Multi-modular Matrix Converter Research Articles

Predictive Voltage Control in Multi-Modular Matrix Converters under Load Variation and Fault Scenario

This paper presents a model predictive control (MPC) strategy to regulate output voltages in a multi-modular matrix converter topology for isolated loads. The converter system harnesses power from a six-phase permanent magnet synchronous generator (PMSG) to deliver sinusoidal voltages to a three-phase load, with LC filters positioned at the output of each MC module within the multi-modular scheme. The proposed MPC approach ensures that the output voltages remain within acceptable ranges of magnitude, phase, and frequency, even under load variations and system faults. This control strategy is particularly suitable for uninterruptible power supply systems, microgrids or other applications where voltage regulation is critical. Experimental studies validate the effectiveness of the control strategy under various load conditions, reference voltage changes, and simulated system fault scenarios. The results highlight the robustness and reliability of the proposed voltage control using the multi-modular matrix converter.

Review, Challenges and Potential of AC/AC Matrix Converters CMC, MMMC, and M3C

This article presents a review and a comparison of the conventional matrix converter (CMC), multimodular matrix converter (MMMC), and multilevel matrix modular converter (M3C) topologies, which are three of the main topologies of the matrix family. The study of the CMC supplies basic knowledge for these structures and then the concept of multilevel matrix converters used in MMMC and M3C topologies is approached. The study addresses modulation strategies and switching sequences for the topologies to provide implementation guidelines and harmonic content reduction. The design is also carried out and results of the three topologies are shown to exemplify their operation. Finally, the article presents a comparison between the topologies to highlight the advantages and challenges of each one. This study contributes information on the three topologies, which are not easily found in the literature, especially in terms of modulation and switching strategies. It also highlights applications and research points that have to improve.

Speed Control of a Six-Phase IM Fed by a Multi-Modular Matrix Converter Using an Inner PTC With Reduced Computational Burden

A variable-speed predictive torque control (PTC) of a six-phase induction machine (SPIM) fed by a multi-modular matrix converter (M-MMC) is presented in this paper. This new system inherits the advantages of both multiphase machines (i.e., inherent fault-tolerance and better distribution of the power/current per phase compared to three-phase machines) and the M-MMC (i.e., smaller size and weight, and has no bulky storage elements). In addition, with the M-MMC topology, it is possible to use two power generation sources of different characteristics instead of a single three-phase source. This article proposes a method that reduces the number of calculations significantly compared to conventional PTC to overcome this issue. Simulation and experimental results are provided for speed control, module failure performance and tolerance to the variation of the magnetization inductance of the SPIM. An experimental test bench on a customized SiC-Mosfets based M-MMC and a 5.5 kW symmetrical SPIM has been used.

Improved Predictive Control in Multi-Modular Matrix Converter for Six-Phase Generation Systems

Distributed generation systems are emerging as a good solution as part of the response to the world’s growing energy demand. In this context multi-phase wind generation systems are a feasible option. These systems consist of renewable AC sources which requires efficient and controlled power conversion stages. This work proposes a novel predictive current control strategy that takes advantage of a multi-modular matrix converter topology in the power stage of a six-phase generation system. The proposed method uses a coupling signal between the modules to decrease the error and the total harmonic distortion compared to independent control of each module. Experimental results validate the new control strategy showing the improvement regarding the target parameters.

Modulation Strategies Based on Mathematical Construction Method for Multimodular Matrix Converter

A family of modulation schemes based on mathematical construction for the multimodular matrix converter (MC) with ordinary multiwindings transformer is proposed in this paper. The key to the schemes are the calculation of offset signals. A geometric method is introduced to determine the range of the offset signals. The modulation schemes could be divided in two categories based on the geometric positions of the offset signals: continuous modulation (Method I) and discontinuous modulation (Method II). The former has the advantages of ease of use and good power quality. While the later has the advantage in power losses. Additionally, both methods can achieve the maximum linear voltage transfer ratio. To obtain better output current quality, a switching pattern with specific sequence is provided. Finally, a scaled-down prototype is built to verify the correctness and effectiveness of the proposed modulation strategies.

一括型ブレーキ回路を用いた多重マトリックスコンバータのFRT制御

This paper proposes an FRT (fault ride through) control method for a multi-modular matrix converter operating under short voltage sag to prevent the unexpected acceleration of the generator. The proposed method uses an external braking circuit and feedback controls to obtain a generator torque same as that before the voltage sag. From experimental results, the proposed method maintains the generator torque to -1.07 p.u. and injects a grid reactive current of 0.60 p.u. during the voltage sag.

