Volume 4 in this book series presents a damaging consequence of switching in converters used in power electronics, studied in the context of a domain known as “electromagnetic compatibility” (EMC). In Volume 1 [PAT 15a], we saw that the switching mode used in converters may seem simplistic in terms of degrees of freedom when controlling the power flowing between a power supply and a load. However, this mode was seen to be satisfactory as long as the load presented an inertia sufficient to avoid effects from voltage of current switching. Once this conceptual difficulty is overcome, the gains in terms of energy efficiency and loss reduction (with associated gains regarding the volume and weight of the converter) are considerable.
Unfortunately, this is not the full picture as it does not include electromagnetic interference produced by electronic switches in switching mode as switching occurs very quickly and at an increasingly high speed (switching times lower – sometimes much lower – than 1 microsecond and switching frequencies from a few hundred hertz in high power applications to several megahertz in some low power highly miniaturized switch mode power supplies). In these conditions, the great variation in (potentially high) voltages and currents over time results in the production of variable electrical and magnetic fields, which can generate x Power Electronics Applied to Industrial Systems a interference in nearby electronic equipment (including subsystems in the converter itself).
EMC can be seen as the study of the interference mechanisms which may exist between equipment creating interference (the source) and equipment subject to interference (the victim). Rules for coexistence are established on this basis in order to guarantee successful operation of elements in proximity to one another. This volume will not focus on the standardization approach (which will, nevertheless, be mentioned in Chapter 1), but will concentrate on the study of disturbance mechanisms and tools used to combat these difficulties. Sources of interference will be presented in Chapter 1.
Including artificial sources (such as electronic switches in switching mode) but also natural interference (lightning and static electricity carried by the human body). Clearly, the key element in this chapter will be the pulse width modulation (PWM) waveform, which is the most common source of interference in an electronic power converter. Detailed consideration will, therefore, be given to spectral modeling of the PWM waveform using an innovative approach, not widely used in power electronics, based on the Heisenberg uncertainty principle.
This principle is widely used in quantum mechanics and signal theory to analyze the duality between notions of temporal and frequency dispersion of a signal. Chapters 2 and 3 will focus on the paths taken by electromagnetic disturbances between the emitter and the receiver. In Chapter 2, conducted interference will be discussed and, more generally, interference using electrical couplings with lumped elements will be presented. In this case, propagation may be modeled using an equivalent electrical diagram (potentially including parasitic capacitances or mutual inductances, along with common impedances in cases where circuits are galvanically connected).
In Chapter 3, we will discuss propagation mechanisms for which the spatiotemporal dimension cannot be reduced (except by the introduction of a cascade of elementary electrical circuits to take account of the non-infinite speed of field and/or voltage propagation, traveling through the length of the propagation channel). This context clearly includes the case of radiated interference, although the division between Chapters 2 and 3 does not fully conform to the classic separation of conducted and radiated interference generally used when studying the EMC. Finally, this volume includes two appendices, also included in the previous volumes.
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