Switch-mode Rectifier Research Articles

Feasible single-phase UPS incorporating switched-mode PFC rectifier with high-frequency transformer link

The general purpose high performance single phase UPS topologies are indispensable for the considerable reduction of harmonic current components in a.c. mains as well as the realization of unity power factor correction (PFC). In particular, the single phase PFC rectifier with a high-frequency isolation transformer link has some feasible advantages as an electrically isolated a.c./d.c. conversion circuit for small scale UPS. This UPS is capable of eliminating harmonic currents and realizing an isolation between a.c. input and d.c. output power stage as well as matching the d.c. side input voltage of the PWM inverter by means of incorporating a compact high-frequency transformer into high-frequency intermediate stage. Electrically isolated PFC rectifiers designed for 2 kVA, 3 kVA and 5 kVA UPSs are put into practical use as new topological versions. This paper presents a circuit configuration of high-frequency link PFC rectifier for small scale UPS, its operating principle and related control strategy. The steady state and dynamic state performances of three power classes of UPSs which incorporate this type of PFC converter are evaluated from a practical point of view.

Dynamic modelling and control of a step up/down switching-mode rectifier

The authors present the dynamic modelling and control of a switching-mode rectifier (SMR) with step up/down voltage and power factor correction control. Depending on the output voltage level, this rectifier can be operated in buck or boost mode during each AC half cycle. It follows that this SMR possesses wide DC output voltage range, and it can be used as a battery charger with large charging flexibility for a serially connected battery bank. The power circuit of the proposed rectifier is first analysed and designed. Then its dynamic model is derived. Based on this, a current waveform controller is designed, such that sinusoidal line current with low harmonics and near unity power factor is obtained. In addition, a charging controller is also designed for yielding good dynamic charging characteristics. After confirming the validity of the designed rectifier by simulations, the circuit implementation is performed and some measured results are provided for further demonstrating its performance.

Bang-bang current control with predecided switching frequency for switch-mode rectifiers

An active current waveshaping/control technique with continuous conduction of input current and suitable for single-phase switch-mode rectifiers (SMRs) is proposed. The nature of input current is similar to that of bang-bang hysteresis current control. The technique does not require a reference hysteresis window. Current control is achieved with constant switching frequency for a given load current. The switching frequency varies inversely with the load current, but is known and predecided. Simulated performance results and selected experimental results are provided.

A new space-vector-modulated control for a unidirectional three-phase switch-mode rectifier

A unidirectional three-phase switch-mode rectifier that delivers sinusoidal input currents in phase with the corresponding input phase voltages is proposed and analyzed in this paper. In the proposed topology, three AC switches are placed before the bridge rectifier and, respectively, across two power lines. A simple control scheme combing space-vector modulation and hysteresis current control is presented. Sinusoidal input line currents are observed in experimental results.

Three-phase step-down reversible AC-DC power converter

Bidirectional DC current flow is not a natural feature of the buck (step-down) switch-mode rectifier, which leaves it at a disadvantage to boost (step-up) designs. A circuit topology is presented that allows bidirectional flow and which, by dual use of components, uses fewer devices than anti-parallel bridges. Sinusoidal current, controlled displacement factor, and variable voltage transfer ratio are demonstrated in a 1.5 kVA prototype. Dynamic performance is investigated through simulation and experiment. A PI plus velocity controller is shown to be adequate provided care is taken over changing between rectification and inversion.

Modelling and design of a reversible three-phase switching mode rectifier

A reversible three-phase switching mode rectifier consisting of a four-active-switch and without current sensor is proposed. To achieve controllable power factor, clean sinusoidal input current, adjustable DC output voltage, and bidirectional power flow capability, a closed-form pulse width modulation (PWM) duty cycle function is derived. The popularly used state space averaging technique is extended for modelling the reversible three-phase four-active-switch rectifier. The space vector representation technique is then used to simplify the modelling process without sacrificing accuracy and valid frequency range. Both steady-state and small signal analyses are made. Results show that the proposed closed-form control law for the rectifier can indeed achieve the desired property. Moreover, the rectifier also possesses a bidirectional power flow capability, which is useful for many applications. Finally, a prototype hardware circuit was constructed and experimental results are presented for demonstration. Guidelines for determining the LC parameters and the PI controller gains are described briefly in the text.

Programmable input power factor correction method for switch-mode rectifiers

A programmable method for single- and three-phase switch-mode rectifiers (SMRs), operating with discontinuous current conduction to control input power factor close to unity, is presented. Single-phase SMR operation is based on variable turn-on time, while three-phase SMR operation is based on constant turn-on time.

Three-phase switch mode rectifier with hysteresis current control

A three-phase configuration of a switch mode rectifier (SMR) that makes use of continuous conduction waveform of the input supply current is suggested. Continuous conduction is achieved by the hysteresis current control (HCC) technique. This three-phase SMR operates at close to unity power factor and has reduced current stresses on the switching devices because of the continuous nature of input current. The conduction period considered for the rectifier diodes is 180/spl deg/. Digitally simulated performance results are provided. Selected experimental results demonstrating the SMR operation are also presented.

