Plug-In Hybrid Power Train Engineering, Modeling, and Simulation

Chapter 10 presents the principles of the plug-in hybrid power train (PHEV) operation. The power trains of the battery-powered vehicle (BEV – pure electric) are close to the plug in hybrid drives. For this reason, the pure electric mode of operation of the plug in hybrid power train is very important. The vehicle’s range of driving autonomy must be extended. It means the design process has to be focused on energy economy, emphasizing electricity consumption. Simultaneously, the increasing of the battery’s capacity causes its mass and volume also to increase. Generally, it is not recommended. After many tests, one can observe the strong dependence between the proper multiple gear speed, the proper mechanical transmission adjustment, and the vehicle’s driving range, which in the case of the plug-in hybrid power train means long distance of a drive using the majority the battery’s energy. The mechanical ratio’s proper adjustment and its influence on the vehicle’s driving range autonomy is discussed in the chapter. Three types of the automatic mechanical transmission are depicted: the toothed gear (ball), the belt’s continuously variable transmission, and the planetary transmission system called the “Compact Hybrid Planetary Transmission Drive,” equipped additionally with tooth gear reducers, connected or disconnected by the specially constructed electromagnetic clutches. The number of mechanical ratios—gear speeds—depends on the vehicle’s size, mass, and function, which in the majority of cases means the maximal speed value.

Basic Simulation Study during the Process of Designing the Hybrid Power Train Equipped with Planetary Transmission

Chapter 9 is devoted to simulation research showing the influence of changes of the power train’s parameters and control strategy on the vehicle’s energy consumption, depending on different driving conditions. The control strategy role is to manage how much energy, frankly speaking, how much of the torque-speed relations referring to the power alteration, are flowing to or from each component. In this way, the components of the hybrid power train have to be integrated with a control strategy, and of course, with its energetic parameters to achieve the optimal design for a given set of constraints. The hybrid power train is very complex and non-linear to its every component. One effective method of system optimization is numerical computation, the simulation, as in the case of the multivalent suboptimal procedure regarding the number of electrical mechanical drive’s elements, whose simultaneous operation is connected with the proper energy flow control. The minimization of a power train’s internal losses is the target. The quality factor is minimal energy, as well as minimal fuel and electricity consumption. The fuel consumption by the hybrid power train has to be considered in relation to the conventional propelled vehicle. First of all, the commonly chosen statistic driving cycles should be taken into consideration. Unfortunately, this is not enough. The additional tests as for the vehicle’s climbing, acceleration, and power train behavior, referring to real driving situations, are strongly recommended during the drive design process.

Generic Models of Electric Machine Applications in Hybrid Electric Vehicles Power Train Simulations

Chapter 4 presents an approach to obtain the power simulation model of electric machines that would be practically useful in hybrid power train simulation studies. The induction motor (AC) and the permanent magnet motor’s (PM) mathematical dynamic models are based on the necessary and fundamental knowledge conveyed in the previous chapter. These generic models are here adapted to the hybrid power train requirements, while the mechanical characteristics of the vehicle’s driving system are relegated to the background. The vector field oriented control of induction and permanent magnet motors is applied in the conducted mathematical modeling. The influence of the controlled voltage frequency is discussed as well. In the case of permanent magnet motors, the adjusted method of magnetic field weakening is very important during pulse modulation (PWM) control. The chapter presents the model of synchronous permanent motor magnetic field weakening. The basic simulation studies’ results dedicated especially to the above-mentioned electric motors are included. One of the targets of these simulations is the determination of these electric machines’ static characteristics (motor’s map) as the function: output mechanical torque versus the motors’ shaft rotational speed. This feature is indicated as the map of electric machines connected with its efficiency in a four quarterly operation (4Q), which means the operation of the motor/generator mode in two directions of the shaft rotational speed, which appears very useful in practice.

