SU728212A1 - Method of controlling autonomous parallel inverter - Google Patents

Description

one

The invention relates to a converter technique, namely, to methods for controlling an autonomous parallel inverter with a wide frequency range.

Known converter control methods are known in which pulses for controlling converter valves are formed using a relaxation generator containing a saturation choke in the charging circuit of the storage capacitor, the magnetic state of the core of which is changed by the current flowing through the control winding until the capacitor is discharged 1. This method is used to increase reliability and provide a wide range of shear angles between the pulses at the input and output of the phase shifter. gadgetry device.

This device is closest to the invention in its technical essence and the achieved result.

However, the use of these methods in devices for controlling the inverter valves does not allow for eliminating a significant decrease in the amplitude of the second pulse produced by the relaxation generator when turned on, and thus to ensure a stable start of the inverter in a wide range of its frequency variation. This is due to the fact that in both cases the magnetization of saturation charge throttles is periodic (each period of operation of the circuit). At the same time, the magnitude of the current in the magnetization remains unchanged both when the circuit is turned on and in the steady state generator operation.

The aim of the present invention is to expand the frequency range and increase the stability of the start-up of an autonomous parallel inverter. The specified goal is achieved initial

one-time magnetization drossel

saturation until the first discharge

capacitor initial current. Magnitude

current is proportional to the absolute value of the difference of negative voltages,

to which the capacitor is recharged in steady state and transient conditions.

FIG. 1 shows a schematic of the device in which the described method is implemented; in fig. 2 - oscillograms of voltages on separate circuit elements.

The circuit in FIG. 1 contains a storage capacitor 1 connected between the saturation charged choke 2 and the primary winding of the pulse transformer 3, the other end of which is connected to the discharge circuit gate 4. On fng. 2 introduced the following notation. -Nuns 5 - input impulses with a frequency that are input to the relaxation generator to control the discharge circuit valve; curve 6 is the voltage across the capacitor; - curves 7, 8 - respectively, the voltage on the saturation choke and the current through it; - impulses 9 - impulses for controlling inverter valves removed from the secondary windings of the transformer. The method is as follows. A supply voltage (H) is applied to the circuit, and the charging choke 2 does not leak current, which charges the capacitor 1 to a voltage of t / d. At the same time, a bias current is passed through the choke 2, the magnitude of which, referred to the number of turns of the working winding of the choke, is approximately determined by the expression. .n. - (- Р) - Л1Uc .ycf., Оpp - voltages to which capacitor 1 is recharged, respectively, in the steady state and transient modes; v.ot - the period of time provided to restore the compatibility of the valve in a steady state; t-g-t-tp - I jB - - coefficients, it is determined from the calculation of the scheme; R is the resistance winding of the saturation droplet; L is the inductance of the saturation droplets in the region of the ideal magnetization curve; IL is the value of saturation droplet; to is the amount of current at the moment of saturation of the core of the throttles. After that, a pulse is applied to the gate 4. The capacitor 1 is discharged through the transformer 3, on the secondary windings of which the control pulses of the inverter valves are formed, then the process of magnetization of the throttles 2 begins, which occurs under the action of the voltage difference of the power supply (Vd) and voltage (f / cn), to which the capacitor 1 is recharged. After saturation of the throttle 2, an oscillating circuit is formed, consisting of the residual inductance of the throttle 2 and the capacitor 1 (active resistance of the dross winding can be ignored). In this case, the capacitor 1 is charged to a voltage higher than the voltage of the power source (Ud. Excess of the Positive voltage on the capacitor 1 above the value On provides a partial demagnetization of the throttles 2. Thus, the initial bias of the throttles 2 leads to a decrease in the time interval ( .c.), provided to restore the controllability of the valve 4 at the start, and contributes to the formation of output pulses, stable in amplitude and in magnitude, slightly exceeding the value of the first output and pulse. When the circuit is turned off, which is always produced by removing the control pulse from valve 4, the capacitor 1 is always charged to a voltage that exceeds the supply voltage of the power source. In this case, the throttle core is demagnetized and returns to its original state , in order to output from which an additional polynomial magnetization is required at the next start of the inverter. A practical implementation of this method, carried out in relaxation generators using pulse discharge in a discharge chamber of unwanted thyratrons, in which leakage currents are insignificant (they are several orders of magnitude smaller than the currents needed to bias the core of the charge droplet) and thyristors (in which the leakage currents are greater) showed that the leakage currents of the discharge circuit devices flowing through the winding droplets of saturation are completely inadequate to bring the core of the droplets into the required magnetic state and in both cases additional initial sublipping of the chokes is required with a current significantly exceeding the current and. The initial bias of the charge droplet saturation can be realized

by using an additional bias winding or resistor connected in parallel to the capacitor through a controlled device.

The use of this method in control devices with an autonomous parallel inverter allowed us to ensure stable start-up of a converter designed for imitating electrothermal installations in the frequency range of 500– 2500 Hz.

Claims (1)

1. USSR author's certificate number 171904, cl. 21d2 12/03 of 1962