RU1812616C - Surge injector of single-polarity pulses - Google Patents

Abstract

The invention relates to high current semiconductor electronics and can be used in laser and EDM technology. The unipolar pulse generator contains a power source 1, a switching capacitor 2, a saturation inductor 3, a reversibly switched dinistor 4, a cut-off diode 5, a load circuit 6, a shunt diode 7, a thyristor 8, a starting capacitor 9, an inductor 10, a charging device 11, 2 transformers 14, 19, 3 additional diodes 15,17,18, feed-through capacitor 16., 2iЈ

Description

00

Yu

Os

Qs

FIELD OF THE INVENTION The invention relates to the ic field of power semiconductor electronics and can be used in laser and electrical erosion engineering.

The prototype is a generator of unipolar 5 pulses based on a new thyristor type semiconductor device - a reversibly switched dinitor (RVD), the switching capabilities of which, due to uniform switching, are several times higher than the switching ones

 thyristor capabilities.

The generator contains (see, Fig. 2) a power supply 1, a switching circuit, consisting of 15 switching capacitors 2 connected in series, saturation throttle 3, reversibly switched dinistor 4, cut-off diode 5 and load circuit b, a also a shunt diode 7, a thyristor 8, a starting capacitor 9, a 20 inductor 10, a charge inductor 20, a charge thyristor 21 and resistors

; 22.23 .. -. ... ...-. :::.

The first output of the capacitor 2 is connected to the anode of the diode 7, with the negative pole of the source 1 and to the cathode of the diode 5. The capacitor 9 is connected in parallel to the high pressure horn 4. The anode of thyristor 8 is connected to the anode of the high voltage hitch 4, the beginning of the winding of the inductor 10 is connected to the cathode of thyristor 8 , a resistor 30 23 is connected between the end of the winding of the inductor 10 and the cathode of the high pressure switch 4, A resistor 22 is connected between the cathode of the diode 7 and the anode of the high pressure switch 4. A load circuit 6 is connected between the cathode of the high voltage switch 4 and the anode of the diode 5. 35 The cathode of thyristor 21 is connected to the second condenser water 2. Saturation reactor 3 is connected between the anode of the WFD 4 and. the thyristor 21 cathode, the inductor 20 is connected between the thyristor 21 anode and the positive

; v the source pole 1.

When turning on thyristor 21 in the circuit

; there is a charge of capacitors 2.9 from source 1. The inductor 20 limits the slew rate of the current through the thyristor 21 and 4S provides a charge of capacitors 2, 9 to

: / voltage close to twice the voltage - v of the source I. After the end of the current

a reverse voltage is applied to the thyristor 21, causing it to 50

...; . shutdown. .

When you turn on thyristor 8 occurs

 fast discharge of the capacitor 9 through the coil 10 and the resistor 23, which is oscillatory in nature. In the process of discharge 55 of the capacitor 9, the inductor 3 having in the initial state a very large inductance,

 blocks the charge voltage of capacitor 2 and actually prevents the discharge of capacitor 2 along load circuit 6.

At the moment of changing the sign of the voltage on the capacitor 9, a reverse voltage is applied to the HPF 4, while the HPF 4 shunts the discharge circuit of the capacitor 9, since its electrical resistance in the opposite direction is very small. As a result, the current passing through the coil 10 is closed through the RVD 4 and, in the structure of the RVD 4, the charge of carriers initiating its subsequent switching begins to accumulate.

During the passage of the control current 1U through the RVD 4, the core of the throttle 3 is magnetized by the charge voltage of the capacitor 2. The parameters of the core of the throttle 3 are selected so that it saturates at the moment when a charge sufficient for uniform switching accumulates in the structure of the RVD 4.

When the core is saturated, the inductance of Drossel 3 decreases sharply. As a result, a direct voltage is applied to the RVD 4, it uniformly switches and switches to the load circuit 6 a current pulse of the discharge of the capacitor 2. Due to the uniform switching of the RVD 4, the switching energy losses in it are small and the RVD. 4 practically does not limit the slew rate of the current in the load circuit b.

The parameters of the switching circuit elements are selected so that during the switching process, the capacitor 2 is recharged to a small reverse voltage. The diode 5 interrupts the recharge current of the capacitor 2. At the same time, a pause in the current is created in the HPP circuit 4, which is necessary to turn it off. In the process of turning off the WFD 4, the capacitor 2 is completely discharged along the circuit of the diode 7.

Resistor 2.3 provides dissipation of the energy stored in the coil 10 during the formation of the control current of the high pressure switch 4. Its value is selected so that after switching the high pressure signal 4, the current 1U passing through the coil 10 drops quickly enough to zero and not. prevented turning off the WFD 4. The resistor 22 scatters the energy stored in the capacitor 2 when it is recharged. This eliminates the possibility of multiplying the voltage on the capacitor 2 due to its resonant charge from the power source.

