Switch mode power supplies

Fig. 8. SMPS = switch mode power supply. Weight reduction of 100 W power supplies from the 1960s through the early 1990s.

Switched mode power supplies (SMPS), ferrites in, 77 77-82... 

Sandler, Steven M. 2006. Switch-Mode Power Supply Simulation with PSpice and SPICE... 

Polystyrene capacitors have exceptionally low tan S values (< 10 q, making them well suited for frequency-selective circuits in telecommunications equipment. Polymer capacitors are widely used for power-factor correction in fluorescent lighting units, and in start/run circuitry for medium-type electric motors used in washing machines, tumble-dryers and copying machines for example. They are also used in filter circuits to suppress radio frequencies transmitted along main leads. Such interference noise may originate from mechanical switches, furnace controllers and switch mode power supplies it not only spoils radio and television reception but can also cause serious faults in data-processing and computer equipment. 

A particularly important application for aluminium electrolytic capacitors is in switch mode power supplies (SMPSs) which are now extensively used, especially in computer systems. In this application the capacitor is used essentially to smooth a rectified voltage, but it inevitably passes a ripple current I which, because of the capacitor s e.s.r., rs, leads to power losses I2rs. The switching frequency determines the size of an SMPS, and frequencies have increased from about 50 kHz to about 300 kHz over the past decade. This has led to the multilayer ceramic capacitor s challenging the aluminium electrolytic in this important application, and the signs are that it will continue to do so. 

Fig. 9.17 Range of soft ferrite components (i) TV scanning yoke (components kindly supplied by Philips Components Ltd.) (ii) UR core and TV line output transformer (iii) E core for switched mode power supply (iv) wide band transformer core (v) core giving good magnetic shielding (vi) high Q (adjustable) filter core (cf. Fig. 9.48) (vii) precision ferrite antenna for transponder (viii) multilayer EMI suppressors (ix) toroids for laser and radar pulse applications (x) typical EMI shields for cables, ((ii)—(x) Courtesy of Ferroxcube UK .)...

Ferrites having a square hysteresis loop (e.g. (Mg, Mn, Zn) Fe204), developed for the now outdated computer core memories, have found applications in the form of a toroidal saturable inductor for regulating the output currents in switched-mode power supplies. 

Until the recent development of switched mode power supplies (SMPS), most industrial precipitators were energized from some type of 50-60 Hz rectified high voltage equipment. This basically comprised a suitably designed and insulated step-up transformer, the output from which can be controlled by employing silicon controlled rectifiers to modulate the incoming... 

High-quality motors and generators, stators and armatures, switched-mode power supplies... 

A particular application requiring soft ferrites that has rapidly grown in importance in the last few years is power supplies for computers, peripherals and small instruments. A compact and efficient power unit can be obtained by using a technique known as switched-mode power supply (SMPS). It may seem peculiar that in this technique, involving a dc to dc conversion, one of the key elements is a high-frequency transformer. 

Power distribution transformers Switched-mode power supplies (SMPSs) 400 Hz transformers Electromagnetic shielding Magnetomechanical transducers Security systems... 

From the description of the possible contributors to noise it is clear that one may expect broadband random noise (often called white noise) and noise contributions at specific frequencies, e.g. like the frequency of electric mains at 50 or 60 Hz or high-firequency voltage spikes from a switch-mode power supply conceptual examples are included in Figure 14.1. 

A ceramic chip capacitor of 100 p.F was developed with nickel electrode system to meet the condition of decoupling capacitors for VLSI and switching mode power supply. The fundamental characteristics of the newly developed X5R 100 xF MLC are shown in Table 5.1.3. A large volumetric efficiency... 

Computer-Aided Analysis and Design of Switch-Mode Power Supplies, Yim-Shu Lee... 

A fully controlled three-phase bridge circuit and a primary-chopped switch mode power supply shall be viewed more closely in the following ... 

This AAA-alkaline battery will last approximately 4.65 years [3]. This duration indicates 16% higher efficiency, which will result in a 7% increase in battery service life with a 60% decrease in battery cost. This particular battery clearly offers impressive improvements in efficiency, cost, and service life by using more modern dynamic concepts of energy conversion. These gains or improvements are strictly dependent on the duty cycle of the functions that derive the maximum advantage from the high-efficiency power supply. As the duty cycle increases, so too do the benefits of using an alkaline battery source with a switched-mode power supply. 

In power applications (transformer, switch mode power supply, etc.), the magnetic induction has the saturation value. The output voltage is given by the relation ... 

The switched mode power supply with direct ac line rectifying, filtering, fast switching power transistors, ferrlt-core transformer for power transfer, fast... 

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