Three-Phase Four-Wire Inverter Topology with Neutral Point Voltage Stable Module for Unbalanced Load Inhibition

Cai, Chunwei,An, Pufeng,Guo, Yuxing,Meng, Fangang The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

A novel three-phase four-wire inverter topology is presented in this paper. This topology is equipped with a special capacitor balance grid without magnetic saturation. In response to unbalanced load and unequal split DC-link capacitors problems, a qusi-full-bridge DC/DC topology is applied in the balance grid. By using a high-frequency transformer, the energy transfer within the two split dc-link capacitors is realized. The novel topology makes the voltage across two split dc-link capacitors balanced so that the neutral point voltage ripple is inhibited. Under the condition of a stable neutral point voltage, the three-phase four-wire inverter can be equivalent to three independent single phase inverters. As a result, the three-phase inverter can produce symmetrical voltage waves with an unbalanced load. To avoid forward transformer magnetic saturation, the voltages of the primary and secondary windings are controlled to reverse once during each switching period. Furthermore, an improved mode chosen operating principle for this novel topology is designed and analyzed in detail. The simulated results verified the feasibility of this topology and an experimental inverter has been built to test the power quality produced by this topology. Finally, simulation results verify that the novel topology can effectively improve the inhibition of an inverter with a three-phase unbalanced load while decreasing the value of the split capacitor.

A Novel Zero-Voltage-Switching Push-Pull Forward Converter with a Parallel Resonant Network

Cai, Chunwei,Shi, Chunyu,Guo, Yuxing,Yang, Zi,Meng, Fangang The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1

A novel zero-voltage-switching (ZVS) push-pull forward converter with a parallel resonant network is presented in this paper. The novel topology can provide a releasing loop for the energy storage in a leakage inductor for the duration of the power switching by the resonant capacitors paralleled with the primary windings of the transformer. Then the transformer leakage inductor is utilized to be resonant with the parallel capacitor, and the ZVS operation is achieved. This converter exhibits many advantages such as lower duty-cycle losses, limited peak voltage across the rectifier diodes and a higher efficiency. Furthermore, the operating principles and key problems of the converter design are analyzed in detail, and the ZVS conditions are derived. A 500W experimental converter prototype has been built to verify the effectiveness of the proposed converter, and its maximum efficiency reaches 94.8%.

A Novel Zero-Voltage-Switching Push-Pull Forward Converter with a Parallel Resonant Network

Chunwei Cai,Chunyu Shi,Yuxing Guo,Zi Yang,Fangang Meng 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1

A novel zero-voltage-switching (ZVS) push-pull forward converter with a parallel resonant network is presented in this paper. The novel topology can provide a releasing loop for the energy storage in a leakage inductor for the duration of the power switching by the resonant capacitors paralleled with the primary windings of the transformer. Then the transformer leakage inductor is utilized to be resonant with the parallel capacitor, and the ZVS operation is achieved. This converter exhibits many advantages such as lower duty-cycle losses, limited peak voltage across the rectifier diodes and a higher efficiency. Furthermore, the operating principles and key problems of the converter design are analyzed in detail, and the ZVS conditions are derived. A 500W experimental converter prototype has been built to verify the effectiveness of the proposed converter, and its maximum efficiency reaches 94.8%.

Three-Phase Four-Wire Inverter Topology with Neutral Point Voltage Stable Module for Unbalanced Load Inhibition

Chunwei Cai,Pufeng An,Yuxing Guo,Fangang Meng 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

A novel three-phase four-wire inverter topology is presented in this paper. This topology is equipped with a special capacitor balance grid without magnetic saturation. In response to unbalanced load and unequal split DC-link capacitors problems, a qusi-full-bridge DC/DC topology is applied in the balance grid. By using a high-frequency transformer, the energy transfer within the two split dc-link capacitors is realized. The novel topology makes the voltage across two split dc-link capacitors balanced so that the neutral point voltage ripple is inhibited. Under the condition of a stable neutral point voltage, the three-phase four-wire inverter can be equivalent to three independent single phase inverters. As a result, the three-phase inverter can produce symmetrical voltage waves with an unbalanced load. To avoid forward transformer magnetic saturation, the voltages of the primary and secondary windings are controlled to reverse once during each switching period. Furthermore, an improved mode chosen operating principle for this novel topology is designed and analyzed in detail. The simulated results verified the feasibility of this topology and an experimental inverter has been built to test the power quality produced by this topology. Finally, simulation results verify that the novel topology can effectively improve the inhibition of an inverter with a three-phase unbalanced load while decreasing the value of the split capacitor.

Design of a misalignment‑tolerant wireless charging system based on multidimensional cross‑coupling for autonomous underwater vehicles

Chunwei Cai,Qinyuan Cui,Xiangyao Meng,Shuai Wu,Wenping Chai 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

In this paper, a misalignment-tolerant wireless charging system based on multidimensional cross-coupling for autonomous underwater vehicles (AUVs) is proposed. The four transmitting coils of the proposed system magnetic coupler are divided evenly into two pairs as bipolar transmitting units. Subsequently, the uniform multi-dimensional horizontal magnetic flux can be obtained by two current vectors with a 90° phase difference exciting in the bipolar transmitting units. For the receiver, a couple of orthogonal coils are designed to form cross-coupling with the transmitter to pick up the maximum magnetic flux. Then, the proposed magnetic coupler combined with the proposed transmitter and receiver is designed through finite element analysis. Finally, a 900 W prototype is built and tested. Experimental results show that the system has stable output characteristics in the ranges of a − 20° to 20° rolling misalignment and a − 30 to 30 mm axial misalignment.

Compact inductive and capacitive combined wireless power transfer system for unmanned aerial vehicle applications

Wenping Chai,Xichen Liu,Shuai Wu,Chunwei Cai 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.4

This paper proposes a novel inductive and capacitive combined wireless power transfer (IC-WPT) system for unmanned aerial vehicle (UAV) applications. First, a new compact inductive and capacitive combined coupler is presented. The magnetic field coupled power transmission of the compact coupler contains one magnetic transmitting unit, which is composed of two biorthogonal L-type cores and two rectangular coils wound on each of the short edges of the L-type ferrite core in the vertical position, and two air-cored receiving coils embedded in the legs. Meanwhile, the electric field coupled power transmission of the compact coupler consists of four pieces of copper foil, where two are attached on the primary side and two are attached on the secondary sides for wireless energy transmission through capacitive coupling. Second, a simple resonant compensation network is developed for the IC-WPT system. To make the secondary side lightweight, the receiver self-inductance of the inductive power transfer (IPT) coupler and compensating capacitance of the capacitive power transfer (CPT) receiver can be used to compensate each other. A prototype of the proposed UAV IC-WPT system is built and tested. Experimental results show that the wireless power transfer system can deliver 130 W at an efficiency of 81.2%, which means it can be adopted to the autonomous charging of UAVs.