SU1249663A1 - Device for controlling transistor converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used to control transistor converters. The purpose of the invention is to increase the accuracy of the stabilization of the output voltage of the converter. In this device, the error of stabilization arising due to the delay. switching off the power transistor is eliminated by the fact that after the capacitor 8 is discharged but the power transistor 12 is not turned off and the voltage at the filter input of the converter continues to be present, the capacitor 8 starts to charge again until the power transistor 12 turns off After turning off transistor 12, this voltage remains constant j i. is remembered, and after the next switching-on of transistor 12, integration begins no longer with zero, but with the additive that has accumulated due to the turn-off delay of transistor 12. Therefore i (L 4i) CO O) O5 CO

Description

the next turn on of transistor 12 occurs earlier. Thus, an automatic adjustment is made of the duration of the on state of the transistor 1 2 as in the case of

The invention relates to electrical engineering and can be used to control transistor converters.

The purpose of the invention is to increase the accuracy of carrying the stabilization of the output voltage of the converter.

Fig. 1 shows the basic diagram of the device and one of the variants of the transistor converter circuit; in fig. 2 - timing diagrams for devices operation

The device contains (Fig. 1); master oscillator 1 connected to source 2 of control voltage and one input of RS flip-flop 3, the other input of which is connected to the output of comparator 4, integrator 5 consisting of operational amplifier 6, resistor 7 and storage element (capacitor) 8 , clamped by the key 9, the sensor 10 of the output voltage of the transistor converter connected to the input of the integrator.

The transistor converter contains a voltage source 11, a power transistor 12, a power slider 13 for controlling the power transistor, a return diode 14, an inductor 15 and a filter capacitor 16 and a load 17,

The device works as follows

The master oscillator generates narrow pulses (Figs. 2, a), which are fed to the input of the RS flip-flop 3, putting it into a state with a high potential at the output (Fig. 2.5). The high potential coming from the output of the trigger 3 to the input of the power amplifier 13 causes a positive control current of the power transistor 12 (FIG. 2, e) to appear,

The input voltage and the change in load current 17, the output voltage remains invariant to both the input and output disturbances, 2 Il.

0

five

corresponds to the open transistor and the appearance on the emitter of transistor 12 is positive, and at the output of sensor 10 (FIG. - 1) a negative voltage proportional to the instantaneous value of the output voltage Uj of the converter to the filter (FIG. 2.6). This voltage , entering the input of the integrator 5, leads to a linear increase in the voltage of the ICs at the output of the integrator (Fig. 2, B) in accordance with the expression

U, i - | u (t) dt, (.1) o.

where R and C are the resistance of the resistor 7 and the capacitance of the capacitor 8, which determines the duration of the open state of the power transistor necessary for accurate stabilization of the output voltage at the level given by the control voltage Uy,

At time t, when the voltage reaches the control voltage U, the comparator 4 for a very short time passes from the state with zero output potential to the state with high output potential and a short pulse is formed at its output (Fig. 2, d). This occurs because a high potential, coming from the output of the comparator 4 to the control input of the switch 9, leads to the discharge of the capacitor 8, i.e. to drastically reduce the voltage at the integrator output 5. (FIG. 2) and, therefore, the transition of the comparator 4 is again in a state with zero potential at the output,

A short pulse formed at the output of the comparator 4, arriving at the input of the RS flip-flop 3, will transfer it to the state with zero potential

at the output (Fig. 2, o), which corresponds to the negative voltage of the emitter-base of the power transistor 12, coming from the 13-amp amplifier. The base current changes its direction to the opposite (Fig. 2, e) and the process of resorption of excess charge in the base begins. The process of resorption of excess charge, during which the transistor is still in the open state, and thereby introduces an error in the stabilization result, defined by equation (1), ends at the moment when the negative current drops to almost zero (Fig. 2, e). This only closes the power transistor and the voltage across its emitter and the output of sensor 10 will become zero.

In the proposed device, the stabilization error arising due to the delay in switching off the power transistor is eliminated by the fact that after the capacitor 8 has discharged the power transistor 12 but not yet turned off and continues to be present. the voltage at the input of the converter filter, the capacitor 8 starts charging again until the power transistor 12 is turned off (Fig. 2, I). After turning off the power transistor, this voltage remains constant, i.e. is remembered, and after the next switching-on of the power transistor, the integration will start not from zero, but from the additive that has accumulated due to the turn-off delay of transistor 12. Therefore, the switching off of transistor 12 will now occur earlier. Thus, the automatic adjustment of the duration of the on state of the power transistor is carried out, both when the input voltage changes, as well. and when the load current changes 1.7. The output voltage remains invariant to both the input and the

travel perturbations. A change in the turn-off time of a power transistor when the load current changes is automatically taken into account by the control device, therefore the rigidity of the external characteristic of the converter increases.

The use of the proposed control device allows refusing additional stabilization circuits by the deviation of the output voltage of the converter, which usually have high inertia and cause difficulties

stable operation with large stabilization factors. The proposed device implements the principle of regulation according to the disturbing influence and, with quite satisfactory stabilization accuracy, has a high speed determined by the switching frequency of the power transistor.

Claims (1)

Invention Formula A device for controlling a transistor converter containing a generator with a first generator, the first output connected to the input of a control voltage source, k.parator, the first input of which is connected to the output of a control voltage source, and the second input is connected to the integrator output, the storage element of which is bypassed key, and the input is connected to the output of the output voltage sensor of the converter, characterized in that, in order to increase the accuracy of stabilization of the output voltage of the converter, RS is entered into it The trigger, the first input of which is connected to the second output of the master oscillator, and the second input is connected to the comparator output, to which the control input of the key is connected, the RS trigger output is used to connect the transistors to the transistors. 2