A new series‐connected 36‐pulse rectifier with hybrid DC‐reinjection method for high power output

Abstract

In this study, a new 36‐pulse rectifier with a hybrid DC‐reinjection circuit is proposed. It multiplies the AC‐side input voltage steps from 12 to 36 using a hybrid auxiliary circuit for voltage and current modulation. Both the AC and DC side harmonics of the rectifier system are efficiently suppressed when combined with filter capacitors at DC side. Only 2 more diodes and an IGBT are used in the proposed approach for constituting the injection circuit. The cascaded structure of rectifier bridges allows for significant voltage gain, making it appropriate for high power output rectification applications. The proposed 12‐pulse rectifier's phase shifting structure and 36‐pulse rectifier's operational theory are introduced. The injection transformer's turn ratio and the IGBT's conduction angle are both designed to have the lowest possible harmonic distortion of the voltage at AC side. Analyses are done on the rectifier's impedance matching feature and energy loss of IGBT. The operating performance of the rectifier is assessed when the active switch fails. With the help of a 1.8 kW prototype and a HIL system based on Starsim, the theoretical portion is confirmed. The results of the simulation and experiments support the effectiveness of the hybrid voltage harmonic injection method studied.

Research on harmonic generation principle of series‐connected multi‐pulse rectifiers and optimization design method for main transformers

“…According to [13][14][15][16][17][18][19] and the structure of the Y-connections and the △-connections, it can be obtained that…”

“…The main transformers of series-connected MPRs are mainly divided into two types, which are the isolation type and the semi-isolation type. In [13][14][15][16][17][18][19], the main transformers are isolation type. In [13,14], the structure of the transformer is delta (△)/delta (△)/star (Y) connections.…”

“…In [13,14], the structure of the transformer is delta (△)/delta (△)/star (Y) connections. In [15,16], the primary windings of the main transformer are connected in △, while the secondary windings are Y-prolonged connection. The transformers in [13][14][15][16] output two sets of three phase voltages with a 30 • phase difference.…”

“…In [15,16], the primary windings of the main transformer are connected in △, while the secondary windings are Y-prolonged connection. The transformers in [13][14][15][16] output two sets of three phase voltages with a 30 • phase difference. In [17], the main transformer outputs three sets of three phase voltages with a 20 • phase difference.…”

“…The primary winding ends of the main transformers are connected with the power supply and one of the rectifier bridge, while the secondary windings are connected in △. Compared to [13][14][15][16][17][18][19], the winding number and the kVA rating of the main transformers in [20,21] is reduced by one third.…”