Quasi current resonant DC link AC/AC converter

A new quasi current resonant DC link (QCRDCL) topology has been developed in this paper. Although prototype current resonant DC link topologies for AC/AC power conversion have had such problems as irregular high current peaks, uncontrollable pulse width, etc., this new topology enables the AC/AC conversion system to have the properties wherein the current peak is limited and the pulse width is adjustable. The system begins to assume an adjustable-width flat-topped current shape, whereby the system becomes particularly suitable for high power application. With control of the pulse width a very fine load current regulation can be obtained. In this system, an open loop PWM control has been adopted and almost the same quality of output waveforms as the conventional current source inverter has been achieved     

Resonant converter with inherent short-circuit protection

Using a systematic procedure for classifying resonant converters, we have synthesized a zero-voltage switching resonant structure with inherent short-circuit protection. We analyze the operating modes of the disclosed converter and derive the control characteristic curve. Experimental verification is presented in a 100-W prototype.     

A single-stage power-factor-corrected AC/DC converter

This paper presents a single-stage isolated converter topology designed to achieve a regulated DC output voltage having no low-frequency components and a high-input power factor. The topology is derived from the basic two-switch forward converter, but incorporates an additional transformer winding, inductor and a few diodes. The proposed circuit inherently forces the input current to be discontinuous and AC modulated to achieve high-input power factor. The converter output is operated in discontinuous mode to minimize the bulk capacitor voltage variations when the output load is varied. Analysis of the converter is presented, and performance characteristics are given. Design guidelines to select critical components of the circuit are presented. Experimental results on a 150 W 50 kHz universal input (90-265 V) 54.75 V output AC/DC converter are given which confirm the predicted performance of the proposed topology     

星载多路输出开关电源的设计

介绍一款星载多路输出开关电源。该电源的设计方法能够满足绝大部分星载多路输出开关电源的需求。重点介绍该电源的部分设计特点,分析工作原理,并给出了设计公式。实践表明,该电源优化了星载开关电源小型化设计,可广泛应用于星载多路开关电源。     

Adaptive output voltage tracking controller for uncertain DC/DC boost converter

This paper presents a cascade output voltage control strategy for an uncertain DC/DC boost converter adopting an adaptive current controller in its inner loop. Considering the non-linearity, load uncertainties and parameter uncertainties of the converter, the proposed controller is designed following the conventional cascade voltage controller design method. The proposed method makes the following three contributions. First, a coordinate transformation is introduced for the inner loop, enabling avoidance of the singularity problem caused by the estimates of uncertain parameters. Second, a slight modification to the adaptation law is performed to guarantee closed-loop stability in the presence of the time-varying component of the load current. Third, the outer-loop controller is devised such that its performance can be adjusted without any parameter information. The closed-loop performance is demonstrated through simulations and experiments using the DSP28335 with a 3 kW DC/DC boost converter.     

Self-oscillating resonant AC/DC converter topology for inputpower-factor correction

This paper presents the analysis and design of a single-phase single-stage high-power-factor AC/DC converter employing a series-parallel resonant topology operating in self-sustained oscillating mode. A control approach is proposed to achieve low total harmonic distortion of the input current. This approach does not require sensing of the input current. In addition, the inverter output current is limited during transients, and the converter operates with zero voltage switching for all operating conditions including open and short circuit. The performance of the proposed scheme is verified experimentally on a 500 W prototype     

A new way for controlling a stand-alone DC/AC converter

The conventional feedback scheme used in a switched-mode power supply is not suited for use in a stand-alone DC/AC converter. A new feedback scheme is presented which uses the input voltage of the LC filter as a feedback signal, instead of the output voltage.     

单片高压AC／DC转换器TOPSwitch—GX系列

输出功率范围从5W至250W,高度设计灵活性,待机功耗低,最大限度降低了系统成本     

An AC/DC converter with high power factor

The television receiver often employs a capacitor-input-type rectifier. In this case, it is regulated as a class D piece of equipment. This paper presents a novel ringing-choke-converter-type switching regulator, which functions as an active filter. The proposed circuit features a simple circuit configuration and cost effectiveness. It achieves a high power factor of about 0.95 and reduces current harmonics (third, fifth, and seventh) in the AC input current to less than 40% of the limit value for class D. The voltage across the input smoothing capacitor does not show large variations and the components in the conventional ringing-choke converter can be used unmodified. Ripple content of the DC output voltage shows a slight increase and is the subject for future research.     

