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RISS 인기검색어
- 검색키워드
- 저자 : B. P. McGrath (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
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Spectral Analysis of Multilevel PWM Strategies Using a One-Dimensional Fourier Series
B. P. McGrath,H. du T. Mouton 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper presents a novel spectral analysis technique for multilevel modulation. Conventionally, such analyses use a Double Fourier series technique, but this approach can become intractable when complex reference waveforms (e.g. multilevel space vector offsets) and regular sampling processes are considered. In contrast, the strategy proposed in this paper separates the multilevel pulse width modulation (PWM) waveform into a spectral image of the reference, and sideband basis functions which are then expanded using a one-dimensional Fourier series. The approach enables previously intractable PWM problems to be solved. Results of this analysis are validated against previously published multilevel inverter Double Fourier series results.
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A. A Nazib,D.G Holmes,B.P McGrath 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Current regulation of inductive-capacitiveinductive (LCL) grid-connected inverters typically require multiple current sensors to actively damp the filter resonance. Unfortunately, while inverter side current regulation avoids this issue because of its inherent LCL filter damping properties, it does not work well with distorted grids. Furthermore, both strategies require voltage sensors for grid synchronization. This paper proposes a novel current control strategy for LCL grid-connected inverters that requires only inverter side current sensors, with the grid voltage phase and capacitor current estimated from the Proportional Resonant current regulator to achieve self-synchronized indirect regulation of the grid-side current. The effectiveness of the approach has been verified using simulation and matching experimental investigations.
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J. Riedel,D. G. Holmes,B. P. McGrath 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Dual Active Bridge (DAB) converters offer an unmatched capability to transfer energy in either direction between two DC sources, while also providing galvanic isolation and high conversion efficiency. However, to operate at high efficiencies, the bridges must operate with Zero-Voltage-Switching (ZVS) over as wide an operating range as possible. The conventional approach to determine ZVS operation uses time domain analysis with ideal AC coupling inductances, which only approximately identifies the ZVS boundaries. This paper proposes a new approach using frequency domain analysis of the bridge switching patterns, which accurately predicts the ZVS boundaries over a full range of operating conditions while also accommodating more complex AC coupling structures and practical impedance non-idealities. An exact theoretical analysis is presented for two level modulation of the two bridges coupled through a general impedance structure. An analytical solution is then presented for a single coupling impedance, while boundaries for more complex coupling structures and practical impedances are solved by numerical integration. ZVS boundaries for selected systems are validated by matching simulation and experimental results.
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An Improved Three Phase Variable Band Hysteresis Current Regulator
D. G. Holmes,R. Davoodnezhad,B. P. McGrath 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the linear modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.
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