RU1777221C - Off-line self-controlled voltage inverter - Google Patents

Abstract

Usage: power supply systems. SUMMARY OF THE INVENTION: the device comprises a gate bridge on thyristors 1-J and diodes 5-8, a capacitor 9 and a reactor 10 connected to an alternating current diagonal, forming an LC switching circuit. A capacitor 11 and a resistor 12, forming a damping RC circuit, and an output transformer 13 are also included in the diagonal of the AC bridge. A filter capacitor and a reactor 15 are connected at the input of the bridge. The control unit includes pulse shapers connected via current transformers to the power part of the inverter. The device provides the conversion of direct voltage into alternating rectangular without pause, which increases the efficiency and reduces the installed capacity of the equipment. 3 ill. Ј

Description

The invention relates to the field of electrical engineering, in particular to power valve converters.

Autonomous voltage inverters are widely known, the controlled valves of which are unlocked by current pulses generated by the control unit with a frequency that is 2 times lower than the natural frequency of the 1-3J communication loop.

The disadvantage of such inverters is the voltage dependence on

output from the load, due to a decrease in the pulse duration at the inverter output, and in the case of its operation on a controlled rectifier with a 1C filter, a decrease in the load capacity due to a decrease in the amplitude of the current pulse of the switching circuit with an increase in the conduction pause of the inverter valves. This, in turn, leads to an increase in the installed capacity of the switching circuit, energy losses in

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idling and reduced efficiency.

The manifestation of these drawbacks is reduced in an autonomous inverter A containing a gate bridge, each arm of which consists of a thyristor and a diode connected in opposite parallel, a switching LC circuit, a damping RC circuit, and an output transformer made with an additional winding connected to an AC diagonal , a filter capacitor connected to a diagonal of a direct current, a control unit including first and second pulse generators with control transformers, in addition it contains a capacitor, shunted by two counter-parallel connected circuits containing each series-connected dynistor, diode and primary winding of a pulse transformer, the secondary windings of which are connected to the control terminals of the diagonal thyristors of the inverter, connected to the additional winding of the specified output transformer through a resistor. Due to this, current pulses are generated with a predetermined delay with respect to the moment of termination of the voltage pulses at the inverter output. As a result, the dependence of the output voltage on the load is limited. However, the presence of a delay in the formation of current pulses by the master oscillator preserves the dependence of the voltage at the inverter output on the load and causes an increase in the installed power of the switching circuit and energy losses in idle mode.

In addition, the delay value of the current pulses depends on the supply voltage, which leads to an additional decrease in the effective value of the output voltage.

The aim of the invention is to reduce the installed power and increase the efficiency of the inverter.

For this purpose, a self-contained self-contained voltage inverter containing a valve bridge, each arm of which consists of a thyristor and a diode connected in opposite-parallel, an LC switching circuit, an RC damping circuit, connected to the AC diagonal of the bridge

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ka and the primary winding of the output transformer, made with an additional winding, and a filter capacitor is connected to the DC diagonal, and the control unit, consisting of the first and second current pulse shapers with control transformers, is additionally equipped with a galvanic isolation unit, a rectifier and a charge the bottom block, and each of the pulse shapers is equipped with a thyristor, a storage capacitor and a limiting reactor connected in series with the primary windings of the transformers boards whose secondary windings are connected to the control terminals of the diagonal thyristors of the inverter, while the control terminals 1 of the thyristors of the pulse shapers through the rectifier are connected to the output terminals of the galvanic isolation unit included in the RC circuit. and the charging unit is made on diodes according to the bridge circuit, while the anodes of the anode group diodes are connected to the cathodes of the thyristors of the pulse shapers and the common connection point of the storage capacitors, and each of the cathode group diodes is connected to the corresponding limiting reactor through the limiting resistor; the unit is connected to an additional winding of the output transformer. pa

Figure 1 shows a schematic diagram of the proposed autonomous inverter, and figure 2 and 3 are diagrams illustrating its operation.

