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Power Electronics, IET

Issue 1 • Date March 2008

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Displaying Results 1 - 17 of 17
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  • Reinjection concept: A new option for large power and high-quality AC-DC conversion

    Page(s): 4 - 13
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (225 KB)  

    A new concept referred to as reinjection AC/DC conversion is described, applicable to both self- commutating voltage source and current source conversions. It combines all the benefits of the multi-level, soft switching and ripple reinjection concepts. The aim is to achieve high-quality waveforms, simplify the structural configuration and the interface with the grid, improve the conversion efficiency, limit the dv/dt and provide flexible active and reactive power controllability. View full abstract»

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  • Nonlinear position controller design with input-output linearisation technique for an interior permanent magnet synchronous motor control system

    Page(s): 14 - 26
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (753 KB)  

    A novel, advanced position controller design for an interior permanent magnet synchronous motor control system is proposed. The input-output linearisation technique is used to transfer the system model into a linearised system model. Then, based on the linearised system model, an Hinfin controller is designed to achieve robust performance of the position control system. To improve the system performance, a load estimator is used to compensate the external load and the influence of the parameter variations as well. In addition, a maximum torque/ampere control is applied to increase the output torque of the motor. A digital signal processor, TMS 320LF2407, is used to execute the speed-loop and position-loop control algorithms. As a result, the hardware circuit is quite simple. Several experimental results show that the proposed system has fast transient responses, good load disturbance rejection responses and good tracking responses. View full abstract»

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  • DC-DC converter with interleaved current doublers and parallel connected transformers- scheme

    Page(s): 27 - 37
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (641 KB)  

    Interleaving method for point-of-load (POL) isolated DC-DC converter topologies is presented to improve conversion efficiency, thermal management and transient response by utilising current sharing between switches and magnetics and by operating the secondary-side switches at a lower switching frequency than the primary-side switches. Moreover, in the presented interleaving method, both primary and secondary sides of the isolation transformers are connected in parallel, allowing current sharing at both primary and secondary sides, while utilising a simple primary side. Theoretical analysis, simulation and experimental results are presented to verify the proposed topology and control method. It is expected that this topology will be a good competitor for low-voltage high-current POL DC-DC converter applications in present and future generation integrated circuits for communication and computer systems. View full abstract»

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  • Second-order predictive direct control of a voltage source inverter coupled to an LC filter

    Page(s): 38 - 49
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (599 KB)  

    The optimisation of high-power converters providing high-quality voltage levels and high-efficiency energy conversion leads to low-switching frequencies and second-order LC filters with high-resonant frequencies. Because of these narrow frequency ratios, classical control schemes comprising an inner current loop and an outer voltage loop are not feasible. The same applies to the single-loop dead-beat strategy or to the direct control technique, as their simple single-order predictive model does not offer the required level of accuracy. This article develops higher order prediction models and computes the prediction error for different frequency ratios and approximation orders. This analysis shows that in the case of an optimised industrial outage and sag compensator, a second-order prediction model provides the required accuracy; hence, the second-order predictive direct control is developed. This control drives both the inductor current and the capacitor voltage simultaneously, assures constant switching frequency and results in robust and stable behaviour. Simulation and experimental results show the validity of the approach. View full abstract»

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  • Analysis, design and implementation of an active snubber zero-voltage switching cuk converter

    Page(s): 50 - 61
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1303 KB)  

    A zero-voltage switching parallel-connected Cuk converter is presented. Active snubber circuit is used in the converter to achieve soft switching and to limit voltage stress across power switches. In the proposed converter, the primary windings of two transformers are connected in series. Two half-wave rectifiers are connected in parallel at the output side to reduce the current stresses on the secondary winding of the transformer. The constant pulse-width modulation scheme is adopted to regulate the output voltage. The principle of operation and system analysis of the proposed converter are presented. Experimental results for a 300 W (12 V/25 A) prototype circuit operating at 70 kHz switching frequency are given to demonstrate the effectiveness of the proposed converter. View full abstract»

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  • High efficiency asymmetrical half-bridge converter using a self-driven synchronous rectifier

