Scr Gate Drive Transformer

Coilcraft s off the shelf gate drive transformers simplify the design of your gate drive circuit and shorten design cycle time.

Scr gate drive transformer.

Some of the common core packages are ee eer etd and efd. Typical gate drive circuit usually triggering is inhibited when the anode voltage of the thyristor is negative. This is because in this mode the thyristor acts like a low gain transistor and amplifies the gate current which is seen as an increase in anode leakage current. The firing circuit of gate pulse by 1 1 pulse transformer is given in the figure b.

Some common schematics and their corresponding turns ratios are listed in fig. A special section deals with the gate drive requirements of the mosfets in synchronous rectifier applications. Procedure for ground referenced and high side gate drive circuits ac coupled and transformer isolated solutions are described in great details. For more information see the overview for mosfet and igbt gate drivers product page.

Choice of the gate current polarity triggering in the 2 nd and 3 rd quadrants for s nubberless triacs. The function of the series resistor r is to limit the holding current of the scr. I have been searching for this everywhere including the books i have but i just can t find the design procedure for the circuit used to drive an scr using a pulse transformer. An scr is a four layer pnpn silicon semiconductor device.

With the use of pulse transformers as shown in figure 1. The scr is tyn612 with a igm peak gate. It has three external terminals anode gate and cathode and uses the alternative symbols of figure 1 a and has the transistor equivalent circuit of figure 1 b figure 2 shows the basic way of using the scr as a dc switch with the anode positive relative to the cathode and the scr controlled via its gate. Typical gate drive transformers are designed using ferrite cores to reduce cost.

The 1 1 1 pulse transformer is used to generate pulse for back to back scr. Galvanic insulation between the power and gate drive circuit a few kv. Gate drive circuit with a few components. Figure 6 shows a gate trigger pulse transformer with properly insulated multiple secondary windings.

An on board power supply accepts 120vac input and generates all power needed for the logic control fiber optic interface and gate drive. The function of diode d is to prevent reversing gate current. The basic gate drive transformer has several design variations each of which is determined by the specific application. An on board microcontroller provides timing and control of the scr gating signals with crystal controlled accuracy allowing precision phase control of the scr being driven.

It is a pair of antiparallel scrs being driven by a 1 1 1 pulse transformer.