Single-switch AC/DC converter with power factor correction

A single-switch, one-stage power factor correction converter with output electrical isolation is proposed. To relieve the voltage spike caused by the leakage inductance of the power transformer, two bulk storage capacitors are used. The proposed converter has both a good power factor correction and excellent line and load regulation capabilities with an efficiency of 87%     

Application-oriented comparison of the methods for AC/DC converter harmonics analysis

Fourier transform (FT) is the most widely used tool for voltage and current waveform analysis. Nevertheless, it has certain drawbacks for time-varying signals analysis. Therefore, a need for another analysis technique appears. windowed FT, wavelet transform, and modulated lapped transform were considered in this paper. Comparison based on practical application shows the advantages of the last one. As an example, it has been applied for ac/dc converter input current harmonics analysis.     

A new modulation strategy for a buck-boost input AC/DC converter

This paper presents a novel modulation strategy for a power factor corrected (PFC), isolated AC/DC converter derived from the integration of a nonisolated, two switch buck-boost AC/DC converter with an isolated dual active bridge DC/DC converter (2SBBDAB). This strategy, termed discontinuous leading/trailing edge (DLTE) modulation, serves to maximize the duty cycle of the input switch while keeping the current in the buck-boost inductor discontinuous. Hence, the crest factors of the currents in the switching devices are minimized, the input switch is turned on at zero current and the zero-voltage switching ranges of the bridge switches are unaffected by the integration. A conventional isolated, PFC AC/DC converter typically consists of a boost converter cascaded with a forward converter. The ratings required of the power switching devices of the 2SBBDAB employing the DLTE modulation strategy are similar to those required of the conventional design for wide line voltage operation. However, the 2SBBDAB converter has higher line voltage surge immunity than that of the conventional design and, unlike the conventional design, it has inherent inrush current limiting. The DLTE modulation strategy may be applied to the family of converters composed of the two switch buck-boost integrated with half and full-bridge forward converters     

A novel voltage sensorless control technique for a bidirectional AC/DC converter

A novel voltage sensorless control technique for a bidirectional AC/DC converter is presented. Only a single current sensor that measures the inductor current is needed in the whole system. The sensed inductor current is used for two functions. The first one is for shaping the current waveform at the AC side and the second one is for deriving the inductor voltage by determining the rate of change of the inductor current. The AC-side and DC-side voltages, which are used for AC current synchronization and DC voltage regulation, respectively, are obtained by extracting the envelopes of the derived inductor voltage. Apart from reducing the number of sensing elements, the proposed method has additional advantages of: (1) inherent electrical isolation and reducing noise coupling between the power circuit and the controller; (2) wide operating range. Design criteria for the differentiator and the envelope detector circuit has been described. The applicability of the proposed method is verified with the experimental results of a laboratory prototype.     

A low-cost CMOS dual-mode AC/DC data converter for signal measuring technique

A low-cost CMOS dual-mode AC/DC data converter for signal measuring technique is newly proposed. Instead of traditional full wave rectification, the realized synchronous rectification circuit is more attractive due to the easier integration and lower cost. In this paper, the design strategies of implementing the signal processing of AC and DC modes in the integrated circuit are discussed completely. Proven through SIMULINK in system level and SPICE simulations in circuit level, simulation results show that the proposed dual-mode AC/DC data converter achieves 8-bit resolution in DC mode and 7-bit resolution in AC mode. Measurement results have successfully verified the correct functions and performance of the proposed data converter and confirmed it for AC/DC signal measuring technique. The area of this chip is 710 × 630 μm² and the measured power consumption is 5.1 mW. The proposed dual-mode AC/DC data converter is suitable for the system of analog and mixed-signal boundary scan.     

