A fixed frequency LCL-Type series resonant converter

A fixed frequency LCL-type series resonant converter (SRC) which uses an inductive output filter is proposed. Steady-state analysis of the converter is presented using complex ac circuit analysis. Based on the analysis, a simple design procedure is given. Detailed space integrated control experiment (SPICE) simulation results are presented to evaluate the performance of the designed converter under varying load and supply voltage conditions. Also, detailed experimental results obtained from a metal-oxide-semiconductor field-effect transistor (MOSFET) based 500 W converter are presented to verify the analysis and SPICE simulation results. The results obtained from the analysis, SPICE simulation and the experimental converter are compared. The proposed converter requires a narrow variation in pulsewidth while maintaining lagging power factor mode of operation for a very wide variation in the load as well as supply voltage     

Single-Stage Single-Switch Switched-Capacitor Buck/Buck-Boost-Type Converter

A new dc-dc converter featuring a steep step-down of the input voltage is presented. It answers a typical need for on-board aeronautics modern power architectures: power supplies with a large conversion ratio able to deliver an output voltage of 1–1.2 V. The proposed structure is derived from a switched-capacitor circuit integrated with a buck converter; they share the same active switch. The proposed solution removes the electromagnetic interference (EMI) emission due to the large di/dt in the input current of the switched-capacitor power supplies. Compared with a quadratic buck converter, it presents a similar complexity, a smaller reduction in the line voltage at full load (but less conduction losses due to smaller input inductor current and capacitor voltage), lower voltage stresses on the transistor and diodes, lower current stresses in the diodes, and smaller size inductors. A similar structure using a buck-boost converter as the second stage is also presented. The experimental results confirm the theoretical developments.     

Tapped-inductor filter assisted soft-switching PWM DC-DC power converter

A novel high-frequency transformer linked full-bridge type soft-switching phase-shift pulsewidth modulated (PWM) controlled dc-dc power converter is presented, which can be used as a power conditioner for small-scale photovoltaic and fuel cell power generation systems as well as isolated boost dc-dc power converter for automotive ac power supply. In these applications with low-voltage large-current sources, the full-bridge circuit is the most attractive topology due to the possibility of using low-voltage high-performance metal-oxide-semiconductor field-effect transistor (MOSFET) and achieving high efficiency of the dc-dc power converter. A tapped-inductor filter including the freewheeling diode is newly implemented in the output stage of the full-bridge phase-shift PWM dc-dc converter to achieve soft-switching operation for the wide load variation range. Moreover, in the proposed converter circuit, the circulating current is effectively minimized without using additional resonant circuit and auxiliary power switching devices. The practical effectiveness of the proposed soft-switching dc-dc power converter was verified in laboratory level experiment with 1 kW 100 kHz breadboard setup using power MOSFETs. Actual efficiency of 94-97% was obtained for the wide duty cycle and load variation ranges.     

Steady-State Analysis of the Series Resonant Converter

The series resonant converter is analyzed in steady state, and for constant switching frequency the output current and voltage characteristics are found to be ellipses. The converter operating point can then be easily obtained by superimposing a load line on these elliptical characteristics. Peak resonant capacitor voltage and inductor current are also plotted in the output plane and are dependent to first order only on output current. When peak voltage and current are plotted in this manner, the dependence of component stresses on operating point is clearly revealed. The output characteristics are modified to include the effect of transistor and diode voltage drops, and experimental verification is presented.     

A novel resonant converter topology for DC-to-DC power supply

A class-E DC-to-DC converter with half-wave controlled current rectifier is proposed. Its output voltage is controlled by the conduction angle of the rectifier switch at constant switching frequency. Zero voltage switching for all the switches can be maintained from full load to no load. Its steady state characteristics are analyzed and the effects of the circuit parameters are studied. Some extensions of the proposed converter are also discussed. The analysis is verified by PSPICE simulation and an experimental prototype     

Buck-flyback DC-DC converter

It is difficult to obtain a large input/output voltage ratio with a DC-DC converter, because the duty factor d may not reach very small values. For the same reason, it is difficult to obtain an output voltage that is adjustable in a large range. A DC-DC converter circuit is proposed that overcomes this limitation by performing a voltage ratio d²/(1-d) in the best operating mode. Circuit operation is analyzed, operating modes are evidenced, and the voltage ratio is deduced in each operating mode as a function of output current, duty factor, and circuit component values. Boundary conditions between different operating modes are obtained; consequently, it is concluded that these conditions do not occur for some operating modes. Component ratings are summarized, to facilitate circuit design. The buck-flyback DC-DC converter is very suitable for low-voltage (e.g. computer) power supplies and for power supplies with the output voltage (adjustable in a large range) supplied from the mains without a mains voltage transformer     

