SU465702A1 - Stand alone inverter - Google Patents

Description

one

A self-contained inverter containing a three-winding transformer is known in which the primary winding is connected to a power source through one or several power thyristors, one secondary winding is connected to a capacitor through one or several rectifier diodes, and the other secondary winding is connected to a load, as well as a control unit.

The purpose of the invention is the improvement of autonomous inverters, which makes it possible to invert the low-voltage driving current into alternating current from ultralow frequencies to several tens of kilohertz without using additional oscillatory circuits for switching the current of power thyristors.

This is achieved by the fact that, in the proposed inverter, the rectifier secondary secondary windings are ground by additional transistors, the basic circuits of which are connected to a square current pulse generator connected through a phase shifter of the control unit.

FIG. 1 is a schematic diagram of the proposed inverter; in fig. 2 - voltage and current diagrams; in fig. 3 - rnntsniyal) On the scheme of the proposed inverter, made by the bridge circuit.

The proposed inverter contains a thyristor 1, a generator 2 of the thyristor control pulses, a three-winding transformer 3, a capacitor 4, a diode 5, a transistor 6, a generator 7 of the rectangular current pulses and a phase shifter 8. One secondary winding of the three-winding transformer 3 is connected to the capacitor 4 through diode 5, and a friend is connected to the load.

When current pulses are applied at the time of time t to the control electrode circuit of thyristor 1 from generator 2, it is switched on, and the current determined by the load flows at the primary winding of transformer 3. In this case, the voltage across the primary winding f / i has a rectangular shape with an amplitude equal to the voltage of the power source, as shown in FIG. 2, and the voltage at the anode of the thyristor Ua drops to the value determined by its voltage drop. At this time, the capacitor 4 is charged from the additional winding through the diode 5. Due to the leakage inductance of the transformer 3 and the capacitance of the capacitor 4

the process of charging capacitor 4 is oscillatory, and the charging current g is sinusoidal. At time 2, the charge current pulse becomes zero, and the voltage across the capacitor 4 Uc has a maximum value. At the time point /, a rectangular current pulse is applied to the base circuit of the transistor 6 from the rectangular current pulse generator 7. In this case, the transistor is unlocked, and the additional winding of the transformer 3 is supplied with a voltage equal to that applied to the co-detector 4, which causes the thyristor 1 to turn off due to the appearance of a reverse voltage in its anode circuit. After the thyristor 1 is turned off, the load component of the current flows through the circuit, forming an additional winding of the transformer 3, capacitor 4 and transistor 6. At time / 4, the current pulse in the base circuit of transistor 6 drops to zero and the last is locked. This leads to the removal of the impulse from the load. At the moment of time / 5 a thyristor control current pulse 1 is applied, and the processes in the inverter circuit are repeated. In order to reliably switch the current of the thyristor 1 in this inverter, it is necessary that the duration of the current pulse generated by generator 7 be twice as long as the turn off time of the thyristor 1, the current in the base circuit is sufficient to keep the transistor open, and to provide a reverse voltage on the thyristor anode. The capacitance value of the capacitor 4 for the proposed inverter is determined from the condition of providing a sinusoidal form of the capacitor charge current and must not exceed a critical value equal to where T "is the duration of the terminal pulse PA: at the output of the inverter; LS is the inductance of the scattering transformer. According to the VINO principle described .M:) / KIIO liUtulnnt and bridge circuit inverto) a (see Fig. 3). It contains one) 1 phase thyristor bridge 1, a generator of 2 thyristor control pulses, a transformer 3, a capacitor 4, a pilot bridge on diodes 5, a switch on transistors 6, a generator 7 of rectangular current pulses and a phase shifter 8. By selecting the ratio of the turns of the primary and the secondary windings of the inverter transformer, it is possible to provide relatively small values of the current through the switching transistors. So, for example, when inverting direct current by voltage 24, the use of KT-805 transistors, which allow maximum voltages of 130 b and maximum values of current pulses, ensures that the inverter, which is a bridge circuit, provides reliable current switching at a value of 40 and; and allows you to implement on the basis of the proposed inverter converter rated power of 1 kW. The subject of the invention is a stand-alone inverter containing a three-winding transformer in which the nervous winding through one or several thyristors is connected to a power source, one secondary winding through one or several rectifier diodes is connected to a capacitor, and the other secondary winding is connected to a load, as well as a control unit characterized in that, for the sake of simplicity, the danes of the receiver are shunted by additional transistors, the basic circuits of which are connected to the generator of direct current pulses, connected driven through the phase shifter of the control unit.

Output

(rig. 1