    Page(s): 62 - 71
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A novel high efficiency asymmetrical half-bridge converter using a self-driven synchronous rectifier is presented. The proposed converter improves the system efficiency using the characteristics of the asymmetrical half-bridge converter and the self-driven synchronous rectifier. The synchronous rectifier applied to the proposed converter is the new topological synchronous rectifier, which is a slightly modified type of the conventional synchronous rectifier used in the conventional asymmetrical half-bridge converter. The type of the new topological synchronous rectifier slightly changes the transformer structure and the synchronous switch connection in the asymmetrical half-bridge converter with a conventional self-driven synchronous rectifier. The operational principle of the proposed converter is explained in detail. Since the proposed converter utilises the transformer leakage inductor as its resonant inductor, its structure is simplified. A design example for a 90 W (12 V/7.5 A) prototype is discussed in detail. Experimental results are shown for the designed prototype converter under universal AC input voltage (180-265 V). It is shown that the efficiency of the proposed converter can be significantly improved. View full abstract»

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  • Analysis and design of a single-phase hybrid mode power factor correction converter

    Page(s): 72 - 83
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (785 KB)  

    Two-stage power factor correction (PFC) configuration usually suffers from low conversion efficiency due to twice power processing. Detailed analysis and operations of a hybrid mode PFC pre-regulator which employs both active and passive PFC techniques at different time slots are presented. The approach can achieve high power conversion efficiency, as well as low output voltage stresses on switch and bulk capacitor. Furthermore, analyses of PF and losses of components with the circuit inductance are also discussed. Experiments were performed to verify the effectiveness of the approach. View full abstract»

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  • Three-level inverter scheme with reduced power device count for an induction motor drive with common-mode voltage elimination

    Page(s): 84 - 92
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (898 KB)  

    A three-level inverter scheme with common-mode voltage elimination and reduced power device count for dual inverter-fed open-end winding induction motor is proposed. The open-end winding induction motor is fed by two three-level inverters, formed by cascading two two-level inverters, from both sides. These two three-level inverters share the top inverter, thereby reducing the power device count. The switching states with zero common-mode voltage variation are selected for pulse-width modulated switching so that there is no alternating common- mode voltage in the pole voltages and phase voltages. Only two DC links, with half the ratings of a conventional three-level neutral point clamped inverter, are used for the proposed scheme. View full abstract»

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  • Forced oscillation in LC circuit used for the ignition of discharge lamps

    Page(s): 93 - 99
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (191 KB)  

    A practical method to reduce device strain in the ballast prior to the discharge process (at the high voltage stage) is presented. An ignitor for high-intensity discharge lamps based on forced oscillation via an external periodic voltage square wave supplied by an inverter digitally controlled is presented. The frequency and amplitude of the ignition voltage of an LC parallel resonant circuit are determined by the design of the proposed ignitor, as shown. Thus, the ignition is achieved without excessive voltage applied to the lamp. View full abstract»

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  • Design optimisation of a 1 MHz half-bridge CLL resonant converter

    Page(s): 100 - 108
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (690 KB)  

    A detailed design optimisation for the CLL resonant converter is presented and zero-voltage switching (ZVS) of MOSFETs is guaranteed in overall operation ranges. A series of analysis and calculations are presented to choose an ideal value of the loaded quality factor meeting the requirement of ZVS behaviour (inductive load and full discharge of the output capacitance of a MOSFET), ensuring the desired maximum voltage gain and optimal design with high efficiency at normal operation point. Corresponding illustrations are provided to clearly show the analysis result. The developed design optimisation method has been implemented into a 1 MHz CLL resonant converter prototype. It is designed to operate with an output voltage of 24 V and full load output power of 250 W. The maximum efficiency reaches 93% and power density reaches 32 W/inch3. Therefore the proposed converter is suitable for high efficiency and high power density applications such as LCD and PDP TV power module. View full abstract»

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  • Series SEPIC implementing voltage-lift technique for DC-DC power conversion

    Page(s): 109 - 121
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (715 KB)  

    The voltage-lift technique is an effective method that could be applied in electronic circuit design. A set of positive output DC-DC converters applying series SEPIC implementing voltage-lift techniques is introduced. Compared with the prototype of the SEPIC converter, these converters can perform positive to positive DC-DC voltage increasing conversion with higher voltage transfer gains. They are different from other existing DC-DC step-up converters and possess obvious advantages, mainly including fewer switches, clear conversion processes and a high output voltage with small ripples. Since the proposed converters avoid using transformers and cascade connection, relative simple structures are beneficial to potential practical applications in future. A detailed theoretical analysis for continuous and discontinuous conduction modes is given. Both simulation and experimental results are provided to verify the main characteristics. View full abstract»

