SU611279A1 - Direct frequency converter with artificial switching of thyristors - Google Patents

Description

(54) DIRECT FREQUENCY CONVERTER WITH ARTIFICIAL TIRISTOR COMMUTATION

the bridge includes a series-connected switching capacitor 12 and a choke 13; as well as a diagonal of direct current - a distribution thyristor bridge assembled on thyristors 14-17, the load 18 and the load current direction sensor 19 connected to the control circuit consisting of the control generator 20, pulse distributor 21 are included in the diagonal of the current and match schemes 22.

In the proposed frequency converter, a method of forming the output voltage is applied by cyclically connecting the load to the linear supply voltage for equal periods of time. The algorithm of operation of the power thyristors is as follows: LV | 1, -LC 11.61- BC | 2.6 I- LVG2,4 | - - LS13D1- -, 5,

where AB, BC, AC are the linear voltages to which the load is connected;

1, 2, 3, 4, 5, 6 - numbers of thyristors connecting the load to linear voltages.

Suppose control pulses from control generator 20 through pulse distributor 21 are fed to power thyristors 1 and 5.

In this case, the computation capacitor 12 is charged with the polarity indicated on the drawing without brackets. Next time, the load switches to another line voltage, suppose using thyristors 1 and 6. Therefore, it is necessary to turn off thyristor 5. To determine which of the distribution thyristors should be switched on, the load current direction sensor 19 is connected in series with the load , the signal of which arrives at the coincidence circuit 22. The pulses from the control generator 20 through the pulse distributor 21 also arrive here. Let the direction of the current in the thyristor 5 be indicated by a dotted arrow. Then the control system pulses to thyristors 11 and 15 and a capacitor, discharging along path 15.5, bridge diode 7, 11, 13 - turns off thyristor 5 and continues discharge along the path + 15, 18.19, 1, bridge diode 7, 11, 13- Through time.m, equal to the recovery time of the locking properties of the thyristor 5, the thyristor 8 is turned on and the capacitor is rapidly recharged to a voltage with polarity indicated in brackets.

If the direction of the current in the thyristor 5 is indicated by an arrowhead and the polarity of the capacitor without brackets, then to control the thyristor 5, the control system pulses the thyristors 8 and 17. At the same time, the capacitor discharges along the path + 8, the bridge diode 7, 5, 17, 13 -, turning off the thyristor 5 and continuing the discharge along the + 8 circuit, the bridge diode 7, 1, 19, 18, 17, 13 - after a time equal to the recovery time of the locking properties of the thyristor 5, the thyristor 8 is turned on and the capacitor recharges rapidly to with the polarity indicated in brackets.

If the direction of the current in the thyristor 5 is indicated by an arrowhead and the polarity of the capacitor is indicated without brackets, then to control the thyristor 5, the control system pulses to thyristors 8 and 17. At the same time, the capacitor discharges along the path + 8 the diode of the bridge 7, 5, 17 , 13. - switch on the thyristor 5 and continuing the discharge through the +8 circuit, the bridge diode 7, 1, 19, 18, 17, 13 -. After a time equal to the time of restoring the blocking properties of the thyristor 5, the thyristor I1 is turned on and the capacitor is rapidly recharged to a voltage with polarity indicated in brackets. In this case, the need for Drossel x 23, 24, 25, in principle, no.

Modification of the converter in FIG. 2 is characterized by another connection of the thyristors of the distribution bridge.

The operation of the switching unit in this case is as follows. Suppose that thyristors 1.5 are still open and thyristor 1 needs to be turned off. The control system pulses to turn off thyristors 8 and 16. Condenser 12, discharging along the path +8, 7, 1, 16, 13 -, turns off thyristor 1 and continues d on the way + 8, 7, 5, 18, 19, 16, 13 -. After a time equal to the recovery time of the blocking properties of the thyristor 1, a control pulse is applied to the thyristor 11, and the capacitor 12 is rapidly recharged through the switched on thyristors 8 and 11. If the direction of the current in the thyristor I is indicated by an arrowhead, the control system gives out control pulses to thyristors 11 and 14. In this case, the capacitor is discharged along the path + 14, 1, 7, II, 13 - and after turning off the thyristor 1 it continues to discharge along the path + 14, 19, 18, 5, 7, II, 13 -. Through the recovery time of the blocking properties of the thyristor 1, a control pulse is applied to the thyristor 8 and the capacitor is rapidly recharged through the open thyristors 8 and 11. Similarly, the thyristors of the right arm are absorbed by the right shoulder 4, 5, 6. In this case, the control pulses are applied to the thyristors 9 and 10 bottom and 15, 17 distribution thyristor bridges.

The expediency of using one or another variant of the described converter is determined by the specific task being solved; The three-phase output of the converter is provided by the installation of an additional two sets of power bridges, two sets of single-phase thyristor bridges and two sets of bridges of distribution thyristors with

the corresponding complication.m of the control unit.

Claims (1)

Invention Formula A direct frequency converter with artificial switching of thyristors, containing anti-parallel-connected power thyristor bridges, a forced switching unit that includes an auxiliary bridge, the input connected