tailieunhanh - Topologies of Power Electronic Converters

Power electronic converters (PECs) are static devices, without any movable parts, that convert electric energy of one set of properties into electric energy of another, different set of properties. The properties that are changed by the action of the converter are one or more of the following: number of phases, frequency, and voltage rms (or average, in the DC case) value. Thus any power electronic converter is essentially a transformer in a broad sense. Action of a power electronic converter is illustrated in Fig | ENGNG3070 Power Electronics Devices Circuits and Applications 3. TOPOLOGIES OF POWER ELECTRONIC CONVERTERS Introduction Power electronic converters PECs are static devices without any movable parts that convert electric energy of one set of properties into electric energy of another different set of properties. The properties that are changed by the action of the converter are one or more of the following number of phases frequency and voltage rms or average in the DC case value. Thus any power electronic converter is essentially a transformer in a broad sense. Action of a power electronic converter is illustrated in Fig. in terms of the defined electric energy properties. mi fi Vi PEC mo fo Vo Fig. Conversion of electric energy by means of a power electronic converter. Electric circuits that constitute power electronic converters vary to the great extent and depend on the function that PEC is supposed to perform in terms of electric energy properties. However the unique feature of any power electronic converter is that it comprises at least one and in reality always more than one power semiconductor that is operated in the switched mode. Operation in the switch mode means that the semiconductor is either fully on in the circuit conducting required current with almost zero voltage drop or it is fully off blocking the required voltage with zero current . Power semiconductors are for this reason usually called switches when PECs are discussed. In order to arrive to a frequently used classification of PECs consider the following couple of examples 1. A DC motor for its normal operation has to be supplied with a DC voltage. Suppose that only mains AC voltage is available. In order to connect the DC motor to the mains an interface has to be used that will convert AC into DC. Thus AC DC conversion is required and it is called rectification. PECs that perform rectification are termed rectifiers. 2. Nowadays one frequently meets in homes light sources whose .