باک-بوست تک فاز بسیار کارآمد با قابلیت تبادل ذاتی
Abstract
I- INTRODUCTION
II- PROPOSED CONVERTER
III- COMPARATIVE ANALYSIS
IV- PERFORMANCE EVALUATION
V- CONCLUSION
REFERENCES
Abstract
This paper introduces a novel single-phase buck-boost (non-)inverting variable-frequency AC-AC converter that offers a higher efficiency compared to the competitors. This converter utilizes a lower number of semiconductors. A simple and flexible switching strategy is also proposed, which generates the desired output waveform avoiding unnecessary high-frequency switching operation of semiconductor devices. A high reliable operation due to the elimination of the input source shoot-through risk, an inherent commutation capability that mitigates the voltage spikes across the semiconductors, a lower semiconductors rating requirement, an improved input current waveform quality and a smaller required input filter inductor are the main advantages of the proposed converter. Thus, the proposed converter can be successfully applied to many industrial applications such as medium-frequency transformer-isolation (MFT) for traction and wind turbine converters, AC-DC high-voltage conversion based on Cockcroft-Walton circuit and induction heating systems. The theoretical achievements and claims are all confirmed through extensive experimental tests on a 200-W laboratory setup.
INTRODUCTION
Many industrial applications such as the adjustable speed drives require AC-AC power conversion systems offering flexible output AC voltage properties. The most recently proposed direct AC-AC converters in [1]–[6], successfully provide a wide range gain buck-boost operation for simultaneous increase or decrease of the output voltage amplitude. These converters offer many advantages including snubber-less operation, inherent commutation, high-quality input current and output voltage waveforms and reliable and efficient operation. However, they do not have the ability to change the frequency of the output voltage waveform, which is already necessary for many industrial applications. On the other hand, the AC-DC-AC converters can generate any arbitrary waveform at the output through several power stages [7]–[10]. In addition, they need large DC-link capacitors and filter inductors, which increase their implementation cost, size and power loss. The other AC-AC converters with the ability to change the frequency are the matrix converters (MCs) that directly connect the input source to the output without needing large DC-link capacitors [11]–[14]. It is worth mentioning that the single-phase MCs, in contrary with the AC-DC-AC competitors, cannot generate pure sinusoidal output voltage waveforms, though they have recently found wide applications such as adjustable speed drives, aircraft power supplies and induction heating systems [15]–[17]. The first single-phase MC, proposed by Zuckerberger et al. in [18], can only decrease the voltage magnitude and increase its frequency with low power quality and harsh voltage spikes. In [19] and [20], a safe commutation strategy is proposed for the converter of [18]. However, the quality of waveforms is not yet acceptable. Some other single-phase MCs are presented in [15] and [20], which are not suitable for the applications requiring both step-up and step-down operation due to their limited gain range. In order to provide a wide gain range, the Z-source-based MC is proposed in [21], shown in Fig. 1(a), which offers the capability of simultaneous buck and boost operation. However, it requires a high number of energy storage components and ten semiconductors leading to low efficiency and high size and cost. Moreover, it suffers from a severe commutation problem leading to large voltage spikes.