2、12-pulse rectifier principle: 12 pulses means that on the basis of the original 6-pulse rectification, a set of 6-pulse rectifiers is added at the input end and after adding the phase-shifting transformer, so that the DC bus current is completed by 12 thyristors, so it is also called 12-pulse rectification.

A rectifier is a device that converts an oscillating two-directional alternating current (AC) into a single-directional direct current (DC). Rectifiers can take a wide variety of physical forms, from vacuum tube diodes and crystal radio receivers to modern silicon-based designs.

It is used in both the inverter and the rectifier and for the first time we are introduced to firing angle alpha (ά). The 6-pulse bridge has a pulse number of 6 and can be thought of as a 6 phase, half wave circuit.

Therefore, a 3-phase system requires six diodes to make up the rectifier. This design is commonly referred to as a 6-pulse rectifier because it draws current from the AC source in six pulses. This non-linear current draw can distort the supplied AC power, causing problems for motors and other electronic equipment.

1. Because of series connection of the converters on the dc side, the mean output voltage is twice that of a 3 pulse converter for the same supply Consequently the power capability doubles. 3. The number of pulses is increased to six and the amplitude of the ac ripple is decreased.

In a bridge circuit configuration, it comprises of four diodes that provide the same polarity of output for either polarity of the input. The main feature of this diode bridge which makes it more efficient than centre tap rectifier is its polarity i.e. the polarity of output is same as that of input.

Two pulse converters is defined as two triggering pulses or two sets of triggering pulses are to be generated during every cycle of the supply to trigger the various SCRs.

General Description. The Pulse Converter component produces a pulse of known width when a pulse of any width is sampled on p_in. Use to interface pulse events from a fast domain to a slow domain or when a specific pulse width must be guaranteed. Translated documents are for reference only.

They are connected in series on the dc side and in parallel on the ac side, It is also a single phase converter.

Pulse number is defined as the number of pulses in the dc output voltage within one time period of the ac source voltage. In high-power applications, ac–dc converters based on the concept of multipulse, namely, 12, 18, 24, 30, 36, 48 pulses are used to reduce the harmonics in ac supply currents.

Now the thyristors are fired in the sequence T1 → T2 → T3 → T4 → T5 → T6 → T1 with 60° interval between each firing. Therefore thyristors on the same phase leg are fired at an interval of 180° and hence can not conduct simultaneously.

Graetz circuit is a two half-period rectifier. It is used for rectifying alternating voltage when consumer with constant voltage has to be powered. It consists of four diodes connected in series by two. In each half period of the alternating voltage the two pairs of diodes transmit a wave.

 A controlled rectifier is a circuit that is used for converting AC supply into unidirectional DC supply & can control the power fed to the load. This process of converting alternating current (AC) to direct current (DC) is also called as controlled rectification.