Energy management system of the hybrid ultracapacitor-battery electric drive vehicles

The search for new, alternative propulsion and energy sources in transport is one of the economic and technological priorities of the current decade. The modern development of hybrid drives and electric means of transport makes it possible to at least partially diversify conventional drive systems. The study discusses the use of a battery and ultraca-pacitor in electric vehicles. Simulation analyzes of energy flow were performed using the solutions of electric drive systems and various energy storage control algorithms. The research was carried out in relation to the use of braking energy, its conversion into electricity and its storage in a battery or ultracapacitor. The operating conditions of the battery and the ultracapacitor were assessed in terms of specific energy consumption while driving. The article pro-posed the use of a drive system connected in series, the last link of which was an ultracapacitor. Such a solution signif-icantly reduced the use of the battery as well as its regular charging-discharging. At the same time, it required the use of a high-capacity ultracapacitor, which contributed to increasing its charging time. The analyzes were carried out using standardized research tests as well as tests in real traffic conditions. The research was carried out with the use of the AVL Cruise software for the analysis of energy flow in vehicles; a middle class passenger vehicle was selected for the tests, equipped with an electrochemical battery and – in the next stage of the research – an ultracapacitor. Three research models were used: I) typical electric drive system; II) a system with the use of ultracapacitors ran by a simple control algorithm; III) a system with the use of ultracapacitors with an advanced control algorithm (the algorithm took into account the change of driving conditions to the ultracapacitor charging conditions). The advantages of using ultracapacitors in the electric drive of a vehicle were demonstrated, especially for results obtained in real traffic condi-tions. Analyzing the simulation tests results allowed to determine the most advantageous options of utilizing these systems, in particular in the aspect of increased possibilities of algorithms controlling the flow of electricity in the drive system

Symulacyjna analiza energochłonności pojazdów elektrycznych w testach badawczych

The assessment of energy flow through electric vehicle systems makes estimating their energy consumption possible. The article presents analyzes of the energy consumption of electric vehicles in selected driving tests (NEDC, WLTC and in real traffic conditions – RDC test) in relation to the vehicles different curb weight. The use of electric motors was also analyzed, providing their operating ranges, data of the energy flow in batteries and the change in their charge level. Simulation tests and analyzes were carried out using the AVL Cruise software. It was found that despite similar vehicle energy consumption values in NEDC and RDC testing, there are significant differences in energy flow in vehicle subsystems. The changes in the battery charge level per 100 km of test drive are similar in both the WLTC and RDC tests (6% difference); for the NEDC test, this difference is the greatest at 25% (compared to the previous tests). The energy consumption of electric vehicles depends significantly on the test itself; the values obtained in the tests are in the ranges of 10.1–13.5 kWh/100 km (NEDC test); 13–15 kWh/100 km (WLTC test) and 12.5–16.2 kWh/100 km in the RDC test. The energy consumption values in the NEDC and WLTC tests, compared to the RDC test, are approximately 20% and 10% lower, respectively. Increasing the vehicle mass increases the energy consumption (increasing the vehicle mass by 100 kg was found to increase the energy consumption by 0.34 kWh/100 km).Ocena przepływu energii przez układy pojazdów elektrycznych umożliwia oszacowanie ich energochłonności. W artykule przedstawiono analizy dotyczące zużycia energii pojazdów elektrycznych w wybranych testach jezdnych (NEDC, WLTC oraz w rzeczywistych warunkach ruchu – test RDC) w odniesieniu do zróżnicowanej masy pojazdów. Analizie poddano również wykorzystanie silników elektrycznych, przedstawiając mapy ich pracy, wielkości przepływu energii w akumulatorach oraz stopień zmiany ich naładowania. Badania i analizy symulacyjne wykonano z wykorzystaniem oprogramowania AVL Cruise. Stwierdzono, że mimo podobnych wartości energochłonności pojazdów w testach badawczych NEDC oraz RDC, to występują znaczące różnice przepływu energii w układach akumulacji pojazdów. Zmiany stopnia naładowania akumulatora odniesione do 100 km testu są zbliżone w testach WLTC oraz RDC (różnica 6%); dla testu NEDC różnica ta wynosi maksymalnie 25% (w odniesieniu do poprzednich testów). Energochłonność pojazdów elektrycznych jest silnie zależne od testu badawczego; wartości uzyskane w testach kształtują się na poziomie 10,1–13,5 kWh/100 km (test NEDC); 13–15 kWh/100 km (test WLTC) oraz 12,5–16,2 kWh/100 km w teście RDC. Wartości energochłonności w testach NEDC oraz WLTC są odpowiednio mniejsze o około 20% i 10% w odniesieniu do testu RDC. Zwiększenie masy pojazdu zwiększa zużycie energii (zwiększenie o 100 kg masy pojazdu zwiększa zużycie energii o 0,34 kWh/100 km)

Numerical investigation of lambda-value prechamber ignition in heavy duty natural gas engine

Turbulent Jet Ignition systems are mainly dedicated to the combustion of lean mixtures of natural gas in heavy duty engines. The use of such a system in combination with lean mixtures leads to an increase in its overall efficiency. The article presents simulation analyzes of the impact of the air excess coefficient occurring in prechamber on the combustion process: combustion indicators and emission indicators. Tests on a single-cylinder engine with a displacement of about 4 dm3 at medium mixture (IMEP = 1.0 MPa) were carried out using the AVL Fire software. It was found that the incineration of global lean mixtures (λ = 2) is effective when initiating this process (in the prechamber) with a charge of a stoichiometric composition. A strong relationship was found between the thermodynamic indicators in both prechamber and main chamber and the air excess coefficient initiating combustion

