Effect of Winding Configuration on the kVA Rating of Wye-connected Autotransformer Applied to 12- pulse Rectifier

Meng, Fangang,Du, Qingxiao,Gao, Lei,Li, Quanhui,Man, Zhongcheng The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

This paper presents the effect of winding configuration on the kVA rating of a wye-connected autotransformer applied to a 12-pulse rectifier. To describe the winding configuration of the wye-connected autotransformer, position and proportional parameters are defined and their quantitative relation is calculated. The voltages across and currents through the windings are measured under different winding connections. Consequently, a relation between the kVA rating and position parameter is established in accordance with the analysis, and the optimal winding configuration is obtained on the basis of this relation. A wye-connected autotransformer with the least equivalent kVA rating and simplest winding configuration is designed and applied to the 12-pulse rectifier. Simulations and experiments are conducted to validate the theoretical analysis.

Two Low-Loss Large Current Rectifiers Based on Low KVA Rating Wye-Connected Autotransformers

Fangang Meng,Zhongcheng Man,Quanhui Li,Lei Gao 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

In this paper, two large current rectifiers are proposed based on two wye-connected autotransformers. The requirements of the ideal large current rectifier are analyzed, and it is concluded that the large current rectifier has a higher power density and a higher energy conversion efficiency when it is made up of two three-phase half-wave rectifiers and a wye-connected autotransformer. According to theoretical analysis results, the two novel wye-connected autotransformers are designed to feed two three-phase half-wave rectifiers. The two autotransformers can generate two groups of three-phase voltages with a 60o phase shifting, and their kVA ratings account for 95% and 80% of the load power, respectively. These values are less than those of a double star rectifier at 30% and 46%. From the input mains and output side, the power quality of the proposed rectifiers is the same as that of the double star rectifier. Some experiments validate the correctness of the theoretical analysis.

Load adaptability of hybrid harmonic reduction method at DC-link of series-connected multi-pulse rectifiers

Meng, Fangang,Liu, Wei,Yin, Xinyu,Gao, Lei The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.10

To verify the harmonic suppression capability of a series-connected 36-pulse rectifier and to improve the load adaptability of its harmonic injection circuit, a reliable selection method for the DC-side output capacitor of the rectifier is proposed. The sufficient and necessary conditions for ensuring the rectifier can operate under the 36-pulse rectification state is summarized, which is the basis for selecting capacitance values under different load types. After using the proposed selection method for the output capacitors, simulation and experimental results indicate that the hybrid harmonic suppression circuit has good performances under a resistive load, a resistive-inductive load, or a load mutation.

Two Low-Loss Large Current Rectifiers Based on Low KVA Rating Wye-Connected Autotransformers

Meng, Fangang,Man, Zhongcheng,Li, Quanhui,Gao, Lei The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

In this paper, two large current rectifiers are proposed based on two wye-connected autotransformers. The requirements of the ideal large current rectifier are analyzed, and it is concluded that the large current rectifier has a higher power density and a higher energy conversion efficiency when it is made up of two three-phase half-wave rectifiers and a wye-connected autotransformer. According to theoretical analysis results, the two novel wye-connected autotransformers are designed to feed two three-phase half-wave rectifiers. The two autotransformers can generate two groups of three-phase voltages with a 60o phase shifting, and their kVA ratings account for 95% and 80% of the load power, respectively. These values are less than those of a double star rectifier at 30% and 46%. From the input mains and output side, the power quality of the proposed rectifiers is the same as that of the double star rectifier. Some experiments validate the correctness of the theoretical analysis.

Effect of Winding Configuration on the kVA Rating of Wye-connected Autotransformer Applied to 12- pulse Rectifier

Fangang Meng,Qingxiao Du,Lei Gao,Quanhui Li,Zhongcheng Man 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

This paper presents the effect of winding configuration on the kVA rating of a wye-connected autotransformer applied to a 12-pulse rectifier. To describe the winding configuration of the wye-connected autotransformer, position and proportional parameters are defined and their quantitative relation is calculated. The voltages across and currents through the windings are measured under different winding connections. Consequently, a relation between the kVA rating and position parameter is established in accordance with the analysis, and the optimal winding configuration is obtained on the basis of this relation. A wye-connected autotransformer with the least equivalent kVA rating and simplest winding configuration is designed and applied to the 12-pulse rectifier. Simulations and experiments are conducted to validate the theoretical analysis.

Novel passive harmonic suppression method for series-connected multi-pulse rectifiers

Quanhui Li,Lei Gao,Fangang Meng 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.3

To improve the power quality and reliability of series-connected multi-pulse rectifiers (MPR), a passive harmonic suppression method is proposed in this paper. According to the topology of the rectifier, the operation modes are examined, and the operating waveforms are studied based on the operation modes. Based on the operating waveform of the rectifier, the relationship between the input voltage and the turns ratio of the auxiliary single-phase transformer (AST) is obtained, and the optimal turns ratio of the AST is calculated. The obtained results express that the input voltage THD is 4.4%, and that the input current THD is about 2.6%. The magnetic rating of the AST is only 1.72% of the output power. The proposed passive harmonic suppression method has the advantages of low loss and good harmonic suppression capability.

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.

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.

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%.