Introduction to The Hybrid Power Train Architecture Evolution

The hybrid power train is a complex system. It consists of mechanical and electrical components, and each of them is important. The evolution of the Hybrid Electric Vehicle (HEV) power trains is presented from the historical point of view. This chapter discusses the selected review of the hybrid power train’s architectural engineering. It includes the development of the hybrid vehicle power train’s construction from the simple series and parallel drives to the planetary gear hybrid power trains. The fuel consumption difference between the pure Internal Combustion Engine (ICE) drive and the hybrid drive is especially emphasized. Generally, there are two main hybrid drive types that are possible to define. Both these hybrid drive types are not mainly differentiated by their power train architecture. The first is the “full hybrid” drive, which is a power train equipped with a relatively low capacity battery that is not rechargeable from an external current source, and whose battery energy balance—its State-Of-Charge (SOC)—has to be obtained. The second one is the “plug in hybrid,” which means the necessity of recharging the battery by plugging into the grid when the final State-Of-Charge (SOC) of the battery is not acceptable. Additionally, the chapter focuses on the fuel cell series hybrid power train, which is only shown because its operation and design are beyond the scope of this book.

Basic Design Requirements of an Energy Storage Unit Equipped with Battery

The storage unit is understood as the battery. Practically, it is true in the majority of cases. However, another type of electro-chemical energy storage unit can be considered, which is the capacitor. The most important is of course the battery and the emphasis is put on the battery’s thermal behavior, its State-Of-Charge (SOC) indication and monitoring as the background of the Battery Management System’s (BMS) design. The chapter discusses the original algorithm base of the nonlinear dynamic traction battery’s modeling, which includes the battery temperature impact factor. The battery State Of Charge (SOC) coefficient presented in this chapter has to be determined in terms of its maximal accuracy. This is very important for the control of the entire hybrid power train. The battery state of charge signal is the basic feedback in power train online control in every operation mode: pure electric, pure engine, or in the majority, the hybrid drive operation. Electro-chemical capacitors applied in hybrid power trains are commonly called super or ultra capacitors. The application of ultra capacitors in hybrid electric vehicle power trains does not seem to be a strong alternative to the batteries. The exemplary complex solution of the parallel connection of the battery and the capacitor as a means of increasing the cell’s lifetime and decreasing its load currents is also discussed in this chapter. Voltage equalization for both energy storage devices is depicted. For the ultra capacitor this is necessary.

Fundamentals of Hybrid Power Trains Equipped with Planetary Transmission

Chapter 8 describes the most advanced hybrid power trains, which were generally depicted in Chapter 1. The presented figures consist of the two degrees of freedom planetary gears. It seems to be the best system of energy, split between the Internal Combustion Engine (ICE), the battery, and the electric motor, but unfortunately, it is also the most costly solution for its manufacture. This type of hybrid power train should be preferred as the best drive architecture composition from the technical point of view. For this reason, this chapter, in a detailed way, describes the features and the modeling approach to the planetary hybrid power train. Certainly, most attention is paid to the planetary two degrees of freedom gears, yet not only to them. Cooperating with the planetary gears, additional and necessary devices are considered. The role and modeling auxiliary drive components, such as the automatic clutch-brake device and mechanical reducers are discussed in this chapter. The design of electromechanical drives related to the planetary gear of two degrees of freedom controlled by the electric motor can be transformed to the purely electromagnetic solution. An example of the mentioned gear is given in the chapter. It is a complicated construction with the rotating stator of a complex, electrical machine requiring multiple electronic controllers. The increasing output torque of the electromechanical converter and its connection with the mechanical two degrees of freedom planetary gears are depicted as well.

Nonlinear Dynamic Traction Battery Modeling

The role of the battery as the source of power in Hybrid Electric Vehicles (HEVs) is basic and significant. The process of battery adjustment and its management is crucial during the hybrid and electric drive design. The approach to battery modeling based on the linear assumption (as the Thevenin model) and then adopted for the data obtained in experimental tests, is here ignored, because the dynamic nonlinear modeling and simulations are the only tools for the optimal adjustment of the battery’s parameters according to the analyzed vehicle driving cycles. The battery’s capacity, voltage, and mass should be minimized, considering its overload currents. This is the way to obtain the minimal cost of the battery. Chapter 5 presents the method of determining the Electromotive Force (EMF) and the battery internal resistance as time functions, which are depicted as the functions of the State Of Charge (SOC). The model is based on the battery’s discharge and charge characteristics under different constant currents that are tested in a laboratory experiment. The algorithm of battery’s State-Of-Charge (SOC) indication is depicted in detail. The algorithm of battery State-Of-Charge (SOC) “online” indication considering the influence of temperature can be easily used in practice. The Nickel Metal Hydride (NiMH) and Lithium ion (Li-ion) batteries are taken into consideration and thoroughly analyzed. In fact, the method can also be used for different types of contemporary batteries, if the required test data is available.