Modeling of Fuel Cells Characteristics in Relation to Real Driving Conditions of FCHEV Vehicles

Fuel cells are one of the zero-emission elements of modern automotive drive systems. This article presents theoretical identification of the component parameters of indicators for the fuel cell operating conditions. Activation, ohmic, and mass transport losses were identified. Current–voltage characteristics were provided along with an analysis of typical cell losses. The actual performance characteristics of fuel cells were analyzed for Toyota Mirai I and II generation vehicles. The fuel cells operating conditions were derived and analyzed in the context of real driving conditions. Therefore, urban, rural, and motorway conditions were used. The vehicles were equipped with PEM fuel cells supplying power equal to 114 kW (1st gen.) or 128 kW (2nd gen.). The average fuel cell stack power values depend on the driving conditions: urban (about 10 kW), rural (20 kW) and motorway (about 30–40 kW) driving modes. The different power ratings of fuel cells combined with different battery generations resulted in a variation in the cells operating conditions. Analyses conducted in various traffic conditions indicated the possibility of determining losses related to the fuel cells. The analysis of fuel cell losses shows the greatest values for activation losses when the cells are under high load (for both generations)—i.e., in motorway driving conditions. The voltage of resistive losses reached its maximum in urban driving conditions when the load on the fuel cells was small

Analysis of mass transfer in marine engine with prechamber combustion spark ignition system

The development of combustion systems construction is associated with the possibility of increasing the thermal or overall efficiency of an internal combustion engine. The combustion systems currently in use (mainly related to direct fuel injection) are increasingly being replaced by hybrid systems, including direct and indirect injection. Another alternative is the use of prechambers in new combustion systems. This article concerns the thermodynamic aspect of this issue – namely, the assessment of the inter-chamber f low of a marine engine equipped with a prechamber combustion spark ignition system. The research was carried out using mainly one-dimensional simulation apparatus, and detailed analyses were presented using three-dimensional modeling. The tests included the engine model at medium load. Differences in mass f lows were shown at different diameters and different numbers of holes from the preliminary chamber (while maintaining the same cross-sectional area). Similar values of excess air coefficient during ignition of the fuel dose in the prechamber were observed, which resulted in changes in the f low between the prechamber and the main chamber. The differences in mass f low affected the temperatures achieved in the individual combustion chambers. Based on three-dimensional analyses, the mass transfer rate between the chambers and the temperature distribution were assessed during fuel ignition initiated in the prechamber

Control algorithms for a Range Extender vehicle with an combustion engine

The combination of two drive sources: the internal combustion engine and the electric motor in the hybrid drive system requires an appropriate control system to manage their operation. It relies on many variables, and the greater the degree of drive hybridization the greater is the degree of interdependence of the parameters involved. The article presents solutions of electric drive control algorithms with an additional power source in the form of an internal combustion engine (Range Extender). The results of simulation analyzes in the AVL Cruise program are presented, taking into account three control algorithms and two driving cycles. The obtained results indicate the necessity to take various input quantities into account in order to optimize the use of the combustion engine

Cooperation of a PEM fuel cell and a NiMH battery at various states of its charge in a FCHEV drive

The development of electromobility is focused on the design and implementation of increasingly more effective electric drives. In such a system, apart from energy recovery, it is not possible to recharge the batteries while driving. Electric vehicles equipped with fuel cells and a battery (FCHEV – fuel cell hybrid electric vehicle) in a parallel configuration boast increased energy transfer capabilities. The article presents an energy flow analysis in a parallel hybrid drive system with fuel cells and a battery. The research was carried out on a 30 W vehicle made in 1:10 scale with a NiMH battery and a fuel cell with a proton exchange membrane (PEM). Increasing driving dynamics causes a 29% increase in energy consumption, 43.6% reduction of energy transfer from a fuel cell and a 23% increase of in the energy share intended for battery charging. Continuous operation of the system in full power mode ensures a much greater efficiency of energy transmission to the drive train (95%) compared to the system operating in dynamic driving conditions – 64–75%

Optimizing the shape of a compression-ignition engine combustion chamber by using simulation tests

Modern solutions used in compression-ignition internal combustion engines are quite similar to each other. The use of high-pressure, direct fuel injection results in high combustion rates with controlled exhaust emissions. One of the combustion system quality criteria is to obtain adequately high thermodynamic indicators of the combustion process, which are obtained through, among others, the right combustion chamber geometry. Its shape influences the fuel atomization process, turbulence of fuel dose, evaporation and the combustion process. Optimizing the combustion chamber shape is one of the decisive factors proving the correct execution of the combustion process. This article presents the methodology of choosing the combustion chamber shape (changes of three selected combustion chamber dimensions) by using the optimization methods. Generating multidimensional data while maintaining the correlation structure was performed by using the Latin hypercube method. Chamber optimization was carried out by using the Nelder-Mead method. The combustion chamber shape was optimized for three engine load values (determined by the average indicated pressure) at selected engine operating conditions. The presented method of engine combustion chamber optimization can be used in low and high speed diesel propulsion engines (especially in maritime transport applications)