SU1596425A1 - Transistor inverter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply and electric drive systems. The purpose of the invention is to increase reliability by increasing the speed of protection against through currents. The transistor inverter contains two power transistors 1 and 2 connected in a half-bridge circuit and controlled in antiphase by the voltages on the secondary windings 5,6 of the control transformer 7. An additional transformer 11 is introduced for protection against through currents when switching power transistors 9 and 10 through diodes 12 and 13 are connected in locking polarity to the inputs of power transistors 1, 2, and the second pair of windings 18, 19 is connected to power electrodes of transistors 1, 2 through diodes 20, 21 and capacitors 22, 23 that charge wife to a voltage on the additional windings 14, 15 of the control transformer 7 through rectifying diodes 16, 17. By the locking action of the voltage on the windings 9, 10 unlocking one of the power transistors will occur only after locking of another power transistor. Capacitors 22, 23 provide the performance of this interlock. 2 Il.

Description

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The invention relates to electrical engineering and can be used in secondary power supply and electric drive systems.

The purpose of the invention is to increase reliability by increasing the speed of protection against through currents.

Figure 1 shows a schematic diagram of the half bridge of a transistor inverter; Fig. 2 stress diagrams.

The transistor inverter contains two power transistors 1 and 2, which are controlled anti-phase along the base circuits through current-limiting resistors 3 and 4 of the voltage of the secondary windings 5 and 6 of the control transformer 7 entering the control unit 8. One of the windings 9 (10) Additional transformer 11 with a series-connected in the forward direction blocking diode 12 (13) shunts the emitter junction of the corresponding power transistor 1 (2). The additional winding 14 (15) of the transformer 7 is turned on in phase with the control winding 5 (6) and is connected by one output to the emitter of the power transistor 1 (2). The rectifying diode 16 (17) is connected by the anode to the second output of the additional winding 14 (15) of the transformer 7. The winding 18 (19) of the additional transformer 11 is connected to the cathode of the rectifying diode 16 (17). The anode of the blocking diode 20 (21) is connected to the second output of the winding 18 (19) of the additional transformer 11, and the cathode is connected to the collector of the power transistor 1 (2). A capacitor 22 (23) is connected between the junction point of the rectifier diode 16 (17) s. winding 18 (19) of the transformer 11 and the emitter of the power transistor 1 (2).

Transistor inverter operates as follows.

Suppose that at the initial moment of time the power transistor 1 is open and the transistor 2 is locked. On the windings of the control transformer 7, a voltage is applied with a polarity indicated without brackets. The voltage from winding 14 (15) is rectified by diode 16 (17) and filtered by capacitor 22 (23). A voltage Die (Fig. 2) of the capacitor 22 is applied to the winding 18 of the transformer 11 through a straight-shifted diode 20 and an open power transistor 1. On the other windings of the transformer 11, voltages are applied with the polarity indicated without brackets (Fig. 1).

After reversing the voltage Us, Ue (Fig.2) on the windings of the control transformer (the polarity is indicated in Fig.1

brackets), power transistor 1 begins to close. But during the resorption time of minority carriers in the area of the base tpi (Fig. 2), the polarity of the voltage

the windings of the auxiliary transformer 11 is maintained. At the same time, to the emitter-base junction of the power transistor 2, through the shifted diode 13, a blocking voltage is applied (Fig. 2) from the winding 10 of the transformer 11. As the power transistor 1 goes out of saturation, the voltage on its collector increases. When it reaches the voltage across capacitor 22, diode 20 will close.

and the voltage across the winding 18 of the transformer 11 becomes zero. In this case, the locking voltage on the winding 10 will disappear and the unlocking voltage IB (Fig. 2) from the winding 6 of the transformer 7 will come to the base of the power transistor 2.

After unlocking the power transistor 2, a diode 21 will open and the voltage Ui9 (Fig. 2) from the capacitor 23 will be applied to the winding 19 of the transformer 11. On the winding 9,

10, 18, the transformer 11 is transformed with the voltage indicated in brackets (Fig. 1). The circuit changes to the second quasistatic state opposite to the initial one.

Thus, in the circuit, the unlocking of the power transistor is automatically delayed by the absorption time of the minority carriers in the area of the base of the locking power transistor.

Claims (1)

Invention Formula A transistor inverter containing two power transistors connected in a half bridge circuit, a control transformer with two secondary windings, one output of each of which is connected to the emitter of the power transistor, and the other output through the current-limiting resistor to the base of this power transistor, and an additional transformer with two pairs of windings, each with a blocking diode in series, each of the windings of the first pair through the first blocking the diode is connected to the base-emitter junction of the power transistor, so that the direction of conduction of this diode corresponds to the direction of the current blocking the power transistor, characterized in that , in order to increase reliability by increasing the protection performance from through-currents, two rectifying diodes, two capacitors and two additional windings on the control transformer are introduced, each of which is connected to the emitter of the power transistor by one and another through a rectifying diode the first terminal of the capacitor and through the corresponding winding of the second pair of additional transformer and the second blocking diode - with the collector of the given power transistor, so that the direction of conduction diode coincides with the direction of conduction of the power transistor, a second capacitor terminal connected to the emitter of the power transistor and the interconnected terminals of the secondary windings and additional control transformer oppositely.