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Power Electronics, IEEE Transactions on

Issue 3 • Date Jul 1993

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Displaying Results 1 - 12 of 12
  • Observability criteria for winding currents in three-phase brushless DC drives

    Page(s): 264 - 270
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    A rigorous method for applying observability criteria to the estimation of winding currents in brushless DC drives is presented. Observability is related to the drive's operating condition, both motoring and regenerating, and to the pulse-width modulated (PWM) switching strategy being employed. The precise conditions under which motor winding currents can be estimated from measurements of DC link current are clearly defined. A modified single current sensor arrangement, in which switching device currents are measured, is shown to improve the observability of currents with complementary switching, but to have an adverse effect on observability with the basic switching strategy. An arrangement involving two current sensors allows discontinuous estimation of the winding currents for all operating conditions and both switching strategies. The primary advantage of this technique is that measurements by each sensor are made equally on all three phases of the motor View full abstract»

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  • Real-time multi-DSP control of three-phase current-source unity power factor PWM rectifier

    Page(s): 295 - 300
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    The design of a real-time multi-DSP controller for a high-quality six-valve, three-phase current-source unity power factor pulse-width-modulated (PWM) rectifier is discussed. With the decoupler preprocessor and the dynamic trilogic PWM trigger scheme, each of the three input currents can be controlled independently. The pole-placement control method implemented, which is based on the a-b- c frame system model and fast parallel computer control, achieves fast AC current response. The low-frequency resonance in the AC filter L-C networks is damped effectively. The experimental results were obtained for a 1 kVA bipolar transistor current-source PWM rectifier with a real-time controller using three TMS320C25 DSPs View full abstract»

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  • Real-time dynamic control of dynamic power filters in supplies with high contamination

    Page(s): 301 - 308
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    A real-time closed-loop system for controlling dynamic power filters under rapidly varying nonlinear loading conditions is tested and evaluated. With the aid of a dedicated microprocessor system, using correlation algorithms, real-time reference signals for a dynamic compensation system are generated. In order to facilitate a cost effective compensation system, separate compensation of the fundamental reactive power component and the harmonic components is further investigated. A total algorithm time of 312 μs for a 50 Hz system is achieved, providing accurate compensation effort up to the 21st power system harmonic View full abstract»

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  • Discrete pulse modulation strategies for high-frequency inverter systems

    Page(s): 279 - 287
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    High-performance, high-frequency inverter systems for UPS (uninterruptible power system) applications cannot be easily realized using conventional hard-switched PWM inverter topologies. Adoption of typical soft-switched inverters such as the resonant DC link inverter, require the use of discrete pulse modulation strategies. New controller structures are necessary to cope with stringent voltage regulation and distortion constraints in the presence of unbalanced and nonlinear loads. A controller that utilizes a load current feedforward strategy with a cost function current regulator to achieve excellent transient performance characteristics is presented. Voltage regulation is ensured using a synchronous frame regulator. Detailed simulation and experimental results verifying the concepts are presented. Although this work focuses on soft-switching inverters, the control concepts can be applied to conventional hard-switching inverters as well View full abstract»

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  • Control-loop modeling of multiple-output feedback of forward converters

    Page(s): 320 - 328
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    A small-signal model is developed for the forward converter with multioutput feedback. In the basis of the model developed, feedback compensation schemes are proposed to stabilize the circuit. The closed-loop circuit performances such as line regulation, cross regulation, and load regulation, are expressed analytically in terms of multiple-loop gains of the system View full abstract»

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  • Unity PF current-source rectifier based on dynamic trilogic PWM

    Page(s): 288 - 294
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    One remaining step in perfecting the stand-alone, unity power factor, regulated current-source pulse-width-modulated (PWM) rectifier is to reduce cost, by bringing the twelve-valve converter (consisting of three single-phase full bridges that operate with two-level or bilogic PWM) to the six-valve bridge. However, the six-valve topology requires a three-level or trilogic PWM strategy that can handle feedback signals. A general method of translating three-phase biologic PWM signals into three-phase trilogic PWM signals is presented. The method of translation retains the characteristics of the bilogic PWM, including the frequency bandwidth. Experiments show that the trilogic PWM signals produced by the method can handle not only stabilizing feedback signals but also signals for active filtering View full abstract»

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  • State-space models for current programmed pulsewidth-modulated converters

