SU936293A1 - Ac voltage-to-elevated dc voltage converter - Google Patents

Description

one

This invention relates to a converter technique and can be used as a power source that converts an alternating voltage to a constant level.

An adjustable high voltage source is known, which contains a valve bridge and a chain of series-connected capacitors connected to its DC terminals, a common point connected to the input terminal t J via a switch.

Also known is a rectified voltage stabilizer containing a valve bridge, a smoothing choke, a filter capacitor, the smoothing choke made with a tap and connected to the control thyristor, which allows to adjust the output voltage + L2J.

The disadvantages of the known devices are low energy characteristics, since the energy from the alternating voltage source is consumed during part of the half-cycle of the mains when the input voltage is higher than the voltage across the filter capacitor. The charge current is limited only by the internal resistance of the source and the resistance of the valves. The short time of current flow, its large amplitude leads to low

to the value of the current distortion factor and the decrease in the power factor of the device as a whole.

The closest to the invention (there is an alternating voltage converter into an increased constant voltage, "containing valves that are connected to one of the input terminals of the opposite polarity, the other ends connected to the two-winding choke, free

The 20 terminals of which are connected to a chain of series-connected capacitors, the common point associated with another input terminal. The disadvantage of this converter is a relatively low power factor and a high level of output voltage ripple amplitude, which affects the quality of the power characteristics of the device.

The aim of the invention is to improve the energy performance.

This goal is achieved by the fact that in an alternating voltage converter to an increased constant, containing a main rectifier, two are a winding choke, the ends of which are connected to a chain of series-connected capacitors, the common point connected to one of the input terminals, is a two-winding choke with outlets from both windings connected to the DC terminals of the main rectifier, and an additional rectifier is introduced, the DC terminals of which are connected to the free ends of the double-winding A throttle and a key element is included between the common connection point of the capacitors and the input terminal.

FIG. 1 is a circuit diagram of a converter; in fig. 2 - diagrams (c (D-8) voltages and currents consumed from the network and at the choke).

The converter contains a main rectifier made on valves 1 - k, an additional rectifier on valves 5-8, a double-wound choke 9 made by taps connected to the DC terminals of the main rectifier. The pins of the permanent additional rectifier are connected to the ends of a double-wired throttle 9, the free ends of which are connected to a chain of serially connected capacitors 10 and 11, with a common point connected via key element 12 to: a single terminal. The load 13 is connected to the terminals of the capacitors 10 and 11.

FIG. Figure 2 shows the following diagrams: a) the voltage across the choke and the currents in its windings with the open key 12; b) the voltage across the choke and the currents in its windings with the key 12 closed; c) mains voltage and current drawn from the mains.

The device works as follows.

If the key element 12 is open, the rectified i, the current is closed

through series-connected windings of throttles W and W. In accordance with FIG. 1, turns of one winding of two-winding droplets E, W2- coils of another winding of two-winding chokes 9.W | , W. W2. + Wj and W. - parts of the turns of the corresponding winding from the output of direct current additional rectifier from the tap;

W. and W - part of the coils from the outlet of the connection point to the capacitor leads.

When the input voltage is greater than the load voltage, energy accumulates in the double-winding choke, current flows through the turns of the windings W, W capacitors 10 and M with load 13 and additional bridge valves (in the diagrams of Fig. 2

time intervals t, t .., etc.). In this case, the valves 5-8 of the main bridge are closed by a reverse voltage applied from the windings V / xf, W-z. ,

When the input voltage is less

load voltage, double winding choke sends energy, rectified current flows through all turns of windings W,. and valves of the main bridge 5 3 (intervals ta. 4 g 7

 in fig. 2 a). At the same time, the reverse voltage is applied to the valves of the additional rectifier and they are locked. Immediately at the moment of equality of the input and load voltages (t, t t, tg.), The current is switched from one winding turn to another with a simultaneous abrupt change in its amplitude. Thus, at times t,, consumed from the network and entering the capacitors and the load, it increases abruptly, and accordingly at times t2, tg- decreases. The jump change in current is due to the fact

 that when converting it from one turn to another due to the invariance of the energy of the throttles before and after the switching times, the equality

C-w

 .

where W, fu is the number of turns of the part

Claims (3)

windings drossel and the current flowing through them; , - respectively, the number of turns of the entire winding of the throttles and its current. If the bi-directional switch is closed, then one of the capacitors is recharged on each of the half-periods and then alternately flows through the winding W or Wj. So, with a positive half-wave input voltage on the tg-tf interval (Fig. 2b), the network current flows through valve 5, the winding Wf Wij, + W, the capacitor 10 and the key 12. In the interval 2. the valve 5 is closed and the charge of the capacitor 10 is induced by the current. flowing through valve 1 and winding W. At interval t, the network current is again closed through diode 5 and winding. When the input voltage is negative, the capacitor P is charged with current flowing at intervals t, tj-- tfe through valve 7 and winding W, V / JL a on the interval t, - tf- through the valve 3 and the winding W (The current consumed from the network, both when the switch is open and closed, has a stepped shape (Fig. 2c) with a reduced content of higher harmonic components, moreover, the first harmonic of the current coincides in phase with the supply voltage. of the converter depends on the ratio of turns W W + W and at n 2 - 3 it reaches the value 0.98. The output voltage also depends on the voltage. When the key 12 is open, the output voltage in the specified range of change p is 0.72 - 0 , 77 from the amplitude of the supply, and when the key is closed, it increases by a factor of 2. If you use a sismstor with a phase control system as a key 12, then by changing its switch-on phase, you can adjust the output voltage by a factor of 2. The use of double-wound throttles and additional straightening of bodies allows to improve the energy characteristics of the converter. Thus, in a known device, the power factor does not exceed 0.9. In a conventional single-phase bridge circuit, a rectifier with an inductive response of the power factor filter also amounts to 0.9. A marked advantage allows the converter to be used effectively to obtain an increased rectified voltage. large power x load. In this case, compared with the classical source circuit with a matching transformer, a significant reduction in the mass and dimensions of the device is achieved. Claims of an alternating voltage converter to an increased constant, containing a main rectifier, a two-winding choke, the ends of which are connected to a chain of series-connected capacitors, a common point connected to one of the input terminals, characterized in that, in order to improve energy performance, the two-winding The choke is made with taps. From both windings connected to the DC terminals of the main rectifier, and an additional rectifier is introduced, the conclusions of the constant t The eye of which is connected to the free ends of a double-winding throttle, and a key element is connected between the common connection point of the capacitors and the input terminal. Sources of information taken into account during the examination 1. USSR author's certificate No. 10368, cl. G 05 F 1/24, 1972. 2. Authors certificate of the USSR, cl. H 02 M 1/12, 1977. 3. US patent number 3177 21, cl. 321-15, 1965. 7 Jl Wf 7