Table-Aided Design of the Energy-Storage Reactor in DC-to-DC Converters

A new procedure for the selection of magnetic cores for use in energy-storage dc-to-dc power converters that eliminates the need for an automated computer search algorithm and stored data file is presented. The converter configurations included in the procedure are the three commonly encountered single-winding converters for voltage stepup, for current stepup and voltage stepup/current stepup, and for the two-winding converter for voltage stepup/current stepup. For each converter configuration, three types of controllers are considered: constant-frequency, constant on-time, and constant off-time. Using concepts developed from analyses of these converters by considering the transfer of energy by means of an energystorage inductor or transformer, a special table of parameters calculated from magnetic core data is constructed, which leads to a considerably simplified design procedure.     

Flyback Converter Output Voltage Stabilization

The expression of the flyback converter output voltage (output power) is derived as a function of the supply voltage, load resistance, transformer ratios, transistor current gain, and base-circuit resistor value. Switching period and duty cycle are also calculated. A converter circuit is designed having stabilized output voltage, with respect to supply voltage, at constant load. The transistor base current is controlled by the supply voltage, via a nonlinear circuit. This feedforward circuit approximates with logarithmic characteristics the ideal hyperbolic dependence of the transistor base current as a function of the supply voltage. The converter has high performance and low cost. A cheaper circuit variant is presented, in which the high-voltage control transistor was eliminated.     

Design optimization for asymmetrical ZVS-PWM zeta converter

In this paper, a new soft-switching Zeta converter with an asymmetrical pulsewidth modulation (PWM) control is proposed. The proposed Zeta converter has the features of constant frequency operation, zero voltage switching (ZVS), and low voltage stress on the active switches. Moreover, it can achieve high power density, high efficiency, low switching loss, and low component count, which make converter operation at low to medium power level feasible. Operational principle of the Zeta converter is presented in detail, and a specific example is designed and implemented to verify its feasibility.     

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.     

Space vector modulation strategy for an eight-switch three-phase NPC converter

A three-phase neutral point clamped (NPC) converter is presented for power factor correction and dc-link voltage regulation. A simplified space vector pulsewidth modulation scheme (SVPWM) is adopted to track line current commands. Using a simplified SVPWM algorithm, the calculated time for the time duration of voltage vector is reduced. The adopted NPC converter has less power switches compared with the conventional three-level NPC converter. Only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used in the circuit configuration. Based on the proposed control algorithm, a reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. Computer simulation and experimental results based on a laboratory prototype are presented to verify the validity and effectiveness of the proposed control strategy.     

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     

Z-源稀疏矩阵变换器励磁的双馈风力发电系统

针对矩阵变换器电压传输比低和其励磁的双馈风力发电系统(DFIG)易受非正常输入波动影响的不足,提出了一种适用于DFIG励磁的Z-源稀疏矩阵变换器系统。利用Z-源的升压特性来提高电压传输比,检测电容电压实现对直通因子的自动调节,从而实现对网侧波动的自动抑制。建立了系统数学模型,推导了DFIG系统定子磁场定向矢量控制策略表达式,搭建试验样机对所提方案进行试验验证,在亚同步、同步、超同步三种发电状态下的波形和并网试验结果验证了方案的可行和有效性。     

Suitability of pulse train control technique for BIFRED converter

Pulse Train/spl trade/ control scheme is presented and applied to a boost integrated flyback rectifier/energy storage dc-dc (BIFRED) converter operating in discontinuous conduction mode (DCM), which avoids the light-load high-voltage stress problem. In contrast to the conventional control techniques, the principal idea of Pulse Train technique is to regulate the output voltage using a series of high and low energy pulses generated by the current of the inductor. The applicability of the proposed technique to both the input and magnetizing inductances of BIFRED converter is investigated. Analysis of BIFRED converter operating in DCM as well as the output voltage ripple estimation is given. Experimental results on a prototype converter are also presented.     