Novel three-phase SMR converter with inherent snubber energy recovery capability

This paper describes the switch mode rectifier (SMR) having a quite new circuit configuration, which has been developed by the authors and given the name "DC clamped type SMR" (DCC-SMR). The DCC-SMR is unique in that no bilateral switching device is used in the frequency conversion circuit. Therefore, the authors have used a DC snubber circuit in conjunction with the switching device of the DCC-SMR. This DC snubber circuit features a very simple structure consisting only of a capacitor with no need for a discharge resistance or for a complicated regenerative circuit for snubber energy. This is because snubber energy is regenerated on the primary side of the high frequency (HF) transformer by the main switch. Furthermore, an innovative method has been applied for magnetic saturation-preventive control of the HF transformer. The authors carried out operational checks on the main circuit and the snubber circuit of the DCC-SMR as well as on the magnetic saturation-preventive control circuit, and through experiments confirmed a satisfactory result. We manufactured an industrial DC power supply prototype of the DCC-SMR system having a DC output of 100 kW (100 V, 1000 A), with which input/output conversion efficiency 91.6%, input power factor 0.99 and input current total harmonic distortion factor 4.6% were obtained.

Improving Input Current Waveforms in a Switching Mode Rectifier with a High Frequency Transformer.

In recent years, switching mode rectifiers (SMRs) which are composed of a capacitor input type rectifier and a DC-DC converter have been used to supply DC power to various electronic systems. Despite their desirable features such as small-size, light-weight, and high-efficiency, there is a disadvantage in that their input current waveforms include many harmonic components, which could severely influence other systems that AC power lines in common with the SMR. Conventional method to improve the waveforms uses bidirectional switch modules or three full bridge conversion circuits. However, this method cannot decrease the size, because the number of the switching devices increase.To solve this problem, a novel SMR with a high frequency transformer has been studied. In it, input 3-phase AC voltage is directly converted into high frequency AC, then rectified. Futhermore, low order harmonics in the input current waveforms can be eliminated by controlling the conduction intervals of switches, proportional to the instantaneous input line to line voltage.This paper describes the configuration of the novel SMR and its operating principle for obtaining sinusoidal input current waveforms as well as discusses the distortion factor characteristics of the input current waveforms.

Three-phase four wire voltage controlled AC line conditioner with unity input power factor and minimised output voltage harmonics

The paper presents a new high performance AC line conditioner isolating any configuration of nonlinear loads for three-phase four wire applications. The proposed conditioner is composed of a switch mode rectifier (SMR) and a ROM based sinusoidal pulse width modulation (SPWM) inverter. The three-phase half bridge type SMR operates under voltage mode control. No current sensing is required. The inverter is also a half bridge type controlled by a ROM based SPWM modulator. Preoptimised SPWM control patterns rejecting the effects of DC link voltage ripples and dead times are programmed. Owing to the nature of the three-phase scheme, the voltage imbalance problem between the DC link capacitors can be lessened. High quality three-phase AC outputs can be obtained while nearly sinusoidal input currents are drawn.

Single-phase switch-mode rectifier employing voltage-reversal circuit switched with a fixed frequency

A single-phase switch-mode rectifier employing a voltage-reversal circuit is studied. The voltage-reversal circuit is switched with a fixed frequency in order to give a supply current with a sinusoidal waveform and a near-unity power factor independent of the working conditions, and to suppress the magnetic noise caused by the low-order harmonics. The operation is macroscopically analysed by a state-space averaging method based on a DC equivalent circuit and such an operation is also simulated by a rigorous state-space method. The arrangement tested, using two insulated-gate bipolar transistors and a 16-bit microcomputer, is implemented to investigate experimentally the steady-state and transient characteristics. The experimental and simulated results confirm the relevance of a switching strategy with a fixed frequency for a single-phase switch-mode rectifier employing a voltage-reversal circuit.

Novel Three-phase SMR Converter.

We already developed a conventional SMR (Switch Mode Rectifier) converter using bilateral switch. A conventional SMR converter has a weak point that is to be need of AC snubber circuit and the complicated circuit for regeneration of snubber energy.This paper discribes a novel three-phase SMR converter which was named DC-Clamped type SMR ( DCC-SMR ) using direct frequency changing technology for industrial use power supply. DCC-SMR consists of frequency changer, HF (High Frequency) transformer and HF rectifier. Frequency changer of DCC-SMR doesn't use bilateral switch. Then, we can use DC snubber for switch. Furthermore, DCC-SMR doesn't-need regenerative circuit and discharge resistance, because snubber circuit is only capaciter and snubber energy is regenerated to primary winding of HF transformer by main switch.We verified usefulness in experimentation. Moreover, we refer to efficiency of 100kw prototype system.

