Overview

In the near future, High Voltage Direct Current (HVDC) transmission systems up to 12 GW are planned. For this kind of edge technology high-power thyristors are the key components. To decrease the amount of electronics on high potential, direct light triggered thyristors (LTTs) are used. These LTTs have the advantage of easy isolated triggering by fiber optic links.

Key features
  • Direct light triggered thyristors
  • Easy isolated triggering
  • Layout simplification
  • Integrated protection functions

Products

About

BoD protection

Our Prime disc family is available with integrated Break over Diode (BoD), dv/dt- and Forward Recovery Protection (FRP), which helps to simplify the layout of modern HVDC converters.

In the light triggered thyristors (LTT) the BoD function was integrated by adjusting the curvatures of the pn-junction in the center. Under forward voltage conditions, this curved pn-junction ensures that the global maximum of the electrical field distribution is always located at the center of the device.

Therefore, charge carrier multiplication starts from the BoD when the applied forward voltage is sufficiently high. The resulting avalanche current turns on the thyristor by using the multistage gate structure. This guarantees that whenever the applied voltage level exceeds the breakdown voltage of the integrated BoD the LTT turns on safely.

dV/dt protection

A voltage pulse with a high dV/dt causes a capacitive current. If this current is high enough, a conventional electrical-triggered thyristor will turn on somewhere in the cathode area. This undesired turn-on process will normally destroy the thyristor. Our LTTs are designed in such a way, that the innermost amplifying gate is provided with the most dV/dt sensitive area. This is achieved by a local adjustment of the sheet resistance of the p-base. Thus, whenever a voltage pulse with a dV/dt-value exceeding the specified dV/dt-capability is applied to the LTT, the integrated dV/dt protection function triggers the LTT via the multistage gate area.

Forward Recovery Protection (FRP)

The FRP concept is based on an additional periodic light pulse which is applied to the LTT at a certain time after the current extinction. The protection light pulse is not only generated on demand but always during the whole operating time. It generates charge carriers in the optical gate with its higher lifetime which will safely turn on the thyristor only when a fault surge forward blocking voltage pulse occurs.

When quality and performance decide

Over 75 HVDC projects are installed under extreme conditions - from the hot middle east to polar regions all around the globe. We have served 15 HVDC projects to transmit hydro-power with nearly 50 GW transmission power and 8 HVDC Offshore wind power projects with more than 5 GW transmission power. Infineon devices for HVDC applications offer the highest quality and reliability due to robust design and outstanding production processes.

BoD protection

Our Prime disc family is available with integrated Break over Diode (BoD), dv/dt- and Forward Recovery Protection (FRP), which helps to simplify the layout of modern HVDC converters.

In the light triggered thyristors (LTT) the BoD function was integrated by adjusting the curvatures of the pn-junction in the center. Under forward voltage conditions, this curved pn-junction ensures that the global maximum of the electrical field distribution is always located at the center of the device.

Therefore, charge carrier multiplication starts from the BoD when the applied forward voltage is sufficiently high. The resulting avalanche current turns on the thyristor by using the multistage gate structure. This guarantees that whenever the applied voltage level exceeds the breakdown voltage of the integrated BoD the LTT turns on safely.

dV/dt protection

A voltage pulse with a high dV/dt causes a capacitive current. If this current is high enough, a conventional electrical-triggered thyristor will turn on somewhere in the cathode area. This undesired turn-on process will normally destroy the thyristor. Our LTTs are designed in such a way, that the innermost amplifying gate is provided with the most dV/dt sensitive area. This is achieved by a local adjustment of the sheet resistance of the p-base. Thus, whenever a voltage pulse with a dV/dt-value exceeding the specified dV/dt-capability is applied to the LTT, the integrated dV/dt protection function triggers the LTT via the multistage gate area.

Forward Recovery Protection (FRP)

The FRP concept is based on an additional periodic light pulse which is applied to the LTT at a certain time after the current extinction. The protection light pulse is not only generated on demand but always during the whole operating time. It generates charge carriers in the optical gate with its higher lifetime which will safely turn on the thyristor only when a fault surge forward blocking voltage pulse occurs.

When quality and performance decide

Over 75 HVDC projects are installed under extreme conditions - from the hot middle east to polar regions all around the globe. We have served 15 HVDC projects to transmit hydro-power with nearly 50 GW transmission power and 8 HVDC Offshore wind power projects with more than 5 GW transmission power. Infineon devices for HVDC applications offer the highest quality and reliability due to robust design and outstanding production processes.

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