The disadvantage of the prototype device generator is the large energy loss in resistors 22,23 when damping the main switching circuit and the control circuit of the WFD 4, as well as the large energy loss in the charge thyristor 21 that occurs when operating at high

frequencies when the slew rate of the current in the charge circuit is high.

The purpose of the invention is to reduce energy losses.

In FIG. 1 shows a diagram of the proposed pulse generator; in FIG. 2 is a prototype diagram.

In FIG. 1: 1 - power supply, 2 - switching capacitor, 3 - saturation inductor, 4 - reversibly switched on dinistor (RVD), 5 - cut-off diode, 6 - load circuit, 7 - shunt diode, 8 - thyristor, 9 - starting capacitor, 10 - inductor, 11 - charging device, 12 - resistor, 13 - additional power supply, .14 - first transformer with a saturable core, 15 - first additional diode, 16 - passage capacitor, 17 - second additional diode , 18-third additional diode, 19 - second transformer.

Capacitor 2, throttle 3, RVD 4, diode 5 and load circuit 6 are connected in series. The first output of the capacitor 2 is connected to the anode of the diode 7 and the negative poles of the power supplies 1, 13. The capacitor 9 is connected in parallel to the HPP 4. The anode of the thyristor 8 is connected to the anode of the HPP 4, the cathode of the thyristor 8 is connected to the beginning of the winding of the inductor 10. The capacitor 16 is connected between the end the windings of the inductance coil 10 and the cathode of the RVD 4. The cathode of the diode 15 is connected to the second terminal of the capacitor 2, the cathode of the diode 18 is connected to the positive pole of the source 1, the anode of the diode 17 is connected to the end of the winding of the inductor 10. Resistor 12 is connected between the positive pole and the source 13 and the second output of the capacitor 2. The beginning of the first winding and the end of the second winding of the transformer 14 are interconnected and connected to the positive pole of the power source 1. The end of the first winding of the transformer 14 is connected to the anode of the diode 15, the beginning of the second winding is connected to the cathode of the diode 7. Start the first winding of the transformer 19 is connected to the cathode of the diode 17, the end is connected to the cathode of the high pressure generator 4 and the anode of the diode 5. The beginning of the second winding of the transformer 19 is connected to the negative pole of the power supply 1, the end to the anode of the diode 18.

The proposed generator operates as follows.

When the HPP 4 is turned on, the capacitor 2 is discharged and the current pulse is switched into the load circuit 6. The parameters of the discharge circuit of the capacitor 2 are selected in such a way that, during the switching process, the capacitor 2 is recharged

to the slight opposite, voltage. Diode 5 blocks this voltage and creates a circuit RVD 4 pause current necessary to turn it off. The process of turning off the RVD 5 4 continues until a positive voltage is applied to it due to the resonant charge of the capacitor 2 from the power source 1 through the first winding of the transformer 14.

0 The windings of the transformer 14 are connected in such a way that at the stage of turning off the HPF 4, the second winding does not actually affect the charging process of the capacitor 2, since the voltage arising from it blocks

5 diode 7. As a result, the charge rate of the capacitor, and therefore the circuit time to turn off the HPF 4, is determined mainly by the inductance of the first winding of the transformer 14.

0 The presence of a reverse voltage on the capacitor 2 leads to an increase in the charge current passing through the first winding of the transformer 14 and to the accumulation of excess energy in the inductance of this winding5. This creates the possibility of charging the capacitor 2 to a voltage exceeding twice the voltage of the source power supply 1, which is clearly undesirable, since subsequent turns on of the HPF 4 can lead to an uncontrolled increase in the voltage on the capacitor 2 and to a breakdown of the HPH 4. The possibility of increasing the voltage on the capacitor 2 eliminates REFERENCE diode circuit 7 to the oscillator circuit,

5, which ensures the recovery of excess energy to the source 1 when the voltage on the secondary winding of the transformer 14 exceeds the output voltage of the power source 1.

0 The amount of excess energy returned to source 1, and therefore the maximum value of the charge voltage of capacitor 2, is determined by the magnetic coupling between the transformer windings

5 14 and the transformation ratio of this transformer.

The parameters of the core of the transformer 14 are selected in such a way that at the stage of turning off the HPH 4 it is not saturated, when

0, the inductance of the first winding of the transformer 14 is large and the recharge rate of the capacitor 2 is small. After some time after the end of the current through the RVD 4, sufficient to turn it off reliably,

5, the core of the transformer 14 is saturated. In this case, the inductance of the first winding of the transformer 14 abruptly

decreases, the current in the circuit of the diode 15 rises sharply and the capacitor 2 quickly charges to the operating voltage. As a result

it is possible to obtain a sufficiently fast charge of the capacitor 2 and a sufficiently large circuit time to turn off the HPH 4 at a low reverse voltage on the capacitor 2. A decrease in the reverse voltage on the capacitor 2 leads to a decrease in the loop currents in the charge and discharge circuit of this capacitor and reduce energy losses on the elements of the generator circuit. .

