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A new single-stage isolated ac-dc converter, which can achieve a better efficiency and a better power factor, is proposed. It is based on a general forward topology so that it can utilise the transformer more than converters based on flyback topology. In addition, since the capacitive output filter is adopted instead of an inductive type filter, the voltages on the secondary rectifiers can be clamped to the output voltage; meanwhile, the capacitor used in the output filter can be utilised for the resonance with the leakage inductance, and the turn-off loss in the primary main switch and the dissipative loss in the snubber can be reduced. Moreover, since this converter can be operated at the boundary conduction mode, the line input current can be automatically shaped as the waveform of a line voltage and quasi-resonant zero voltage switching can be also obtained. Therefore, it features higher efficiency, lower voltage stress and a smaller-sized transformer than other topologies. A 100 W prototype has been built and tested for the verification of the proposed topology. [ABSTRACT FROM AUTHOR]

An analysis and design of single-stage, single-switch bi-flyback ac/dc converter is presented. The main flyback stage controls the output power from the link capacitor voltage with Discontinuous Conduction Mode (DCM) or Continuous Conduction Mode (CCM) operation, while an auxiliary flyback stage supplies the power to the output directly from ac line input with DCM operation. This scheme can effectively reduce the voltage stress on the link capacitor and can achieve the power factor correction (PFC) without a dead band at line zero-crossings, which reduces the harmonic distortion in ac line current. Theoretical analysis of the converter is presented and design guidelines to select circuit components are given. The experimental results on a 60 W (15 V, 4 A), 100 kHz ac/dc converter show that maximum link voltage and maximum efficiency are around 415 V and 82%, respectively. The power factor is above 0.96 under universal line input and load conditions. [ABSTRACT FROM AUTHOR]

A very simple control approach using a neural network for the robust position control of a permanent magnet synchronous motor (PMSM) is presented. The linear quadratic controller plus feedforward neural network compensator is employed to obtain the robust PMSM system approximately linearized using a field-orientation method for an AC servo. The neural network is trained in on-line phases and a feedforward recall and error back-propagation training compose this neural network. Since the total number of nodes is only eight, this system is realized easily by the general microprocessor. During normal operation, the input-output response is sampled and the weighting value is trained multi-times by an error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. The state space analysis is also performed to obtain the state feedback gains systematically. In addition, the robustness is also obtained without affecting overall system response. A floating-point digital signal processor DS1102 board (TMS320C31) realizes this method. The basic DSP software is used to write C-program, which is compiled by using ANSI-C style function prototypes. [ABSTRACT FROM AUTHOR]

Describes strategies for obtaining a stable output voltage from a recently-developed rectification circuit called a quantum boost-series resonant rectifier (QBSRR). Output voltage regulation loop having a sampling time corresponding to the zero crossing point of the AC line voltage; Maintenance of a deadbeat control scheme.

Proposes a push-pull type quantum series resonant rectifier for the power factor correction. Development of a samples data dynamic model for the rectifier; Analysis for the internal operational characteristics.

Focuses on the use of a quantum series resonant inverter as a direct-current motor drive. Sampled-data dynamic model; Optimal predictive resonant current control technique; Minimization of current error.

A high frequency and soft-switched AC-to-DC rectifier employing a series-type resonant circuit is proposed to overcome the disadvantages of the conventional peak-rectifying circuit. Using the proposed rectifier, a high power factor and low harmonic currents are obtained in the AC line. Furthermore, several advantages such as high power density and wide output voltage range can also be available. Through simulation and experimental results, the usefulness of the proposed rectifier is verified. [ABSTRACT FROM AUTHOR]

Presents a discrete time domain modeling for pulse-width modulated series resonant converters with a discontinuous current mode. Linearization of the nonlinear system; Verification of the signal's usefulness by dynamic simulation.

A dynamic model and an improved current control technique for a quantum series resonant converter with non-periodic integral cycle mode are proposed to overcome the disadvantages of the integral cycle mode controlled series resonant converter. With the proposed dynamic model, a simple and exact analysis for the internal operational characteristics is newly explored. Based on this analysis, a new improved current control technique is developed and its advantages over other types of current control techniques are discussed. With respect to current ripple and current offset, near optimum operational mode patterns can be obtained using the proposed control technique. Furthermore, fast transient response with negligible overshoot can also be achieved. [ABSTRACT FROM AUTHOR]