SU1403283A1 - Solid-state push-pull d.c. voltage converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in power supply and electric drive systems. The purpose of the invention is to increase the efficiency and reliability by pushing the forced-on transistors of the power amplifier. The control pulses of the pulse-width modulator 12 are fed to the input of the adjustable power amplifier 5 through the locking key 7. The serial and consonant connection of the locking winding 4 located on the saturating control transformer 2 of the autogenerator 1. and the auxiliary winding 8 of the transformer 9 of the power amplifier 5 provides the forced locking of the transistors when the cutoff of the control pulse hits the interval of increasing the magnetizing current of the saturating control transformer 2. At the moment of opening Neither the locking key 7 supplies the bases of the transistors of the power amplifier 5 with the total voltage of the locking 4 and additional 8 windings, since the voltage of the additional winding 8 retains its previous polarity due to the delay in turning off the previously open transistor. Thus, both the resorption process and the process of current decay of the collector are accelerated. 2 Il. (Oh cl

Description

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The invention relates to electrical engineering and can be used in secondary power supply systems for converting a constant voltage.

The purpose of the invention is to increase efficiency and reliability by forcing the locking of power transistors.

FIG. 1 is a circuit diagram of a push-pull transistor converter; in fig. 2 are time diagrams of current and voltage variations.

The device contains an auto-oscillator 1 with an open-loop generator, a control transformer 2 having secondary windings 3 and a locking winding 4 controlled by a power supply; power 5 is made two-stroke: on power transistors, the bases of which are using a key 7 connected to the corresponding terminals of the locking winding 4 and the additional winding 8, connected in series and according to. Additional winding 8 is placed on the output transformer 9 of the amplifier 5 power. The output voltage of the converter, taken from the main winding 10 of the transformer 9, through a rectifier with filter 11 is fed to the output of the converter and to the input of the pulse-width modulator 12, the output of which is connected to the input of the locking key 7.

Locking diode transistor switch

7 includes, in addition to the first pair of driving diodes 6, the second pair of driving diodes 13, and a control transistor 14.

The device works as follows.

When the input power supply is applied, the autogenerator I starts to work and rectangular voltage pulses (voltage Ui in Fig. 2) arrive at the input of adjustable power amplifier 5, modulating the duration of which by changing the duration of the open state of the locking key 7 at the output the signal of the pulse-width modulator 12 (voltage Ui2 in Fig. 2).

The module 12 compares the part of the output voltage with the reference one and converts the error voltage (voltage Uo in Fig. 2) into a time interval. Each change in the feedback voltage corresponds to a certain open state duration of the transistors of the power amplifier 5, which ensures the stabilization of the output voltage of the converter. For example, at ti, when a sawtooth voltage is being compared (voltage U2 in FIG. 2) with a mismatch voltage Uo, after a time tj determined by the delay of the converter

the voltage is time, the locking switch 1, key 7 is opened, and the total voltage of the locking 4 and additional 8 windings through the connecting diodes 6, 13 is applied to the base of the corresponding transistor of the power amplifier 5. The voltage of the additional winding 8 exists and retains its former polarity due to the delay in switching off the previously open transistor. In this way,

0 until the open transistor is closed, a blocking voltage of increased magnitude is applied to the input, which ensures the forced locking of the transistor (current 1b in Fig. 2), reducing the dynamic losses and the likelihood of the power transistors failing. In this case, the avalanche breakdown of the control transition of the power transistor does not occur in the holding process, since the shutdown of the forcing source occurs immediately after the completion of the locking process, i.e., both the resorption process and the collector current decrease. After locking the power amplifier 5 at the time t, the voltage of the additional current winding 8 becomes zero (the voltage Ug in Fig. 2) and the transistors are kept in the locked state by windings 3, 4. At time is when comparing the front of the sawtooth voltage with a voltage that is not matched with a delay (the ff jumps the output voltage of the pulse-width modulator 12 and the locking key 7 switches to the cut-off mode. Next, the device processes are repeated.

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Claims (1)

Invention Formula A push-pull transistor converter of direct voltage, containing a master oscillator with a control transformer having a primary, the locking and secondary windings that are connected to the bases of the transistors of the power amplifier, the output transformer of which has the main and additional windings, the main winding through The rectifier and filter are connected to the output pins of the converter and to the input of the pulse-width modulator, the output of the co-ordinator is connected to the input of the locking IODC, the outputs connected to the inputs of the transistors are power amplifiers, in order to increase efficiency and reliability by forcefully locking the transistors of the power amplifier, the locking winding of the control transformer and the additional winding of the output transformer included consistently and consistently with each other. U1 XV ./H W XX, tf p 15 / // v EG Il qjus.Z