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Low Cost Range Extender Technology for Hybrid Electric City Scooters
Abstract
Electric driving is generally limited to short distances in an emission sensible urban environment. In the present situation with high cost electric storage and long charging duration hybridization is the key to enable electric driving. In comparison to the passenger car segment, where numerous manufacturers are already producing and offering different hybrid configurations for their premium class models, the two wheeler sector is not yet affected by this trend. The main reason for the retarded implementation of this new hybrid technology is its high system costs, as they cannot be covered by a reasonable product price. Especially for the two wheeler class L1e, with a maximum speed of 45km/h and an engine displacement of less than 50cm3, the cost factor is highly important and decisive for its market acceptance, because the majority of vehicles are still low-cost products equipped with simple carbureted 2 stroke engines. Hybridization of this vehicle class is therefore a very cost sensitive task and enforces low-cost solutions. The present paper (within the framework of the ECO-PowerDrive [7] project conducted at the Institute of ICE, research area design, located at Graz University of Technology) assesses a hybridization concept with range extender. Special emphasis is put on the interaction of the main components - generator and combustion engine - in order to deduce specifications. The application of a simple port scavenged two stroke engine is evaluated on the basis of experimental data and simulation results with respect to the principles of economy, emissions and consumption. Part reduction and system simplification are the keys for a suitable cost efficient hybrid system.
... Energy consumption can be found to calculate size of battery. [5] Power to weight ratio = Rated power / Mass of vehicle PWR=PP/mv PWR = 6/0.32 PWR ~ 19 kW/tonne Since the power to weight ratio is lesser than 22 kW/tonne, WLTC Class 1 test standards are to be followed. ...
With the world shifting to EVs from conventional fossil fuel run automobiles, there should exist a mediator to effectively make this switch effortless and smooth, atleast to overcome range anxiety and the resistance to use new technology. Therefore, we propose a self- charging HEV and not a complete PHEV. Since the Indian automobile market comprises of mostly two-wheelers that make up 50% of the total sales, it is a good platform to introduce a hybrid powertrain. Key factors are that it should be cheap, easy to run and maintain, highly fuel efficient and should give good performance than its traditional ICE only counterparts. The main idea for this paper is from old diesel-electric locomotives that used a rudimentary hybrid layout to put power to the wheels via an electric motor. Our concept uses the same principle but optimised for a two-wheeler. The bike is powered by a single cylinder petrol or a single cylinder diesel engine that acts as a generator to power a battery which in turn powers a motor to drive the rear wheel. The older locomotives used traction motors to pull heavy loads, whereas our motorcycle can be set to a speed of high torque and low fuel consumption to increase its range which ultimately matters to the Indian consumer. The battery itself can be smaller to reduce the weight that is attributed to EVs. This kind of self-charging EV is especially useful in emerging EV markets like India who is planning a shift to EVs in the near future.
Due to the small number of two wheelers in Europe and their seasonal use, their contribution to the total emissions has been underestimated for a long time. With the implementation of the new emission regulation 168/2013 [3] for type approval coming into force 2016, the two wheeler sector is facing major changes. The need to fulfil more stringent emission limits and the high demand on the durability of after treatment systems result in an engine control system that is getting more complex and therewith more expensive. Especially the low cost two wheelers with small engine capacities will be affected by increasing costs which cannot be covered by the actual competitive product price. Therefore, new vehicle concepts have to be introduced on the market. A vehicle concept of a plug in hybrid electric city scooter with range extender as well as the range extender itself have already been published in SAE Papers 2011-32-0592 [1] and 2012-32-0083 [2]. The low cost range extender is composed of a simple, throttle-less operated, port controlled two stroke engine and an externally controlled generator. The number of sensors is intentionally reduced for economic reasons. In this paper, the experimental investigation focusing on the control of the above described range extender subsystem for L1e class PHEV two-wheelers and its impact on the tail pipe emissions are presented. Different configurations of range extender system controls, categorized according to their complexity, will be discussed and evaluated with regard to their impact on tail pipe emissions in the official ECE-R47 test cycle. The results of these studies determine the final operation strategy of the hybrid system to fulfil the emission limits in accordance with the procedure described in regulation 168/2013 [3]. The research has been performed by a research consortium under the patronage of the ECO-PowerDrive project [6], which is funded by the Austrian government within the COMET excellence initiative.
