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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.

A new single-stage power factor corrected ac–dc converter for universal line applications is proposed in this paper. This converter has a buck topology as a power factor corrector. The dc bus voltage of the proposed converter is always lower than the peak input voltage at any load condition. Therefore, the problem of high dc bus voltage under the light load condition for the single-stage converter is solved, especially in the case of universal line applications. The design equations are presented for the proposed converter and a design example for a 5V 12A application is presented. The theoretical analysis and experimental results show that the dc bus voltage can be limited within 260V and the line input current harmonics can meet IEC 61000-3-2 Class D requirements at any load conditions for the line input voltages from 90 to 260Vac.

A new phase-shifted parallel-input/series-output (PISO) dual convertor for high-power and high-output voltage applications is proposed. The new convertor is based on a two-module PISO modular dual convertor operating at a constant duty cycle and employs an auxiliary circuit to control the output voltage with a phase shift between two modules. This convertor shows a high step-up ratio, fast control-to-output dynamics, significantly reduced switch turn-off stress, and high efficiency due to the reduced switch voltage rating. The steady-state operation is analysed and the mathematical models based on this analysis are presented. A comparative analysis with the conventional two-module PISO dual convertor is performed to explore the various features of the proposed convertor. Also, experimental results from a 50 kHz, 800 W, 350 V dc prototype with an input voltage range of 20–32 V dc are presented to confirm the validity of the proposed convertor. The new convertor compares favourably with the conventional PIS...

SummaryThe design of a single-stage a.c/d.c. converter operated in discontinuous conduction mode (DCM) for low power level applications is proposed. The proposed converter gives the good power factor correction, low line current harmonic distortions. and tight output voltage regulations. This converter also achieves a high efficiency by employing an active damp method and synchronous rectifiers. The modelling and detailed analysis for the proposed converter are performed. To verify the performances of the proposed converter, a 90 W-converter has been designed. This prototype meets the IEC 61000-3-2 requirements satisfactorily with nearly unity power factor and high efficiency.

A high efficiency interleaved active clamp forward converter with self-driven synchronous rectifiers for a modular power processor is presented. To simplify the gate drive circuits, the n–p MOSFETs coupled active clamp method is used. An efficiency of about 90% for a load range of 50-100% is achieved. Details of design for the power stage and current mode control circuit are provided, and also some experimental results are given.

A novel isolated zero voltage switching (ZVS) PWM power factor correction circuit is proposed. This circuit provides the input power factor correction and direct conversion from AC line to 48VDC bu...

A predictive current control technique for a permanent magnet synchronous motor (PMSM) employing a resonant DC link inverter is proposed to overcome the disadvantage of the current regulated delta modulation (CRDM) control technique. Also, the discrete model of a PM synchronous motor and estimation of back EMF are investigated. Based on this discrete model and estimated back EMF, a predictive current control technique is newly developed. Using the proposed control technique, the minimized current ripple with a small number of switchings can be obtained. Finally, the comparative computer simulation and experimental results are given to show the usefulness of the proposed technique.

An overcurrent protection control technique of a zero current switched (ZCS) series resonant rectifier (SRR) is proposed. With the proposed control technique, the rectifier can be operated safely, and optimum rating devices can be used. By employing a zero current switching operation for all switches, the series resonant rectifier can be operated at high switching frequencies and high power levels. Based on the dynamic model of this rectifier, the characteristics of an internal operation are explored. With the proposed control technique, the unity power factor without an overcurrent and a wide range of output voltage can be obtained.

A new push-pull type quantum series resonant rectifier for the power factor correction is proposed. The proposed single phase rectifier enables the zero-current switching operation of all power devices, allowing the circuit to operate at high switching frequencies and high power levels. A samples data dynamic model for this rectifier is developed and an analysis for the internal operational characteristics is explored. Based on this analysis, a predictive current control technique is investigated and its advantages over the other types of current control techniques are discussed. With the proposed control technique, the unity power factor and greatly reduced line current harmonics can be obtained.

A quantum series resonant inverter (QSRI)is utilized as a DC motor drive. A sampled-data dynamic model including both a QSRI and a DC motor is proposed to obtain an effective analytical tool. Based on this model, an optimal predictive resonant current (OPRC) control technique that minimizes the current error is developed and compared with other types of current control techniques. In respect of the current ripple and offset current, near optimum operational mode patterns can be obtained using the proposed OPRC control technique. The usefulness of an OPRC-controlled QSRI for a DC motor drive with four-quadrant operation is verified by employing motor current and speed controllers in simulation and experiment.

A discrete time domain modelling is presented for the pulse-width modulated series resonant converter (PWM-SRC) with a discontinuous current mode. This nonlinear system is linearized about its equilibrium state to obtain a linear discrete time model for the investigation of small signal performances such as the stability and transient response. The usefulness of this small signal model is verified by dynamic simulation.