نشریه تحقیقات موتور
پیاپی 58 (بهار 1399)

Hybrid electric vehicles are getting more attention due to the fuel consumption and emission issue in megacities. Energy management strategy and battery capacity are the primary factors for the energy efficiency of range-extended hybrid electric vehicles. Iran khodro Powertrain Company has unveiled a series of hybrid electric vehicles and is improving its performance constantly. In the present study, minimum battery and generator capacity based on experimental data of this vehicle for different driving conditions are presented. Based on the direct integration of experimental data, minimum battery size is calculated to get extremums in energy consumption. Generator capacity is also calculated based on energy slope curve. Small battery size improves battery integration into the vehicle and also the vehicle weight is reduced that improves fuel consumption. The hybrid electric vehicle is also simulated on different driving cycles to ensure that the calculated battery and generator size is appropriate in different conditions.

Nowadays, environmental pollution is increasing more and more and in the big cities, because of the concentration of the population, is more intense. Air pollution in the big cities has become a serious problem especially in Iran. High fossil fuel consumption of vehicles is a major cause to increase in the amount of air pollution. Using new technology of powertrain, like other developed countries, is only way to control and reduce the air pollution. Electronic vehicle, which is known as zero-emission vehicle, is one of the solutions that are noticed by most of the car manufacturer. Hybrid Vehicle is actually a stepping-stone to eliminate fossil fuel as an energy source of the vehicles. In this research, the latest hybrid electric vehicle of IPCO as the first developed Hybrid vehicle in Iran is introduced and the real experimental result for the Euro standard emission test of the vehicle is presented. Electric and fuel consumption of the vehicle in the standard cycle NEDC are 12.5 kwh/100km and 3.3 liter/100km, respectively.

In this study, the Li-ion batteries temperature increase during the discharge process was measured empirically and evaluated using numerical simulation. Moreover, the battery packs cooling using the water, air and water-nano composition fluids such as water-alumina, water-copper oxide, and water-gold was studied through numerical simulation. Accordingly, the battery cooling was simulated by CFD method and the results were compared with water and air coolants. The results indicated the significant effect of nanofluid on the battery packs cooling under the same conditions. The batteries mean temperature with 5C discharge rate with the cooling process with water-alumina was decreased to 305.31 K after 300-sec discharge (Initial temperature: 300 K). The mean temperature of batteries under the cooling process with water-copper oxide and water-gold nanofluid was decreased to 307.09 and 301.14 K, respectively. However, the temperature of the battery packs was respectively decreased to 362 and 313 K using air and water-fluid cooling. Another important point is that lithium-ion batteries are subject to spontaneous discharge at 60%, which confirms the results of the present research. In air cooling method, the discharge rate of batteries reached 61.5%, while other nanofluids (water, water-copper oxide, and water-alumina) decreased the discharge rate by 57% and water-gold nanofluid dropped the discharge rate to 53%.

Due to the air pollution crisis and increase in greenhouse gases, emission standards are getting tougher gradually. In the other hand reducing the consumption of nonrenewable resources is one of the main goals of the automotive industries in the world. Using electric propulsion along with internal combustion engine is one of the answers. Different designs of Hybrid Electric Vehicles (HEV) have been represented in recent years. Considering the limitations and cost of these vehicles, mild hybrid technology is one of the main choices of manufacturers. These vehicles can be a cost effective choice due to low variation in propulsion system and components, along with its reliability. This paper discusses the reduction of fuel consumption caused by implementing a 48V mild hybrid system in a conventional vehicle. A complete internal combustion engine (ICE) powered vehicle model, is simulated through the GT-SUITE software and fuel consumption during the NEDC & WLTC driving cycles is studied. Based on results, mild hybrid system provides respectively 5% & 9% better fuel economy in WLTC & NEDC driving cycles.

Whereas reducing carbon pollutant and fossil fuel energy consumption have become the most important environmental and economic concerns in the world, electric vehicles and their cooling system are in automotive industry manufacturers and designers agendum more than ever. Various motor electromagnetic and mechanical losses act as heat sources and could lead to performance falloff and premature exhaustion indisputably, if they don’t dissipate by an appropriate cooling system. Thus, in present work, a model has been prepared in Motor-CAD software for Nissan LEAF’s BPM electric motor and after modelling various losses in it by means of 2D and 3D simulations with finite element method, it has been attentively investigated in terms of cooling system performance and hotspot temperatures and locations in four popular distinct standard driving cycles. It has been revealed in results that diversities in driving patterns can lead to different thermal reactions in vehicle’s electric motor. These changes can even rearrange thermal critical points and move hotspots to different parts of motor. Beside quantitative point of maximum temperatures, various transient responses have been monitored in simulations results and hotspot location moved differently in each cycle. Main novelty of the present research is clarifying the point that in order to design an efficient and suitable cooling system for electric motors in vehicles, driving pattern characteristics must be taken into account.

In driving and when you brake, a lot of energy is dissipated to stop the car; especially in urban areas where the vehicle is driving in a stop-and-go pattern. This energy, which is dissipated by the brake pads, can be stored in the vehicle's battery. In Hybrid and Electric Vehicles, a regenerative brake can be used alongside the mechanical brakes to regenerate some energy while braking. The purpose of this article is to investigate the appropriate time to use the regenerative brake, the amount of energy recoverable versus the vehicle's speed, braking power and deceleration rate, the amount of energy on front and rear axles, to investigate the braking power to meet the two requirements of providing the required brake force and not locking the wheels (not to slide the wheels) and to investigate two parallel and fully controlled hybrid braking systems. To this end, a Dena hybrid vehicle was used and the recovered energy during Europe and Tehran city driving cycles was computed and compared with each other. The results shows a significant and efficient effect of the use of the regenerative brake system to utilize the braking energy and consequently the energy consumption reduction for the hybrid vehicles in Tehran city driving.