Power Circuit Analysis

Comparing an FCV with the internal combustion engine, there is a big difference in the way power transmission takes place. In an internal combustion engine, energy from gasoline or diesel is transmitted from the engine to the wheels through a mechanical power circuit (Fig. 9.3). 

FCVs are special as they have electrical power transmission, whereas a hybrid vehicle may be a combination of electrical and mechanical power transmission. Hybrid vehicles are further categorised as FCV with parallel hybrid power circuit and FCV with series hybrid power circuit as shown in Figs. 9.4 and 9.5, respectively. 

As shown in Fig. 9.4, in parallel hybrid power circuits the fuel cell delivers power to the motor and charges the battery when required. It also provides extra power to the motor for acceleration once the battery is fully charged. In the case of a series hybrid power circuit, all the power is delivered by battery so it needs to be large. The function of the fuel cell is only to charge the battery depending on driving conditions it can be of relatively low power. Such vehicles generally use alkaline fuel cells. 

In the case where the fuel type is hydrocarbon for a solid oxide fuel cell (SOFC) unit, it can be catalyticaUy converted into hydrogen and carbon monoxide within the cell stack, known as internal reformation. Carbon monoxide and hydrogen thus produced are then electronically oxidised to carbon dioxide and water at the anode with the production of heat and electric current. Internal reforming can be of two types, as shown in Fig. 9.6  

The elevated operating temperatures of SOFC provide it a key advantage of fuel flexibility over other types of fuel cells. SOFCs show greater tolerance to carbon monoxide, and other impurities and variations in fuel composition. This allows for the possible use of a variety of renewable fuel sources such as biogas, vegetable matter, etc., which are not viable in other types of fuel cells. 

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A frequently demonstrated problem in beginning circuit analysis courses is, what value of RL in the circuit of Figure 4-1 will deliver maximum power to RL With a little bit of circuit analysis and some calculus, it can be shown that for fixed Rs, maximum power will be delivered to RL when RL is equal to Rs. We will demonstrate this result using PSpice. Wire the following circuit ... 

Steven M. Sandler is the founder of AEi Systems, LLC, the world leader in SPICE modeling and worst case circuit analysis since 1995. He has developed and taught courses at Motorola University and has published many books and articles on circuit simulation for McGraw-Hill and Power Electronics, PCIM, and PEIN magazines. 

The diagnostic power of the equivalent circuit analysis is seen in Fig. 4.16, in which the effect of increasing dissipation (resistance R) on the shape of the spectrum is clearly visible. 

The fundamental laws for circuit analysis are Ohm s law and Kirchhoff s laws. Ohm s law, described above, can be used to find the current, voltage, and power associated with a resistor. However, in some cases Ohm s law by itself cannot analyze the circuit. Analytical solutions for most electric networks need to combine Ohm s law and Kirchhoff s laws, the latter being also known as Kirchhoff s current law (KCL) and Kirchhoff s voltage law (KVL). 

However, although powerful numerical analysis software, e.g., Zview, is available to fit the spectra and give the best values for equivalent circuit parameters, analysis of the impedance data can still be troublesome, because specialized electrochemical processes such as Warburg diffusion or adsorption also contribute to the impedance, further complicating the situation. To set up a suitable model, one requires a basic knowledge of the cell being studied and a fundamental understanding of the behaviour of cell elements. 

H. Qian, S. R. Nassif, S. S. Sapatnekar. Power Grid Analysis using Random Walks. IEEE Trans, on Computer-Aided Design of Integrated Circuits and Systems, Vol. 24, No. 8, Aug. 2005, pp. 1204- 1224. 

As a first constraint, recall that all passive tags require that power be derived from the incident carrier frequency broadcast by the reader. For low-cost applications, this will likely be in the high frequency (HF) or UHF bands, as discussed previously. Given the performance limitations of organic materials, it is highly unlikely that harvesting of UHF frequencies will be possible. As a result, the circuit analysis here will focus exclusively on HF tags. 

All circuits which contain inductive reactance and resistance have an X-to-R ratio, in practice between 2.0 and 100.00. In short-circuit analysis it is usually necessary to relate the asymmetrical current to the symmetrical current. This can only be done if the short-circuit power factor of the circuit and hence the X-to-R ratio is known. Table 8.1 shows the relationship between these parameters and currents. Normally the short-circuit power factor is low, between 0.01 and 0.45. It is customary in short-circuit analysis to assume that one of the phases has the worst-case situation of fully asymmetrical current. Figure 8.1 shows an example, together with the various definitions of times and currents. 

Electrical cable schedule Voltage drop calculations Electrical area classification Electrical instrument interface drawings Underground electrical cable and cable trench arrangement Electrical equipment layout drawings Motor control center and power layout Load and short-circuit analysis VSDs configuration Plant lighting plan... 

The Finite Element Method Using MATLAB , Second Edition, Young W. Kwon and Hyochoong Bang Fluid Power Circuits and Controls Fundamentals and Applications, John S. Cundiff Fuel Cells Principles, Design, and Analysis, Shripad Revankar and Pradip Majumdar Fundamentals of Environmental Discharge Modeling, Lorin R. Dams... 

FIGURE 1.25 Loudspeaker power response by circuit analysis. 

Ideal, perfect Linear inductor having only a pure inductance, i.e., no power loss is related to the flow of time-varying current through the inductor winding. In the ideal inductor, the current of sine wave lags the induced voltage by angle (p = 90° (jt/2 rad). The concept of the ideal inductor is used only in idealized or simplified circuit analysis. 

Sneak circuit analysis is usually performed with complex computer codes and is very expensive. It only becomes cost-effective on subsystems that are safety critical, such as an aircraft control system. Obviously, sneak circuit analysis should be teamed with the software safety analysis tools discussed in Chapter 8. This is a very powerful combination, but not cheap, certainly, very important for the most safety-critical circuits of very high-risk systems. 

Later in the risk assessment process, once the scenarios of particular interest are clear, FMEA is a very powerful tool for focusing on which component is the trigger in the event and how to make it more robust in the system. The same is true of sneak circuit analysis, cause-consequence analysis, or dispersion modeling. 

Clarke, E, 1943. Circuit Analysis ofA-C Power Systems, Vol. 1, Symmetrical and Related Components. New York Wiley. 

After the basic methodology was set, WSRC began to establish a bounding set of equipment necessary for safe shutdown given any single credible fire. Power, instrument, and control cables for the safe shutdown equipment were identified associated circuits and cabling were also identified. Fire areas for the safe shutdown analysis were defined. Each fire area was analyzed for postulated credible fire, with and without reactor area power. This analysis included the ability of reactor operators to perform necessary safe shutdown plant manipulations given. the fire.,... 

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