This paper proposes a novel nonisolated single-input dual-output three-level dc-dc converter (SIDO-TLC) appropriate for medium- and high-voltage applications. The SIDO-TLC is an integration of the ...three-level buck and boost converters, whose output voltages are regulated simultaneously. Reducing voltage stress across semiconductor devices, improving efficiency, and reducing inductors size are among the main merits of the new topology. Moreover, due to the considerably reduced volume of the step-down filter capacitor, a small film capacitor can be used instead, whose advantages are lower equivalent series resistance and a longer lifespan. A closed-loop control system has been designed based on a small-signal model derivation in order to regulate the output voltages along with the capacitors' voltage balancing. In order to verify the theoretical and simulation results, a 300-W prototype was built and experimented. The results prove the aforementioned advantages of the SIDO-TLC, and the high effectiveness of the balancing control strategy. Furthermore, the converter shows very good stability, even under simultaneous step changes of the loads and input voltage.
Three-phase variable speed drives play a key role in energy conversion systems. To comply with the electromagnetic compatibility standards for the 0-2 <inline-formula><tex-math ...notation="LaTeX">\text{kHz}</tex-math></inline-formula> frequency range, magnetic chokes are typically placed at the dc or ac sides of the drive systems. Recently, compatibility levels have been defined at 9-150 <inline-formula><tex-math notation="LaTeX">\text{kHz}</tex-math></inline-formula> for the public network in accordance with IEC 61000-2-2. At this frequency range, common-mode noise is an important factor affecting electromagnetic compatibility. This article analyzes the effect of choke placement on common-mode noise at the 9-150 <inline-formula><tex-math notation="LaTeX">\text{kHz}</tex-math></inline-formula> frequency range. In particular, a comparative study on choosing either two dc-link choke inductors or three ac-line inductors is carried out via mathematical calculations. To this end, single-phase common-mode equivalent models are extracted for each placement of dc and ac chokes. Subsequently, by calculating the transfer functions of the currents in the single-phase equivalent circuits, the attenuation rate of common-mode currents from the motor to the grid side is analytically modeled for each choke configuration. The developed theories prove that ac-line inductors are more effective at suppressing low-frequency common-mode contents, while dc chokes are useful in attenuating high-order noise contents. Laboratory test results are used to prove the validity of the presented theoretical modeling and analysis.
In this article, we propose a robust control strategy using direct Lyapunov strategy (DLS) for a single-input dual-output three-level dc-dc converter (SIDO-TLC) while the output loads and voltage ...references are disturbed. The first proceeding is to concurrently focus on the current and voltage dynamics of the converter buck and boost segments for exerting the related variable errors to the DLS-based function. Accordingly, through a comprehensive analysis based on the outcome of this proceeding, the proportional-integral controller coefficients allotted to the current reference design process are enabled to reach their maximum robustness capabilities against any output voltage variation. Moreover, the converter reference current tracking-based assessment leads to several smooth hyperbolic curves with their unique geometric properties. Consequently, the alteration trend of these curves facilitates the Lyapunov coefficients to be adjusted commensurate with the dynamic operation of the converter while converging to zero steady-state errors. Using a TMS320F28335 digital signal processor, disparate experimental results are conducted on the SIDO-TLC to verify the accurate and robust performance of the proposed control strategy.
Motor drive systems with long feeder cables are widely used in mining and energy sectors, such as offshore oil and gas drilling. In recent decades, to prevent issues with electromagnetic ...interference, power quality standards have been defined for the 2-150 kHz frequency range. In order to comply with these standards, manufacturers need to design filters to avoid exceeding the thresholds set by the standards. An important aspect that needs to be considered is the accurate modeling of currents circulating through common-mode loops. This article addresses this modeling by using a mathematical approach. The power cable's common-mode model is extracted from the measurement data using the finite-element method via finding the effective permittivity of the PVC materials. The common-mode noise sources, including the grid side voltage through the front-end diode rectifier and the output voltage through the rear-end inverter, are both modeled by extracting the Fourier series calculations. Consequently, noise emissions circulating through different common-mode loops are analytically modeled. Through the proposed modeling strategy, the harmonic spectrum of resonances can be precisely analyzed. The results are validated through simulation and experimental data.
