Adrian Ioinovici

Design-oriented analysis of common switching DC to DC converters

A general, computer-aided analysis of power electronic circuit dynamics is proposed. An automatic generation of dynamic models from a circuit specification is the starting point for a symbolic, automatable, exact, ‘top-down’ procedure, that contrasts with circuit-specific analyses. The algorithm is suitable for analysing any converter containing two reactive elements, covering the common switching power stages: buck, boost, buck-boost converters. The method is illustrated by application to the computation of the transient response of a boost converter; the computer results are compared with those obtained by applying the ‘state space averaging’ method and with laboratory results.

Budworm-forest system: application of quantitative feedback theory†

The budworm-forest system is modelled as a non-linear multiple-input multiple-output feedback system with uncertain parameters. The initial values of the variables S (branch surface area per acre) and E (quality of the foliage, on a scale from zero to one), are assumed unsatisfactory. More desirable values are to be achieved, and tolerances compatible with practical constraints are assigned on the time histories of E and S, from initial to final values, over a 100-year time interval. An ecological policy is determined which assures the achievement of these specifications, so long as the model and its parameters are within the assumed ranges. The policy involves periodic measurement of E and S. Relatively simple processing of these data dictates the logging and spraying which are required as functions of time.

New approach to the synthesis of filters with parameter uncertainty

Abstract The problem is to design a filter system to satisfy insertion loss tolerances over a frequency range, despite a specified range of variation of parameter values. It is shown how a technique based on the theory of feedback system design may be used for this purpose.

General algorithm for computer-aided transient and steady-state analysis of DC to DC converters

A symbolic, automatable, exact, ‘top-down’ algorithm for computing the transient and steady-state response of DC-to-DC converters is presented. The procedure is applicable to any DC-to-DC converter, regardless of its structural complexity, number of reactive elements, and number of electronic switching devices. Each linear switch configuration that the circuit goes through during a cycle is described by a set of state equations. Their solution represents the state variables waveforms which characterize the dynamic behaviour of the converter in the interval corresponding to the configuration taken into account. As the state variables are the same in all configurations, and the state is continuous across each switching change, the above partial solutions are alternatively used for computing the transient and steady-state response of the circuit. The result is exact and the continuous character of the converter variables is preserved. The method is illustrated by application to the computation of the dynamic...

Exact transient solution of the boost converter computed using the alternor equations

A new approach to the computation of the transient response of DC-to-DC converters is presented. The key of this approach is the introduction of a new circuit element, ‘the alternor’, defined as a two-port formed by two electronic elements operated as synchronous switches. The constitutive equations of the alternor are used in obtaining the modified nodal equations of the cyclically switching circuit, a frequency-domain description of the power-stage being thus developed. The solution of the equations serves to the computation of the exact, analytic, transient response of the converter. The method is applied to a boost converter operating in the continuous conduction mode

Algorithm for the design of multi-input filters with parameter uncertainty

A design method is developed for multi-input filters with components subject to a statistical distribution of their parameter values, due to manufacturing tolerances and variation in the operating environment. The circuit with uncertain component parameters is embedded in a feedback structure, which is designed to achieve the system specifications, despite the uncertainty. A two-input filter example illustrates the design theory.

Application of the quantitative synthesis of feedback systems with uncertain non-linear plants

An improvement of the quantitative feedback theory for uncertain non-linear single-input-single-output (SISO) systems is obtained, by using a new procedure to convert the uncertain non-linear plant into an “equivalent” linear time-invariant plant set. The method is applied to the control of uncertain Van der Pol plant and Duffing plant. The results, compared with those obtained by following the classical approach, show the superiority of the new technique in reducing the “cost of feedback” in bandwidths of the compensation, for the same extent of plant uncertainty.

Simulation of cyclically switching systems using the generalized alternor definition

A new method for simulating cyclically switching systems (power electronics circuits) is presented. Partial results of this paper were reported at I.E.E.E. Power Electronics Specialists Conference (PESC ‘89), Milwaukee. The starting idea is the application of a familiar tool for engineers: the Laplace transform for studying such systems, whose basic cell is an electronic converter. The switching elements of the converter are extracted in a two-port (alternor), which is defined in order to simulate the possible cyclically circuit operation both in continuous and discontinuous conduction mode. The remaining part of the circuit is linear time-invariant; its nodal equations are formulated. By adding the generalized alternor equations, an s-domain system of equations is obtained. This describes the global dynamic behaviour of the converter. The s-domain solution is computed and its inverse Laplace transform is found. The transient and steady-state responses, computed in such a way, mirror exactly the converter...

Computer-aided analysis of boost-buck converter in optimal topology

Abstract An exact algorithm for computing the transient response and the steady-state of DC-to-DC converters containing three reactive elements is proposed. The procedure is ‘top-down’ and automatable; it starts from a general, symbolic formulation and works down to the actual circuit. The method is applied to the analysis of the boost-buck converter operating in both continuous and discontinuous conduction modes. The basic circuit considered for the boost-buck converter contains mutual coupling between the input and output inductors, DC resistances of the inductors and on-resistance of the switching elements, but no load capacitor. The influence of the mutual inductance on the currents ripple is studied. The results are compared with the response, computed using a numerical method, of the boost-buck converter containing a load capacitor.

Design of a speed regulator electronic system for a DC motor fed from a semi-converter supply†

A feedback system for controlling the speed of a separately excited DC motor supplied from a 3-phase semi-converter circuit is presented. The electronic feedback structure is designed to assure that, in the starting transient state, the motor speed climbs from zero to its steady-state value within specified ‘customer’ bounds. This has to be achieved, despite random variations in the characteristics of the supply voltage, of the motor and of the converter, and despite uncertain values of the load, keeping at the same time the starting current peak below a dangerous level. When feedback is applied, the system becomes highly non-linear; but owing to its quantitative approach, the design algorithm uses no small-signal linearizations.