AC, air cooled On Board Charger (OBC), EVPT23-32010 type.It's equipped with CAN communication interface to realize real-time communication with BMS.The charger with high efficiency, high stability and high protection grade (IP67) realizes an intelligent temperature compensation function in the charging process, preventing the damage to battery caused by charge-off or charge due, greatly extending the lifespan of battery.
The socket integrated on the front of the vehicle (figure 9, right) is a standard Mennekes socket, Type 2 with charging protocol for communication between vehicle and charging station.To monitor state of operation of the plug-in charger, an operation indicator is mounted near to the socket and the plug is removed from the socket with a release button (figure 9, left).In Standard mode the 9.8 kWh, 400 V battery is charged by a 3.3 kW, 10 A OBC from a Wallbox in at least 180 minutes.

The Premium Wireless charging system and standardization
For the GASTER Electricway 4WD PHEV Premium charging version, a bi-directional charger has been designed to enable G2V/V2G/V2L [6] combined with a wireless charging system.This solution is described in Figure 9.The system contains an integrated bi-directional charger for controlled charging/discharging of the battery in the V2G/G2V/V2L system [6] and a system for receiving the energy transmitted wirelessly via the Rx coil located in the lower rear part of the PHEV (Figure 11).The V2L (Vehicle to Load) scheme is a function that allows stored energy to be used to power external devices such as camping equipment, power tools and a variety of consumer devices.Because the battery capacity is relatively small, powering appliances in a home (fridge, air conditioner, etc.) can only be done for a short time.Switching from the plug-in to the wireless system is done from the vehicle on-board via the static switches Sw1 and Sw2 operated via the Comm block.Table 3 shows the position of the SW switches according to the chosen mode.
IOP Publishing doi:10.1088/1757-899X/1303/1/0120088 The wireless system is powered either from the grid or from a range extender G which can be a photovoltaic, wind, portable electric or CNG-powered motor generator.Contactless charging (WPT-Wireless Power Transfer) of EV PHEV batteries is currently a consolidated technique through standards created by IEC [7] and SAE [8].The situation was completely different in 2014-2017 when the DACIA Electron EV concept, the first Romanian electric car [9] on a DACIA Sandero vehicle base was developed.The theoretical and practical experience gained then was used in the GASTER Electricway 4WD PHEV.
These standards offer solutions for three power classes: 3.7, 7.2 and 11 kW, generically referred to as WPT1, WPT2 and WPT3, and three working distances depending on the ground clearance of the vehicle in question, defined as follows: Z1 =100-150, Z2=140-210 and Z3=170-250 mm.The standards impose a single operating frequency (85 kHz) for the transfer of electrical energy between the Tx-Rx coils of the inductive coupler associated with the system interoperability conditions according to ISO 19163 [10].The three WPT power classes and Z distances must be interoperable so that both residential and public charging stations can be used regardless of the power level for which they have been sized.
The Table 4 shows the interoperability conditions according to the power class and the Table 5 shows the interoperability conditions according to the ground clearance of the studied vehicle.For GASTER Electricway 4WD PHEV class Z2 is chosen which covers all payload regimes at which it could be used: 140 mm for maximum load up to 210 mm for unloaded vehicle.The choice of power class for the 9.8 kWh battery depends on the duration of the charging process desired by the user.The 9.8 kWh battery at 400 V has a capacity of 24.5 Ah.When charging at power class WPT1 (3.7 kW), the charging current is 9.25 A (C-Rate = 0.38) and the charging time is 160 min, and at power class WPT2 (7.2 kW) the charging current is 18 A (C-Rate = 0.73) and the charging time drops to 78 min.As a result, it is considered that the Tx/Rx sizing in class WPT2 is acceptable depending on the battery cooling conditions.

The sizing the inductive coupler
As shown above, the GASTER Electricway 4WD PHEV Premium is equipped with an Rx receiver sized for WPT2/Z2 according to J2954 [8] shown in Figure 11.The Rx is square-shaped with rounded corners, has 8 turns and 4 mm pitch.Under the coil is a magnetic field concentrator made of ferrite and a 0.5 mm Al plate that prevents the residual magnetic from penetrating the vehicle's steel underbody.The whole assembly is placed in a rugged housing made of a dielectric material.

Conclusions
The GASTER Electricway 4WD is a Plug-in Hybrid Electric Vehicle Concept in development within the Automotive Engineering Research Center of the National University of Science and Technology Politehnica Bucharest -Pitesti University Center in a partnership project between Automotive Engineering Research Center and Renault Technologie Roumanie.
It represents an experimental vehicle for studying the ways of reducing the pollutant emissions of DACIA DUSTER car under 100g CO2/km, using a hybrid system with engine fueled by Compressed Natural Gas (CNG) coupled by an intelligent transmission CVT and a part time all-wheel drive by rear axle electrified.
For reducing the pollutant emissions, we building a new gasoline tank that stopping the gasoline vapors during the CNG and electric mode functioning.
The starting of the thermal engine fueled by GNC is assisted by the ThermoSTART system, an auxiliary system for preheating.This system uses both the thermal energy from the previous use of the engine and the electricity from the network (through the plug-in system).
The battery charging system depends on the GASTER Electricway 4WD PHEV version: the Standard version has only Plug-in charging and the Premium version has both charging/discharging via a bidirectional Plug-in charger with V2G/G2V/V2L and wireless charging from various renewable sources.
Our academic research on this subject will continue with the following stages:  Performing the road tests in order to determine all the performances in real conditions.
 Simulation of the driving, consumptions and performances of the car with the CRUISE software from AVL Austria.

Figure 3 .
Figure 3.The new thermal powertrain of the GASTER Electricway 4WD PHEV with engine fueled by CNG and coupled with an automatic gearbox, CVT Type

Figure 4 .
Figure 4.The refill sockets of CNG and gasoline (left) and the CNG fuel tank with 2 cylinders (right) of the GASTER Electricway 4WD PHEV concept.

Figure 5 .
Figure 5.The cockpit of the GASTER Electricway 4WD PHEV concept with Continuously Variable Transmission.

Figure 6 .
Figure 6.The rear axle "H" type (left), the electric powertrain (center) and the pneumatically supplementary air suspensions (right) of the GASTER Electricway 4WD PHEV concept.

Figure 7 .
Figure 7.The Traction Battery of the GASTER Electricway 4WD PHEV concept installed above the rear axle.

Figure 8 .
Figure 8.The diagram of the ORION 2 Battery Management System adapted of the GASTER Electricway 4WD PHEV Traction Battery [5].

Figure 9 .
Figure 9.The socket 1 Phase, Mennekes Type 2 of the GASTER Electricway 4WD PHEV for charging the traction battery in Standard Mode.

Figure 11 .
Figure11.The Tx transmitter located on the ground (left) and the Rx dimensions according to[8] (right).

Table 1 .
Main GASTER Electricway 4WD PHEV performances.board battery charger (16), the auxiliary 12 V battery charger (18) are mounted in the rear side.The refill socket of the traction battery (17) and the auxiliary 12 V battery (19) are placed on the front side.
3 rear right side.The lithium-ion battery (14) is installed above the rear axle.The Traction Inverter Module for the electric motor (15), the on

Table 2 .
The Traction Battery characteristics.

Table 4 .
The interoperability at different power classes.

Table 5 .
The interoperability at different distances Tx-Rx.