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Posted on 29 June 2019

New Power Semiconductor Devices

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A practically all range of power semiconductors

Proton-Electrotex JSC is one of the leading Russian companies in terms of development and production of high-power semiconductor devices: diodes, thyristors, and modules on their base, heat-sinks.

By Loktaev Yu. M., Stavtsev A.V., Surma A.M., and Chernikov A.A., Proton-Electrotex

 

The released production covers practically all range of power semiconductor thyristors and diodes with voltage from 100 to 6500 V and with current from 100 to 3000 A. Thyristors and diodes are produced of disk and stud constructional type. Along with thyristors and diodes which are supposed to operate under industrial frequency Proton also produces fast and pulse-frequency thyristors, fast-recovery diodes as well as diodes with soft reverse recovery characteristic. A wide nomenclature of modules is also produced on the base of thyristor and diode elements in different circuit configurations in full press-pack construction with isolated basement. Modules are produced from 100 to 1250 A.

The main tendencies of new equipment development can be characterized as following:

1. Development and exploitation of production of high voltage thyristors and high power diodes including the devices on the base of silicon crystals of 100 and more millimeters in diameter.
Today the thyristors and diodes with voltage to 6500 V are developed on the base of silicon crystal of 23-80 mm in diameter with average current from 200 to 1250 A and as well thyristors on the base of silicon crystal of 100 mm in diameter with voltage to 6000 V and average current to 2000 A. The development of thyristors with voltage to 8500 including thyristors on the base of crystals of 1000 mm in diameter with average current of 1850 A is close to completion. It is planned that such devices will be applied to the native power-efficient electro converter equipment of a new generation in electro energy and transport. Our foreign partners are interested in new high-voltage and high-current thyristors and diodes.

2. Development and exploitation in production of high-voltage thyristors and diodes with precise controlled characteristics of reverse recovery not only with increased operation speed but also for the operation with industrial frequency.
TFI 473-1600 on the base of a crystal of 80 mm in diameter was developed and exploited. This device possesses unique characteristics even in comparison with the best foreign analogues: voltage to 4300 V, average current to 1600 A, turn-off time less then 80 µs, recovered charge (125Ñ, di/dt = - 50 À/µs) not more than µC with the opportunity of precise selection in a delivered part with variation not less than 2%. The company also offers high voltage thyristors and diodes (with voltage to 6500 V) with precisely selected characteristics of reverse recovery for operating in simultaneous applications of these devices. Grouping of devices by characteristics of reverse recovery is made on a special booth which reproduces the operating conditions in series type connection in the regimes close to operational conditions. Usage of these testing application and special methods allows making the selection of the devices groups reliably operating in consequential columns even without matching RC-circuits. Proton is also supposed to produce power stacks KT.5.11-800 on the base of thyristors grouped according to the described technology for being used in high-voltage soft starters of asynchronous motors (to 6 kV) with power from 630 kW.

3. Development and exploitation of high-voltage modules with isolated basement on the base of thyristor and diode crystals of 24-56 mm in diameter.
New devices of such type with voltage from 4000 to 6500 V have been developed and in the nearest time the voltage diapason is planned to be extended to 8500 V.

4. Development and exploitation of a series of thyristors of increased reliability.
The new more reliable cover peripheral areas are being used, a new technology of connection of crystals with thermal compensator is being developed. Proton has developed a series of high-voltage thyristors with elements of self-protection integrated in silicon structure which allows switching the device safety in peak overvoltage and also in voltage supplying on the thyristor with incomplete recovery of blocking capability.

5. Development of high-power semiconductor devices using new constructional technological decisions and physical operating principals.
The interesting results of the investigations leading in these directions in our opinion are:

5.1.) Symmetrical voltage suppressors with improved power capacity containing hidden n-layers.
Symmetrical avalanche voltage suppressors of "traditional" construction and a new device containing hidden n-layers with reduced specific resistance, they are schematically shown in Figure 1.

Numbers: 1 – copper case contact, 2 – contact metallization of semiconductor structure, 3 – compound, 4 – semiconductor structure 5 – molybdenum thermal compensator

For the devices of traditional type the problematic area which limits the maximal impulse values of dissipated power and avalanche current as well as the maximum allowable loss energy is the edge area bordering with the bevel. In this area under any polarity of applied voltage there is concentration of current density and besides the conditions of heat rejection were made worse because the size of the upper case contact is smaller than the size of semiconductor structure. In Figure 2 dependence of current and voltage for an experimental avalanche symmetrical suppressor of new construction is shown. The diameter of this semiconductor structure was 32 mm, the voltage of the beginning of avalanche discharge – 1650 V. The peak stroke power was about 300 kW, the loss energy to 150 J under single impulses.

Current and voltage dependence on time and isothermal dynamic volt-ampere characteristic

5.2.) Power high-voltage impulse dinistors Power high-voltage impulse dinistors are produced on the base of four layers thyristor structures with integrate transistor element – overvoltage suppressor (Figure 3).

High-voltage impulse dinistors are produced on the base of four layers thyristor structures with integrate transistor element

The basic structure of the devise is a thyristor, a thyristor at that plays a role of a gate commutator of currents of high amplitude. Instead of a fast voltage suppressor there is a three layers suppressor integrated in the device structure the avalanche current of which includes a thyristor structure. If a thyristor structure has multistage regerative gate this element on the whole can be placed in the limits of any gate areas or in each of them. Such a device may be used as a very powerful and very fast protective element or commutator of current and voltage impulses with exclusively fast rise times. In Figure 4 there are oscillograms of voltage and current while commutation of experimental dinistor the semiconductor element of which is shown in Figure 5.

Commutation of current impulses with rise times about 5 kA/ μs (a.) and about 200 kA/ μs(b.)

Experimental dinistor semiconductor element

5.3.) High-voltage high current diodes with ultrasoft reverse recovery characteristics. In Figure 6 there is oscillogram of reverse recovery current of experimental high voltage diode (UR=4800 V) produced on the base of silicon crystal of 56 mm in diameter. The examinations were held with primary inductive load which determined the anode current loss speed under reverse voltage of voltage source U R (DC) about 1000 V. The original DC was about 1000 A, loss speed was about 1600 A/µs. Typical values of Sfactor has been 1.6-2.

Oscillogram of reverse recovery current of experimental high voltage diode (UR=4800 V)

 

 

 

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