IEE Proceedings - Electric Power Applications
Print ISSN
1350-2352
Online ISSN 1359-7043
Online ISSN 1359-7043
Published from 1994-2006, IEE Proceedings - Electric Power Applications contained significant and original contributions on the applications of electric power. The scope covered a wide range of applications and apparatus in the power field. In addition to papers focussing on the design and development of electrical equipment, papers relying on analysis were also included.
This publication was previously known as IEE Proceedings B (Electric Power Applications) 1980-1993. ISSN 0143-7038. more..
This publication is continued by IET Electric Power Applications 2007-. ISSN 1751-8660. more..
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Load-imposed instability and performance degradation in a regulated converter
- Author(s): M. Hankaniemi; M. Karppanen; T. Suntio
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p.
781
–786
(6)
The stability and performance of a regulated converter is analysed based on its closed-loop output impedance. System theory is used to obtain a set of transfer functions that define the internal stability of an interconnected system consisting of source and load converters. The internal stability is described in terms of the ratio of the output impedance of the source converter and the input impedance of the load converter known as the minor-loop gain. Thus, the closed-loop output impedance of a source converter can be used to define safe operating areas that avoid instabilities in the load impedance. It is shown that the margins associated with the minor-loop gain (i.e. the gain and phase margins) do not generally match the margins of the output-voltage loop gain. The relationship is especially weak at frequencies close to and beyond the crossover frequency of the loop gain. This means that the margins given to the minor-loop gain should be gradually increased as the voltage-loop-gain crossover frequency is approached so as to avoid performance degradation (i.e. changes in margins and crossover frequency) in the supply converter. Experimental evidence is provided based on a buck converter under voltage- and peak-current-mode control.
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Simplified control method for parallel-connected DC/AC inverters
- Author(s): K.-D. Wu; J.-C. Wu; H.-L. Jou; C.-Y. Chen; C.-Y. Lin
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p.
787
–792
(6)
The parallel operation of several low-capacity inverters is better than a singular high-capacity inverter owing to the advantages of better extensibility and reliability. A simplified control method for parallel-connected inverters is proposed, which can balance the current distribution among the parallel-connected inverters with no interconnected communication lines. To verify the performance of the proposed control method, a prototype consisting of two inverters has been developed. The experimental results verify that the performance of the proposed control method is as desired.
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Radial force density and vibration characteristics of modular permanent magnet brushless AC machine
- Author(s): J. Wang; Z.P. Xia; S.A. Long; D. Howe
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p.
793
–801
(9)
The radial force density harmonics and vibrational characteristics of a three-phase modular permanent magnet brushless AC machine is investigated. It is shown that, owing to the presence of a large number of low- and high-order stator space harmonic magnetomotive forces, modular machines are more likely to exhibit higher low-frequency vibrations than conventional permanent magnet brushless machines. Experimental results support the analysis and its findings.
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Classification and synthesis of power gyrators
- Author(s): A. Cid-Pastor; L. Martinez-Salamero; C. Alonso; G. Schweitz; J. Calvente; S. Singer
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p.
802
–808
(7)
A systematic procedure to synthesise power gyrators for variable switching frequency operation is presented. Based on the gyrator equations, topological constraints are first established and two types of gyrators, i.e. G and R, are defined. A boost converter with an output filter and the Čuk converter are shown to have the unconditionally stable characteristics of G-gyrators with a controlled input current whereas a buck converter with an input filter and also the Čuk converter are shown to behave as G-gyrators with a controlled output current if damping networks are inserted and certain stability conditions are accomplished. Similarly, a boost converter with an output filter is shown to behave as a power R-gyrator with stable dynamics.
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Integral variable-structure grey control for magnetic levitation system
- Author(s): H.-K. Chiang; C.-A. Chen; M.-Y. Li
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p.
809
–814
(6)
An integral variable-structure grey control for a magnetic levitation system for position tracking is presented. The sliding-mode control is insensitive to system uncertainties and disturbances when it is within expected limits. It produces chattering when uncertainty values are overestimated, or steady-state error when underestimated. The method uses a mathematically simple and computationally efficient grey compensator for the integral variable structure controller to reduce chattering and steady-state error. The stability of this magnetic levitation system is proven by using the Lyapunov function. The experimental results verify that the proposed controller is valid for a magnetic levitation system.
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Mechanical-sensorless induction motor drive based only on DC-link measurements
- Author(s): M.O. Sonnaillon; G. Bisheimer; C. De Angelo; J. Solsona; G.O. García
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p.
