Transformerless synthesis of transistor and thyristor switching RLC 1‐ports

Abstract

SUMMARYAs an extension of the synthesis method developed in a previous paper, the transformerless synthesis of reciprocal switched 1-ports is presented in this paper. The transformerless structures of resistance switching n-ports described by impedance, admittance or hybrid matrices have been proposed. These structures enable the synthesis of dynamical switching RC, RL and RLC 1-ports. Using the state variables method, the realizability conditions and identification formulae for constant and sinusoidal input functions have been derived. Three numerical examples illustrate the developed methods. The present theory can be applied to create new thyristor and transistor arrangements, particularly compensators and auxiliary switching LC circuits facilitating the commutation of thyristors and transistors. . INTRODUCTIONThe synthesis theory of power electronic circuits was originated only a few years ago, whereas the analysis of such circuits has a long history. Synthesis methods of passive switched circuits have been presented in References 1-5. The structures presented in the previous works contain a large number of transformers. This ensued from the fact that the synthesis of resistance n-ports with the use of transformers is well investigated, whereas the theory of transformerless synthesis of passive resistance networks is still incomplete. On the other hand, transformerless constructions are desired for practical arrangements because of the high cost and weight of transformers. The present paper deals with a transformerless synthesis of reciprocal switching 1-ports.Input and output time functions are required as data for the achieved synthesis method. Let us assume that the 7'-periodic time functions ~( t ) , y ( t ) and x ( t ) are an input function, an output function and a state vector respectively. The functions u ( t ) and y ( t ) are one-dimensional since they are 1-port functions. The state vector x ( t ) is n-dimensional. We also assume that a synthesized circuit is switched twice within the period T a t instants t = 0 and t = T/2. During the first half-wave (0 < t < T/2) a circuit is described by the minimal realization [ A , B, C, D ) and during the second half-wave (T/2 < t < 7') by the minimal realization [ A ' , B' , C' , D' 1. The considerations presented in the paper are carried out with the assumption that state variables are continuous at switching instants. This means that x ( O -) = x(O+), x ( T / 2 -) = x ( T / 2 + ) and x ( T + ) = x ( 0 -) . It was shown in References 1 and 6 that time functions u(t), y ( t ) and x ( t ) of a switched reciprocal 1-port must satisfy one of the following symmetry conditions:Condition (i) defines the inverter operation and condition (ii) defines the rectifier operation. For both operations the minimal realizations are related as follows: A ' , B', C', D ' ] = [ A , -B, -C, D ) . This relationship will be used in the present paper. The transformerless structures of resistance switched k-ports are presented in Section 2 . The structures are associated with a speci...

A new method for reduction of current and voltage harmonic distortion in power systems

“…The basic switching structure generating odd or even harmonics has been presented in [3]. This structure is shown in a change not only of the phase displacement cp, but also of the amplitude I / , , I :…”