8131 Hysteresis Current Controller

FIGURE 8.12 (a) Hysteresis current control and PWM output. (b) Ramp comparison control and PWM output. FIGURE 8.12 (a) Hysteresis current control and PWM output. (b) Ramp comparison control and PWM output. The hysteresis current controller can be used in a three-phase PWM inverter, with each phase having its own PWM controller. If the actual current is higher than the reference current by the amount of half of the hysteresis band, the lower leg switch of the bridge inverter is turned on to...

Figure P33

A 12 V battery is connected to a series RL load as shown in Figure P3.3. The battery has a rated capacity of 80 Ah. At t 0, the switch is closed, and the battery begins to discharge. (a) Calculate and plot the battery discharge current, i(t), if the steady state discharge rate is C 2. Neglect battery voltage drop. (b) Calculate and plot SoD(t) in Ah for 0< t< 2 h. (c) Calculate and plot SoC(t), assuming that at t 0 the battery is charged to rated capacity. Assume also that the rated...

333 Liion Battery

Lithium metal has high electrochemical reduction potential (3.045 V) and the lowest atomic mass (6.94), which shows promise for a battery of 3 V cell potential when combined with a suitable positive electrode. The interest in secondary lithium cells soared soon after the advent of lithium primary cells in the 1970s, but the major difficulty was the highly reactive nature of the lithium metal with moisture, restricting the use of liquid electrolytes. Discovery in the late 1970s by researchers at...

36 Targets And Properties Of Batteries

The push for zero-emission vehicles led to numerous research and development initiatives in the United States, Europe, and Japan. The California legislative mandates in the early 1990s led to the formation of the U. S. Advanced Battery Consortium (USABC) to oversee the development of power sources for EVs. The USABC established obj ectives focusing on battery development for mid-term (1995 to 1998) and long-term criteria. The purpose of the mid-term criteria was to develop batteries with a...

552 Simplified Torque Expression

A simplified linear torque expression is sufficient to analyze the motor-load interaction, because the induction motor is invariably always operated in the linear region at maximum flux density with the help of a power electronic feed circuit. The segment of interest in the torque speed characteristic curve of the induction motor is shown by the firm line in Figure 5.20. Synchronous speed is set by the applied voltage frequency, and the slope of the linear region is set by design dimensions and...

42 Supercapacitors And Ultracapacitors

Capacitors are devices that store energy by the separation of equal positive and negative electrostatic charges. The basic structure of a capacitor consists of two conductors, known as plates, separated by a dielectric, which is an insulator. The power densities of conventional capacitors are extremely high ( 1012 W m3), but the energy density is very low ( 50 Wh m3).9 These conventional capacitors are commonly known as electrolytic capacitors. They are widely used in electrical circuits as...

544 Space Vector Representation

The extensive amount of coupling existing among the circuits of three-phase AC machines makes analysis a formidable task. Axes transformations or reference frame theory is necessary to decouple the voltage expressions of the phases as well as to implement control algorithms that achieve the best performance. Space vector representation is a convenient method of expressing the equivalent resultant effect of the sinusoidally space distributed electrical and magnetic variables in AC machines, in a...

31 Battery Basics

The batteries are made of unit cells containing the chemical energy that is convertible to electrical energy. One or more of these electrolytic cells are connected in series to form one battery. The grouped cells are enclosed in a casing to form a battery module. A battery pack is a collection of these individual battery modules connected in a series and parallel combination to deliver the desired voltage and energy to the power electronic drive system. The energy stored in a battery is the...

10212 Air Standard Otto Cycle

The Otto cycle is the idealized air-standard version of the practical cycle used in SI engines. The airstandard Otto cycle assumes that heat addition occurs instantaneously under constant volume when the piston is at the TDC. The cycle is illustrated on ap-v(pressure-volume) diagram in Figure 10.6. The intake stroke starts with the intake valve opening at the TDC to draw a fresh charge into the cylinder. The intake valve is open between 1 to 5 to take the fresh charge, which is a mixture of...