The formation of the control current of the WFD 4 in the proposed generator is carried out when the thyristor 8 is turned on. As a result, the recharging current of the starting capacitor 9 is closed through the inductor 10 and the passage capacitor 16, the charge of which is carried out simultaneously with the charge of the capacitor 2.

When the polarity changes on the capacitor 9, a negative voltage is applied to the RVD 4. In this case, the RVD 4 shunts the circuit of the capacitor 9 and the current of the inductor 10, which is the control current 1y, passes through it.

In the process of recharging the capacitor 9, a saturation inductor 3, which has a very large inductance in the initial state, blocks the charge voltage of the capacitor 2 and prevents the discharge of this capacitor through the thyristor circuit 8. After some time, after the reverse circuit appears in the RVD 4 1U current saturates the core of Drossel 3 and the inductance of Drossel decreases sharply. As a result, the current through the RVD 4 rises sharply, a positive voltage is applied to the RVD 4, it switches and switches a powerful pulse of the discharge current of the capacitor 2 into the load circuit 6.

To ensure uniform switching of the WFD 4 with low switching energy losses, the parameters of the elements 3,9.10,16 are selected so that the relation:

.flyWdt Adl / dt,

where ty is the duration of the control current;

dl / dt is the slew rate of the switched current;

A is a coefficient determined by the structural and electrophysical characteristics of the WFD 4: A (0.5-1.5).

 Simultaneously with the process of switching the current to the load circuit 6 in the circuit, the capacitor 16 is charged by the current of the inductor 10 to some extent) and U, which is the inverse of the thyristor 8 and ensures its shutdown.

The turn-off time of the thyristor 8 is determined by the recharge time of the capacitor 16 through the first winding of the transformer 19. The coefficient of the transformer 19 is selected so that the recharge voltage of the capacitor 16 is stabilized at a certain level. The excess energy is discharged through the second winding of the transformer 19 to the source 1. The remaining charge in the capacitor 16 is used to generate the control current of the WFD 4 when the thyristor 8 is turned on 8. The diodes 17, 18 serve to separate the circuits

5 of the first and second windings of the transformer 19., v. ..:. .- ... . -;. A characteristic feature of the generator under consideration is the presence of magnetic elements with saturating

0 cores whose magnetization reversal times are known to be proportional to the magnitude of the applied voltage. The latter circumstance has a rather strong effect on the operation of the generator, especially in the start-up mode, when the voltage values on the circuit elements are low.

To ensure reliable start of the generator, low-power

0 charging device 11, consisting of an additional power supply 13 and resistor 12. Using this device, the capacitors 2, 9 are pre-charged to the voltage corresponding to the voltage of the charge of these capacitors in the steady-state mode of operation of the generator. For this, transients in the circuit at the time of the start of the generator and in the steady state of its operation

0 practically coincide. Since the resistance value 12 is selected sufficiently large, after the start-up, the influence of the device 11 can be neglected. Source 13 after starting the generator may

5 be disabled altogether.

In the circuit of FIG. 1, the demagnetization of the cores of the nonlinear elements 3, 14 is carried out by the reverse current passing through the 5.15 diodes, in the process of restoring their blocking properties. Deeper demagnetization can be obtained by introducing additional demagnetization currents into these elements.

So thanks to the introduction to

5, the generator circuit of three additional diodes, two transformers and a feed-through capacitor, the energy remaining in the RVD control circuit and in the switching capacitor of the load circuit is not dissipated by damping resistors, as in the prototype device, but is recovered to the source. power supply and is used in subsequent switching cycles. In addition, as a result of introducing these elements, as well as a low-power charging device, reliable operation of the generator at a high frequency is ensured without the use of a charging thyristor, which has large energy losses during fast charging of a switching capacitor.

Since the prototype device, the energy losses at the damping resistors and the charge thyristor are comparable with the energy losses at the remaining elements of the circuit, the total energy losses in the proposed generator are reduced by no less than 1.5-2 times. . . ::. : ./; . .-.

The novelty of the set of essential features of the proposed device is as follows.

It is known to use recovery transformers in an inverter based on thyristors. However, they were used in the mode without core saturation and had a constant charge inductance. As a result, when operating at a high frequency, when the charge time of the inverter switching capacitors is short, the initial charge rate becomes excessively high. Moreover, in order to obtain a sufficiently large circuit time for switching off the thyristors, a large value of the reverse voltage on the switching capacitors was required after the end of the process of switching the current to the load. The consequence of this: there was an increase in the loop currents in the inverter circuits and the energy losses on its elements.

