Power converters

Utdity power distribution grids normally operate at a fixed frequency of 50 or 60 Hz. These frequencies can be utilized directiy for the induction process if the load characteristics are appropriate. If they are not, specific appHcations can be optimized by the use of variable and higher frequencies produced by soHd-state frequency power converters connected between the supply and the load. 

The efficiency of an induction furnace installation is determined by the ratio of the load usehil power, P, to the input power P, drawn from the utihty. Losses that must be considered include those in the power converter (transformer, capacitors, frequency converter, etc), transmission lines, cod electrical losses, and thermal loss from the furnace. Figure 1 illustrates the relationships for an induction furnace operating at a constant load temperature with variable input power. Thermal losses are constant, cod losses are a constant percentage of the cod input power, and the usehd out power varies linearly once the fixed losses are satisfied. 

Specifications of basic requirements for power converters 14256/1995 BSEN 60146-1-/1993... 

ANSI/lEEE-519/1993 Guide for harmonic control and reactive compensation of static power converters ... 

Fig. 5.65 Dependence of the solar conversion efficiency (CE) on the threshold wavelength (Ag) for a quantum converter at AM 1.2. Curve 1 Fraction of the total solar power convertible by an ideal equilibrium converter with no thermodynamic and kinetic losses. Curve 2 As 1 but the inherent thermodynamic losses (detailed balance and entropy production) are considered. Continuous line Efficiency of a regenerative photovoltaic cell, where the thermodynamic and kinetic losses are considered. The values of Ag for some semiconductors are also shown (according to J. R. Bolton et al.)... 

Troubleshooting switching power converters a hands-on guide / By Sanjaya Maniktala. p. cm. 

A major Taiwanese customer was once having trouble with the DC-DC power converters on their rather complex board meant for a high-end notebook computer. My company eventually ended up with a rather bloody nose, losing several million dollars in a derailed deal. But it was not really all their fault. When I looked at the board, I was quite aghast. 

Volvo is also a partner in another European project, the Capril project, which is managed by Volkswagon. A fuel cell VW Golf was built to run on methanol. Volvo developed the compressor, power converter and energy control system. 

We have selected a broad cross section of analog and mixed-mode designs, which we have simulated, as well as constructed. The circuits are grouped into logical chapters. Generic topics, such as oscillators, amplifiers/receivers, power converters, and filters, all head their own chapter. Each chapter starts with a brief overview of the function of the circuits in the chapter. This is followed by several circuit examples. For instance, in the chapter on reference circuits, the beginning details what reference circuits are and their uses at the system level. This is followed by a detailed discussion on a single type of reference circuit, the band gap reference. 

Power converter circuits are often the most overlooked aspect of a system. During the engineering phase, power is not a concern. There are plenty of bench power supplies scattered around the laboratory for use in breadboarding. Even in SPICE, the trusty voltage source element provides infinite voltage and infinite current for new circuit designs. 

Multiple output power converters may not provide regulation that is good enough to meet the requirements of every output. The regulation of a single output of the converter may require some type of post regulation to meet the regulation requirements of that output. In many... 

Now the difference between the total power input (Eq. E2.5-22) and the total viscous dissipation (Eq. E2.5-24) is the power converted into pressure. Indeed, if we subtract the latter from the former, we get exactly qiPr — Pq), which is the power input required for raising the pressure. This pressure also will be converted into heat through a die, and therefore the expression given in Eq. E2.5-23 correctly gives the total power input into the exiting fluid. 

The energy for driving all high-capacity electric motors is obtained from the AC network. AC motors can be supplied directly from the AC network, as long as the motor is to be operated at nominal speed. If variable speed is specified, AC motors are equipped with a frequency converter. In DC motors, power converters are used. 

A power converter generates a pulsating DC voltage from the three-phase mains. DC motor speed is determined by the amount of DC voltage generated that can be altered via the thyristor control angle of the power converter. 

A DC motor is feedback-controlled by a current sub-control loop and a primary speed control loop. In order to close the control loop, the actual current value is fed back to the current control loop and a speed signal to the speed control loop. While current is measured in the power converter, a shaft encoder on the motor is required for speed signal feedback. Either a tacho-generator or a digital encoder is used as a speed transmitter. If speed measurement accuracy is not very important, the speed feedback can be measured via armature voltage. In this case, this measurement can also be done within the power converter. Static control accuracy reaches... 

The total energy dissipation of a power converter under maximum load is less than 1 % of motor output. 

Finally, an AC-DC power converter is also installed in the system, having a cost of ca. 670 /kW (Khan and Iqbal, 2005). The total installed capacity of the converter is 10 kW, therefore the total capital cost of the converter accounts for 6700 . 

If the review is conducted overseas, two main issues may arise. Firstly, the local language may be inconsistent with available specific safety review software or a consultant, if used, may not be available in the host country language. A translator is sometimes used in these instances. Secondly, if a portable personal computer is used, its power requirements may be different both in voltages and plug connections. In these circumstances it is best to plan ahead and bring power converters, adapters and multiple outlet busbars. 

Also obtainable from abb.com is PCS 500 - Power Converter Systems modular standard converter system, showing PEBBs (Power Electronics Building Blocks) a modular approach to converter design. 

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