Due to the significant advances in fast switching semiconductor devices, harmonic emissions caused by the adjustable speed drives (ASDs) have been changed in terms of frequency range and magnitude. ...The frequency range of 2-150 kHz has been distinguished as a new interfering frequency range, disturbing the distribution networks. This article proposes a behavioral model of an ac motor to predict the common-mode (CM) current in ASDs. An approach is presented to calculate the parameters of the model, through which the dominant impact of each element at a specific frequency is considered. Moreover, along with the proposed motor model, a system modeling strategy is presented for filter design considerations at an emerging frequency range of 2-150 kHz. To verify the effectiveness of the proposed model, real-time experiments are conducted. The results prove that the introduced model can accurately predict the resonances of the CM loop created by the motor. Consequently, the proposed model is suitable for electromagnetic interference (EMI) filter design covering the 2-150-kHz standard.
This study proposes a control technique for single-input dual-output three-level dc–dc converter (SIDO-TLC) using feedback (FB) and feedforward (FF) principles. Through the proposed control strategy, ...SIDO-TLC can smoothly function in both buck and boost operating conditions with a fast dynamic. Major duties of the designed FB control loops are to noticeably decrease the recovery time of transient responses under the load variations and accurately balance the boost capacitors voltages. To effectively decouple the introduced control inputs, an external FF controller is assigned that can also enhance the buck and boost voltage regulations. Furthermore, a step-by-step assessment is contemplated based on the proposed control loops to make an offline adjustment for the FB and FF coefficients. The proposed controller implemented on SIDO-TLC is highly suitable for portable applications, where efficiency, cost, and speed are of important factors. The simulation results and the laboratory test setup of SIDO-TLC using DSP TMS320F28335 are presented to prove the validity of the presented theoretical subjects.
Three-phase motor drive systems are the foundation of modern industrial and commercial applications, providing an efficient and dependable way to operate electric motors. In order to meet ...electromagnetic compatibility requirements within the frequency range of 0 to 2 kHz, magnetic chokes are frequently utilized, being connected to either the DC or AC sections of drive systems. Recently, worldwide standard committees adopted new emission limitations for the 2-9 kHz frequency range to minimise power quality problems caused by the increased penetration of power electronics equipment. The influence of choke location on differential-mode supra-harmonics in the 0-9kHz frequency range is investigated in this work. Mathematical calculations are employed to conduct a comparative analysis in choosing between two DC-link inductors or three AC line inductors for mitigating differential-mode noise at the grid. To that end, single-phase equivalent circuits are used to calculate differential-mode noise components. Following that, supra-harmonic contents of currents are estimated based on the commutation of the front-end rectifier. In consequence, through the derived mathematical equations, conducted noise emissions entering to the grid are analytically modeled. The findings of laboratory tests are utilised to verify the theoretical concepts.
In this paper, a robust control approach using a sliding-mode-based (SLMB) control strategy has been designed for a solar multi-port three-level dc-dc converter that is specifically tailored for ...harsh environmental conditions, such as solar panel failure and load fluctuations. The multi-port three-level dc-dc converter has one solar input, one buck battery port, and a boost output. The sliding-mode control is designed to regulate the main boost output voltage at the desired magnitude in a three-level control structure, while the maximum power tracking is simultaneously executed for the solar input. To maintain robustness against harsh system uncertainties, a sliding mode control law in which the load and input power parameters are eliminated is constructed. Therefore, the proposed control strategy is theoretically insensitive to input current and load fluctuations. The proposed control strategy's efficacy is validated in simulations, and its performance is compared to that of a well-tuned conventional PI controller.
In this paper, the configuration of a cutting-edge DC Micro-Grid system to produce Hydrogen (DCMG-H2) from Renewable Energy Sources (RESs) is described. Towards that aim, first, the practical insight ...on preferring a DCMG to an AC Micro-Grid (ACMG) system is elucidated. This analysis clearly highlights the unnecessary power conversions in an ACMG in practice, when the system can be converted to a DCMG. Next, based on eliminating these AC-DC converter components from ACMG, an efficient fully DCMG system is introduced that contains DC loads, such as electrolysers, and Photovoltaic (PV) and Battery Energy Storage (BES) systems. The proposed investigations can significantly address the new technical demand for implementing DCMG-H2 using the low-cost energy from PVs and can enable up-scaling of hydrogen production. The performance of the proposed DCMG configuration is verified by presenting the 24 hours simulation results of a similar real-world network.
In this paper, a bidirectional Dual-Active Bridge (DAB) DC-DC converter has been designed and implemented for energy transfer to an electrolyzer in a green hydrogen production system. The converter ...transfers power between an energy storage system (here battery) and the DC busbar, respectively rated at 48 V and 380 V. It can also be used to supply the 48 V electrolyzer from the busbar through a unidirectional power flow. A closed-loop control system based on the Proportional Integral (PI) compensator is devised for the SiC-based DC-DC converter using the F28379D control chip. Experiments are conducted to validate the design procedures.