Phase-Shifting-Transformer-Fed Multimodular Matrix Converter Operated by a New Modulation Strategy

Multimodular matrix converters (MMMCs) built with three- to single-phase modules have emerged as a candidate for high-power applications. In order to reach higher voltage and power levels, constituent modules of an MMMC are fed by isolated secondary windings of a phase-shifting transformer, while their outputs are connected in series to supply the load. This paper presents a new modulation strategy for the MMMC. Unlike previously proposed strategies that aim to simultaneously fabricate sinusoidal output voltage and input current, the new method only focuses on generating multilevel output voltage waveforms. Nonetheless, because power balance among modules on a same output phase is guaranteed, and owing to the harmonic elimination capability of the phase-shifting transformer, sinusoidal input current with good quality can still be achieved. Compared with previous methods, the proposed strategy cannot adjust the input power factor but is simpler, more straightforward, and associated with lower switching losses. Its use makes possible the employment of an indirect module structure that significantly reduces the total number of switches and, thereby, the overall semiconductor cost and eliminates the need for complex device commutations, which is essential in direct matrix converter modules. The presented concepts are verified by simulation and experimental results.

Damping Control of Filter Resonance Focusing on Output Stage for Multi-Modular Matrix Converter

This paper discusses a damping control that is applied to multi-modular matrix converters in order to suppress the oscillation due to the LC resonance of the input filter. The multi-modular matrix converter connects a multiple winding transformer and several modules. The module consists of a three-phase to single-phase matrix converter and filter capacitors. It is found that the multi-modular matrix converter has a resonance problem between the leakage inductance of the transformer and the filter capacitors in the modules. In this paper, a damping control combined with the output current control of the multi-modular matrix converter is proposed to suppress the resonance and to achieve better input current quality. The proposed damping control can divert the output current sensors for an ACR (auto current regulator), which is generally used in the adjustable speed drive system of a motor. Therefore, the proposed damping control does not require additional sensors, which is an advantage over the conventional damping control applied to the input stage of the multi-modular matrix converter. From the experimental results, the proposed damping control improves the input current THD (total harmonic distortion) by 75.5%. In addition, the proposed damping control obtains a higher damping performance than the conventional damping control.

Indirect Space Vector Based Modulation Techniques for High-Power Multi-Modular Matrix Converters

Combining concepts of traditional multilevel converter and matrix converter (MC), the multimodular MCs (MMMCs) have reached the medium-voltage high-power level. These topologies possess features such as elimination of dc components and are able to output high-quality multilevel waveforms. Due to the MMMC's particular topological structure, modulation strategies for the conventional converters cannot be directly adopted. This necessitates the design of specially tailored modulation schemes for them to generate sinusoidal input/output waveforms. In this paper, indirect space-vector-based modulation techniques are proposed for the MMMCs. The study begins by establishing an indirect circuit model for the three-module MMMC topology, before using space vector calculations to derive duty ratios for the model's rectification and inversion stages. As the inversion stage can be viewed as multiple sets of three-phase outputs, its switching states and duty ratios are then converted and combined with those from the rectification stage. Finally, the gating signals are produced according to two switching patterns. As demonstrated by simulation and experimental results, the presented modulation techniques can generate sinusoidal waveforms with variable frequency and magnitude, as well as adjustable angle and power factor. The superiority of the second switching pattern is also proved by the obtained results.

Multimodular Matrix Converters With Sinusoidal Input and Output Waveforms

Multilevel voltage-source converter topologies are widely used today in high-power applications such as medium-voltage drives. On the other hand, studies on matrix converters (MCs) have been mainly limited to the low power range. With the intention to combine benefits from both multilevel structure and direct power conversion, this paper investigates the topologies and operating principles of multimodular MCs (MMMCs). Composed of three-phase-to-single-phase MC (3 × 2 MC) modules, two versions of MMMCs are presented and studied. Modulation schemes to synthesize sinusoidal waveforms on both input and output sides of the converters are elaborated. Having features such as modular design, relatively low switching frequency, and capability of using low-voltage power semiconductor devices, the presented MMMCs are intended for possible use in higher power applications where four-quadrant operation and fast dynamic response are expected. Simulation and experimental results are provided to verify the validity of the study.