Online ISSN
1755-4543
Print ISSN
1755-4535
IET Power Electronics
Volume 4, Issue 2, February 2011
Volumes & issues:
Volume 4, Issue 2
February 2011
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- Author(s): F. Gao ; P.C. Loh ; D. Li ; F. Blaabjerg
- Source: IET Power Electronics, Volume 4, Issue 2, p. 181 –193
- DOI: 10.1049/iet-pel.2009.0213
- Type: Article
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p.
181
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This study presents two types of embedded Z-source inverters with each type further divided into asymmetrical and symmetrical realisations. Being different from their traditional counterparts, the presented inverters have their dc sources inserted within their X-shaped impedance networks so as to achieve implicit source current or voltage filtering without requiring additional hardware, and therefore avoiding its accompanied control and resonant complications. Passive and active components used by the proposed inverters are also found to experience a lower-voltage/current stress at their dc front ends, which indirectly translates to a lowering of overall system cost. These noted advantages are indeed appropriate for applications like photovoltaic and fuel cell energy harnessing, and have already been confirmed in simulation and experimentally using a laboratory-implemented inverter prototype. - Author(s): A.A. Boora ; F. Zare ; A. Ghosh
- Source: IET Power Electronics, Volume 4, Issue 2, p. 194 –208
- DOI: 10.1049/iet-pel.2009.0269
- Type: Article
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p.
194
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This study presents a new multi-output DC/DC converter topology that has step-up and step-down conversion capabilities. In this topology, several output voltages can be generated and can be used in different applications such as multi-level converters with diode-clamped topology or power supplies with several voltage levels. Steady-state and dynamic equations of the proposed multi-output converter have been developed; these can be used for steady state and transient analysis. Two control techniques have been proposed for this topology, based on constant and dynamic hysteresis band height control, to address different applications. Simulations have been performed for different operating modes and load conditions to verify the proposed topology and its control technique. Additionally, a laboratory prototype is designed and implemented to verify the simulation results. - Author(s): C.D. Xu and K.W.E. Cheng
- Source: IET Power Electronics, Volume 4, Issue 2, p. 209 –217
- DOI: 10.1049/iet-pel.2008.0333
- Type: Article
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209
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The exact formulation based on stroboscopic discrete maps is used to investigate the dynamical behaviours of the peak current-programmed buck-boost AC–DC converters using simple capacitor rectifier. The impact of the input capacitor on the dynamics of the converters is shown. Fast-scale instability and the relationship between the periodicity of the intermittent behaviours and input line cycle are reviewed under the condition of using input capacitor rectifier. Finally, a detailed investigation of input capacitor on the stable border in the buck-boost converters is studied and the Jacobian derivation has also been used to predict the border of the bifurcation. Experimental results are given to verify the analysis and simulation, which are very useful for the prediction of stable boundary and design of input filter in the power electronics systems. - Author(s): P.C. Loh ; Y. Tang ; F. Blaabjerg ; P. Wang
- Source: IET Power Electronics, Volume 4, Issue 2, p. 218 –226
- DOI: 10.1049/iet-pel.2009.0222
- Type: Article
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p.
218
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In this study, repetitive current controllers operating in either the mixed or stationary frame are proposed for high-precision reference tracking and disturbance rejection of power converters. Both controllers use a proportional-resonant regulator in the stationary frame for regulating the positive- and negative-sequence fundamental currents, which are known to directly influence the flow of active and reactive power in most energy conversion systems. Moreover, for the tracking or compensation of harmonics, the controllers include a repetitive control path in either the synchronous or stationary frame, whose inherent feedback and feedforward structure is proven to resemble a bank of resonant filters in either reference frames. Unlike other existing controllers, the proposed repetitive controllers function by introducing multiple resonant peaks at only those harmonic frequencies typically produced by most non-linear loads, with no high-resonant gain introduced at all other non-characteristic components. Hence, they are expected to be more robust and less sensitive to implementation noises. By performing synchronous transformation using an unfiltered angle or by using its equivalent frequency-shifted variant, the tracking abilities of the controllers are also shown to remain undisturbed even if a distorted grid or back-emf source is intentionally connected to the system. These described performance features, together with the controller simple implementations, were physically tested with a digitally controlled commercial converter. - Author(s): G. Zhou ; J. Xu ; Y. Jin
- Source: IET Power Electronics, Volume 4, Issue 2, p. 227 –234
- DOI: 10.1049/iet-pel.2009.0180
- Type: Article
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227
