Rectifier System Research Articles

Reduced Active Switch Front-End Multipulse Rectifier With Medium-Frequency Transformer Isolation

This paper presents a reduced switch count multipulse rectifier with medium-frequency (MF) transformer isolation. The proposed topology consists of a three-phase push–pull based ac to dc rectifier with a MF ac link employing two active switches. A three-phase, five-limb, multiwinding MF transformer is employed for isolation. The secondary side of the transformer is connected in a zig-zag configuration and is fed to two six-pulse diode rectifiers, achieving 12-pulse rectifier operation. The primary advantage of the proposed system is reduction in size/weight/volume compared to the conventional 60 Hz magnetic transformer isolation rectifier system. Operating the transformer at 600 Hz is shown to result in three times reduction in size. Furthermore, the proposed system employs only two active semiconductor switching devices operating under a simple pulse width modulation scheme. Also, the zig-zag transformer connection helps to balance leakage inductance on the secondary side. Detailed analysis, simulation, and experimental results on a 208Vl-l, 3.15 kW laboratory prototype are presented to validate the performance of the proposed approach.

Three-phase diode rectifier with current modulator in DC circuit based on multi-channel converter

AbstractIn the paper the 3-phase power diode rectifier system with quasi-sinusoidal input (power grid) current is presented. In order to benefit from it, the current modulation in the DC circuit of a rectifier is used. The essential part of the current modulator is the wide-band power electronics controlled current source based on a multi-channel converter. The control algorithm of the current modulator respects impact of aliasing phenomena at system stability by using the method proposed by the authors. The paper includes the rectifier system description and rules of operation of the current modulator. Also, some results of research on both the rectifier simulation model and the laboratory prototype of a current modulator are presented.

Design and Simulation of Grid-Connected Rectifier and Boost Control Circuit for Micro-Turbine

本文对微型燃气轮机并网整流与升压控制回路进行了设计与仿真。整流部分(Rectifier system)选用电压型PWM整流器(VSR)，所搭建模型主要包括输入滤波电感(Reactor)、整流桥(Three-Level Bridge Rectifier)、整流控制器(Rectifier Controller)和直流滤波电容(C1, C2)。本次研究课题的斩波电路选用的是升压Boost斩波电路，将电压调节器用作外环控制，电流内环则根据id*、iq*的值来控制电流，从而实现对交流侧电流的快速调节作用。Boost Controller模块主要是通过产生合适的控制脉冲信号来控制可控开关Mosfet的通断，最终实现调节输出电压的目的。仿真结果表明本文设计的整流电路与升压控制回路输出电压波形稳定性优良。 In this paper, the design and simulation of the micro-turbine grid-connected rectification and boost control circuit are carried out. Rectifier system selected voltage-type PWM rectifier (VSR), the proposed model includes input filter inductors (Reactor), rectifier bridge (Three-Level Bridge Rectifier), rectifier controller and DC filter capacitor (C1, C2). The chopping circuit of this research topic is the step-up Boost chopper circuit, the voltage regulator for the outer ring control, and current inner ring can be based on id*, iq* value to control the current, in order to achieve the ra- pid adjustment of the AC side of the current role. Boost Controller module is mainly through the generation of appropriate control pulse signal, thus controlling the control switch Mosfet off, and ultimately achieving the purpose of adjusting the output voltage. The simulation results show that the design of the rectifier circuit and the boost control circuit output voltage waveform stability is excellent.

Design of an Efficient Rectifier Circuit for RF Energy Harvesting System

An efficient rectifier system along with an impedance matching network is proposed in this article. Impedance matching network is designed using two microstrip lines. Rectifier system for better RF to DC conversion is designed using a bridge rectifier. The proposed rectifier system provides a maximum efficiency of 50%. The impedance matching network improves the overall system performances significantly. The circuit simulator ADS 2015 is used for this system design. Performances of the proposed system are analysed using simulation results only. This proposed rectifier system along with the impedance matching network can be useful for the design of an efficient RF energy harvesting system.

EMI Filter Volume Minimization of a Three-Phase, Three-Level T-Type PWM Converter System

In this study, the power density of a two-stage, i.e., LCLCL, electromagnetic interference (EMI) filter for a 10 kW three-phase, T-type three-level, boost-type PWM rectifier system is optimized concerning construction volume. It is found that reasonable boundary conditions limit or define most component values and only few degrees of freedom are remaining. In this context, the ratio of the first filter stage's common to differential mode inductance, k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cm,1</sub> /L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dm,1</sub> , is identified to particularly affect the total filter volume. For given switching frequency and DC-link voltage of f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> = 48 kHz and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> = 700 V, a flat minimum of the overall filter volume results for 10 <; k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> <; 40. The boxed volume of the filter realized for k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> = 18 is 763 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (46.6 in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ), which corresponds to a filter power density of 13.1 kW / dm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (215 W / in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). Measurements of conducted EMI confirm that the rectifier system complies with the considered limits of conducted EMI (CISPR 11, class A).