The self-controlled autonomous voltage inverter contains a gate bridge, each arm of which consists of thyristors 1-A, diodes 5-8, a capacitor 9 and a reactor 10, which form a switching LC circuit, a capacitor 11 and a resistor 12 of a damping RC circuit and an output transformer 13 connected to the AC output of the bridge. At the input of the bridge, a filter capacitor And reactor 15 are connected. The control unit includes the first and second pulse shapers, each of which contains thyristors 16 and 17, storage capacitors 18 and 19, and limiting reactors 20 and 21, connected in series with primary windings of control transformers 38-41. The control transitions of thyristors 16 and 17 are shunted by resistors 22 and 23 and through resistors 2k and 25 and rectifier 26 are connected to the output terminals of the galvanic isolation unit (current transformer) 2 7, the primary winding of which is connected in series to the circuit of the damping RC chain 11 and 12.

The charging unit is made on diodes 28-31 according to a bridge circuit, the cathode group of which is connected through the limiting resistors 32 and 33 to the limiting reactors 20 and 21. The AC terminals of the charging unit are connected to the terminals of the additional winding.

transformer 13.

The control terminals of thyristors 1,2 and 3,4 are shunted by diodes 34-37 and, through control transformers 38-41, are connected, respectively, of each diagonal pair in series with the storage capacitor and limit reactor 18,20 and 19,21.

In addition, in the proposed self-contained autonomous inverter, a starting device is provided comprising a toggle switch 42, resistors 43-45, a capacitor 46 and a diode 47.

In the initial state, the thyristors 1–4 and 16.17 are in the locked state, the capacitors 9.11 and 19 are discharged, the capacitor 14 is charged to the voltage of the power source, and the capacitors 18 and 46 to the stabilization voltage of the zener diode 48 connected to a power source through a resistor 49.

Turning the toggle switch 42 to the start position causes the discharge circuit of the capacitor 46 to be closed through a resistor 45, a diode 47, and resistors 22-25. In this case, a current pulse in is generated (see Fig. 2), which through resistors 24 and 25 enters the control transition circuits of thyristors 16 and 17. Since the storage capacitor 10 is discharged in the initial state and the capacitor 18 is charged to a positive voltage stabilization of the zener diode 48, then the thyristor 16 is unlocked. In this case, the storage capacitor 18 is discharged through the limiting reactor 20 and the primary windings of the control transformers

and

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38 and 39. As a result of this, a current pulse is generated and a short current pulse i, (see Fig. 3), which ensures their unlocking, flows in the control terminal of thyristors 1 and 2. In this case, the storage capacitor 18 is recharged to a voltage u V (negative polarity. As a result, an LC switching circuit including a capacitor 9 and a reactor 10, a damping RC circuit 11 and 12, and a primary winding of the output transformer 13 15 are connected to the filter capacitor 14. Since the capacitance of the capacitor 14 is an order of magnitude greater than the capacity of the capacitor 9, the voltage across the windings of the output transformer 13 has a shape close to rectangular.

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and on the output of the additional winding 0

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Ki output transformer 13, indicated. a charge 5 of the storage capacitor 19 takes place along the circuit formed by the indicated winding, the diode 30, the resistor 33, the on-line reactor 21, the storage capacitor 19 and the diode 31, and the voltage UV2 on the thyristor 17 is gradually increased. In this interval, due to the large resistance value of the resistors 43 and 44, the voltage across the thyristor 16 and the storage capacitor 18 maintains a negative polarity.

With the parameters of the LC switching circuit providing a characteristic resistance lower than the load resistance, the current through the inverter valves iv (see Fig. 3) first flows through the thyristors 1 and 2, and then at the moment t2 passes to the chain of counter diodes 5 and 6.

with current conduction interval iy

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In inverse diodes, the locking ability of thyristors 1 and 2 is restored.

At time t, the current ivl through the counter diodes 5 and 6 becomes equal to 0. However, they remain on due to the presence of residual carriers and the current in their circuit begins to flow in the opposite direction. Typically, for power diodes such as DL161, D1b1, the reverse recovery time taafc, Rrt is important

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6-7 μs. When the rate of change of current through the valves is 10 A / μs,

the maximum value of the reverse current through counter diodes reaches 60-70 A. At time t4, diodes 5 and 6 are turned off, the reverse current of the diodes goes into the circuit of the damping RC chain 11 and 12 and the voltage is quickly restored Well and the voltage drops at the inverter output .

