Efficiency Improvement Of Electric Vehicle By Using Dual Speed Transmission

doi:10.21203/rs.3.rs-4365238/v1

The future of transportation leads significantly towards sustainability and efficiency, which are optimized by the development of electric vehicles. This project explores the development of a dual-speed transmission model for EVs using MATLAB simulation to assess the potential gains in efficiency and overall vehicle performance by using the MIDC drive cycle. System requirements, including the desired gear ratios, drive cycle, vehicle mass, motor torque, etc., to achieve specific efficiency and performance goals. MATLAB Simulink is used to create a simulation model that includes a dynamic EV powertrain with a dual-speed transmission subsystem. The project will compare the implications of integrating a single-speed transmission system with a more complex dual-speed transmission system, examining their impacts on the vehicle's range and SOC consumed.

Single speed transmission

Dual speed transmission

Range

MATLAB Simulink

SOC

drive cycle

Electric vehicles (EVs) represent a promising solution for sustainable transportation, offering reduced emissions and operational costs compared to conventional vehicles. Range anxiety is one of the major concerns for the electric vehicle industry. To further optimize the performance of EVs, this project investigates the integration of a dual-speed transmission system. By leveraging MATLAB Simulink for simulation and analysis, the aim is to enhance both efficiency and range, key factors influencing the adoption of electric mobility. Through the exploration of dual-speed transmission technology.

Efficiency improvement in electric vehicles (EVs) is a major concern, as it directly impacts range, energy consumption, and the overall performance of vehicles. One innovative approach to enhancing EV efficiency is the integration of a dual-speed transmission system. Dual-speed transmissions optimize and improve performance under varying driving conditions. This technology allows for more efficient use of the electric motor's power, resulting in reduced energy consumption and increased range. In this project, we explore the electric vehicle design in MATLAB Simulink and simulation for single-speed transmission and dual-clutch speed transmission. Through modeling, analysis, and optimization, we aim to demonstrate how this technology can contribute to the advancement of sustainable and energy-efficient transportation solutions. The electric vehicle model consists of a DC motor, a lithium-ion battery, a motor controller, a vehicle body, a single- and dual-speed transmission system, and an and an MIDC drive cycle.

When the physical model is ready in Matlab Simulik, run the simulation for both single and dual speed transmission separately and check for how much range increases in dual speed transmission as compared to single speed transmission. At the same time, also check for how much battery SOC is consumed to cover a distance for a particular time run of the simulation of the vehicle. In this way, we can also check the SOC consumed for both single-speed and dual-speed transmissions to get an idea of the battery SOC consumed.

2.1 Drive cycle: The drive cycle block source is taken from Matlab Simulink. In this block, the FTP-75 drive cycle by default comes, but there is an option to add or load a different drive cycle, and these (.mat,.xls,.xlsx, or.txt) file formats are supported. In this block set, the MIDC drive cycle is added, with a maximum speed of 50 km/h.

Ports:

Output: RefSpd — Vehicle reference speed

Refspd :Referance speed of vehicle

Input: VelFed — Vehicle longitudinal speed

Velfed : Feedback velocity of vehicle

2.2 Longitudinal Driver: The longitudinal driver is an in-built block provided by the powertrain blocks. It acts as a speed controller to generate braking and acceleration commands based on reference and feedback velocities that can vary from 0 to 1.

The VelFdbk port corresponds to the feedback velocity. The actual velocity output given by the vehicle body is connected here. By comparing the actual (feedback) velocity with the reference velocity, the driver block generates acceleration and braking signals in order to minimize the error between the two concerned velocities. The grade corresponds to the grade angle. For this simulation, no inclination is considered, and hence, a constant block with a value 0 is connected.

Acceleration and deceleration commands are generated, respectively, and are connected to the corresponding ports of the Controlled Voltage block. Proportional-integral (PI) control is used by the block to monitor feed-forward and wind-up gains.

Figure 3 shows the acceleration graph based on the longitudinal driver acceleration commands, which vary from 0 to 1.

2.3 H-bridge: The PWM port's input signal determines the controlled voltage source. It is connected to both the H-bridge's output, which supplies the DC motor with a controlled voltage, and PWM, which regulates voltage signals.

Ports:

+: Positive load connection port

-: Negative load connection port REF: REF is the floating zero-volt reference.

REV: Reverse threshold voltage

BRK: Braking threshold voltage

PWM: This stand for pulse width modulation, which provides the voltage pulses to H-bridge average mode, is used.

2.4 DC Motor: The DC motor is connected with single- and dual-speed transmission separately. In this case, the case, the thermal effect of the motor is not considered.