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%)     

Multimodule parallel series-loaded resonant converters

The design and implementation of a multimodule parallel series-loaded resonant (SLR) converter system is presented. The SLR converter to be paralleled is operated in the n=2 discontinuous mode (DCM). Its dc analysis and dynamic modeling are made. In parallel operation, an average control technique is proposed to compensate the mismatch in current control characteristics of each parallel converter. Good dynamic and static current sharing characteristics are obtained. In addition, to obtain good output voltage regulating control performance, a design procedure is presented to find the parameters of feedback voltage controller according to the prescribed specifications     

Three-phase single-stage ac/dc boost integrated series resonant converter

A new ac/dc 3-/spl phi/ single-stage converter is proposed integrating a 3-/spl phi/ discontinuous current mode (DCM) boost with a dc/dc fixed frequency series resonant converter (SRC). This converter has the following features: natural power factor correction, soft switching, high-frequency (HF) transformer isolation with the series resonant tank operating in above resonance mode, etc. A new complementary gating control scheme is used for simultaneous control of boost converter and the SRC. Modes of operation are presented and analyzed. Based on the analysis, design curves are obtained. An optimum design is given and a design example is presented. Results obtained from SPICE simulation for the designed converter are given to verify the performance of the proposed converter for varying load as well as line voltage. Experimental results obtained from a laboratory prototype converter are presented to verify the theory.     

永磁同步电机有限集模型预测直接转矩控制

针对永磁同步电机(PMSM)模型预测直接转矩控制(DTC)转矩脉动大、功率元件开关频率不恒定等问题,将两电平逆变器的8个电压空间矢量作为有限控制集,应用到PMSM DTC中。设计考虑转矩误差、最大转矩电流比及电流约束的成本函数,利用成本函数来估算有限集合中各电压矢量的占空比,从而求得逆变器的最优电压矢量作为系统控制量。与传统模型预测控制方法相比,该方法的电流谐波和转矩脉动显著降低,且转矩动态性能也得到改善。仿真试验结果验证了所提出的控制方案有效性。     

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.     

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.     

Single-phase grid-connected PV system using three-arm rectifier-inverter

A grid-connected photovoltaic (PV) power supply system with on-line voltage regulation capability is presented. It employs the three-arm rectifier-inverter topology with PV modules connected directly on the dc-link. The common-arm is with line-frequency switching and synchronous to the input voltage, aiming for a lower switching loss and decoupling the control of rectifier and inverter portions. As a result, the rectifier and inverter portions can be controlled independently with the rectifier-arm and inverter-arm, respectively. For maximum power point tracking (MPFF) of the PV modules and balancing the power among utility, PV, and the load, a variable dc-link voltage is adopted and controlled by the rectifier-arm based on the MPPT control algorithm. The inverter-arm then regulates the load voltage with good regulation and low distortion. Due to large variation of the dc-link voltage, a feedforward plus feedback control technique with variable gain is developed to keep constant bandwidth of the current loop at any operation condition. Therefore, the performance of the rectifier and inverter portions can be ensured. A system containing a 2 kVA converter and a 1.2 kW PV module is set up, and some experimental results are provided for demonstrating the effectiveness of the proposed method.     

Full bridge ZCS PWM converter for high-voltage high-powerapplications

This paper presents a comprehensive study of a full bridge (FB) zero-current switched (ZCS) PWM converter which is suitable for high-voltage and high-power DC application that achieves ZCS for all active switches, and zero-voltage-switched (ZVS) operation for all diodes on the high voltage side. The given converter utilizes component parasitic parameters, particularly for the high-voltage transformer, and employs fixed-frequency phase-shift control to implement soft-switching commutations. Detailed steady state analysis of the converter power stage is presented for the first time and the major features of the converter's power stage are discussed. Small-signal characteristics are also presented and accompanied by a discussion of the controller design and implementation. A design example is also presented based on the steady state analysis and is validated by simulation. Theoretical and simulated results are in good agreement     

Soft-switching single-stage AC-to-DC converter with low harmonic distortion

A 1 /spl phi/ high-frequency (HF) transformer isolated, soft-switching single-stage ac-dc converter with low line-current harmonic distortion is presented. Its operation is explained with equivalent circuits for the various intervals. The converter is analyzed and design curves are obtained. An optimization parameter is introduced and a systematic design procedure is illustrated with a design example. Detailed SPICE simulation and experimental results of a 500 W converter with load as well as line voltage variation are given to verify theory. The proposed converter employs a zero-voltage transition (ZVT) network to ensure zero-voltage switching (ZVS) at all loads, and natural power factor correction is ensured using a simple control circuit.     

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     

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     

A new zero-voltage switching DC/DC boost converter

A pulsewidth-modulated (PWM) zero-voltage-switching quasi-resonant boost converter operating at constant switching frequency is presented. In contrast to the frequency-modulated (FM) zero-voltage-switching quasi-resonant boost converter, this converter possesses better controllability and higher operating performance, and overcomes the instability caused by the parasitic oscillation. The principle of operation and performance of the converter are presented. Its two-dimensional state trajectories and steady-state characteristic curves are derived which are useful for the converter design. Both the SPICE simulation and experimental result agree with the theoretical prediction