A novel forward AC/DC converter with input current shaping and fast output voltage regulation via reset winding

This work presents a novel simple forward AC/DC converter with harmonic current correction and fast output voltage regulation. In the proposed AC/DC converter, a transformer incorporating reset winding provides two main advantages. First, the bulk inductor used in the conventional boost-based power-factor-correction cell is omitted in the proposed converter, allowing significant volume and weight of magnetic material to be saved. Second, the voltage across the bulk capacitor can be held under 450 V by adjusting the transformer winding ratio, despite the converter operating in a wide range of input voltages (90/spl sim/265 V/AC). This new converter complies with IEC 61000-3-2 under a load range of 200 W and has fast output voltage regulation.     

A high-efficiency soft-switched AC/DC converter with current-doubler synchronous rectification

An improved ac/dc converter based on asymmetrical half-bridge topology is proposed in this paper. To substantially enhance the efficiency for low-voltage/high-current output applications, a current-doubler synchronous rectifier is combined with a modified asymmetrical half-bridge converter that retains the inherent zero-voltage-switching property. The power losses in the secondary rectification stage and the primary switches can be significantly reduced. The proposed architecture exhibits extreme simplicity and lower cost while providing unity power factor, well-regulated output, and high power density. The detailed operating principles and design procedures for the proposed converter are described in this paper. Simulation and experimental results for a laboratory prototype are discussed to verify the feasibility.     

Performance of MCT's in a current-regulated AC/DC PDM converter

An AC/DC current-regulated pulse density modulated (PDM) power converter is presented. The MOS-controlled thyristor (MCT) is used in this power converter because of its promising advantages over existing power devices. A unique bidirectional switch configuration is used, which allows the MCT to switch easily at zero voltage. The converter performance is evaluated driving a 5 hp induction motor. MCT switching was performed satisfactorily, but the device fails before its ratings are reached. The MCT will be better than other devices when used in applications that require critical timing and high voltage blocking capability     

A single-switch AC/DC converter with voltage regulated storage capacitor

A single-stage power-factor-corrected AC/DC converter (SSPFC) usually causes high voltage stress on the intermediate storage capacitor, due to the lack of control of this voltage. The storage capacitor voltage varies largely with line voltage, and load current and is usually higher than the peak line voltage. This paper presents a new single-switch SSPFC based on a flyback topology for which the storage capacitor voltage is loosely regulated by the output voltage. Without using extra power switches to increase the control dimension, the proposed converter uses a flyback converter with dual-output transformer to achieve the control purpose. The range of storage capacitor voltage change against the change of input voltage and load current is significantly reduced. Moreover, the maximum storage capacitor voltage can stay below the peak line voltage at high line condition. Experimental results verifying the operation of the proposed SSPFC are also reported.     

A family of closed-form duty cycle control laws for three-phaseboost AC/DC converter

In this paper, a basic closed-form duty cycle control law is first derived for the proposed AC/DC converter to achieve clean sinusoidal input current, adjustable DC voltage, controllable power factor and bidirectional power flow capability, and fixed switching frequency, without using any current sensor. Then, a second dead-band scheme is derived from the previous basic form to achieve the same function and to reduce switching loss and thermal stress. Similarly, a four-switch scheme is also derived to provide a new operation mode to enhance the reliability of the converter. Modified control laws of the above family are also considered to handle the effect of unbalanced input voltage. It is very interesting to see that a unified theory can be used to give the above family of duty cycle control laws under both balanced and unbalanced input voltage. Some simulation and experimental results are presented for verification     

A unity power factor resonant AC/DC converter for high-frequencyspace power distribution system

This paper presents analysis and design of a resonant AC/DC converter topology, suitable for use in an advanced single-phase, sine-wave voltage, high-frequency power distribution system of the type that was proposed for a 20 kHz space station primary electrical power distribution system. The converter comprises a transformer, a double-tuned resonant network comprising of series- and parallel-tuned branches, a controlled rectifier, and an output filter. Symmetrical phase control technique that generates fundamental AC current in phase with the input voltage is employed. Steady-state analysis of the converter in continuous current mode of operation is provided, and the performance characteristics presented. The proposed converter has close-to-unity rated power factor (greater than 0.98), a wide range of output voltage control (0%-100%), low total harmonic distortion in input current (less than 8%), and high conversion efficiency. Finally, selected experimental results of a bread-board converter are presented