SU989744A1 - Method of putting into operation and taking-out of operation of voltage inverters - Google Patents

Description

The invention relates to a conversion technique, and in particular to methods for controlling converters of power supplies made on the basis of autonomous inverters connected in series to the output.

Known power sources; executed based on autonomous inverter operating in series on a common load, in which the putting into operation and You are a) from ₀ water of individual inverters mozhen cart only when the current LOAD ki and application switching mouth * -. Food [1].

Also known is a power source designed to operate on a resonant load [2].

The commissioning of individual inverters in this source is carried out with a smooth increase in the output voltage of the inverters, and the conclusion is made with a smooth decrease.

Closest to the proposed technical essence is the way in which the change in the output voltage of the inverter, put into operation or taken out of work, is made by changing the moments of unlocking the valves of this inverter with respect to the moments of unlocking the valves of the other inverters [3].

However, in the inverter taken out of operation, the current flows mainly along the reverse diodes, which leads to their current overload and reduces the reliability of the power source. The presence of voltage at the input of the inverter taken out of operation does not allow the power source to operate at output frequencies that are large, the resonant frequency of the load, since in this case there is a violation of the switching of the inverter taken out of operation and a short circuit in its supply voltage. In addition, the need for additional regulation

989744. 4 instants of unlocking the inverter valves complicates the entire converter.

The aim of the invention is to preserve the working frequency range with one or more inverters taken out of operation, simplifying the circuit and increasing reliability.

This goal is achieved by the fact that according to the method of putting into operation and decommissioning of voltage inverters, the outputs of which are connected in series, namely, that the output voltage of the inverters is changed, before the output, from work or commissioning of 15 separate inverters, the operating frequency of all inverters below the resonant frequency of the load, reduce the supply voltage of the inverters in operation to zero or increase the supply voltage of the inverters put into operation to a value equal to the supply voltage Nia working inverters, then

- set the desired frequency of the operating range. 25

In Fig. · 1 shows a structural diagram of a power source; in FIG. 2 - time diagrams of her work.

The power source consists of autonomous inverters 1, connected at the output _{30 in} series and supplying a total load 2 of a resonant nature. At the shoulders of the inverter bridges are fully controlled valves 3-6 and reverse diodes 7-10. Fully controllable $ ₃ gates are circuits with forced pulsed current switching, made using thyristors and diodes.

Each inverter is powered by an adjustable rectifier 11, in parallel with which a capacitor filter 12 is connected. Normal operation of the source is carried out at almost equal input voltages of the inverters. At a frequency of inverters higher than the resonant frequency of the load, the current lags the voltage by an angle ((^ 7 0, Fig. 2 a), and when the supply voltage decreases at the input of one inverter, the switching in it is violated.

At a frequency lower than the resonant current, c leads the voltage by an angle I / (Ψ <0, Fig. 2-6) and switches from the valves of the working diagonal of the bridge (for example, 4, 5) ⁵⁵ to the reverse diodes 8 and 9 without the participation of forced switching circuits, under action of reactive EMF in the load circuit. This transition occurs at the moment of changing the direction of the current C, when the currents in the valves and in stop. currents flow » _8d in diodes (Fig. 2d).

When the valves 3, 6 and 4, 5 are unlocked by control pulses (Fig. 2 b), the polarity of the voltage e changes at the output of the inverter, the supply voltage of which is less than E (Fig. 2 8). In the conductivity interval of diodes 8 and 9, corresponding to the angle Ч, a negative voltage g equal to δ (J, which provides restoration of their blocking ability (Fig. 2e), is applied to the thyristors of fully controlled gates 4 and 5).

In accordance with the change in voltage at the inverter input, the amplitude of the output voltage e changes (Fig. 2 9). As for ''<0 and for ψ? О in the inverter, taken out of operation, valve currents ϊ. _s , ΐ „. and diode currents

I »TJ 3, D ¹ 7 70» 9 ^is half of the total current ΐ ^, since the current for most of the half-period is divided by two parallel branches formed by diode 7 (10) and valve 5 (4) connected in series in each branch, or 9 (8) and 3 (6), respectively.

At 44: 0, in the interval of the angle Ψ, the current flows only along the diodes and through the filter capacitor 12.

With the inverter commissioned, i if the voltage E is equal to the voltage on! the inputs of the remaining inverters, switching the load current is provided at any frequency of the operating range, since with Ψ 7 O the forced-use system is used. real switching.

Thus, the corresponding change in the output frequency and voltage at the inverter inputs during their commissioning and decommissioning allows you to save the operating frequency range with a part of the inverters taken out of operation, simplify the control circuit and increase reliability.

Claims (3)

1. Author's certificate of SSHZR No. 34OO38, cl. H O2 M 5/42, 1970, 2. USSR author's certificate number 330515, cl. H 02 M 5/42, 1969. 3. Author's certificate CXXJP No. 336752, cl. H 02 M 5/42, 1969. S ( X FIG.