Simulation of Vehicle Performances with Different Power Systems

Introduction

This chapter underscores the imperative to curtail fossil fuel consumption, emphasizing the urgency of transitioning to alternative automotive power systems. With finite reserves of fossil fuels and the escalating costs associated with their energy production for transportation, shifting away from conventional petrol/diesel technologies toward hybrid and electric vehicles becomes an inevitable trajectory for the automotive industry. The recent notable transition indicates a paradigm shift towards sustainability. Hybrid vehicles, incorporating power electronics, embedded powertrain controllers, electric motors, and energy storage devices like ultra-capacitors and batteries, present a viable solution to enhance overall vehicle performance and energy efficiency.

Automated Highway System

The strategic use of advanced computer modelling and simulation before the prototyping phase is recommended to address the challenge of seamlessly integrating electric components into drive train configurations. This approach not only aids manufacturers in navigating complexities but also contributes significantly to cost reduction and enhanced safety during the design phase. This paper delves into the discussion of how modelling and simulation principles serve as a valuable platform to achieve hybrid vehicles' efficient and safe design.

Fossil fuel consumption extends beyond transportation, impacting various industries, including power and heating. Studies indicate an escalating demand for fossil fuels compared to the time required for energy conversion, so exploring alternative energy sources is imperative (Zaroofi, 2008). Furthermore, as highlighted by researchers such as Jalil (1997), the environmental ramifications of fossil fuel use necessitate urgent consideration. The detrimental environmental impact, including global warming and air pollution, underscores the importance of swiftly transitioning to alternative energy sources to address impending environmental challenges.

• Hybrid Vehicles as an Alternative Solution

Given the environmental challenges outlined earlier and the integral role of transportation in our daily lives, there's a pressing need for a sustainable energy source with minimal carbon emissions. As previously discussed, using electric batteries and fuel cells for vehicle propulsion emerges as an economically feasible and environmentally friendly solution. Continuous advancements in power electronics technology and electric components now enable the recapture of renewable energy and the identification of more efficient operating parameters for vehicle combustion systems (Gao and Emadi, 2007). Additionally, various energy management methods can eliminate engine idling time.

The enhanced technology empowers hybrid vehicles to reduce emissions significantly, elevate overall efficiency and performance, and extend the life cycle of nearly all mechanical components. Considering the multitude of benefits associated with hybrid vehicles (HV), it's evident that this technology provides a cost-effective and reliable means to curb carbon emissions, enhance fuel economy, and meet customer demands for improved performance and comfort.

• Hybrid Vehicle Background

In the early 19th century, the United States witnessed a market offering a variety of vehicles, including combustion-powered, electric, and steam-engine vehicles. However, the automotive landscape underwent significant changes as fossil fuels like petrol, diesel, and gas became widely accessible at competitive prices. Pioneers such as Edson, Westinghouse, and Edison led the electric car industry in the United States during this period (Williamson, 2004). In the 1890s and 1900s, it became apparent that electric batteries had limited scope and practicality, prompting manufacturers to prioritize the production of combustion-driven vehicles deemed more suitable for frequent travellers and long journeys.

The inception of hybrid cars in Europe dates back to 1901 when a Jenatzy parallel hybrid system, featuring a 6HP engine, drive, and a 14HP generator, was showcased at the Paris Motor Show. In 1903, a collaborative effort by Lohner Porsche produced another hybrid vehicle with a 21 kW DC Generator and a 20 HP engine, featuring electric motors in each front wheel. The subsequent introduction of the Mercedes Mixte, a collaboration between Mercedes and Lohner Porsche, occurred five to six years later. Unfortunately, due to technological limitations at the time, coupled with increased weight and cost, the production of hybrid cars eventually ceased.

• Hybrid Vehicles Simulation

In comparing conventional and hybrid vehicles, the pivotal role of electric components, including embedded power train controllers, power electronic converters, supercapacitors, batteries, electric motors, and modern mechanical parts, cannot be overstated. Hybrid vehicle (HV) designs integrate these elements with internal combustion engines, presenting a comprehensive approach to improve overall cost-effectiveness, fuel consumption, reliability, and vehicle design (Williamson, 2004).

