Wenjing Xiong

Review of Active Power Decoupling Topologies in Single-Phase Systems

Active power decoupling methods are developed to deal with the inherent ripple power at twice the grid frequency in single-phase systems generally by adding active switches and energy storage units. They have obtained a wide range of applications, such as photovoltaic (PV) systems, light-emitting diodes (LEDs) drivers, fuel cell (FC) power systems, and electric vehicle (EV) battery chargers, etc. This paper provides a comprehensive review of active power decoupling circuit topologies. They are categorized into two groups in terms of the structure characteristics: independent and dependent decoupling circuit topologies. The former operates independently with the original converter, and the latter, however, shares the power semiconductor devices with the original converter partially and even completely. The development laws for the active power decoupling topologies are revealed from the view of “duality principle,” “switches sharing,” and “differential connection.” In addition, the exceptions and special cases are also briefly introduced. This paper is targeted to help researchers, engineers, and designers to construct some new decoupling circuit topologies and properly select existing ones according to the specific application.

AC/DC Matrix Converter With an Optimized Modulation Strategy for V2G Applications

To adapt the battery voltage and increase charging efficiency in vehicle to grid (V2G) systems, an ac/dc matrix converter topology is presented. Aim to solve the problem of relatively large charging current ripple in the classical current space vector modulation strategy, a sectional optimized modulation strategy, is proposed, which can reduce the charging current ripple within the whole output range. And the comparative analysis is carried out between them. A simple controller with active damping is briefly introduced; it can work at two charging modes: constant voltage charging and constant current charging. The simulation and experimental results demonstrate the validity and effectiveness of the proposed method.

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.

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.

Carrier-Based Modulation Strategies With Reduced Common-Mode Voltage for Five-Phase Voltage Source Inverters

Two modulation strategies based on carrier-based modulation (CBM) scheme (named RCMV-CBM1 and RCMV-CBM2) are proposed to reduce the common-mode voltage (CMV) of a five-phase voltage source inverter. The basic characteristic of them is that two kinds of carriers with opposite phase are adopted. By applying the opposite carrier to some specific phases, the switching states with higher CMV absolute value can be avoided. In RCMV-CBM1, the output phase with the third largest modulated signal uses the opposite carrier, and the peak-to-peak value of CMV is reduced by 40%. In RCMV-CBM2, the output phases with the second largest and fourth largest modulated signals use the opposite carrier, and the peak-to-peak value of CMV is decreased by 80%. However, the ripple analysis reveals that RCMV-CBM1 has an advantage over RCMV-CBM2 in current quality. In addition, the optimized RCMV-CBM1 and RCMV-CBM2 are presented for reducing the output current ripple. Finally, a scaled-down prototype is built to verify the correctness and effectiveness of the proposed modulation strategies.

Carrier-based modulation strategy of indirect matrix converters for common-mode voltage reduction

A carrier-based modulation (CBM) method is proposed for indirect matrix converters (IMC) to reduce common-mode voltage (CMV). The proposed method is developed by utilizing two triangle carriers with opposite phase, and the phase with the minimum absolute output voltage uses the different carrier. The range of zero-sequence signals is given, and the selection of zero-sequence signals and the arrangement of carrier pattern are flexible. By choosing the zero-sequence signals as the central point or the boundary point, the proposed method can show the identical results with the existing space vector modulation (SVM) methods. The simulation results prove the validity of the proposed methods.

A carrier-based modulation strategy for multi-modular matrix converters with zero common-mode voltage

This paper presents a carrier-based modulation strategy for 3×1-modular matrix converters (MC) to achieve zero common mode voltage (CMV). A geometric method is introduced to determine the range of the modulation signals. Due to the nonzero CMV during the commutation time with the traditional four-step current-based commutation method, a modified four-step current-based commutation method is presented. Additionally, to expand the modulation strategy to multi-modular MC properly, the phase-shifted (PS) method is applied. The 3∗3-modular MC is built on Matlab/Simulink platform to verify the validity of the proposed modulation strategy.