The Energy–Power Requirements for HEV Power Train Modeling and Control

The first step in the hybrid vehicle power train design, of course, after choosing the drive architecture, is the analysis of the power distribution and energy flow between the Internal Combustion Engine (ICE) (considered in this book only as the primary source of energy – PS) and the energy accumulator (called the source of power, or a secondary energy source – SS). The role of the Primary Source (PS) is to deliver to the system the basic energy, while the Secondary Source (SS) feeds the hybrid power train during its peak power loads and stores the vehicle’s kinetic energy during the regenerative braking. The target of these considerations is to search for the minimal necessary power of the Primary Source (PS) and the minimal energy capacity of the Secondary Source (SS). Certainly, this computation requires the proper energy flow model and the basic vehicle driving cycle, in the role of which the statistic driving cycle is recommended. The main aim of this chapter is the depiction of the above problem, as well as the finding of its solution. The background of the energetic evaluation of the hybrid drive structure is the dynamic determination of the internal watt efficiency of each of the propulsion system’s components. The complex construction of the hybrid drives requires an appropriate control strategy from its designers. In order to achieve this aim numerical optimization methods of nonlinear programming can be applied.

Basic Hybrid Power Trains Modeling and Simulation

Chapter 7 is devoted to the basic and existing in present-day vehicles, power train modeling, and simulation. Generally, there are series and parallel hybrid power trains. In both cases, the role of the internal combustion engine and its dynamic modeling is significant. The two aspects of modeling should be considered. The one devoted to the energy distribution, the second to the local internal combustion engine’s control. For the Internal Combustion Engine (ICE) the dynamic modeling method is proposed. Using the simulation of the well-determined map of the ICE can be accepted. In the practical application of a series power train, it is necessary to consider different control strategies of the internal combustion engine’s operation. The most significant are the “constant torque” and the “constant speed” control method. The other important problem, because the Internal Combustion Engine’s (ICE) generator unit is a strong nonlinear object, is the modeling of the permanent magnet generator, connected by the shaft with the ICE. As for the common parallel hybrid power train, two of its types were, in dynamic modeling, tested by simulation. One of them is the hybrid power train equipped with an automatic (robotized) transmission. Generally, it is possible to state that this transmission can be used as the Automatic Manual Transmission (AMT) or the Dual Clutch. The second one is the split sectional hybrid power train and is the most simple solution. The Hybrid Split Sectional Drive (HSSD) applied in an urban bus is also presented.

Electric Machines in Hybrid Power Train Employed Dynamic Modeling Backgrounds

The Alternative Current (AC) induction, asynchronous motor, and the Permanent Magnet (PM) synchronous, or the Brushless Direct Current (BLDC) motor, which are types of the Permanent Magnet (PM) synchronous machines, can be applied in hybrid power trains. This chapter presents the fundamental theory as a necessary background to the mentioned motors’ generic dynamic nonlinear model determination. The differential equations based on the phase quantities as a complete system of equations describing the transients should include the equations of winding voltages and the equations of motion for the rotating parts of the machine. The phase quantities in terms of the resultant phasors as the background to dynamic modeling are taken into consideration. Introducing a complex (a, ß)-plane stationary relative to the stator of a two-pole model equations set is carried out including transformation from the a- and ß-axis components of the stator quantities to the d- and q-axis components of rotor quantities. This chapter is a source of the advanced knowledge concerning the principles of electric machine modeling. It might be useful for mechanical engineers engaged in the hybrid vehicle power train design process, but also for electrical engineers, especially those attending master and doctoral courses.