Energy Management of a Series Hybrid Electric Powertrain (this one)
- 1. Energy Management of a Series Hybrid Electric Powertrain System (EMoSHEPS) By: Saifuddin Abdul Halim (Mech Eng MEng) Project Supervisor: Dr Saber Fallah
- 2. Introduction Why Hybrid? • Due to the increasing vehicle emissions, researchers and vehicle manufacturers resorted to develop electric vehicle as an alternative. • Disadvantages of EV results in the introduction of hybrid vehicle.
- 3. Why series HEV? • Equivalent Consumption Minimization Strategy (ECMS) was originally introduced by Paganelli et al., in 2002 for parallel configuration. • Series HEV has a huge potential due to the downsizing of the engine as well other factors such as the removal of gearbox, simplifying the configuration reducing vehicle mass. • Beneficial for urban-driving cycle.
- 4. What is ECMS? • The basis of ECMS is that discharging of power from the battery at any instant will results in equivalent fuel being consumed by the ICE to recharge the in the future and vice versa. • ECMS reduces the overall fuel consumption by minimizing the total equivalent fuel consumption. • The total fuel consumption is the sum of fuel consumed by the ICE to drive motor via generator and the fuel consumed to recharge the battery. 𝐺𝑡 = ṁ𝐼𝐶𝐸 𝑃𝐼𝐶𝐸,𝑑𝑒𝑚 𝑡 + ṁ 𝐵𝑎𝑡𝑡,𝑒𝑞 𝑃𝐵𝑎𝑡𝑡 𝑡 𝑃𝐼𝐶𝐸,𝑑𝑒𝑚 𝑡 = 𝑃𝐼𝐶𝐸,𝑑𝑟𝑖𝑣𝑒(𝑡) 𝜂 𝑔𝑒𝑛 + 𝑆𝑐ℎ𝑔 𝜂 𝑔𝑒𝑛 𝜂 𝐵𝑎𝑡𝑡 𝑃𝐼𝐶𝐸,𝑟𝑒𝑐ℎ𝑔(𝑡) ṁ 𝐵𝑎𝑡𝑡,𝑒𝑞(𝑡) = 𝑆 𝑑𝑖𝑠 𝑃𝐵𝑎𝑡𝑡 𝜂 𝐵𝑎𝑡𝑡 𝐻𝐿𝐻𝑉
- 5. Disadvantages • Tendency of significant power source variation that leads to dramatic wheel-torque oscillation. • Possibility of delayed and hesitation of torque response / poor throttle response. • In series HEV, these problems can be reduced due to having only one type of energy, electrical energy, supplied to the EM and since the ICE is decoupled from the driving the wheels.
- 6. Objectives Modelling a conventional and a series hybrid powertrain. Identifying and applying basic operating conditions. To simulate the Equivalent Consumption Minimization Strategy (ECMS) control strategy. Carrying out forward simulations for both models under two different driving conditions. Comparing fuel economy as well as the velocity performance of both vehicles. Optimizing the ECMS parameters to achieve a minimum of 15% reduction in fuel consumption.
- 7. Modelling Model of Series HEV
- 8. Model of Conventional vehicle
- 9. ECMS controller & power distribution Driver determines current angular speed Accelerate Decelerate Increase in Angular Speed Decrease in Angular Speed Determine corresponding torque demand at EM via characteristic curves; +ve for driving or -ve for RBS Calculation of Power demand, P(dem); +ve for driving or -ve for RBS Negative Power (RBS) Positive Power (Driving) SoC P(ICE,opt)=P(maxICE) P(Battery,opt)=0 P(ICE,rchg)=0 P(ICE,opt)=P(dem) P(Battery,opt)=0 P(ICE,rchg)=P(maxICE)-P(dem) P(demand,EM)=P(ICE)+P(Battery) P(demand,EM) = P(Battery) P(ICE,opt)=0 P(Battery,opt)=0 P(ICE,rchg)=0 P(EM,rchg)=P(dem) SoC ≥ SoC (max)SoC ≤ SoC (min) SoC (min) < SoC < SoC (max) P(dem)>P(maxICE) P(dem)<P(maxICE) Fuel consumption Determination of Fuel Consumption using ICE fuel flow map Calculation of torque supplied to drivetrain Drivetrain Transmission system Vehicle velocity Wheels
- 12. Change in equivalency factor The performance evaluated • Overall fuel consumption at the end of the drive. • Velocity trend of the vehicle. Equivalency Factor, 𝑺 𝒅𝒊𝒔 1.125 (-10%) 1.250 1.375 (+10%)
- 13. Results Cruising mode Series HEV Conventional Fuel consumption 0.989 1.199 Max Velocity 92.5 79.0 Improvement in fuel consumption (%) 17.5 N/A
- 14. Random driving mode Series HEV Conventional Fuel consumption 0.699 0.975 Max Velocity 113.5 159.7 Improvement in fuel consumption (%) 28.3 N/A
- 15. Change in equivalency factor, Sdis Equivalency Factor, 𝑺 𝒅𝒊𝒔 Total Fuel Consumption (L) Cruising mode Random Driving mode 1.125 (-10%) 0.985 0.685 1.250 0.989 0.699 1.375 (+10%) 0.991 0.711 N/A 1.199 0.975
- 16. Conclusion The implementation of ECMS in series HEV managed to reduce fuel consumption up to 17.5% than the conventional vehicle under cruising mode and up to 28.3% under cruising mode. Although fuel consumption is reduced, but the downsizing of engine in series HEV means that the benefit is achieved at the expense of vehicle velocity. ECMS controller also able to adapt to change in its own parameter. In addition, the benefits of the ECMS are also transferable between configurations and also driving conditions.