Bidirectional DC-to-AC inverter with improved performance

Switch-mode DC-to-AC inverters using DC-to-DC converter topology have many advantages over the traditional bridge-type inverter. A bidirectional power circuit combined with a nonlinear robust control is proposed to form a high performance inverter. The output voltage of the inverter can be stabilized regardless of large changes in input voltage and output current. The distortion near the zero crossing point can be minimized. The load of the inverter can be resistive, inductive, or capacitive. Simulation results and experimental verification are provided     

Single-phase power-factor-correction AC/DC converters with threePWM control schemes

Three pulse-width modulation (PWM) control schemes for a single-phase power-factor-correction (PFC) AC/DC converter are presented to improve the power quality. A diode bridge with two power switches is employed as a PFC circuit to achieve a high power factor and low line current harmonic distortion. The control schemes are based on look-up tables with hysteresis current controller (HCC) to generate two-level or three-level PWM on the DC side of diode rectifier. Based on the proposed three control schemes, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage, and two capacitor voltages on the DC bus are controlled to be balanced. The simulation and experimental results of a 1 kW converter with load as well as line voltage variation and shown to verify the proposed control schemes. It is shown that unity PFC is achieved using a simple control circuit and the measured line current harmonics satisfy the IEC 1000-3-2 requirements     

Current-fed multiresonant isolated DC-DC converter

A novel topology, current-fed multiresonant dc-dc converter (CF-MRC) was studied theoretically and experimentally. The new topology differs from previously described current-fed push-pull parallel-resonant topologies in the fact that the output is coupled to the current of the resonant inductor and in the addition of a second capacitor across the transformer. The main features of the proposed converter are an inherent protection against a short and open circuit at the output, a high voltage gain and zero voltage switching (ZVS) over a large range of output voltage. These characteristics make it a viable choice for applications, such as a high voltage capacitor charger, that require controllable current sourcing over a wide output voltage swing.     

Power factor correction circuits with robust current control technique

A dynamically robust current control method to synthesize a sinusoidal input current for AC-to-DC converters with boost type topology is presented. Under this control strategy, the inductor current and the diode current of the boost converter are fed back and combined in a special way which makes the input current of the AC-to-DC converter stable and robust. The input current is solely determined by the reference current. When the reference current signal is derived from the sinusoidal input voltage, the input current is sinusoidal and in phase with the input voltage. Theoretical analysis is first provided. Small signal analysis shows that the current loop is inherently stable and has a fast dynamic response. Large signal analysis reveals that the control system is not affected by large disturbances in supply voltage or output load. Computer simulations have been carried out and experimental prototype models have been built to verify the analysis and demonstrate the feasibility of the control strategy. A power factor of 0.998 and a total harmonic distortion (THD) of 3.18% are measured.     

小束斑电子束脉冲轰击偏压电源的研制

为了获得一种性价比较高的电子束表面处理技术,采用定频调压电路,研制出一种新型偏压脉冲电源。这种电源由偏压主电路拓扑、偏压变压器和偏压整流滤波电路组成,其中偏压主电路由偏压基值发生电路和偏压脉冲发生电路组成。偏压基值发生电路控制偏压脉冲基值,偏压脉冲发生电路控制偏压脉冲频率和占空比。脉冲偏压电源的脉冲基值、脉冲频率、占空比均连续可调,相应实现脉冲束流的幅值、束流频率和占空比的调节。检测分析了脉冲偏压电源的输出电压波形,带载时的输出束流波形,并观察分析了电子束轰击后钨合金组织变化规律。结果表明所研制的脉冲偏压电源输出电压稳定、可调性好,能满足小束斑脉冲电子束轰击工艺的要求。     

AC/DC converter topologies for the Space Station

A new class of AC/DC converter topologies (Type-1 converters) is described, 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 resonant network, a current controller, a diode rectifier, and an output filter. The input AC voltage source is converted into a sinusoidal current source using the resonant network. The output of this current source is rectified by the diode rectifier and is controlled by the current controller. The controlled rectified current is then filtered by the output filter to obtain a constant voltage across the load. Three distinct converter topologies, Type-1A, Type-1B, and Type 1-C, are described, and their performance characteristics are presented. All three types have a close-to-unity rated power factor (greater than 0.98), low total harmonic distortion in input current (less than 5%), and high conversion efficiency (greater than 96%)     

ADC1210型12位A/D转换器的应用开发

 一、引言 ADC1210是美国National Semiconductor公司生产的一种低功耗、中速、低价格的12位二进制码（原码、或反码、或偏置码）逐次逼近式A/D转换器。该器件采用CMOS工艺和薄膜工艺相结合的微电子技术制成。器件中包含了R-2R梯形薄膜电阻网络、CMOS模拟开关和逐次逼近逻辑电路、以及场效应管电压比较器等有关电路。其基本技术指标为分辨     

Computer-Aided Design and Graphics Applied to the Study of Inductor-Energy -Storage Dc-to-Dc Electronic Power Converters

A series of nine programs are developed for the design of the inductors of single-winding flyback converters. Three converter types are considered: voltage step-up, current step-up, and voltage step-up/current step-up. For each of the converter types, three pulse modulators are considered: constant frequency, constant transistor on-time, and constant transistor off-time. Computer-graphics displays are used to assist in evaluating characteristics of the various converter-modulator combinations.     