The use of a transformer with a saturating core and a rapidly varying inductance of the charging winding in the charging circuit of the generator allows a very low initial slew rate of the voltage across the switching capacitor to be obtained. In this case, even with a small reverse voltage, a sufficiently large circuit time for switching off the semiconductor devices of the generator power circuit is provided on this capacitor.

A decrease in the reverse voltage at the switching capacitor leads to a fuller use of the energy accumulated in it, and, consequently, to a decrease in the circuit currents in the generator circuits and to a decrease in the energy losses at its elements.

For the purpose of controlling the WFD, energy recovery has not previously been used. To carry out the recovery of excess energy from the RVD control circuit to the power source, two additional diodes, a transformer and a feed-through capacitor, are included in the generator circuit. At the same time, the combination of 5 connected elements introduced ensures not only a decrease in energy losses in the control circuit, but also an increase in the reliability of the operation of the starting thyristor, since it is connected to it after the end of the control current

0 for a sufficiently long time, a negative voltage is applied. As a result, the thyristor shutdown conditions are substantially improved.

According to the proposed scheme, an ultrasonic range generator with an average power of 3 kW was assembled.

As RVD 4 and diode 5 were used prototypes developed at the Physicotechnical Institute of the USSR Academy of Sciences. Devices had a working

0. A smg area and a repeating voltage of 1000 V. The turn-off time of the WFD is 4-10 μs, the recovery time of the diode is 5 - 0.3 μs. Thyristor TCHI 100 was used as thyristor 8, 7.15 5 HF 200 as diodes, KD 210 G as diodes 17, 18. Choke 3 was assembled on six ferrite rings of the NMS 2500 grade with a size of 45x30x20 mm and had 3 turns . Transformer 19 was made with an air core, the inductance of its first winding was 200 μH, the number of turns of the first and second windings was 1:12, transformer 14 was assembled on ten ferrite rings of IMI 1600 brand size 80x50x11 mm and

5 had 30 turns in the first winding and 20 turns in the second winding. As capacitors 2, 9, 16, K 78-2 brand capacitors were used, the capacitance of the capacitor was 2-1 μF, the capacitor 9 was 0.047 μF, and the capacitor was 16 - 2 μF. The resistance of the resistor is 12-20 kOhm. Coil inductance 10 - 2.5 μH. Source 1 consisted of a bridge diode rectifier powered by se -; ty 220 V, 50 Hz, filter inductance 3000

5 μH and a filter capacity of 3000 μF. Source Nickname 13 consisted of a bridge diode vyr mitel powered from a 220 V, 50 Hz network, a step-up transformer, and a 10 μF filter capacity. Output voltage

O source 13 - 800 V. Elements of the circuit were cooled by blowing air. During testing, the generator worked successfully at frequencies up to 10 kHz at various resistance values for 5 loads. The amount of energy loss on the elements of the generator did not exceed 10% of the amount of energy switched in the circuit., The load, which is about 1.5 times less than in the prototype generator. The duration of the output current pulses was 2 μs

when working on a low inductance resistor and 0.1 μs when using a two-link magnetic compression system in the load circuit.

The electrical characteristics obtained make it possible to use the proposed generator as a power source for lasers and EDM machines, .. .... ../

SUMMARY OF THE INVENTION A unipolar pulse generator comprising a series-connected switching capacitor, a saturation inductor, a reversibly switched dinistor, a cut-off diode and a load circuit, as well as a power source, an inductor, a starting capacitor connected in parallel with a reversibly switched dinistor, bypass a diode connected by the anode to the first output of the switching capacitor and to the negative pole of the power supply, and a thyristor. connected by the anode to the anode of the reversibly switched-on dynistor, and by the cathode to the beginning of the winding of the inductance coil, which means that, in order to reduce energy losses, three additional diodes, two transformers, a passage capacitor and a charging device are introduced into the generator, the first the transformer has a saturable core, the beginning of its first winding and the end of the second winding are connected to the positive pole of the power source, the end of the first

the windings are connected to the anode of the first additional diode, the beginning of the second winding is connected to the cathode of the shunting diode, the charging device is connected in parallel with the switching capacitor and connected

a negative terminal with the first terminal of this capacitor, the cathode of the first additional diode is connected to the second terminal of the switching capacitor, the anode of the second additional diode is connected to

the end of the winding of the inductor and with the first output of the feed-through capacitor, the second output of the feed-through capacitor and the anode of the cut-off diode are connected to the cathode of the reversibly switched dynistor,

the beginning of the first winding of the second transformer is connected to the cathode of the second additional diode diode, the beginning of the second winding is connected to the negative pole of the power source, the end of the first winding is connected to the cathode of the reversibly switched dinistor, the end of the second winding is connected to the anode of the third additional diode, the cathode of the third additional diode is connected to the positive power supply pole.