Table no.1 DC motor parameter

Motor: Rated by load and speed

Maximum Speed (rpm)	14000
DC voltage (V)	320
Rated load (KW)	84

2.5 Battery: The Battery Pack subsystem consists of a battery block, a controlled source, a power GUI block, and a bus selector. The controlled current source receives a signal from the H-Bridge, which is current, and these blocks m are connected to the battery block. A bus selector is connected to Li-ion batteries, which show the SOC, voltage, and current of the battery.

Table No. 2: Battery Parameters:

Rated capacity (Ah)	106.31
Nominal voltage (V)	326.4

2.6 Vehicle body: A two-axle vehicle in longitudinal motion is modeled by the Vehicle Body Block, a simulation tool that takes into account factors like body mass, aerodynamic drag, road inclination, weight distribution, and externally defined mass and inertia.

Table No. 3: Vehicle Parameters:

Vehicle mass (Kg)	1360
No. of wheels per axle	2
Acceleration due to gravity (g)	9.81 m/s^2
Aerodynamic drag coefficient (Cd)	0.15
Rolling resistance coefficient (µ)	0.01
Gradiability	5°
Vehicle frontal area (A)	2.9 m^2
Gear ratio	11.8, 8.2

Single-speed transmission: Matlab simulation run for 1000 seconds in which the vehicle covers a distance of 21.23 km, initial SOC of the battery is 100, and the SOC drops from 100 to 70.85 Ah.

In Figure 4, feedback velocity and reference velocity for single-speed transmission are shown. In which feedback velocity flow the reference velocity based on the MIDC drive cycle, which is shown in figure no. 2 in the MIDC drive cycle.

The initial SOC of the battery is 100% and drops to 70.85% during the vehicle simulation run for 1000 seconds for single-speed transmission. As shown in figure no. 5

Dual speed transmission: Matlab simulation run for dual clutch speed transmission t = 1000 sec in which vehicle cover a distance of 29.35 km and initial SOC of battery is 100 and SOC drop from 100 to 67.08Ah.

In figure no. 8, the feedback velocity flow is based on the reference velocities based on the MIDC drive cycle, in which the maximum speed is 50 km/h.

Discharge of battery SOC during dual-speed transmission. As shown in figure 9,

As shown in figure 10, In a dual-speed transmission, switching between gears alters the motor's RPM and torque output. The low-speed gear increases torque at lower RPM for better acceleration and climbing, while the high-speed gear sacrifices some torque for higher RPM and efficiency during cruising.

Figure 12 shows the gear change from gear 1 to gear 2.

A physical model of an electric vehicle made in Matlab Simulink for single-speed transmission and dual-speed transmission in the MIDC drive cycle The results of single- and dual-speed transmission are then obtained by running Matlab Simulink. Electric vehicle models run for t = 1000 sec for both single-speed and dual-speed transmissions. The single-speed transmission covers a distance of 21.23 km, and the battery SOC drops from 100% to 70.85%. In the case of dual-speed transmission, cover a distance of 29.35 km and the battery SOC drop from 100% to 67.08 (Ah)..

Table no.4 Result of range improvement and SOC

MIDC drive cycle	Distance (KM)	SOC Consumed
Single speed transmission	21.23	70.85
Dual speed transmission	29.35	67.08
Range efficiency(Based on distance covered)	27%
SOC Consumed (Dual speed transmission) more SOC consumed		5.32%

As shown in Table 4, Hence, the range of the vehicle increases by 27% based on the distance covered by dual-speed transmission when compared with single-speed transmission. The battery SOC drop for both single-speed transmissions is less than that for dual-speed transmissions. Dual-speed transmission consumed more energy than single-speed transmission.

In this study, we find a result of the dual-speed transmission system on the efficiency and range of electric vehicles, particularly under the MIDC drive cycle. When a dual-speed transmission is integrated instead of a single-speed transmission, our results show an improvement in the distance traveled but consume more SOC.

In the MIDC drive cycle, the electric vehicle physical model in Matlab Simulink equipped with a dual-speed transmission achieved a distance of 29.35 kilometers, consuming only 67.08% of the battery SOC. In contrast, the same vehicle with a single-speed transmission covered a distance of 21.23 kilometers while consuming 70.85% of the battery SOC. This represents a notable increase in range efficiency, with the dual-speed transmission configuration demonstrating a 27% improvement in distance covered.

However, it is important to note that the dual-speed transmission resulted in a slightly higher SOC consumption, approximately 5.32% more than the single-speed transmission. This suggests that while the dual-speed transmission enhances overall efficiency and range, it may require further optimization to minimize energy consumption.

Author Contribution

Both author work equally in this project.

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No competing interests reported.

Efficiency Improvement Of Electric Vehicle By Using Dual Speed Transmission

Status:

Version 1

Abstract

Figures

1. INTRODUTION

2. METHODOLOGIES

3. RESULT AND DISCUSSION

4. CONCLUSION

Declarations

Author Contribution

References

Additional Declarations

Status:

Version 1