Control Concepts for Hybrid Rectifiers Utilizing a Flying Converter Cell Active Current Injection Unit

A passive three-phase rectifier circuit equipped with a “Flying Converter Cell” (FCC) active current shaping network, based on the third harmonic injection concept, has been introduced recently. This additional/optional circuit allows the upgrade of a standard B6 diode rectifier to a low harmonic input stage with unity power factor. In order to guarantee properly shaped sinusoidal mains input currents, dedicated current and voltage controllers of the active circuitry must be designed carefully. As the active current injection unit consists of an assembly of three individual converter stages, the design procedure of both current and superimposed voltage controllers results in fairly high complexity. It is, therefore, going to be discussed in detail in this work. Based on the analysis of the rectifier system, an appropriate control concept is developed which is implemented using a digital signal processor. It is furthermore shown that the midpoint voltage of the FCC can advantageously be used for balancing of the dc capacitor stage of the cell without deteriorating total harmonic distortion of mains input currents. Measurement results taken from a 10 kW/10 kHz laboratory prototype finally confirm promising characteristics of the total hybrid system.

Design, fabrication, simulation and testing of an ocean wave energy converter with mechanical motion rectifier

Many wave energy converters have been developed in the past century with various power takeoff systems, including those devices with air turbines, linear electromagnetic motors, and hydroelectric components. Although these systems have their own advantages, power takeoffs are still recognized as the most important challenge in ocean wave energy technology. In this paper, a mechanical motion rectifier (MMR) based power takeoff system is proposed and prototyped for wave energy converter. This power takeoff system can convert the bidirectional wave motion into unidirectional rotation of generator by integrating two one-way bearings into a rack pinion system. A wave energy converter which contains a 1.2m buoy and MMR based power takeoff system was designed and fabricated in this paper. The models of power takeoff system and single-body wave energy converter were built and analyzed. The simulation results in regular wave show that MMR based power takeoff can produce more power comparing with linear damping power takeoff system and the optimal PTO damping of MMR system is smaller than that of linear damping system. Lab testing of power takeoff mechanism and ocean testing of the overall ocean wave converter system were also conducted to validate the concept of MMR design. The disengagement and engagement of one-way bearings in the mechanical motion rectifier system were verified in both lab and ocean test.

A Novel 24-Pulse Diode Rectifier with an Auxiliary Single-Phase Full-Wave Rectifier at DC Side

A simple and robust 24-pulse diode rectifier for low-voltage and high-current applications is proposed in this paper. The proposed 24-pulse diode rectifier consists of a conventional four-star 12-pulse diode rectifier and an auxiliary single-phase full-wave rectifier (ASFR) installed at dc side. The low-power (3.4%Po) ASFR extracts two rectangular currents from the modified second-stage interphase transformer and injects a square current into the output of the rectifier system. This modification extends the conventional four-star 12-pulse operation to 24-pulse operation. The proposed 24-pulse rectifier draws near sinusoidal input line currents with the absence of 5th, 7th, 11th, 13th, 17th, and 19th harmonics. The average value of current through the ASFR has only 1.7% of load current, which means the current rating and conduction losses of ASFR are very small. The proposed scheme has low-diode conduction losses, and it is more suitable for low-voltage and large-current applications. Since only an additional ASFR is needed, the proposed scheme is low cost and simple to implement. The detailed analysis for the proposed rectifier is presented, and experimental results are provided to verify the proposed concept.

Performance and Design Analysis on Round-Shaped Transformers Applied in Rectifier Systems

In this paper, a novel rectifier transformer that has a round-shaped structure is investigated. The transformer can convert three-phase power into 12-phase, which supplies to a rectifier composed by four bridges for producing dc voltage with 24-pulse. With such transformers, rectifier performance can be improved in both input and output waveforms. The principle of harmonics elimination is explained and some critical problems may be encountered in design are discussed. The experiments on the prototype are carried out for performance assessments regarding characteristics, such as ripple factor, total harmonic distortion, efficiency, etc. The results demonstrated the effectiveness of the novel transformer in harmonics mitigation.

