Hanbing Dan

Modulation Strategy Based on Mathematical Construction for Matrix Converter Extending the Input Reactive Power Range

In this paper, a modulation strategy based on mathematical construction is proposed to extend the input reactive power range for the three-phase matrix converter, which offers clear physical meanings and less computational efforts. This strategy is developed based on the construction of the modulation matrix composed by the sum of several matrices, one of which is used to generate the required output voltage. The others are intended to provide more degrees of freedom for control such that the matrix converter can produce the input reactive power as much as possible. In the framework of mathematical construction method, an optimization problem for the maximum input reactive power is formulated, whose analytical solution is difficult to obtain. Usually, optimization problem can be solved by using some numerical methods, but lots of time will be consumed. Therefore, a suboptimal method is presented to mitigate the computational burden. Besides, the proposed strategy is compared with the optimum-amplitude and indirect SVM methods, in terms of the maximum input reactive power for different operating conditions. It is shown that the proposed method can obtain the maximum input reactive power over most situations. Finally, the correctness of the proposed method is confirmed by simulation and experimental results.

Indirect Matrix Converter-Based Topology and Modulation Schemes for Enhancing Input Reactive Power Capability

A new topology based on indirect matrix converter (IMC) is proposed to enhance the input reactive power capability. This topology consists of a conventional IMC and an auxiliary switching network (ASN), which is connected to the dc-link of the IMC in parallel. With the aid of ASN, an implicit current source converter-based static synchronous compensator can be embedded into an IMC, which lays a foundation for the input reactive power control. Based on the proposed topology, two modulation schemes are presented, and the formations of the output voltage and input reactive current are decoupled in both of them. To minimize power loss and improve input current quality, a double closed-loop control algorithm is introduced, in which the current through the dc inductor in ASN is controlled to be minimum. Different from the conventional IMC, the input reactive power of the topology is independent of its load condition without considering the practical constraints. The effectiveness of the proposed topology and modulation scheme is confirmed by experimental results.

Carrier-Based Modulation Strategies for Multimodular Matrix Converters

Based on the equivalency between the full-bridge indirect matrix converters (MCs) and the 3 × 1modular MCs, the carrier-based modulation strategy is first tailored for the 3 3×1-modular MC. It can be directly expanded to 3×N-modular MC, but in order to improve the power quality, the phase-shifted (PS) method and phase disposition (PD) method are proposed. The former is suitable for the 3×N-modular MC with any multiwinding transformers (including phase-shifting transformers). Moreover, the latter is only applicable to the 3×N-modular MC with ordinary multiwinding transformers. The PD method has advantages over the PS method in the output current quality and efficiency. However, the PS method is superior to the PD method in the input current quality. Experimental results verify the correctness and effectiveness of the proposed modulation schemes.

Topology and Modulation for a New Multilevel Diode-Clamped Matrix Converter

To expand the matrix converter application in high power area, a new three-level diode-clamped matrix converter topology as well as a related multicarrier-based modulation scheme is proposed. The topology inherits the features from the conventional multilevel inverter and the indirect matrix converter, which is composed of a cascaded-rectifier and a three-level diode-clamped inverter. The proposed topology can overcome the voltage rating limits of the power semiconductors for high-voltage applications to some extent. Meanwhile, except the general advantages, such as bidirectional power flow, sinusoidal input and output currents, simple switch commutation, and a compact structure, it also avoids the voltage balance issue that exists in most conventional multilevel inverters. Finally, the functionality and effectiveness of the proposed topology and modulation scheme are verified by simulation and experimental results.

Open-Switch Fault Diagnosis and Fault Tolerant for Matrix Converter With Finite Control Set-Model Predictive Control

To improve the reliability of the matrix converter (MC), a fault diagnosis method to identify a single open-switch fault is proposed in this paper. The introduced fault diagnosis method is based on finite control set-model predictive control (FCS-MPC), which employs a time-discrete model of the MC topology and a cost function to select the best switching state for the next sampling period. The proposed fault diagnosis method is realized by monitoring the load currents and judging the switching state to locate the faulty switch. Compared to the conventional modulation strategies such as carrier-based modulation method, indirect space vector modulation, and optimum Alesina-Venturini, the FCS-MPC has known and unchanged switching state in a sampling period. It is simpler to diagnose the exact location of the open switch in MC with FCS-MPC. To achieve better quality of the output current under single open-switch fault conditions without any redundant hardware, a fault tolerant strategy based on predictive control is also studied. The fault tolerant strategy is to select the most appropriate switching state associated with the remaining normal switches of the MC. Experiment results are presented to show the feasibility and effectiveness of the proposed fault diagnosis method and fault tolerant strategy.

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.

Error-voltage based open-switch fault diagnosis strategy for matrix converters with model predictive control method

This paper proposes an error-voltage-based open-switch fault-diagnosis a strategy for a matrix converter (MC). A finite control set model predictive control method is used to operate the MC. The MC system performances under normal operation and under a single open-switch fault operation are analyzed. A fault-diagnosis strategy has also been implemented in two steps. First, the faulty phase is detected and identified based on a comparison of the reference and estimated output line-to-line voltages. Then, the faulty switch is located by considering the switching states of the faulty phase. The proposed fault-diagnosis method is able to locate the faulty switch accurately and quickly without additional voltage sensors. Simulation and experimental results are presented to demonstrate the feasibility and effectiveness of the proposed strategy.

A Finite Control Set Model Predictive Control Method for Matrix Converter With Zero Common-Mode Voltage

In this paper, a novel finite control set model predictive control (FCS-MPC)-based solution is proposed to eliminate the common-mode voltage (CMV) in matrix converters. Different from the existing MPC-based CMV reduction methods, which usually utilize all the possible switching configurations, in the proposed method, only the six rotating vectors, which produce no CMV, are included in the FCS to synthesize the output voltage and the input current. Therefore, zero CMV can be achieved naturally and no CMV related term needs to be included in the cost function. In addition, compared with other zero CMV methods, e.g., the enhanced space-vector modulation using rotating vectors, the proposed MPC-based method can significantly reduce the computational complexity without detracting the CMV elimination performance. Moreover, a modified four-step commutation strategy is proposed to effectively mitigate the CMV spikes due to the dead time, which usually exists when using the conventional current-based four-step commutation strategy. Finally, the feasibility and effectiveness of the proposed method are validated by using experimental studies.

A modulated model predictive control scheme for the brushless doubly-fed induction machine

Brushless doubly fed induction machines (BDFIMs) feature some important advantages, such as high reliability and low maintenance cost, over alternative solutions for brushless machine applications. This paper proposes a modulated model predictive control (MPC) algorithm for BDFIMs, which achieves a fixed switching frequency and superior system performance. An improvement of power quality is shown in this paper when compared to the conventional finite-control set-MPC. This paper examines the design and implementation of the modulation technique as well as presenting the simulation and experimental results to verify the technique’s operation.

Matrix converter open circuit fault diagnosis with asymmetric one zero SVM

An open-circuit fault detection and diagnosis strategy for a direct matrix converter is proposed in this paper. The current recirculating path during an open circuit condition is considered in detail with the aim of contributing more expert knowledge to the fault detection system for matrix converter. Simulation results are presented demonstrate the open circuit fault behavior of matrix converter. This expert knowledge is extremely important for the fault detection system to avoid false diagnosis. This work leads to the presentation of a reliable and fast fault detector for the Matrix Converter.