72 Power Electronic Switches

An electronic switch is one that can change an electric circuit configuration by switching states from on to off and vice versa. The electronic switch of Figure 7.3a FIGURE 7.3 Ideal switch and its conduction characteristics. (a) Switch symbol (b) switch characteristics in four quadrants. FIGURE 7.3 Ideal switch and its conduction characteristics. (a) Switch symbol (b) switch characteristics in four quadrants. is an ideal four-quadrant switch, which means that it can handle bidirectional...

Table of Contents

Chapter 1 Introduction to Electric Vehicles 1 11 EV System 2 1.1.1 Components of an EV 2 1.2.5 Recent EVsand HEVs 8 1.3 EV Advantages 9 1.3.1 Efficiency Comparison 9 1.3.2 Pollution Comparison 10 1.3.3 Capital and Operating Cost Comparison 11 1.3.4 U.S. Dependence on Foreign Oil 13 14 EV Market 13 2.1 Roadway Fundamentals 18 2.4 Dynamics of Vehicle Motion 25 2.5.1 Force-Velocity Characteristics 27 2.5.2 Maximum Gradability 28 2.6 Velocity and Acceleration 29 2.6.1 Constant Ftr. Level Road 29...

4123Direct Methanol Fuel Cell DMFC

The direct methanol fuel cell (DMFC) is a result of research on using methanol as the fuel that can be carried on-board a vehicle and reformed to supply hydrogen to the fuel cell. A DMFC works on the same principle as the PEM, except that the temperature is increased to the range of 90 to 120 C such that internal reformation of methanol into hydrogen is possible. The electrical efficiency of DMFC is quite low at about 30 . This type of fuel cell is still in the design stages, because the search...

541 Sinusoidal Stator Windings

The three-phase stator windings of AC machines are sinusoidally distributed spatially along the stator circumference, as shown in Figure 5.9a, to establish a sinusoidal mmf waveform. Although the windings are shown as concentrated in locations aa', bb', and cc' for the three phases, the number of turns for each of the phase windings should vary sinusoidally along the stator circumference. This theoretical space sinusoidal distribution of Phase-a winding is shown in Figure 5.9b, which has been...

6221 Voltage Balance Equation

The general equation governing the flow of stator current in one phase of an SRM can be written as where Vph is the DC bus voltage, iph is the instantaneous phase current, Rs is the winding resistance, and ph is the flux linking the coil. The SRM is always driven into saturation to maximize the utilization of the magnetic circuit and, hence, the flux-linkage ph is a nonlinear function of stator current and rotor position The electromagnetic profile of an SRM is defined by the i characteristics...

321 Cell Discharge Operation

In the cell discharge operation (Figure 3.2), electrons are consumed at the positive electrode, the supply of which comes from the negative electrode. The current flow is, therefore, out of the positive electrode into the motor-load, with the battery acting as the source. FIGURE 3.2 Lead-acid battery cell discharge operation. FIGURE 3.2 Lead-acid battery cell discharge operation. The positive electrode equation is given by > hO is . 411- x i + SO.' cup -i > > ly A(), t- i .() . A highly...

10324 Maximum Gradability

The maximum gradability condition must be checked once the sizing of the IC engine and the electric motor is done from the previous three requirements. The maximum gradability of a vehicle is given by If the condition is not met, then the size of the engine or the motor or both must be increased or the gear ratio must be changed to meet the gradability requirements. Although the design philosophy outlined above states that the IC engine sizing primarily comes from the rated cruising velocity,...

Problems

A length of road is straight, and it has a profile in the x-y plane described by where 0 x 3 miles 15,840 ft f(x) and x are in feet. (a) Plot the road profile in the x-y plane for 0 x 15,840 ft. (b) Derive an expression for B(x). Calculate B(500 ft). (c) Derive an expression for percent grade (x). Calculate percent grade (500 ft). (d) Derive an expression for tangential road length s(x), such that s(0) 0. Calculate s(500 ft). (e) Can you find an expression for x(s), i.e., can you express x as a...

131 Efficiency Comparison

To evaluate the efficiencies of EV and ICEV on level ground, the complete process in both systems starting from crude oil to power available at the wheels must be considered. The EV process starts not at the vehicles, but at the source of raw power whose conversion efficiency must be considered to calculate the overall efficiency of electric vehicles. The power input PIN to the EV comes from two sources the stored power source and the applied power source. Stored power is available during the...