High power factor AC/DC/AC converter with random PWM

A three-phase AC/DC/AC converter is presented with a power factor preregulator to improve the power quality in the input side and a pseudorandom noise generator to reduce the emitted acoustic noise and the mechanical vibration for an induction motor drive. The space vector modulation with hysteresis current control for a voltage source rectifier is adopted to simplify the hardware circuit. A control scheme is presented to drive the supply current following the reference current. The amplitude of reference current for the pulsewidth modulation (PWM) rectifier is derived from the DC bus voltage regulator and the estimated output power. Random switching frequency technique for a three-phase PWM inverter system to reduce the annoying tonal noise and resonant vibration from an induction motor is described. By randomly varying the instantaneous PWM switching frequency from one cycle to the next, the frequency distribution of harmonics is spread in a wide frequency range. The major advantage for using such a strategy is the nonrepetitive output spectral characteristic that results in reduction of torque pulsations in motor drive systems. The nearly unity power factor at the three-phase rectifier and the absence of acoustic noise concentrated at the specific tones which is usually present with conventional sinusoidal modulation are verified by the experimental tests     

Fourier theory of jumps applied to converter harmonic analysis

The Fourier theory of jumps (FTJ) is demonstrated as an aid in deriving closed-form analytical equations for converter switching harmonics. The switching waveforms analyzed are the input current and output voltage and current of a three-phase, ac-dc, step-down, dead-band pulsewidth modulated (PWM), unity power factor converter. The input current closed-form harmonic equation is derived for two parallel-connected, interleaved-PWM converters supplying the same load and sharing a common input filter. The equations are compared with PSpice^TM simulations and practical results     

A Closely Regulated TWT Converter

The design concept for the traveling wave tube amplifier converter for possible use in the Thermoelectric Outer Planet Spacecraft (TOPS) is presented. An unusual combination of semiconductors and magnetics were utilized to achieve very stable voltage regulation on a number of separate outputs to satisfy the requirements of a high-power traveling wave tube (TWT), and at the same time operate at an efficiency of better than 90 percent from a 30-volt source. The circuitry consists of an output filter, an auxiliary Jensen oscillator driving a high-reactance transformer to provide current limiting to the heater, a variable time delay, a main Jensen oscillator driving the power transformer with a maximum step-up ratio of 120 to 1, and series transistorized post regulators to provide precise voltage adjustment and low output impedance. This paper discusses the design of the high-reactance transformer and the high step-up ratio transformer, as well as the high-voltage series regulators that are limited in range and operate at the top of the unregulated output voltage. Test data is presented, and details of current transients caused by charging the filter circuits, input current ripple, and output voltage ripples are considered. The circuit provides better than 0.5 percent regulation against load change, input voltage change, and over-operating temperature range of from -20 to + 80°C, with output ripple voltage of less than 2 volts peak-to-peak on top of the 3600-Vdc output. The measured efficiency was typically 87 percent. and recommendations are included to improve this to in excess of 90 percent.     

单端正激ZVT功率变换器实现

介绍一种单端正激工作方式的零电压过渡（ＺＶＴ）软开关ＤＣ－ＤＣ变换器;描述该变换器的原理和特征;给出了应用ＺＶＴ软开关技术和集成控制块ＳＧ３５２５Ａ的２４Ｖ／９ＡＤＣ－ＤＣ变换器电路和实验结果。     

ZCS-PWM boost rectifier with high power factor and low conduction losses

A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented.     

Analysis of a PWM-resonant converter

When a parallel resonant tank is excited by a bipolar current pulse train a sinusoidal voltage develops across the tank whose amplitude depends on the duty cycle of the pulse train. An isolated secondary can be derived by applying the tank voltage to an isolation transformer whose magnetizing inductance acts as the resonant inductor of the tank circuit. A dc output voltage is obtained after rectification and filtering of the sinusoidal secondary voltage and regulation is achieved by controlling the duty cycle of the pulse train. The sinusoidal nature of the voltage across the isolation transformer alleviates some of the noise problem associated with parasitic capacitances of an isolation transformer when operated with square voltage waveform. In this work the dc and small-signal analysis of the converter is given and an equivalent small-signal circuit model is derived. Experimental results which confirm the validity of the model are presented.