    Page(s): 271 - 278
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    State-space models are derived for pulse-width-modulated (PWM) converters operating at constant switching frequency under current programmed control. One model neglects the sample-and-hold effect of the current loop and is therefore representative of the traditional approach to modeling current programmed converters. The order of the model is the same as that of the power stage. A second state-space model is derived which incorporates the sample-and-hold effect. The order of this model is two higher than that of the power stage. A comparison of the two models is made which clearly demonstrates the superiority of the second modeling approach. As the models are in state-space form they may be quite readily used in a CAD package for general converter analysis and design, to determine all transfer functions and associated pole/zero locations of interest View full abstract»

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  • Phase-controlled series-parallel resonant converter

    Page(s): 309 - 319
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    A constant-frequency, phase-controlled, series-parallel resonant DC-DC converter is introduced, analyzed in the frequency domain, and experimentally verified. To obtain the DC-DC converter, two identical series-parallel resonant inverters are paralleled and the resulting phase-controlled resonant inverter is loaded by a voltage-driven rectifier. The converter can regulate the output voltage at a constant switching frequency in the range of load resistance from full-load resistance to infinity while maintaining good part-load efficiency. The efficiency of the converter is almost independent of the input voltage. For switching frequencies slightly above the resonant frequency, power switches are always inductively loaded, which is very advantageous if MOSFETs are used as switches. Experimentally results are given for a converter with a center-tapped rectifier at an output power of 52 W and a switching frequency of 127 kHz. The measured current imbalance between the two inverters was as low as 1.2:1 View full abstract»

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  • Economic single-phase to three-phase converter topologies for fixed and variable frequency output

    Page(s): 329 - 335
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    Several component-minimized circuit topologies for single-phase to three-phase conversion are proposed. The topologies employ fewer semiconductor devices and generate high-quality output voltages. Suitable modification to achieve active input current shaping is illustrated in detail. Analysis and simulation of the proposed schemes are carried out to show the high-performance features. Suitable guidelines for the selection of filter components and for facilitating circuit design are presented. Selected results are verified experimentally on laboratory prototype converters View full abstract»

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  • Multimodular current-source SPWM converters for a superconducting magnetic energy storage system

    Page(s): 250 - 256
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    The advantages of using multiple modules of the current-source, sinusoidal pulse-width-modulated (SPWM), three-phase, six-valve converters as the power conditioner for the superconducting magnetic energy system are highlighted. A high degree of controllability is obtained by using dynamic SPWM trilogic as the operating strategy. Very low switching losses are assured by using two carrier triangles per modulated cycle. By partial connection of converter modules, and by phase-shifting the triangle carriers, the following are obtained: increasing the current capacity to the level required by the superconducting magnet; reducing conduction losses; meeting harmonic standards, without the need of an expensive filter, by harmonic cancellation; and achieving a high frequency bandwidth View full abstract»

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  • 400 MW SMES power conditioning system development and simulation

    Page(s): 237 - 249
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    A conceptual design for a 22 MWh superconducting magnetic energy storage (SMES) system engineering test model (ETM) was developed. The objectives of the SMES-ETM are to demonstrate the feasibility of using a SMES system to perform load-leveling and system stabilization for commercial utilities and to supply 400 MW power pulses for ground-based defense systems. The performance requirements and configuration of the proposed 22 MWh SMES-ETM and its power conditioning system are presented. The power conditioning system consists of a DC-DC chopper linked to a GTO-based voltage source converter interfacing the superconducting energy storage coil to the AC power system. The SMES system operation in the charging and discharging modes is described and the results of digital simulations demonstrating the feasibility of the proposed power conditioning system and exploring its overall behavior under normal and fault conditions are prevented View full abstract»

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  • Commutation of SR motors

    Page(s): 257 - 263
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    Commutation schemes for most common types of switched reluctance (SR) motors are presented. Commutation can be achieved using two- or three-positions sensors and a simple commutation logic in a similar fashion to brushless electronically commutated motors. The commutation logic can be easily housed on a programmable logic array (PLA) or similar device. Two-quadrant operation, usually with two position sensors with variable phase shift and dwell angles, can be tuned up to achieve optimum efficiency at low cost. Four-quadrant operation with multimode commutation schemes, such as normal, boost, longdwell, and brake, which cover most of the SR drive applications, can be easily implemented with simple logic control and feedback from low-resolution position sensors. The speed range can be increased beyond the limit reachable with pulse-width modulation (PWM). A 100% increase in the speed range can be easily obtained by switching modes View full abstract»

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Aims & Scope

IEEE Transactions on Power Electronics covers fundamental technologies used in the control and conversion of electric power.

Full Aims & Scope