Damped High Passive Filter—A New Filtering Scheme for Multipulse Rectifier Systems

Multipulse rectifier systems are commonly used to reduce harmonic emission. However, they still require the installation of noncharacteristic harmonic filters to prevent harmful resonance between its high-pass filter and the system impedance. The advantage of a multipulse configuration-very low noncharacteristic harmonic emission-is, therefore, not fully utilized. In view of this shortcoming, a novel filter called the damped high-pass filter is proposed. The filter does not cause resonance at the noncharacteristic harmonic frequencies. As a result, traditional noncharacteristic 5th and 7th harmonic filters are no longer needed, resulting in significant cost and space savings for the multipulse systems. The core idea behind this filter is a frequency-dependent resistor block that provides high damping at the noncharacteristic harmonic frequencies. The design procedure for the proposed filter is presented. Performance and usefulness of the new filtering scheme has been demonstrated through comparative studies on two actual industry cases.

Single-Phase Grid-Connected Motor Drive System With DC-Link Shunt Compensator and Small DC-Link Capacitor

The single-phase diode rectifier system with small dc-link capacitor shows wide diode conduction time and it improves the grid current harmonics. By shaping the output power, the system meets the grid current harmonics regulation without any power factor corrector or grid filter inductor. However, the system has torque ripple and suffers efficiency degradation due to the insufficient dc-link voltage. To solve this problem, this paper proposes the dc-link shunt compensator (DSC) for small dc-link capacitor systems. DSC is located on dc-node in parallel and operates as voltage source, improving the system performances. This circuit helps the grid current-shaping control during grid-connection time, and reduces the flux-weakening current by supplying the energy to the motor during grid-disconnection time. This paper presents a power control method and the design guideline of DSC. The feasibility of DSC is verified by simulation and experimental results.

Grid Current Shaping Method with DC-Link Shunt Compensator for Three-Phase Diode Rectifier-Fed Motor Drive System

This paper proposes grid current shaping method using dc-link shunt compensator for three-phase diode rectifier system without electrolytic dc-link capacitor. In the proposed method, the diode rectifier system can satisfy the grid regulation IEC61000-3-12 without any power factor correction circuit or heavy grid filter inductor. The proposed grid current shaping method can be realized by applying DSC with reduced-rating components and without electrolytic capacitor, which is connected parallel to the dc link. Since DSC has no electrolytic capacitor, the system with DSC has high circuit reliability. Furthermore, DSC can enhance the system efficiency, especially in flux-weakening area, since the motor drive inverter recovers the reduced modulation index, which has been spent in the additional control for small passive components. This paper presents the control method for DSC and analyzes the effect of proposed method. The feasibility of proposed method is verified by simulation and experimental results.

Analysis of power and energy losses in power systems of electric bus battery charging stations

Two variants of electricity transmission from the Transfer-Switching Station (TSS) to the battery charging station were analysed in the paper. The first variant under analysis referred to the transmission of electricity via a three phase a.c. line with rated voltage of 15 kV. In the second variant of electricity transmission, the d.c. line with the working voltage of 1500 V was used. For both variants, lines and other equipment such as transformers, rectifier system and voltage stabilisation system in the battery charging station were modelled. For both solutions, analysis of energy per annum was conducted depending on the distance of the charging station from the TSS. On top of this, the simultaneous operation of several chargers was taken into account, which would correspond to the case of charging many buses at the same time from a single power line. The paper demonstrates that in the case of the analysed electricity transmission systems in the electric bus battery charging systems it is possible to use a more advantageous solution, which is characterised by reduced power and energy losses.

Efficiency improvement of WPT system using inexpensive auto‐adaptive impedance matching

An inexpensive auto-adaptive impedance matching rectifier for wireless power transfer (WPT) systems is proposed. In most WPT systems, due to environment variations, the received power varies during the time. Owing to nonlinear characteristics of diodes, variation of received power results in impedance mismatch which degrades the efficiency of the system. The proposed rectifier system changes the matching circuit using two switches based on the level of the output voltage. This strategy provides matching in a wide range of power levels and consequently improves the efficiency of the system up to 20%. The proposed rectifier is fabricated and the output DC voltage is measured showing very good agreement with simulation result.

