The Study of Using Various Types of Twelfth-Pulse Rectifier for DC Link of Power Converter

When designing test-benches SI150 NF4 and SI310 NF4, it was decided to use the twelfth-pulse rectifier to generate DC link voltage. Three well-known types of the twelfth-pulse rectifier are considered. Expressions for calculating the parameters of these types of rectifiers are obtained. For clarity, the parameters of each type of rectifier considered are normalized to the parameters of the twelfth-pulse rectifier with a balanced transformer. The analysis showed that the lowest current of the power diode has the twelfth-pulse rectifier with a balanced transformer. At the same time, power diodes have the lowest reverse voltage in the series twelfth-pulse rectifier. Expressions are obtained and the power of static losses in power diodes of three types of the twelfth-pulse rectifier are surveyed. For this purpose, a linear approximation of the volt-ampere characteristic of power diodes was used, taking into account the threshold voltage and the active resistance of the power diode in the open state. For the test-bench SI310 NF4, the junction temperatures of the power diodes used in the twelfth-pulse rectifier were additionally surveyed. For this purpose, it was developed a thermal model and it was obtained expressions for calculating the junction temperature of a power diode depending on the average output current of the rectifier. The results obtained show the advantages and disadvantages of various types of twelfth-pulse rectifier. This article has practical application, it allows developers of power converters to make the right choice of the type of twelfth-pulse rectifier, and then choose the type of power diode.