Power Electronics Specialists Conference, 1995. PESC '95 Record., 26th Annual IEEE

A neural controller implementing a variable structure control (VSC) algorithm as a control law is proposed as an alternative to control power converters. VSC control laws yield fast response and a robust behavior against large parameters variations. An analog neural network (ANN) learns to approximate this control law by means of a learning algorithm. This implementation possesses all the good pro... View full abstract»

Two predictive space vector control strategies for direct frequency converter structures are presented. Both algorithms require output current feedback in order to decide the next best state of the converter. The performance of the control techniques are evaluated against a high performance fictitious link direct frequency converter. Computer simulation using Microsim PSpice 5.3 is used to examine... View full abstract»

A fuzzy control algorithm for switching power converters is proposed. Being free of complex equations and heavy computation, the control algorithm can be implemented by a digital controller using a fixed point signal processor. This paper presents experimental results which demonstrate the capability of the fuzzy controller in regulating high speed switching DC/DC power converters View full abstract»

This paper presents a novel single-phase unity power factor rectifier, which features current-sense frequency control and zero-current switching with no auxiliary switches. The reduced conduction losses are achieved by the employment of a single converter, instead of the typical configuration composed of a front end rectifier followed by a boost converter. Experimental results of a 250 W converter... View full abstract»

This paper presents a new control strategy for a permanent magnet synchronous motor drive that provides high-performance vector control without position and speed sensor. The rotor position is estimated by calculating the flux linkages which are obtained by the integrator using the estimation error compensator. Due to the compensator the estimated flux linkages are nearly equal to the actual flux ... View full abstract»

The reverse recovery characteristics of high-power GaAs Schottky and silicon P-i-N rectifiers are studied at various temperatures. Devices were first characterized to obtain measured data for forward and reverse I-V, C-V, reverse breakdown voltage, and reverse recovery performance and then simulated using an advanced two-dimensional (2-D) mixed device and circuit simulator. The measured and simula... View full abstract»

A major cause of input current distortion in active power factor correction systems is the second harmonic components. Propagation of the ripple components in the feedback and feedforward paths and their interaction in the current shaping controller are examined. Based on this analysis, a ripple cancellation method is proposed. It entails a modification of the feedforward and feedback filters and ... View full abstract»

A model for the capacitive effects in magnetic components for switch mode power supplies (SMPS) has been developed. It can be applied to multiwinding transformers. A finite element analysis (FEA) tool is used to compute the frequency behavior of the magnetic component, taking into account geometry and materials. The parameters of the model can be calculated before the magnetic component is built. ... View full abstract»

A soft switching active snubber is proposed to reduce the switching losses of the IGBT in a DC-AC power converter. The active snubber provides zero-voltage switching for the IGBTs, thereby reducing the high turn-off losses due to current tailing. The proposed active snubber uses two auxiliary switches in order to recover the switching energy during turn-off. The snubber is itself an inverter leg, ... View full abstract»

Design oriented criteria are developed for distributed power systems with constant power loads to guarantee stability during large disturbances. The criteria place design constraints on the input filter parameters, such as the Q factor, and constraints on the amount of “ideal” constant power load that a system can support. The criteria are based on Lyapunov stability theory, mixed pote... View full abstract»

This paper presents a class of soft-switched power factor correction circuits (PFC) based on the quasi-resonant (QR) principle. All power devices in the PFC converter can be switched at zero-voltage and/or zero current conditions, thus reducing switching loss and enabling high-frequency switching. At constant and high switching frequency, the new circuits allow simple EMI filter design, minimisati... View full abstract»

We introduce in this paper a novel three-phase AC-DC power factor preregulator. The proposed converter operates in discontinuous conduction mode, and requires only a single-control loop. The number of switches (one or two) is a function of the gain of the converter. The input currents of the converter have a little ripple, and the output voltage is free of low-order harmonic content. The output st... View full abstract»

The term HF-AC resonant link converters usually denotes a circuit, whose main part is a resonant tank circuit. The main goal of designers of such circuits is to reach a constant magnitude of output voltage with constant frequency and independence of load conditions. In this paper the possibility of maintenance of the constant HF-AC voltage on parallel resonant circuits (frequency 25 kHz) from the ... View full abstract»