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In the conventional digital peak current (DPC) predictive controlled switching dc–dc converters, the duty ratio in each switching cycle is usually calculated and predicted based on the status of the previous switching cycles. Therefore at least one-switching-cycle time delay usually exists in such a predictive control technique, which significantly degrades the control performance of digitally controlled switching dc–dc converters. To eliminate this one-switching-cycle time delay and to improve the control performance, an improved digital peak current (IDPC) predictive control technique for switching dc–dc converters is then proposed and studied in this study. The control laws of DPC and IDPC control with different pulse width modulations are derived and their stabilities are analysed. A simple digital slope compensation method is proposed to eliminate the sub-harmonic oscillations of DPC and IDPC control laws. Steady-state and transient performances of DPC- and IDPC-controlled buck converters are investigated and compared by experimental results. The comparison studies between DPC and IDPC control show that transient performance of IDPC is much better than that of DPC. - Author(s): A.F. Zobaa and A. Lecci
- Source: IET Power Electronics, Volume 4, Issue 2, p. 235 –241
- DOI: 10.1049/iet-pel.2009.0201
- Type: Article
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A family of optimisation methods based on particle swarm optimisation (PSO) is proposed and applied to compute the best parameters of a resonant controller. The resonant controller is applied to properly inject compensation waveforms in a power quality application of power converters. The evaluation of proposed optimisation methods is based on different figures that involve current and voltage errors as well as response times and more. Several simulation results are shown in order to highlight the viability of the described solutions. - Author(s): Y.-C. Hsieh and C.-S. Huang
- Source: IET Power Electronics, Volume 4, Issue 2, p. 242 –247
- DOI: 10.1049/iet-pel.2009.0206
- Type: Article
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p.
242
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This study is aimed to design and implement a battery charger for 40 series-connected Li-ion batteries. The batteries together set up a rated 144 V DC bus for the latter stage. To obtain higher power output capability and achieve higher conversion efficiency, a phase-shift full-bridge converter is adopted as the power stage of the charger. The operation modes and design considerations are carefully studied and depicted. This charger is controlled by a digital signal processor controller which is responsible for steering the circuit to fulfil constant-current constant-voltage charging profile, accompanied by the overcharging protection mechanism of Li-ion batteries. - Author(s): B.-R. Lin and H.-Y. Shih
- Source: IET Power Electronics, Volume 4, Issue 2, p. 248 –256
- DOI: 10.1049/iet-pel.2009.0258
- Type: Article
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248
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A parallel zero-voltage switching (ZVS) forward converter is proposed to achieve load current sharing, output ripple current cancellation and conversion efficiency improvement. Two forward converters are connected in parallel to achieve interleaved pulse width modulation operation. Thus, the ripple currents on the output side are partially cancelled on each other so that the size of output chokes and capacitor is reduced. Only two switches are used in the proposed converter instead of four switches in the conventional parallel ZVS forward converter. Therefore the proposed converter has less power switching devices. An active snubber is connected between two power transformers to absorb the energy stored in the leakage and magnetising inductances of transformers, to limit voltage stresses across switches and to realise the ZVS turn-on of all switches. Thus, the conversion efficiency is improved by the soft-switching operation of switching devices. Finally, the performance of the proposed converter is evaluated on a 480 W (24 V/20 A) laboratory prototype. - Author(s): B.-R. Lin ; K.-L. Shih ; J.-J. Chen
- Source: IET Power Electronics, Volume 4, Issue 2, p. 257 –268
- DOI: 10.1049/iet-pel.2009.0272
- Type: Article
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An interleaved zero-voltage switching (ZVS) forward converter is presented in this study. Two forward converter circuits with active snubber are used in the proposed circuit to share the load current. The interleaved pulse-width modulation (PWM) scheme is adopted to achieve current ripple reduction in the output capacitor. Thus, the size, weight and conduction losses of the output chokes are reduced. Only two switches instead of four switches in the conventional parallel ZVS forward converter are used in the proposed converter. Thus, the switch counts are reduced in the proposed circuit. The PWM signals of two switches are complementary each other with a small delay time in order to realise the ZVS turn-on at the transition interval. Thus, the switching losses and thermal stresses of the power switches are reduced. Experiments based on a 650 W prototype were provided to verify the theoretical analysis and the effectiveness of the proposed converter.
Asymmetrical and symmetrical embedded Z-source inverters
Multi-output buck–boost converter with enhanced dynamic response to load and input voltage changes
Examination of bifurcation of the non-linear dynamics in buck-boost converters with input capacitor rectifier
Mixed-frame and stationary-frame repetitive control schemes for compensating typical load and grid harmonics
Improved digital peak current predictive control for switching DC–DC converters
Particle swarm optimisation of resonant controller parameters for power converters
Li-ion battery charger based on digitally controlled phase-shifted full-bridge converter
Implementation of a parallel zero-voltage switching forward converter with less power switches
Interleaved DC–DC zero-voltage switching converter with series-connected in the primary side and parallel-connected in the secondary side
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