The current pulse ia through the damping RC circuit, flowing through the input circuit of the galvanic isolation unit (current transformer) 27, creates a current pulse (see figure 2) through the control terminals of the thyristors 16 and 17 and ensures the thyristor 17 is unlocked by the presence of a positive voltage on the storage condensate 19. As a result of this, a short current pulse 12 is generated, which, flowing through the restriction reactor 21 and the primary windings of the current transformers 41 and 40 and the thyristor 17, ensures the re-storage of the storage conductor 19 d voltage of negative polarity and induces a short pulse 1 and 2 (see Fig. 3) in the control circuit of the thyristors 3 and k of the valve bridge. When thyristors 3 and k are enabled, a sharp decrease in the voltage of 1 Kg occurs, a change in the porosity of the voltage pulse U1 at the inverter output and the windings of the output transformer 13. In this case, the load currents and the commuting LC circuit flow in the opposite direction. From this moment, a positive voltage pulse will occur at the anode of diode 28, which will charge the storage capacitor 18 along a circuit containing an additional winding of the output transformer 13, diode 28, limiting resistor 32, limiting reactor 20, storage, capacitor 18 and diode 29. In this time interval, the voltage Uy2 on the thyristor 17 and the storage capacitor 19 maintains a negative polarity, which ensures a locked state of the thyristor 17 and eliminates the appearance of current pulses in the circuit actuating pins thyristors 3 and 4 of the valve bridge at the onset of the current pulse 10 in the circuit of thyristors actuating pins 16 and 17.

When the thyristors 3 are unlocked, the i-vi current flows along a circuit containing

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mu capacitor 14, reactor 15, thyristor 3, parallel connected LC switching circuit and the primary winding of the output transformer 13, and thyristor 4. At time tg, current 1y2 passes to the counter diode circuit 7 and 8. At time tg, current. reverses its direction and continues to flow through diodes 7 and 8.

At time t7, the diodes 7 and 8 turn off and the reverse current iY2 passes to the circuit of the damping RC circuit 11 and 12 and the primary winding of the current transformer 27. As a result, a current pulse 10 is again generated in the control circuit of the thyristors 16 and 17. When This provides sufficient conditions for the unlocking of the thyristor 16 and the formation of a pulse i (and the control current in the control circuit of the thyristors 1 and 2 of the valve bridge. When these thyristors are unlocked, electromagnetic processes in the power section of the inverter and impulse drivers sov occur similar to those previously described.

Thus, the proposed self-contained voltage inverter provides the conversion of a constant voltage into an alternating rectangular shape without a pause, which reduces the installed power of the equipment and increases the efficiency.

Claims (1)

The claims A self-contained stand-alone voltage inverter containing a gate bridge, each arm of which consists of oppositely connected thyristor and diode connected to the diagonal of the bridge AC alternating LC circuit, the primary winding of the output transformer made with an additional winding, and an RC damping circuit, and a filter capacitor is connected to the DC diagonal, a control unit consisting of first and second pulse shapers with control transformers, characterized in that, with In order to reduce the installed power and increase the efficiency, it is additionally equipped with a galvanic isolation unit, a rectifier and a charging unit, and each of the pulse shapers is equipped with a thyristor, a storage capacitor and a limiting reactor connected in series with the primary windings of the control transformers, the secondary windings are connected to the control the conclusions of the diagonal thyristors of the inverter, while kidney, and the charging unit is made on diodes according to the bridge circuit, while the anodes of the diodes of the anode group are connected to the cathodes of the thyristors of the shapers 5 pulses and a common connection point, storage capacitors, and each of the diodes of the cathode group is connected through a limiting resistor Of the new thyristors and the P-type - wi .-,., Cl. Control leads of the thyristors of formiro-10 to the corresponding winders through a rectifier connected by an alternating current, the charging block with the output terminals of the galvanic block is connected to an additional winding of the electrical isolation included in RC-output transformer. 7221 10 kidney, and the charging unit is made on diodes according to the bridge circuit, while the anodes of the diodes of the anode group are connected to the cathodes of the thyristors of the shapers 5 pulses and a common connection point, storage capacitors, and each of the diodes of the cathode group is connected through a limiting resistor 21 W b FIG. I Jt. Jt