The general purpose modeling language Dymola is used in conjunction with the ACSL simulator to provide an environment for the simulation of power electronic systems. The object-oriented nature of Dymola, along with its high-level handling of discrete events, makes it ideally suited to modeling switching converters and complete systems of several converters. Converter models can be constructed usin... View full abstract»

The acceptable performance of the central-limit control (CLC) requires that the weighting functions, which determine the power converter load current contribution, add up to unity. However, the sum of the weighting functions may not add up to unity due to changes in component values resulting from aging or changes in ambient conditions. This paper shows how the CLC performs when the weighting func... View full abstract»

The paper describes the operation of an AC-DC power converter in which the harmonic distortion in the input current is reduced using a second harmonic-injected PWM scheme. The boost power converter uses a constant switching discontinuous current mode. Expressions for the harmonic components are derived. Simulated and experimental waveforms of an AC-DC power converter are presented and the total ha... View full abstract»

A high frequency transmission line transformer for DC/DC power converters is proposed. A DC isolated transformer is formed using cascades of interconnected transmission line sections. The energy transfer takes place via electromagnetic waves. The distinct feature of the transformer is that the voltage ratio is determined solely by the characteristic impedance of transmission lines forming the tran... View full abstract»

This paper establishes an analytical model for a resonant snubber based soft-switching inverter. The model adopts the loss separation method to evaluate losses in individual components. Because of symmetry of the inverter circuit, the developed model is suitable for both single-phase and three-phase inverters. A single-phase inverter has been built and tested with a single-phase induction motor dr... View full abstract»

The closed loop characteristics of a boost power converter were examined for different control schemes. The H∞ control was found to exhibit low output impedance over the widest frequency range. The major disadvantage of this control scheme, as compared to the classic ones, is possible static error due to the lower open loop gain at low frequencies. Good agreement was found between... View full abstract»

Planar magnetic components are playing an increasingly important role in the goal of increasing the power handling capability of power supplies, and in the fabrication of magnetic components using microelectronic techniques. Resistance of these devices varies greatly over their operating frequency range, due to magnetic flux linkage within the wide flat conducting sections. However, it is not poss... View full abstract»

The theoretical performance limits of two-phase switched-capacitor (SC) DC-DC power converters are discussed in this paper. For a given number of capacitors k, the complete set of attainable DC conversion ratios is found. The maximum step-up or step-down ratio is given by the kth Fibonacci number, while the bound on the number of switches required in any SC circuit is 3k-2. Practical im... View full abstract»

This paper presents the design-oriented analysis of the combined voltage-resonant inverter for electronic ballasts of fluorescent lamps. In this inverter, the voltage-resonant active filter and inverter are combined, and a switch of the active filter is used simultaneously as that of the inverter. The operation mechanism and the relationship between the circuit parameters and the performance chara... View full abstract»

This paper states a comparative study of six three-level zero-voltage-switching TL-ZVS-PWM DC-DC converters. All converters operate at fixed frequency and offer zero-voltage-switching for all active devices. The studied TL-ZVS-PWM converters are namely: TL-ZVS-PWM, TL-ZVS-PWM with one commutation auxiliary circuit (CAC), TL-ZVS-PWM with two CAC, TL-ZVS-PWM parallel-resonant, TL-ZVS-PWM series-reso... View full abstract»

Bidirectional DC current flow is not a natural feature of the buck (step-down) switch-mode rectifier which leaves it at a disadvantage to boost (step-up) designs. A circuit topology is presented that allows bidirectional flow and which, by dual use of components, uses less devices than anti-parallel bridges. Sinusoidal current, controlled displacement factor and variable voltage transfer ratio are... View full abstract»

We have developed an electrothermal model for the bipolar power transistor, implemented in the Saber simulator, in which the device's temperature becomes an interactive variable during the simulation. Two approaches for the electrothermal coupling are compared and discussed. The accuracy of the model is appreciated with the electrical and thermal characterization of a NPνN power bipolar transis... View full abstract»