SU930571A1 - Method of control of n-phase voltage converter - Google Patents

Description

(54) METHOD FOR CONTROLLING P-PHASE-PERMANENT VOLTAGE CONVERTER TO CONSTANT

The invention of fire protection to electrical devices of the control of the magnitude of the DC voltage. A known frequency-pulse voltage control method is l. The disadvantage of this method is the large weight and size parameters of the transformer implementing this method. The closest to the proposed method is a control of a C-phase converter of constant voltage & constant, according to which the output circuit is made in the form of a series-connected inductive element and pinout diodes, in which the change in the value of the output voltage carried out by changing the switching frequency of each of the phases, with a constant JANO time of its on state, and the phases of the converter are connected in series with a time shift between exception of the two adjacent phases. equal to the 5th part of the period of phase 2 operation. A disadvantage of the known method is to reduce the inductance of the coil of the smoothing reactor of the controlled converter by a factor of 10 to 12 in the intermittent phase mode, due to saturation of the reactor core. This was found to decrease, as compared with reactors for separate connection, the cross section of reactor steel calculated from the difference of currents of the magnetically coupled phases in the nominal mode. Therefore, the voltage on the isolation diodes of the converter increases sharply, and therefore the number of successively included separation diodes in each phase before / the window is increased. Due to saturation of the core of the smoothing reactor, the output voltage amplitude and the ripple factor also increase. A significant disadvantage of this method is also an abrupt increase in the reverse voltage on the disintegrating circuits when the current stops flowing through the UN of the phases, which requires special measures to limit the rate of increase in the reverse voltage. The purpose of the invention is to reduce the number of semi-zinc valves and reduce the amplitude of the output voltage and the pulsation coefficient, i.e., a reduction in weight and size. indicators and improving the quality of the output voltage. The goal is achieved by changing, as a function of the load current, the number of operating phases and the switching frequency of each phase, while, as the load current decreases, the number of operating phases decreases and the frequency of the phase increases proportionally, and when the load current / number increases, increase and proportionally decrease the frequency of the phase operation. FIG. 1 shows a circuit diagram of a device that implements the proposed method; in fig. 2 - control block circuit. As an example, a 12-phase DC / DC converter is considered; / every four phases of the converter contain four 1-4 thyristors, two commutating reactors 5 and 6, two commutating capacitors 7 and 8, two separation diodes 9 and 10, two reverse diodes II and 12, two inductive elements in the form of a smoothing reactor 13. with two seconds PILs 14 and 15, load 16 (traction motors) common to all phases, switching device 17. When voltage is applied to the input, switching capacitors 7 and 8 charged before mains voltage through dividing diodes 9 and 1O, sections. 14–15, smoothing reactor 13 and load 16. When the taristor 1 is opened, load 16 is powered through the following circuit: reactor 5, thyristor 1, diode 9, section 14 At a time, the recharger of the consenter 7 recharges through switching reactor 5 and thyristor I, in the process of recharging, the voltage on the capacitor plates changes its polarity, while the potential on the plate from the network side is retained, and on the side of the separation diode 9 by the end of the recharge, it reaches double the value of the network potential. During the reverse recharging along the oscillatory circuit, the recharge current of the capacitor 7 replaces the current of the thyristor 1 and closes it. A further recharge of the capacitor occurs through the diode 9, section 14 and load 16. During the power consumption from the network through the thyristor I and capacitor 7, the current in section 14 of the reactor 13 increases, while in section 15, connected in opposite with section 14, the electromotive .than mutual induction force, supporting the current in the adjacent circuit 15, 16, 12. After the end of the period of energy consumption from the contact network, the load current is maintained EV: through the return diode II due to the energy stored in the inductive elements of the circuit 14 and 16. With a quarter shift period.ra The boilers of the power thyristor 1 opens the thyristor 3 and the process described for the phase of the thyristor 1 proceeds in this phase. At the same time, in the interval of current increase in section 15, section 14 of reactor 13 is induced by a mutual inductance voltage supporting the current in the adjacent circuit 14,1,1,11. A thyristor 2 opens with a shift of half the period of operation of the thyristor 1, and a thyristor 4 with a shift of three quarters of the period. The voltage on the load is controlled by varying the switching frequency of the thyristors 1-4 of the regulator by varying the energy release time inductive elements 13 and 16 with a constant open state of thyristors 1-4. A multiphase voltage regulator is made up of identical four-phase blocks described, with the thyristors being switched on with a uniform shift corresponding to the number of phases of the entire regulator. At the maximum load current, all And phases of the controller work. When the load current decreases to a value corresponding to the moment of the phase transition to intermittent operation, one four-phase unit turns off, and the frequency of the remaining I-4 phases, which continue to operate in continuous mode, increases proportionally. With a further decrease in the load current, the next four-phase unit shuts off with a corresponding increase in the frequency of the remaining I-8 phases, etc. As the current increases, the alternate connection of the four-phase units in reverse order is applied. The switching of the number of phases of the regulator is performed by applying or removing control pulses on the thyristors under the action 4 of the switching device 17.

The basis of the control circuit of the controller is the master oscillator 18 (Fig. 2) and the distributor in the pulses 19, designed for such a number of output pulses, which would be a multiple of all combinations of the phase numbers of the regulator Vi, I-4, ... 4 possible when switching.

Distributors 2O, 21. 22 for a different number of operating phases (Fig. 2) give impulses to open thyristors epic phases wired to supply their respective pulses from the main distributor 19 and the presence of a corresponding signal from the switching device 17. This circuit ensures the symmetry of the operating phases relative to the Network and It is time-varying, but with the switching of the number of phases, the change in the frequency of the operating phases, ensuring the smoothness of the transition from one phase to phase. on the other.

The use of this control method allows to reduce the number of isolation diodes of the device by 1.82 times, the amplitude of the variable component voltage of the voltage is 1.4-1.5 times and the ripple factor of the load current is 1.15 ;.

The advantage of this control method is a gradual increase in the reversal voltage on the separation diodes simultaneously with an increase in the voltage on the load, which is why they do not take special measures to limit the rate of increase in the reverse nagfing on these diodes.

Claims (1)

1. Rosenfeld, V.Ye., et al. Thyristum control of electric rolling stock of constant current, M., Transpt, 197O d. 62, fig. 2eG. 2 USSR Author's Certificate N (568134, cl, H 02 M 3 / 135.1975. if lfebr 574