815
–822
(8)
Sensor count reduction for high-performance induction motor (IM) drives is considered. A novel strategy to compute the three phase currents, based on a single current sensor and an adaptive observer, is proposed. The observer estimates the motor state variables, allowing then implementing an IM field-oriented controlled (FOC) drive with closed speed loop based only on DC-link measurements. To demonstrate the practical feasibility of this proposal, representative experimental results, obtained with a FOC experimental prototype, are presented. The FOC prototype showed results similar to those from a conventional FOC drive with individual phase current sensors. The sensor count reduction achieved represents a significant cost diminution in the implementation of low-power high-performance drives.
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Adaptive controller design for a sensorless IPMSM drive system with a maximum torque control
- Author(s): J.-L. Shi; T.-H. Liu; Y.-C. Chang
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p.
823
–833
(11)
An advanced controller design for a sensorless interior permanent-magnet synchronous motor control system is proposed. A maximum torque/ampere control algorithm is used to improve the torque performance of the drive system. In addition, an adaptive controller combined with the maximum torque/ampere control is proposed to obtain a good transient response and a good load disturbance rejection capability. The proposed control method can be applied to both a sensorless adjustable speed control system and a sensorless position control system. Using the Lyapunov stability theory and Barbalat’s lemma it is shown that the closed-loop sensorless control system is an asymptotical stable system. A 32-bit digital signal processor is used to execute the rotor position estimation algorithm and the control algorithm. Experimental results validate the theoretical analysis and show the correctness and feasibility of the proposed system.
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Design of a multispeed winding for a brushless DC motor and its sensorless control
- Author(s): C.-H. Chen; M.-Y. Cheng
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p.
834
–841
(8)
V-belt-linked continuously variable transmissions (CVTs) find extensive use in both internal-combustion-engined and electric scooters. The CVTs are used to increase the starting torque and also extend the range of the operating speed of the vehicles. Unfortunately, the efficiency of a CVT is relatively low due to friction effects and the alternative techniques based on flux weakening control are both complex and costly to implement. To circumvent these problems a multispeed winding is designed that is able to increase the starting torque at low speeds and extend the constant-power speed ratio for small and midsized brushless DC motors. Moreover, in order to increase the reliability of the drive system, a cost-effective sensorless control algorithm is developed. The commutation signals can be directly extracted from the average terminal voltages of the motor using simple RC circuits and comparators. This means that the sensorless commutation can be implemented by simply using low-cost CPLDs or microcontrollers. The proposed approach is particularly suitable for application to cost-sensitive electric vehicles such as wheel chairs, bikes and scooters and also hybrid electric scooters. A theoretical analysis of the pattern is performed and various experiments are conducted to evaluate the effectiveness of the proposed method.
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Synthesis of power gyrators operating at constant switching frequency
- Author(s): A. Cid-Pastor; G. Schweitz; L. Martinez-Salamero; C. Alonso; J. Calvente; S. Singer
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p.
842
–847
(6)
A systematic procedure to synthesise power gyrators for constant switching frequency operation is presented. The equivalence between ideal sliding dynamics and PWM zero dynamics is used to derive the control law of the duty cycle. As a consequence, any power gyrator with stable behaviour in sliding-mode results in a stable equivalent gyrator at constant switching frequency with the same stability conditions. The design of a PWM G-gyrator with controlled output current based on a buck converter with input filter illustrates the procedure. Simulations and experiments are in good agreement with the theoretical predictions.
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Detection of broken rotor bars in induction motor using starting-current analysis and effects of loading
- Author(s): R. Supangat; N. Ertugrul; W.L. Soong; D.A. Gray; C. Hansen; J. Grieger
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p.
848
–855
(8)
The detection of broken-rotor-bar faults based on common steady-state-analysis techniques, such as the fast Fourier transform (FFT), is known to be significantly dependent on the loading conditions of the induction motor. At light load, it is difficult to distinguish between healthy and faulty rotors because the characteristic broken-rotor-bar fault frequencies in the stator current are very close to the fundamental-frequency component and their amplitudes are small in comparison. As a result, detection of broken bar faults and classification of the fault severity under light load is very difficult. To overcome this problem, the analysis of the envelope of the transient starting-current waveform using the wavelet-transform has been investigated. The envelope extraction is used to remove the strong fundamental-frequency component, which would otherwise overshadow the characteristic differences between a healthy motor and a faulty motor with broken rotor bars. The wavelet-transform results are processed to develop a normalised parameter called the ‘wavelet indicator’ which is sensitive to the presence of broken-rotor-bar faults. The results are verified using tests on machines with a varying number of broken bars, as well as partially broken rotor bars, over a wide range of loading conditions. The effects of initial rotor position and supply imbalance are also investigated.
