SU1582306A1 - Two-ended 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 block voltage at the control input of the transistor. The push-pull inverter contains two controllable switches 1 and 2. In each control switch 1/2 / transistor 8/9 / is controlled by a transformer 14/15 / current. The inclusion in the base winding circuit of each transformer 14/15 current / connected in parallel a second resistor 16/17 / and an additional diode 18/19 / increases the blocking voltage at the control input of the transistor 8/9 / during the demagnetization interval of the transformer core 14/15 / current. 2 Il.

Description

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

The purpose of the invention is to increase reliability by increasing the blocking voltage at the control input of the transistor. ^;

Figure 1 presents the circuit diagram of the proposed Converter; figure 2 is a diagram explaining the principle of operation.

Figure 2 used the following

U, U voltage on

Ur notation:

the first secondary windings in the absence of elements 16-19;

the voltage at the base-emitter junction of transistors 8 and 9 at the end of the half-wave of elements 16-19; U ^,, Uy ₅ ~ dressing on the same windings with the opposite - yes; П ^ ·, Ц voltage at the transitions base ~ emitter of transistors 8 and 9, respectively, in the presence of elements 1619; i is the current in the diagonal of the resonant circuit,. The inverter (figure 1) contains two series-connected controlled keys 1 and 2 with proportional-current control and two series-connected capacitors 3 and 4 "Between the common points of the connection of the capacitors and the keys connected reso. Dans circuit '5, output transformer 6, and load 7. Keys 1 and 2, respectively, contain transistors 8 and 9, first resistors 10 and 11, quoting the base – emitter junction, return-diodes 12. And 13, and current transformers 14 and 15. The beginning of the primary winding and the end of the base winding of the current transformer 14 (15) are connected to the emitter of the transistor 8 (9). about

The ends of the primary windings through the return diodes 12 and 13 are connected to the collectors of transistors 12. and 13. In each key, between the beginning of the base winding of the current transformer and the base of the transistor, a second resistor 16 (17) and an additional diode 18 (19) are connected in parallel.

The inverter operates as follows,

If there are no elements 16-19, the control voltages U and Judah on the windings of the current transformers 14 and 15 are formed from the moment of supplying control signals from the inverter control system (Fig. 2).

Suppose that until the moment the diagonal current ί flows through the return diode 13. As soon as the control voltage U _y g becomes positive (time t ₀ ), the transistor 8 is turned on and the diagonal current is switched from the return diode to the transistor 8, in the time interval (t ₀ -t _f ) 10 the current of the resonant circuit ί flows through the transistor 8, as soon as the current of the oscillating circuit 5 drops to zero and changes polarity (time t <), the return diode 1 $ 12 is unlocked and the current of the circuit flows through the return diode 12, At the moment control pulses Uу _d unlock the transistor 9 and the current from the return diode 12 is switched to the transistor 9, i.e.

2Q begins the next half-cycle of the inverter operation similarly to the previous one.

The amplitude of the control pulses cannot be increased due to the limited direct voltage base-emitter of transistors, which naturally reduces the amplitude of the negative blocking voltage, since the areas of negative and positive voltages U _yj and U _knots should be equal. As a result, the time interval during which the reverse voltage acts on the base-emitter junction of the transistor decreases.

To eliminate these drawbacks' * and increase reliability, diode-resistor circuits 16, 17 and 18, 19 were introduced into the converter circuit.

The principle of operation of the inverter in the presence of elements 16-19 is similar to the previous one. The difference is that, under the action of positive control pulses, the base windings. transformers 14 and 15 are loaded with higher resistance loads than in the previous case · (during this time, the diodes 18, 19 are closed). However, the forward voltage at the junction UjsjGJjgg) does not increase, since the resistors 16 and 10 (17 and 11) work as a voltage divider and limit the voltage to the desired level. With a negative voltage polarity U $ 3g (Uf ₃₃ ), diode 18 (19) is unlocked and the indicated voltage is completely applied to the base-emitter-ter transition, and the process of resorption of minority carriers occurs through diode 18 (19). This removes 1582306 restrictions on the dynamic characteristics of transistors.

Thus, the connection of additional diode-resistive elements 16-19 allows, due to an increase in the reverse blocking voltage at the base-emitter junction of the transistor, to significantly increase the reliability of operation.

Claims (1)

Claim A push-pull inverter containing two controlled keys, each of which consists of a transistor, between the base and emitter of which the first resistor and current transformer are connected, the primary winding is started and the end of the basic winding of which is connected to the emitter, and the end of the primary winding is connected through the return diode to 5 to the collector of the transistor, characterized in that, in order to increase reliability by increasing the blocking voltage at the control input of the transistor, in each controlled key between the beginning of the base winding of the current transformer and the base of the transistor, parallel-connected second ed resistor and an additional diode connected in opposite direction are connected relative to the direction of conductivity of the base-emitter transistor junction. FIG. 2