Decoupled control strategy for the operation of capacitor‐excited induction generator for DC power applications

In this study, voltage oriented decoupled current mode control technique has been proposed for the operation of the capacitor-excited induction generator with pulse-width modulation (PWM) rectifier systems for supplying isolated DC loads. The proposed controller maintains constant voltage at the DC load terminals and also maintains unity power factor with very less harmonics at the PWM rectifier input terminals. The configuration and implementation of the control scheme employing dSPACE 1103 real-time controller have been fully described. A method for predetermining the steady-state performance of the proposed system has been developed and described with relevant analytical expressions. The effective load at the generator terminals becomes only resistance, since unity power factor is maintained at the PWM rectifier input terminals by the closed-loop controller. To verify the successful working of the proposed control strategy during transient conditions, the proposed system has been modelled in the MATLAB/Simulink toolbox and results are presented. A prototype system consisting of CEIG, PWM rectifier and the associated control circuits has been built in the laboratory for experimental verification. A close agreement between the experimental results and predicted values confirms the validity of the analysis and successful working of the proposed control strategy.

Analysis, Measurement, and Compensation of the System Time Delay in a Three-Phase Voltage Source Rectifier

The system time delay, which can be several times greater than the switching period, is typically neglected during the design of a three-phase voltage source rectifier system. As a result, the system time delay can cause different types of deteriorations, including a surge in the ac current, an overshoot in the dc-link voltage, and a decrease in system stability. This study first develops a dc model and linear model to form the basis of the analysis of the relationships between the system time delay and deteriorations. A novel method is then proposed to provide an accurate measurement of the system time delay to improve the efficiency of compensation methods. Based on the analysis and measurement results, two new compensation methods are subsequently proposed to effectively mitigate these deteriorations. The efficiency of the measurement and compensation methods is finally demonstrated via simulations and experiments.

An AC–DC converter for human body-based vibration energy harvesting

This paper presents an optimized AC–DC converter designed in 65nm low power process technology. Two topologies of the AC–DC converter are designed, namely, Bias-Flip rectifier and Voltage Doubler. The design is part of a piezo electric energy harvesting system targeting wearable electronics. Voltage doubler and full-bridge rectifier are fabricated to support a start-up mechanism while the bias-flip rectifier supports higher efficiency for the normal operation mode. Using a piezo electric energy harvester mounted on a shaker and operated at 4.5Hz, the maximum extracted power from the voltage doubler is measured as 79.8nW at 0.21g. In addition, the maximum extracted power from the full-bridge rectifier is measured as 22.2nW. As such, voltage doubler is more efficient than full-bridge rectifier by 71%. The experiment uses MIDE V22BL piezo electric harvester with 25Hz resonance frequency. However, the harvester was used at 4.5Hz (human frequency) which degrade the energy extracted from the harvester. If another harvester was designed to tune to lower frequency, higher energy level can be extracted. Another contribution in this paper is to compare the on-chip voltage doubler to board level with discrete components. Our experimental results show 11% improvement in efficiency for the on-chip design compared to off-chip for the same input power. The combined bias-flip rectifier and voltage doubler support energy autonomous systems where no start-up power is needed.

Isolated Swiss-Forward Three-Phase Rectifier With Resonant Reset

This paper presents a new isolated single-stage pulse-width modulation rectifier system based on the recently presented Swiss rectifier topology providing the isolation by replacing a buck with a forward converter. The principle of operation and a new modulation technique which compensates the reactive power generated by the input filter at light load and maximizes the power factor are discussed. Furthermore, the analytical equations for the stress in the semiconductor devices useful for the system optimization are derived. The proposed topology and modulation technique are experimentally validated on a 3.3-kW 115 Vac to 270 Vdc prototype demonstrator.

An Inductively Filtered Multiwinding Rectifier Transformer and Its Application in Industrial DC Power Supply System

In this paper, a new industrial direct-current (dc) power supply system with the four-winding inductively filtered rectifier transformer (FW-IFRT) is proposed based on an inductive filtering (IF) method, which can effectively solve the power quality problems generally existing in the high-power rectifier system, such as high energy consumption, serious harmonic pollution, low power factor, and so on. The single-phase equivalent circuit model of such a new system is established based on the multiwinding transformer theory, and then its operating characteristics are investigated in detail. The harmonic suppression factor is proposed, and the influences of system and transformer impedances on the harmonic suppression characteristic are revealed. Finally, the simulation and experimental case studies are used to verify the effectiveness of the proposed system on the comprehensive improvement of power quality and operating efficiency.

Simplification and unification of IEEE standard models for excitation systems

This work proposes the generalization of models for excitation systems. Thirteen models according to IEEE standard are reduced to three main types by the development of a common universal excitation control model. The original IEEE division of exciter types into alternator-supplied rectifier and static excitation system is rearranged into non-controlled and controlled rectifier types. This division is suitable for model classification and for authors and users of network simulators. Proposed simplification may facilitate a data collection of dynamic models for studies of large power system.