RU176085U1 - High-voltage switch of powerful bipolar current pulses - Google Patents

Abstract

Scope: pulsed electrical engineering and power engineering in power systems of lasers, accelerators, tokamaks.

The technical result of the utility model is the creation of a high-voltage high-current semiconductor switch for switching powerful bipolar current pulses in the submilli- and microsecond ranges.

This is achieved using the design of a high-voltage switch, consisting of a start block and a switching block, made in the form of series-connected reverse-switched dynistors with reverse conductivity, to each of which a resistor is connected in parallel.

Description

The proposed utility model relates to high-voltage high-current semiconductor switches used in pulsed energy for switching powerful current pulses in the submill and microsecond ranges in the power systems of lasers, accelerators, tokamaks.

A known design of a switch based on reversible-switched dynistors (RVD) [1], which is a launch unit 1 and a switching device consisting of a high-voltage dinistor unit 2 connected in series to reverse-switched dynistors 3, 4, shunted by varistors 5, 6, 7, 8 blocking diode 9, shunted by resistor 10, and a high-voltage diode block 11, consisting of series-connected diodes 12, 13, shunted by varistors 14, 15, 16, 17, saturation inductor 18 (Fig. 1). Moreover, the diode block is connected to the RVD block counter-in parallel, its operating voltage is equal to the operating voltage of the dinistor block. The anode of the RVD block and the cathode of the diode block are connected to each other by copper buses through the saturation reactor 18, and the cathode of the block of the RVD and the anode of the diode block are connected directly through the bus.

The high-voltage diode block 11 shunts the high-voltage block 2 and is designed to protect the high pressure block from breakdown, since the dinistor block has high voltage drops and large losses of electric energy when the reverse current flows. Protective circuits connected in parallel to each RVD and diode, consisting of two varistors connected in series, are designed to equalize the voltage on the RVD 3, 4 and diodes 12, 13 in series and to limit the short overvoltage pulses that occur in the power circuits when alternating current pulses pass through the switch. The total number of varistors in the switch is equal to twice the total number of RVD and diodes. The RVD block is protected against reverse current flow by the blocking circuit “diode 9 - resistor 10”. The diode 9 serves to block the flow of reverse current through the RVD for the delay time of the forward current rise through the block of diodes. The resistor 10 serves to bypass the diode 9 during transients in the reverse current diodes at the moment of changing the polarity of the switched current pulse. As a result, the switching mode implements the switching mode of powerful bipolar current pulses.

The disadvantage of this design of the switch is a relatively complex electrical circuit with a large number of main and auxiliary components. This increases its cost and complicates maintenance, and the high internal parasitic inductance associated with a large number of interconnects, a saturation inductor and power buses leads to an increase in switching overvoltages and a decrease in the operational reliability of the switch.

These shortcomings are eliminated in the proposed design of a high-voltage switch, consisting of a start block and a switching block, made in the form of series-connected reverse-switched dynistors with reverse conductivity, to each of which a resistor is connected in parallel.

Reversible-switched reverse conductivity dinistor (RVDD) is a new power integrated circuit that combines in one semiconductor crystal a power RVD switch and a powerful reverse current diode located in one low-inductance cermet casing. The use of the RVDD block as a switching device allows switching powerful bipolar current pulses not with two high-voltage blocks (RVD and diode, as in the prototype), but with only one high-voltage RVDD block, which has low internal inductance and low energy losses when switching pulses compared to the prototype current in the forward and reverse directions.

The main differences of the new switch in comparison with the prototype are as follows:

1. There is no high-voltage diode unit and saturation inductor, since the control current from the start-up unit and the reverse half-wave of the switched power current flow through the reverse current diodes built into the HPR with low power losses.

2. There is no blocking circuit, consisting of a power diode and a shunt resistor, since the high pressure hoses have high reverse conductivity and can switch sufficiently high reverse currents.

3. The protective varistors are replaced by simpler and more reliable resistors that equalize the voltage on the assembly of the RVDD in static mode, since overvoltages arising from switching currents in the diode block and in the blocking diode are excluded in the block of the RVDD.

4. Reduced dynamic losses during switching of bipolar current pulses due to the effective pumping of the WFDD by reverse current.

The design of the utility model is illustrated in the following electrical diagram (Fig. 2):

1 - start block;

2 - a high-voltage block of series-connected reverse-switched dynistors with reverse conductivity;

3, 4- reversibly switched reverse conductors;

5, 6 - shunt resistors

In this design, the high-voltage RVDD block is switched using the start block 1. In the process of switching, the reverse polarity voltage is briefly applied from the start block to the RVDD block 2 and a control current pulse flows through the dinistors 3, 4. As a result, a triggering electric charge is introduced into the structure of the dinistors, which ensures the formation of a high concentration electron-hole plasma layer at the collector junction. Then, a direct voltage is applied from the external power circuit (capacitive storage of electric energy, not shown in the diagram) to the HPH unit, while the plasma layer causes a counter injection of emitter junctions. RVDD 3, 4 switch and switch the discharge current of the external power circuit (capacitive storage) into the load. After the direct current flows through the RVDD block in the external circuit, a reverse polarity power current is generated, which is then freely switched to the RVDD block through 3 and 4 reverse current diodes integrated into the silicon structures of the RVDD. The magnitude of the reverse current is determined only by the intrinsic inductance of the RVDD unit and the accumulated charge in the external circuit. At the same time, the power reverse current serves as the effective control current of the high pressure hitch to the moment of switching the repeated forward pulse. As a result, powerful weakly damped bipolar current pulses are switched into the load circuit using the high-voltage RVDD block.

We will consider the specific implementation of the proposed solution using the example of a switch of powerful bipolar current pulses KPI2-50-25 for a pulse current of 50 kA, voltage 24 kV. The KPI2-50-25 switch is manufactured on the basis of reversible-switched dynistors with reverse conductivity (RVDD) with a diameter of 50 mm semiconductor elements assembled in low-profile metal-ceramic cases of a tablet design with a height of 14 mm. The high-voltage switch unit consists of 15 series-connected RVDDs, between which 1 mm thick copper busbars are laid for fastening shunt resistors. On the side of the anode and cathode of the high-voltage block, the same busbars are 2 mm thick, designed to connect the switch to an external power circuit and to the starting block. In parallel to each RVDD shunt resistors are connected. Semiconductor devices and buses in the high-voltage block of the high pressure switch of the switch are compressed with a force of 25 kN using a clamp device.

The results of comparative tests showed that the RVDD switch switches alternating current pulses of the same power as the RVDD switch (prototype). The tests were carried out in the discharge circuit for the preionization of the pump lamps of a high-power laser in the normal mode of switching bipolar current pulses: forward current with an amplitude of 20 kA, a duration of 200 μs, and the next reverse current immediately with an amplitude of 18 kA and a duration of 250 μs. The test results are positive. At the same time, the overall dimensions and cost of the RVDD switch compared to the prototype is 2.5 times less due to the exclusion of the high-voltage diode block and 11 elements that make up the prototype.

Bibliography:

[1] C.V. Short, Yu.V. Aristov et al. “High-voltage diode-thyristor switches of powerful alternating current pulses” INSTRUMENTS AND TECHNIQUE, 2014, No. 4, p. 61-66.

Claims (1)

High-voltage switch of powerful bipolar current pulses, consisting of a start generator and a switching unit, characterized in that the switching unit is made in the form of series-connected reverse-connected dynistors with reverse conductivity, to each of which a resistor is connected in parallel.

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