A new PWM control method for AC to DC converters with high-frequency transformer isolation

A PWM control method for a switch-mode rectifier (SMR) based on the idea of coordinate transformation is presented. This method realizes sinusoidal input current waveforms, a controllable input displacement factor, and an arbitrary output voltage waveform. This method is advantageous for reducing higher and fractional harmonic components of the input waveforms and is suitable for real-time control. Simulations and experiments are carried out to confirm the feasibility of the proposed method. >

A novel current-assisted output voltage control technique for switch-mode-rectifier converters

A current-assisted voltage control technique for high-power switch-mode-rectifier (SMR) converters is proposed. This technique implements a fast-forward AC current loop by sensing the current through the output filter capacitor. The control loop forces the AC current component of the output filter inductance to be synchronized with a symmetrical triangular reference waveform. As a result, the converter behaves like a fixed-frequency current-regulated voltage source with a low-output impedance and an increased bandwidth. A small-signal linear model is derived and the dynamic performance of a buck-derived SMR using the proposed control technique is analyzed. Simulation and experimental results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis and design of a three-phase offline DC-DC converter with high-frequency isolation

Single-phase offline switch mode rectifiers (or offline DC-DC converters) face severe component stresses in higher than 10kW applications. The authors show that in three-phase, switch-mode rectifier (SMR) topologies' component stresses are reduced, and performance is improved substantially. These improvements include faster response times, reduced switching stresses of the power semiconductor devices, and reduced size and ratings of associated reactive components. The authors also present an analysis and design approach for three-phase SMR converters under large-input voltage and load variations. Output voltage control is achieved by varying the duty cycle of the inverter power semiconductor switches. Theoretical results are verified experimentally. >

Novel PWM-based control strategy of HF link SMR with sinusoidal line current

A novel PWM control strategy is presented, based on the current-mode control approach for a high-frequency (HF) link switch mode rectifier (SMR). This control strategy allows sinusoidal wave shaping of the line current and power-factor correction while ensuring amplitude modulation of the HF transformer waveform in a single power processing stage. The method is based on the sampling of the inductor current during transfer time into several HF transfer cycles using a sampling signal. The sampling signal is introduced to avoid HF transformer saturation and to allow operation at an extremely high frequency (50 k-100 kHz). Power MOSFETs modules (450 V/50 A) which are suitable for operation at frequencies ranging up to hundreds of kHz are used for the experimental set-up. A bridge configuration which is a boost-like convertor is used for the boosting and the inverting stages. The proposed HF link SMR is intended for use in high-frequency link UPS equipment for a power range of 1–5 kVA. Analysis and experimental results show that operation is possible with a sinusoidal line current in phase with the utility voltage and with approximately unity power factor.

Novel full bridge semicontrolled switch mode rectifier

A novel semicontrolled switch mode rectifier (SMR) topology is proposed and analysed. Its advantages when compared with other existing SMR topologies are high true power factor at the AC source (almost unity), high displacement power factor at the input of the SMR unit (almost unity), high efficiency, low implementation cost and high power density.

A waveform control method of AC to DC converters with high-frequency links.

Transformer isolation is a usual practice for ohmic isolation between a source and a load. The transformer designed for commercial frequency (50/60Hz) makes the converter bulky and heavy. Therefore, high-frequency link converters have been studied to make the transformer smaller and to minimize the weight, size and cost of the converters.This paper presents a new real-time control method of AC to DC converters with high-frequency links (switch mode rectifiers: SMR's). Results are as follows:(1) The new method makes the switching frequency of the SMR smaller than the conventional method.(2) The proposed method realizes sinusoidal input current, arbitrary output voltage waveform and controllable input displacement factor. The maximum output voltage ratio to the input liveto-neutral voltage is 3/2.(3) The new method is suitable for real time control and suppression of DC magnetization of the high-frequency transformer can easily be implemented.(4) Feasibility of the proposed method is confirmed by simulations and experiments.Using this method, it is easy to control the voltage waveform of the primary winding of the high-frequency tranformer by changing the output function, so that it is possible to compensate the unbalance of the source voltage and influence of the dead time.

A method to reduce the output voltage ripple in a switched mode rectifier with a feedforward circuit

Electrical Engineering in JapanVolume 109, Issue 1 p. 100-107 Article A method to reduce the output voltage ripple in a switched mode rectifier with a feedforward circuit Tadahito Aoki, Tadahito Aoki NTT Applied Electronics LaboratoriesSearch for more papers by this authorYutaka Kuwata, Yutaka Kuwata NTT Network Systems Development CenterSearch for more papers by this author Tadahito Aoki, Tadahito Aoki NTT Applied Electronics LaboratoriesSearch for more papers by this authorYutaka Kuwata, Yutaka Kuwata NTT Network Systems Development CenterSearch for more papers by this author First published: January/February 1989 https://doi.org/10.1002/eej.4391090111AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume109, Issue1January/February 1989Pages 100-107 RelatedInformation