What is GTO (Gate Turn Off Thyristor)?
A gate turn-off thyristor (GTO), as the name indicates, is basically a thyristor-type device that can be turned on by a small positive gate current pulse, but in addition, has the capability of being turned off by a negative gate current pulse.
How is the enhanced capability of a GTO obtained?
The turn-off capability of a GTO is due to the diversion of P-N-P collector current by the gate, thus breaking the P-N-P / N-P-N regenerative feedback effect.
What ratio of negative gate current is required to turn off a GTO?
The turn-off current gain of a GTO, defined as the ratio of anode current prior to turn-off to the negative gate current required for turn-off, is very low, typically 4 or 5. This means that a 6000 A GTO requires as high as –1500 A gate current pulse. However, the duration of the pulsed gate current and the corresponding energy associated with it is small and can easily be supplied by low-voltage power MOSFETs.
What are Common applications of a GTO?
GTOs are used in motor drives, static VAR compensators (SVCs). and ac/dc power supplies with high power ratings. After large-power GTOs became available. they ousted the force-commutated, voltage-fed thyristor inverters.
What are series and shunt snubber and what is their application in power electronics?
The snubber consists of a turn-on component (R, L) called a series snubber and a turn-off component (R, C, and D), called a shunt snubber. This type of converter is typically used for a subway dc motor propulsion drive.
What do you mean by snubber loss?
The snubber loss may be substantial in a high-power and/or high-frequency converter. This, in turn, may reduce the converter's efficiency and put a burden on the cooling system. To combat this problem, various regenerative or energy recovery schemes have been proposed.
What are methods to cope with snubber loss
Passive energy recovery and the other is regenerative snubber.
What is Passive energy recovery method to overcome snubber loss?
When the GTO is turned off, the snubber capacitor„ charges to the full supply voltage, as usual. At the subsequent turn-on of the GTO, the stored energy is transferred to capacitor resonantly through the inductance and diode. When the GTO turns off again, the energy in capacitor is absorbed in the load and capacitor, charges again to voltage V.
What is regenerative snubber scheme to overcome snubber loss?
This scheme uses an auxiliary chopper. At GTO turn-off, the snubber capacitor, charges to supply voltage. At subsequent turn-on of the device, the energy is resonantly transferred to capacitor, as before. The energy in capacitor is then pumped to the source through a dc-to-dc boost converter.
What are common applications of regenerative snubbers and RC snubbers?
The idea of a regenerative snubber appears very attractive, but its application should be carefully weighed against the extra cost, loss, complexity, and equipment reliability. High-power GTO converters normally use regenerative snubbers. Otherwise, RC snubbers are commonly used.
