SU641611A1 - Self-sustained self-excited inverter - Google Patents

Description

The invention relates to electrical engineering and can be used to construct secondary power sources.

Known autonomous thyristor inverter with output transformer, oscillatory circuit and control circuit I

Its disadvantage is the inability to control the frequency due to the absence of an adjustable element.

The closest to the proposed invention in its technical essence is an autonomous inverter, which contains power switches with a control unit, an oscillatory KOHTyji, in series with an inductance coil which includes a symmetric switch consisting of two thyristors connected in opposite directions, with which control circuits are connected secondary windings of the output transformer of the control unit 2.

The disadvantage of the inverter is reduced reliability, since the circuit does not provide protection measures against false activation caused by the interference signal.

The aim of the invention is to increase reliability with frequency control.

This goal is achieved by the fact that in the proposed autonomous inverter with self-excitation, which contains power switches with a control unit, the oscillating circuit is sequentially connected with an inductance coil

which includes a symmetric key consisting of interconnecting two thyristors, with control circuits of which are connected to the secondary windings of the output transformer of the control unit,

the control unit is designed as a key amplifier, whose input through a resistor connected in parallel to the output of the first rectifier is connected to the input terminals of the control unit, the output of the amplifier is connected to the output of the second rectifier, whose input is connected to the additional winding of the output transformer the mittel is connected to the secondary winding of the additionally inserted current transformer, the primary winding

the output transformer through a resistor, and the primary winding of the current transformer through a choke is connected in parallel to the oscillatory circuit.

Claims (2)

The drawing shows a schematic diagram of an autonomous inverter with self-excitation. The inverter contains power switches 1, 2 with a control unit 3, an oscillating circuit consisting of a capacitor 4 and an inductor 5, a series of which includes a symmetric switch on thyristors 6, 7, a transformer 8, a smoothing switch 9 and a control unit on a key amplifier 10 , an output transformer 11 with windings 12-15, a current transformer 16 with windings 17, 18, a choke 19, resistors 20, 2, and rectifiers 22, 23. The inverter operates as follows. In the absence of a control signal (when Uc 0), the key amplifier 10 is closed by the voltage Lfe coming from the rectifier 22. The voltage induced on the windings 13 and 14 of the transformer 11 opens alternately the thyristors 6 and 7, each of which provides current flow through, inductance coil 5 in one -from the half-cycle of current oscillations. In this case, the oscillation frequency of the inverter is determined by the resonant frequency of the oscillating circuit. When a control signal Uo is applied (via a resistor 21) to the input of the key amplifier, the latter for some part of the period (when Uc Utf) is open and closes the transformer 11 winding 15 via the rectifier 23, which prevents the occurrence of voltage on the windings 13 and 14 After the voltage IJfe exceeds the value of Uc, the amplifier 10 closes, which makes it possible to open one of the thyristors, 6 or 7. The resulting time shift between the initial phase of the first harmonic of the current and the moment of opening the thyristor of the symmetric key and causes that the current through the coil 5 mind: 1shaets. This causes an increase in the equivalent inductance of the coil-circuit 5-symmetric key, which, in turn, leads to a decrease in the frequency of oscillation of the inverter. By changing the size of the input signal, you can smoothly adjust the frequency of the output voltage of the inverter. A closure to a certain part of the period (when both thyristors of the symmetric key must be closed) by the key amplifier 10 of the winding 15 of the transformer 1 eliminates the possibility of interfering impulses on the windings 13 and 14 and thereby falsely turning on the thyristors of the symmetric key. This increases the reliability of the circuit when adjusting the frequency. Claims of the Invention A self-excited, self-excited inverter comprising power switches with a control unit, an oscillating circuit, in series with the inductance of which a symmetric switch consisting of two thyristors connected anti-parallelly connected with control circuits of which are connected to the secondary windings of the output transformer of the control unit, characterized in that, in order to increase reliability in frequency control, the control unit is designed as a key amplifier, the input of which is through a resistor, connected in parallel to the output of the first rectifier, is connected to the input pins of the control unit, the output of the amplifier is connected to the output of the second rectifier, the input of which is connected to the auxiliary winding of the output transformer, and the input of the first rectifier is connected to the secondary winding of the additionally introduced current transformer, and the primary output winding transformer through a resistor, and the primary winding of the current transformer through a choke is connected in parallel to the oscillating circuit. Sources of information taken into account in the examination: 1.Berkovich E. N., Ivensky G. V. and others. Thyristor converters of high frequency, “Energie, L., 1973, fig. 3-1, p. 29, fig. 5-12, s. 174. 2.Labuntsov V.A., etc. Electric drives with semiconductor control. Autonomous thyristor inverters, “Energy, 1% 7, Fig. 12.