SU1728949A1 - Method of controlling current inverter - Google Patents

Abstract

SUMMARY OF THE INVENTION: Set the moments of formation of control pulses in the continuous current mode and generate control pulses. The output voltage of the inverter is measured. The interval for the absence of the input current of the inverter is fixed. Prohibit the formation of control pulses at specified times in this interval. At each half period of the inverter operation, the magnitude of the square of the measured value of the output voltage of the inverter is calculated and used to calculate the square of the effective value of the output voltage of the inverter. Using a reference voltage, the desired value of the effective value of the output voltage of the inverter is set, and thereby determines the duration of the dead-time pause between half periods. Control pulses are generated at the time of the end of the dead time. 2 Il. (Ls

Description

The invention relates to electrical engineering and can be used to control a current inverter operating in a discontinuous current mode.

A known method of controlling an inverter in a discontinuous mode is by supplying control pulses corresponding to a predetermined advance angle of the inverter valves, in which, in the absence of inverted current, the difference between the output and input voltages of the inverter is integrated to the predetermined advance angle, and after a predetermined advance angle the negative the values of the output and input voltages of the inverter and at the time of equal to zero of the integrated voltage generate gate control pulses inverter.

The disadvantage of this method is that it does not provide sufficient reliability and accuracy of the output voltage when the inverter operates at high frequencies (up to 20 kHz).

As a prototype, a method of controlling the current inverter operating in the discontinuous current mode is used. It consists in setting the moments of control pulses in the continuous current mode and generating control pulses, measuring the input Uex and output 1) inverter output voltages and calculating the difference (Dux - 11) output1) of the input and output voltage modules, fix the interval of the absence of the input current of the inverter and prohibit the formation of pressure pulses at specified times at this

VI

go

00

you j o

interval, with that, for each half-period of operation of the inverter, the values of the input current of the inverter are calculated

(UBx - llWDdt, where Li is the inductance of the input reactor of the inverter,

then, the sign of the calculated value of Bx is monitored; the indicated fixation of the interval of no input current is carried out at negative values of the calculated current lex; control pulses are generated at the moment the calculated current I passes from negative values of Bx at the time of generation of control pulses.

The disadvantage of this method is that it does not ensure the stability of the effective value of the output voltage, since the determination of the moment of formation of the control pulse occurs not by measuring the actual effective value of the pressure at the output of the inverter, but by comparing and analyzing indirect parameters.

The aim of the invention is to increase the stability of the effective voltage value at the output of the inverter, which allows, for example, in the heating unit of the thyratron, which is part of an excimer laser as a switching element, to increase the stability of the output voltage of the heating unit, and therefore, increase the stability and reliability of the thyratron, which improves the parameters of the laser.

This goal is achieved by setting the moments of formation of control pulses in the continuous current mode and generating impulses of pressure, measuring the output voltage Oiw, recording the onset of dead time and the absence of the input current of the inverter and inhibiting the formation of control pulses on this interval, during each half-period the operation of the inverter at the time of termination of the control pulse calculates the magnitude of the square of the measured value of the output voltage 112V and the magnitude of the square of the effective value yhodnogo voltage inverter for one half-cycle

t

about

U eff

l-JuLxdt,

about

where K and T are constant integrations, set the reference value of the effective voltage Wet and the transfer coefficient Kat, calculate the duration of the dead time Tn between half periods according to the formula

TP T

Zeff - Kat 11et Kat Ugr

Begin the counting of the calculated duration at the recorded moments of the beginning of the dead time, after the end of which the next control pulses are formed.

Figure 1 shows a block diagram of a device implementing the proposed method; 2 shows timing diagrams explaining the operation of the device and the method in the discontinuous current mode.

The device implementing the method contains (FIG. 1) a sensor 1 of the output voltage of the inverter, the output of which is connected to the input of square 2, which, in turn, is connected to the integrator 3, the output of which is connected to one of the inputs of the adder 4, the other input of which is supplied the reference voltage from the source 5 of the reference voltage through inverter 6, the output of the adder 4 is connected to one of the inputs of the comparator 7, to the other input of which the output is connected the time of the master integrator 8 to one of the inputs of which the reference voltage is appliedm source 5. The output of the comparator 7 is connected to the input 9 of the generator control pulses, taken the analysis of which is connected to the input of integrator 3 and the driving time of the integrator 8, and also to the input 10 the control pulse distributor.

The method is carried out as follows.

The signal (Fig. 2a) from sensor 1 is fed to the input of the Quad 2 and then in the form of 02V to the input of integrator 3, after which the output of the integrator 3 appears

K-} uLx (t) dt,

about

t

where K kvK2 is the product of the coefficient of transmission of the sensor 1 (ki) and quad of 2 (k2);

T is the integration time determined by the half-life of the inverter output voltage.

The signal u2eff is fed to one of the inputs of the adder 4, to the other input of which is supplied from the source 5 of the reference voltage through the inverter 6 the voltage Wet. As a result, one of the inputs of the comparator

7, the voltage U eff - WET is supplied, and to the other input - output voltage 1) int (fig.2b) the time of the master integrator b, which begins to integrate voltage 1) at at time c (fig.2b). The output pulse of the comparator 7 is formed at the time ts, when the output pressure Kint time of the master integrator 8 exceeds the value of the output voltage 112eff - 1) at the adder 4. Thus, the interval of the dead time Tp between the half cycles of the inverter is determined:

TP T

Weff - Kat Jat Kat Wet

where Cat is the reference voltage transfer ratio.

The control signal Uynp (Fig. 2b) is formed by the key elements of the current inverter using a generator 9 control pulses at the time of the appearance of the output pulse of the comparator 7 (r3 in figure 2), then this signal goes to the input of the control pulse distributor 10, from which - to the inverter. As a result, when the load changes and, accordingly, the magnitude of the voltage 1) 2eff, the duration of the dead time TP between half-periods changes, thus maintaining the stability of the effective value of the voltage at the output of the current inverter.

Claims (1)

Claims The method of controlling an inverter current, which is to set the moments of formation of control pulses in the continuous current mode and form control pulses, measure the output 0 five voltage Uvih, fix the beginning of the dead time and the interval of the absence of the input current of the inverter and prohibit the formation of control pulses on this interval, characterized by the fact that, in order to increase the stability of the effective voltage value at the output of the inverter, at each time the control the pulse calculates the magnitude of the square of the measured value of the output voltage U2 and the square of the effective value of the output voltage of the inverter for one half period and 2eff: u2eff - g / i1ihsN I p where K and T are constant integrations, set the reference value of the effective voltage 1) fl and Ket transfer coefficient, calculate the duration of the current-free pause Tn between half-periods using the formula TP T C | FF - Kat Cet Cat U3T Begin the counting of the calculated duration at the fixed moments of the beginning of the dead time, after the end of which the next control pulses are formed. 2