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  • Zero-voltage-switching pulse-widthmodulation full-bridge transformer-isolated step-up/down converter

    Page(s): 122 - 131
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (786 KB)  

    A novel zero-voltage-switching pulse-width-modulation (ZVS-PWM) full-bridge transformer-isolated step- up/down converter is proposed. The output voltage of the proposed converter can be higher or lower than the DC input voltage, depending on the instantaneous duty cycle. Furthermore, in the proposed converter, besides operating at constant frequency, all semiconductor devices operate at soft-switching without additional voltage stress and current stress. An average approach is employed to analyse the system. A design example of 1000 W proposed ZVS-PWM full-bridge converter is examined to assess the converter performance. View full abstract»

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  • Comparative study of hysteretic controllers for single-phase voltage regulators

    Page(s): 132 - 143
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (935 KB)  

    A comparative study of hysteretic controllers for single-phase voltage regulators used in low-voltage applications is presented. The voltage-mode (VM) and current-mode (CM) control schemes considered here are designed with identical specifications. The regulator performance is evaluated in aspects such as load transient response, switching frequency design and component tolerance effects. Other aspects such as complexity and cost are also considered. Experimental results are reported in order to validate the theoretical predictions. Essentially the study demonstrates that: (1) both VM and CM controllers exhibit high performance for nominal power components, (2) the operation of the CM controller is extremely robust with respect to power-component tolerance and (3) the VM controller is a simple, low-cost control solution. View full abstract»

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  • Family of isolated zero-voltage transition PWM converters

    Page(s): 144 - 153
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    A new family of zero-voltage transition (ZVT) PWM converters is introduced. In this family of converters, zero-voltage switching condition is achieved for main switch and zero-current switching condition is attained for auxiliary switch. A ZVT flyback converter from the proposed family of converters is analysed and various operating intervals are presented. The introduced ZVT flyback converter characteristics are compared with other ZVT converters. A laboratory prototype of this converter is realised and experimental results are shown. View full abstract»

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  • Analysis and design of a novel, single-stage, three-phase AC/DC step-down converter with electrical isolation

    Page(s): 154 - 163
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (813 KB)  

    A novel, single-stage, three-phase AC/DC step-down converter with electrical isolation has been presented. The front semi-stage, which is a three-phase AC/DC buck-boost converter, is operated in discontinuous conduction mode (DCM) to achieve unity power factor, pure sinusoidal input current and low total harmonic distortion of input current. The rear semi-stage, which is a DC/DC forward converter, is operated in continuous conduction mode at heavy load and is operated in DCM at light load for step-down voltage conversion. Also, the proposed converter has low voltage stress across the DC-link capacitor. In addition, the sixth times line frequency ripple component of DC-link voltage can be eliminated. Thus, smaller DC-link capacitor is required. Furthermore, the steady-state analysis of voltage gain and boundary-operating condition are discussed. The selections of inductors and capacitors are presented. Finally, simulated and experimental results are supplied to verify the theoretical analysis. View full abstract»

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  • Novel power converter topology for threephase four-wire hybrid power filter

    Page(s): 164 - 173
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    A novel power converter topology for three-phase four-wire hybrid power filter is proposed. It is configured by a three-arm bridge structure without split capacitors. The salient feature of the three-phase four-wire hybrid power filter using the proposed power converter is that it permits the neutral line of the utility directly connecting to the negative or positive terminal of the DC capacitor located in the DC side of the power converter. Consequently, the power converter uses less number of power electronic switches to reduce the manufacturing cost. A three-phase four-wire hybrid power filter prototype is developed and tested to demonstrate the performance of the three-phase four-wire hybrid power filter using the proposed power converter. Experimental results show that the proposed three-phase four-wire hybrid power filter using the proposed power converter has the expected performance. View full abstract»

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Aims & Scope

IET Power Electronics brings together five principal power electronics themes including: applications of power semiconductor technology; circuits; devices; techniques; and performance management.

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