Intro: Key devices in power electronics

Silicon-controlled rectifiers (SCRs), additionally known as thyristors, are semiconductor power devices with a four-layer three-way joint framework (PNPN). Since its introduction in the 1950s, SCRs have been widely made use of in industrial automation, power systems, home device control and other fields because of their high endure voltage, big current carrying ability, quick response and easy control. With the advancement of modern technology, SCRs have actually advanced into several kinds, including unidirectional SCRs, bidirectional SCRs (TRIACs), turn-off thyristors (GTOs) and light-controlled thyristors (LTTs). The distinctions between these types are not just shown in the structure and functioning concept, yet likewise determine their applicability in various application circumstances. This article will begin with a technical perspective, incorporated with details specifications, to deeply evaluate the primary differences and regular uses these 4 SCRs.

Unidirectional SCR: Fundamental and secure application core

Unidirectional SCR is one of the most fundamental and common kind of thyristor. Its structure is a four-layer three-junction PNPN setup, consisting of three electrodes: anode (A), cathode (K) and gateway (G). It only permits present to move in one direction (from anode to cathode) and turns on after the gate is set off. Once turned on, even if eviction signal is removed, as long as the anode current is higher than the holding existing (usually less than 100mA), the SCR stays on.

(Thyristor Rectifier)

Unidirectional SCR has solid voltage and current tolerance, with a forward repetitive top voltage (V DRM) of approximately 6500V and a ranked on-state average present (ITAV) of approximately 5000A. For that reason, it is widely utilized in DC motor control, industrial furnace, uninterruptible power supply (UPS) correction components, power conditioning devices and various other occasions that require constant conduction and high power processing. Its benefits are basic structure, affordable and high integrity, and it is a core element of numerous traditional power control systems.

Bidirectional SCR (TRIAC): Perfect for AC control

Unlike unidirectional SCR, bidirectional SCR, additionally known as TRIAC, can accomplish bidirectional transmission in both positive and unfavorable half cycles. This framework contains 2 anti-parallel SCRs, which enable TRIAC to be triggered and turned on at any moment in the a/c cycle without transforming the circuit connection technique. The symmetrical transmission voltage range of TRIAC is generally ± 400 ~ 800V, the maximum tons current has to do with 100A, and the trigger current is much less than 50mA.

Because of the bidirectional conduction characteristics of TRIAC, it is especially suitable for air conditioner dimming and rate control in family appliances and consumer electronics. For instance, gadgets such as lamp dimmers, follower controllers, and a/c unit follower rate regulatory authorities all rely upon TRIAC to achieve smooth power law. In addition, TRIAC also has a lower driving power demand and appropriates for integrated design, so it has been widely used in wise home systems and small appliances. Although the power density and switching speed of TRIAC are not like those of new power gadgets, its inexpensive and convenient use make it a vital gamer in the area of little and moderate power air conditioning control.

Gateway Turn-Off Thyristor (GTO): A high-performance agent of energetic control

Gate Turn-Off Thyristor (GTO) is a high-performance power gadget created on the basis of standard SCR. Unlike common SCR, which can only be shut off passively, GTO can be shut off actively by using a negative pulse current to the gate, therefore accomplishing more flexible control. This feature makes GTO execute well in systems that require constant start-stop or fast action.

(Thyristor Rectifier)

The technical criteria of GTO show that it has very high power managing ability: the turn-off gain is about 4 ~ 5, the maximum operating voltage can get to 6000V, and the maximum operating current is up to 6000A. The turn-on time has to do with 1μs, and the turn-off time is 2 ~ 5μs. These efficiency signs make GTO extensively used in high-power scenarios such as electric engine traction systems, large inverters, commercial electric motor regularity conversion control, and high-voltage DC transmission systems. Although the drive circuit of GTO is fairly intricate and has high changing losses, its performance under high power and high vibrant reaction requirements is still irreplaceable.

Light-controlled thyristor (LTT): A reputable choice in the high-voltage seclusion environment

Light-controlled thyristor (LTT) utilizes optical signals as opposed to electric signals to trigger conduction, which is its largest function that distinguishes it from various other sorts of SCRs. The optical trigger wavelength of LTT is usually between 850nm and 950nm, the action time is gauged in nanoseconds, and the insulation level can be as high as 100kV or above. This optoelectronic isolation mechanism greatly boosts the system’s anti-electromagnetic disturbance capability and safety.

LTT is primarily made use of in ultra-high voltage direct existing transmission (UHVDC), power system relay protection devices, electro-magnetic compatibility defense in medical tools, and armed forces radar communication systems and so on, which have incredibly high requirements for safety and security. For example, numerous converter stations in China’s “West-to-East Power Transmission” job have actually taken on LTT-based converter valve modules to make certain secure operation under incredibly high voltage problems. Some progressed LTTs can additionally be integrated with gateway control to attain bidirectional transmission or turn-off functions, additionally increasing their application variety and making them an optimal choice for resolving 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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