Intro: Key tools in power electronics

Silicon-controlled rectifiers (SCRs), also referred to as thyristors, are semiconductor power devices with a four-layer triple joint framework (PNPN). Since its intro in the 1950s, SCRs have actually been extensively used in industrial automation, power systems, home appliance control and various other fields due to their high withstand voltage, big current bring capability, fast action and straightforward control. With the advancement of innovation, SCRs have actually developed right into many kinds, including unidirectional SCRs, bidirectional SCRs (TRIACs), turn-off thyristors (GTOs) and light-controlled thyristors (LTTs). The distinctions between these types are not only mirrored in the framework and working concept, but likewise determine their applicability in various application situations. This short article will start from a technical point of view, incorporated with particular criteria, to deeply evaluate the primary distinctions and typical uses of these four SCRs.

Unidirectional SCR: Fundamental and stable application core

Unidirectional SCR is the most fundamental and usual type of thyristor. Its framework is a four-layer three-junction PNPN setup, including three electrodes: anode (A), cathode (K) and gate (G). It only enables existing to stream in one instructions (from anode to cathode) and switches on after the gate is triggered. Once switched on, even if eviction signal is eliminated, as long as the anode current is higher than the holding current (generally less than 100mA), the SCR remains on.

(Thyristor Rectifier)

Unidirectional SCR has solid voltage and current tolerance, with a forward recurring optimal voltage (V DRM) of approximately 6500V and a rated on-state typical present (ITAV) of as much as 5000A. For that reason, it is widely utilized in DC motor control, commercial furnace, uninterruptible power supply (UPS) rectification parts, power conditioning tools and other occasions that need continuous transmission and high power processing. Its advantages are straightforward structure, inexpensive and high reliability, and it is a core part of many standard power control systems.

Bidirectional SCR (TRIAC): Ideal for air conditioning control

Unlike unidirectional SCR, bidirectional SCR, additionally known as TRIAC, can accomplish bidirectional conduction in both favorable and unfavorable half cycles. This structure contains 2 anti-parallel SCRs, which allow TRIAC to be caused and turned on at any time in the a/c cycle without changing the circuit connection technique. The balanced conduction voltage variety of TRIAC is generally ± 400 ~ 800V, the optimum tons current has to do with 100A, and the trigger current is much less than 50mA.

Due to the bidirectional transmission attributes of TRIAC, it is especially appropriate for a/c dimming and speed control in home devices and consumer electronics. For instance, tools such as lamp dimmers, fan controllers, and a/c follower rate regulatory authorities all count on TRIAC to attain smooth power policy. Additionally, TRIAC also has a lower driving power need and appropriates for integrated style, so it has been extensively made use of in wise home systems and little appliances. Although the power thickness and switching speed of TRIAC are not as good as those of new power gadgets, its low cost and convenient usage make it a vital player in the area of small and moderate power AC control.

Gateway Turn-Off Thyristor (GTO): A high-performance rep of active control

Gate Turn-Off Thyristor (GTO) is a high-performance power tool created on the basis of traditional SCR. Unlike regular SCR, which can only be shut off passively, GTO can be switched off proactively by using an unfavorable pulse existing to eviction, hence accomplishing more flexible control. This function makes GTO perform well in systems that call for regular start-stop or quick response.

(Thyristor Rectifier)

The technological criteria of GTO reveal that it has incredibly high power handling capacity: the turn-off gain is about 4 ~ 5, the optimum operating voltage can reach 6000V, and the maximum operating current is up to 6000A. The turn-on time is about 1μs, and the turn-off time is 2 ~ 5μs. These efficiency signs make GTO widely made use of in high-power situations such as electric locomotive grip systems, huge inverters, commercial electric motor frequency conversion control, and high-voltage DC transmission systems. Although the drive circuit of GTO is relatively intricate and has high switching losses, its performance under high power and high vibrant reaction demands is still irreplaceable.

Light-controlled thyristor (LTT): A trusted choice in the high-voltage seclusion setting

Light-controlled thyristor (LTT) uses optical signals instead of electric signals to set off transmission, which is its greatest function that differentiates it from various other sorts of SCRs. The optical trigger wavelength of LTT is typically between 850nm and 950nm, the action time is measured in milliseconds, and the insulation degree can be as high as 100kV or over. This optoelectronic isolation mechanism substantially enhances the system’s anti-electromagnetic interference capacity and security.

LTT is generally used in ultra-high voltage direct current transmission (UHVDC), power system relay defense gadgets, electro-magnetic compatibility protection in medical equipment, and military radar interaction systems and so on, which have extremely high requirements for safety and stability. As an example, numerous converter stations in China’s “West-to-East Power Transmission” project have taken on LTT-based converter shutoff components to make sure stable procedure under very high voltage conditions. Some progressed LTTs can likewise be integrated with gate control to accomplish bidirectional transmission or turn-off features, additionally increasing their application range and making them an optimal option for fixing high-voltage and high-current control troubles.

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Luoyang Datang Energy Tech Co.Ltd focuses on the research, development, and application of power electronics technology and is devoted to supplying customers with high-quality transformers, thyristors, and other power products. Our company mainly has solar inverters, transformers, voltage regulators, distribution cabinets, thyristors, module, diodes, heatsinks, and other electronic devices or semiconductors. If you want to know more about , please feel free to contact us.(sales@pddn.com)

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