When engineers embark on designing new hybrid vehicles, the meticulous selection and integration of drive-train components are crucial. These components are then intricately controlled and modified to enhance cost-effectiveness, fuel efficiency, and vehicle reliability. However, achieving these goals is a complex process that may take engineers days or months to finalize. A critical aspect of this design process is creating a simulation environment for each drive train component or part. The simulation of individual components accurately reflects their actual behaviour, proving invaluable in refining designs and reducing vehicle costs.

Simulation and modelling are indispensable before prototyping and analyzing hybrid vehicles, especially when dealing with innovative hybrid power train controllers and configurations. This becomes even more critical when testing novel energy management systems and configurations through computer simulations, offering advantages such as cost reduction, design efficiency, and increased component life cycle. Computer simulations also provide a safer, more cost-effective alternative to executing dangerous, strategically undesirable, complex, and expensive tests and studies. Addressing concerns related to the dependence of power trains on various control strategies is another significant advantage computer simulations offer.

As the name suggests, hybrid vehicles utilise at least two energy sources, typically electric and combustion or heat energy. Achieving optimal power-sharing management between these sources is crucial for ensuring high-class performance. A hybrid vehicle's main components/parts include the transmission, control system, secondary energy converter, primary energy converter, primary energy storage system, and secondary energy storage system.

• Principles/Rules of Modelling and Simulation

Comprehensive computer simulations are conducted for each vehicle type for each component, with users selecting from three modelling categories: quasi-state, dynamic, and steady-state models.

Quasi-state and steady-state models are primarily employed for long-term analyses over varying drive cycles, serving as valuable tools for making high-level operational decisions and architectural choices. Although these models allow for fast computations, they lack accuracy in dynamic simulations (Zaroofi, 2008).

In contrast, dynamic models focus on intricate details, such as lower-level comparisons among support subsystems and designs. Achieving accuracy in dynamic simulation is feasible as these models rely on the differential equations of the components. Studies highlight the essential use of dynamic modelling for achieving precise hybrid vehicle (HV) designs and determining the power requirements of all involved components. Given the higher switch frequency of power electronic devices in hybrid vehicles, dynamic modelling is recommended to compute the peak rating of these electronic components during operation.

Unlike steady-state models, dynamic modelling is recommended for rating components, calculating overall drivetrain efficiency, determining conduction, and estimating switching losses in power converters. Computer simulations encompass various aspects of interest for engineers and manufacturers, including modelling for packaging and cost, emissions, performance, prediction, and optimization for evaluating fuel consumption.

As the level of detail increases, the models become more sophisticated and intricate, potentially leading to a significant increase in simulation runtime. Understanding the relationship between simulation runtime and model complexity is crucial to achieving optimal results.

• Drive Cycles

The drive cycle command proves immensely advantageous as it encapsulates the pattern dictated by a scheduled speed. Drive cycle assumptions posit that acceleration remains constant during the time step, resulting in speed being a linear function of time. Consequently, the required mechanical energy can be determined as a function of time, given the known acceleration and speed at each time point. The formula for the mechanical energy function over time will be explored later (Sandberg, 2001). For motorway driving cycles, a dynamometer may be employed. In the case of internal combustion engine (ICE) driven vehicles, emissions and fuel consumption are directly calculated. It is important to note that primary energy is computed from the fuel consumption.

• CVT

Continuously Variable Transmission (CVT) is an automatic transmission type that enhances fuel economy, amplifies power and delivers a superior driving experience compared to conventional transmission systems (CVT, 2013).

• MATLAB

MATLAB is a mathematical software that is extensively utilized for numerical calculations and visualization. MATLAB emerges as the clear and preferred choice when dealing with programs that involve fundamental data elements such as matrices and array-based data.