Hybrid electric vehicles are today being touted as the answer to the depleting petroleum reserves, growing concerns for environmental protection and in meeting stricter emission norms [4]. The fact that these vehicles offer a marked improvement in the fuel economy of the vehicle and that their usage does not call for any infrastructural change as in the case of pure electric vehicles, is bound to make these vehicles play a significant role. This paper describes an alternate charging system for a series hybrid two wheeler, using the traditional 12V starter motor [7]. The paper presents MATLAB simulation results to compare the variation in vehicle battery voltage in case a single battery is used with a 12V starter system as compared to a combination of a lead acid and Li-ion batteries. The second part of the paper describes a controlled power distribution system to optimize the power distribution during the charging cycle for the same vehicle [6]. MATLAB simulations are used to show that this system helps reduce the load on the alternator thereby increasing fuel efficiency and also prevents deep discharge of the vehicle battery in conditions when a large load is applied to an already discharged battery.
Nowadays, politicians are forced by air pollution prevention to demand zero emission vehicles (ZEV) in the form of pure electric vehicles. The poor capacity to weight factor of actual batteries compared to any kind of liquid or gaseous hydro-carbon fuel is the main reason for the retarded implementation of ZEV. Solutions offered by automobile manufacturers are mild to full hybrid powertrains based on the well established ICE platform. The difficulty of those approaches of electrification is to compete with the performance and benefit costumers expect from standard automobiles. Pure electric vehicles are rare and often disappointing regarding range and/or performance. Additionally the costs for such vehicles, which are mainly driven by the battery prices, are comparatively high, impeding their market entrance and acceptance. Low price electric city scooters are actually offered as pure electric vehicles in a wide variety of different models. The category of city scooters (L1e [1]) is regulated regarding limited speed and engine capacity. The driving distance is generally short and additional comfort features (such as heaters or air condition) are not expected nor demanded by the customers. The selling numbers of electric city scooters are strongly depending on the local legislation. In case of the establishment of restricted areas with exclusive access for zero emission vehicles, their share will be positively affected due to the capability of pure electric driving. The only disadvantage is range distance uncertainty due to the small battery size of such economic vehicles. This can either be improved by increasing the battery capacity (negative influence on costs) or by implementing a Range Extender technology (greening influence) with a simultaneous decrease of the battery size. A small combustion engine with a generator, loading the batteries in case of long distance driving, is required. The analysis of existing electric scooters and the theoretical implementation of a small Range Extender in a simulation model (via PHEM [2] MATLAB, and MS Excel) of a scooter are able to assess the application of Range Extender technologies in electric scooters for standard driving cycles. Additionally, decisions concerning engine and generator have to be made as well as careful considerations on packaging, costs, weight, economics and other ecological factors. Finally, the presentation of a draft design of a Range Extender package demonstrating its potential completes this study.
Intensive R&D is currently performed worldwide on hybrid and electric vehicles. For full electric vehicles the driving range is limited by the capacity of currently available batteries. If such a vehicle shall increase its driving range some range extending backup system should be available. Such a Range Extender is a small system of combustion engine and electric generator which produces the required electricity for charging the batteries in time. Since the acoustic response of an electric motor driving the vehicle and of a combustion engine as part of a Range Extender is very different by nature an extensive acoustic tuning of the Range Extender is necessary to meet the requirements of exterior vehicle noise and passenger comfort. This paper describes the NVH (noise, vibration & harshness) development work of a range extender within the AVL approach of an electrically driven passenger car with range extender. This work started with an acoustic front loading in the concept and design stage and was continued with intensive testing during combustion and engine development followed by the acoustic integration into the electric vehicle.
In this paper, the deterioration of catalysts in small, four-stroke, spark-ignition engines is described. The laboratory testing performed followed a proven test method that mimics the lifetime of a small air-cooled utility engine operating under normal field conditions. The engines used were single-cylinder, 6.5-hp, side-valve engines. These engines have a nominal 125-hr lifetime. The effectiveness of the catalysts was determined by testing exhaust emissions before and after the catalyst to determine the catalyst's efficiency. This was done several times during the lifetime of the engines to determine the deterioration in the performance of the catalysts at lowering pollutant emissions. Additional testing was performed on the catalysts to determine wear patterns, contamination, and recoverable activity. The results indicate that considerable catalyst deterioration is occurring over the lifetime of the engine. The results reveal that soot buildup, poisons, and active surface loss appear to be the contributing factors to the deterioration. These results were determined after analyzing the exhaust emissions data, scanning electron microscope results analysis, and the impact of regeneration attempts. An ANOVA statistical analysis was performed, and it was determined that the emissions are also impacted, to some degree, by time and the engine itself.