SU1367116A1 - D.c. to a.c. voltage converter - Google Patents

Abstract

The invention relates to power converter technology and can be used to power a passive inductively active load. The goal is to increase reliability, reduce the cost and weight of the converter. The device contains a capacitor 2, a single-phase bridge on thyristors 3-6 with load terminals 7 connected to the diagonal of alternating current and additional thyristors 12-14. The anode thyristors 3.5 of the bridge are shunted by oppositely connected thyristors 8.9, and the cathode thyristors 4.6 bridge - counter-enabled diodes 10,11. The capacitor 2 with its first plate is connected to the output of the direct current of the anode group of the thyristors of the bridge, and the second facing to the anodes of the second 13 and third 14 additional thyristors and to the cathode of the auxiliary thyristor 15. The form of the load current 7 repeats the form-signal of the control circuit . I il. with y. (L

Description

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The invention relates to power converter technology and can be used to power a passive inductively active load.

The aim of the invention is to increase reliability, reduce cost. and mass converter.

The drawing shows an electrical circuit for converting a constant voltage to an alternating voltage.

The converter contains a power source 1, a capacitor 2, thyristors 3-6, forming a single-phase thyristor bridge with a passive inductive load 7 connected to the diagonal of an alternating current, reverse thyristors 8 and 9, connected anti-parallel to the anode thyristors 3 and 5 of the single-phase bridge, reverse diodes 10 and 11, connected in parallel to each other thyristors 4 and 6 of a single-phase bridge, the first additional thyristor 12, the cathode of which is connected to the positive input terminal, and the anode is connected to the direct current output of the anode tyre tori-phase bridge, second and third additional thyristors 13 and 14, whose anodes are connected to the capacitor plate, and cathodes connected) to first and second output terminals of the auxiliary thyristor 15 connecting the liner, a capacitor with a positive input terminal.

The converter works as follows.

The shape of the load current 7 of the converter repeats the shape of the reference signal produced by the control circuit and, in a particular case, is a sinusoid or any pre-specified sign changing function of time.

The converter creates in the load 7 a positive current half-wave (the current direction coincides with the arrow shown in the diagram) and a negative current half-wave (the current direction in the load is opposite to the arrow shown in the diagram).

The operation of the circuit when creating both half-waves of current is as follows (for the positive half-wave, the list of considered elements is given without brackets, and for the negative half-wave - in brackets; the absence of a duplicate list in brackets means.

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that these elements are the same for both half-current).

In the initial state, let the capacitor 2 be charged with the polarity indicated in the diagram without brackets.

Thyristors 15.3, 6, 6 (15.5, 4) are unlocked and capacitor 2 begins to be recharged along the circuit 1-15-2-3-7-6-1 (1-15-2-5-7-4-1) . The sign of the voltage of a capacitor charged at the end of this process corresponds to the signs on the diagram in brackets. As a result of the recharging of the capacitor 2, the current in the load 7 increases.

At the point in time when the voltage on the capacitor 2 exceeds in magnitude the voltage of the source I of the power supply, the voltage on the load 7 changes sign. Therefore, the diode 10 (11) is unlocked, and the load current 7 is closed along the circuit 7-6-10-7 (7-4-11-7), and the thyristors 15.3 (15.5) are closed. In this case, the rate of decrease of the load current 7 is determined by its parameters.

After this, the thyristors 13.9 (14.8) are unlocked, the thyristor 6, the diode 10 (4.11) is closed, and the capacitor 2 is recharged along the circuit 2-13-7-9-2 (2-14-7-8- 2). The current in load 7 increases. The polarity of the capacitor 2 at the end of this mode is indicated in the diagram without brackets.

When the voltage on the capacitor 2 in absolute value approaches the voltage of the power source, but less than it, the thyristor 6 (4) opens. In doing so, the thyristors 3.9 (14.8) are locked. The load current 7 is again closed through the thyristor 6 and diode 10 (thyristor 4 and diode 1I), decreasing. with a constant time determined by the parameters of the load.

Thus, one cycle of increasing the current in the load consists of successively carried out processes of charging the capacitor from the power source through the capacitor overload load and closing the load current through the thyristor 6, diode 10 (4.11).

With an increase in the load current, the cycles described are repeated one after another until the load current reaches a predetermined value.

When the load current is closed through the thyristor 6, the diode 10 (4.11), the rate of decrease of the current depends on the parameters of the load. For some passive 31

Inductively active loads (windings of electromagnets, excitation windings of electric machines), this rate of current reduction is insufficient and needs to be increased by recovering the stored energy to the power source.

The process of reducing the current is carried out as follows.

The described cycle of recharging capacitor 2 is repeated with power from source 1 of power along circuit 1-15-2-3-7-6-1 (1-15-2-5-7-4-1) and charging capacitor 2 to voltage, the polarity of which is indicated in parentheses. At the end of this and the other, the thyristors 5, 3 (15.5) are locked, and the increased load current is closed through the thyristor 6, the diode 10 (4.11).

Next, recharge of the condenser 2 is carried out along the circuit 2-13-7-9-2 (2-14-7-8-2). The polarity of the voltage of the capacitor 2 at the end of this mode is indicated in the diagram without brackets. As a result of the recharging of the capacitor, the current in the load increases.

When the voltage on the capacitor 2 exceeds the voltage of the power source 1 in absolute value, the thyristor 12 and diode 10 (11) are unlocked. Thyristor 13 (14) is locked. The electromagnetic energy stored in load 7 is transmitted to a power source through a circuit 1-10-7-9-12-1 (1-11-7-8-12-1). As a result, the load current is intensely reduced. When the load current becomes less than the required value.

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the thyristor 6 (4) is turned on, the load current is closed along circuit 7-6-10 (7-4-11), and thyristors 12.9 (12.8) are locked. As a result, the circuit is ready for a subsequent cycle of increasing or decreasing the current in the load.

Claims (1)

Invention Formula The DC / AC converter contains a single-phase thyristor bridge, the diagonal of the alternating current of which is connected to the output terminals, the thyristors of the cathode group are connected to the negative input terminal and are bridged by the reverse valves, and the thyristors of the anode group are connected to the first capacitor plate, the second capacitor which, via an auxiliary thyristor, is connected to a positive input terminal, as well as two inverse and three additional thyristors, characterized in that, in order to increase and reliability, cost and mass reduction, diodes are used as return valves, and reverse thyristors shunt the thyristors of the anode group of the bridge connected to the anode of the first additional thyristor connected by the cathode to the positive input terminal, the anodes of the second and third additional thyristors are connected to the second capacitor plate, and their cathodes are connected to the AC diagonal of the bridge.