SU1677699A1 - Pulse-type voltage transducer - Google Patents

Abstract

The invention relates to the secondary power supply sources of electronic equipment. The purpose of the invention is to increase the dynamic stability of the output voltage in case of input voltage disturbances. The pulses arriving at the control input of the power switch 1 are formed according to the principle of constancy on the switching period of the volt-second voltage integral present at the input of the output filter. In the established mode, the frequency of the control pulses generated at the output of element 2 and 11 is constant and is determined by the frequency of the generator 5 clock pulses. In this case, the moment of formation of the control pulse is delayed relative to the pulses of the generator 5 by an amount inversely proportional to the value of the input voltage. This is achieved by comparing the sawtooth voltage of the generator 8 with the voltage of the analog adder 12, inversely proportional to the input voltage, and forming at the moment they are equal at the output of the second threshold element 10 a signal that includes the power switch 1. With a sharp increase in the input voltage, the delay pulse duration increases which prevents the change in the constant component of the current of the choke 2 of the output filter, i.e. improves the dynamic stability of the output voltage. 2 Il.

Description

The invention relates to electrical engineering, more specifically to converter technology, and can be used in the construction of stabilized switching converters with a constant and variable output voltage (converters and inverters), which are controlled according to the width-pulse modulation principle. Such converters are widely used to power various electrical and radio equipment.

The purpose of the invention is to increase the dynamic stability of the output voltage in case of disturbances from the input voltage side.

Fig. 1 shows a functional circuit of a pulse voltage converter; 2 shows timing diagrams for his work.

The pulse voltage converter contains a series-connected power switch 1 and a smoothing filter, including a choke 2 and a condenserN

x | Oh oh

about

Sator 3 connected to terminals for connecting load 4, clock pulse generator (GTI) 5, analog divider 6, integrator 7 with zero input, sawtooth generator 8 (GPN) 8, two threshold elements (PE) 9 and 10, logic element 2, 11, analog adder 12 and control voltage source 13. The device also includes a matching unit 14. The operation of each is determined by the specific design of the power switch 1.

The GTI forms short pulses of 11T with a constant period T (see FIG. 2a). Its output is connected to the installation input of the integrator 7 and to the synchronization input of the FPG 8. The output of the source 13 of the control voltage Uy is connected to one of the inputs of the analog divider 6 and to one of the inputs of the first PE 9. The second input of the analog divider 6 is connected to the input output ( voltage Un). The output of the integrator 7 is connected to the second input of the first PE 9, the input of which is connected to the output of the power switch 1. The output of the analog divider 6 is connected to the inverted input of the analog adder 12, to the non-inverted input of which is connected a constant voltage source E, the value of which is proportional to the switching period power switch 1. The outputs of the analog adder 12 and GPN 8 are connected to the inputs of the second PE 10. The outputs of the first 10 and second 9 PEs are connected to the inputs of the element 2I 11, The output of the element 2I is connected through the matching unit 14 control input of the power switch 1.

The pulse voltage converter operates as follows.

At the beginning of each cycle, the GTI 5 sets the voltage to zero at the output of the integrator 7 (Un 0) and starts GPN 8 (see Figs. 2b, d).

At the output of the analog divider 6 at each time point, the voltage

and - and.

US Un 2 and the output of the analog adder 12 is the voltage

.

If Е j-, then

(D

t y t t p un

about PG YOU W

2 Un

Un

At the output of FCN 8 voltage is formed

silt k (3)

where t is the time counted from the beginning of each cycle;

k is a constant coefficient, k 1.

When U Uc at the output of the second PE 10 signal Uio 0, when Uj UcUio 1. The moment corresponds to the moment. The duration of the interval n (see Fig. 2b) is determined from expressions (2) and (3):

"-Ji -ftrM1- m

Slips during the interval in Uio

0, then at the output of element 2И 11 Un О,

This value Un corresponds to

power switch keys state,

at which Ui 0.

When Ui 0 at the output of the integrator UM 0 is flowing through -i, with ui Uy, the signal at the output of the first PE is 9 Ug 1.

After the appearance of the signal Uio 1 at the time at the output of element 2 And 11 Un 1, the power switch 1 switches to the position corresponding to Ui Kt Un, where Km is the voltage transfer coefficient, for example, the transformation ratio of the transformer entering the structure power switch 1. Upon further consideration take CT 1.

At the output of the integrator 7, a voltage is generated.

Un (t) / Ui (t) dt. (5)

1 c where Tn is a constant of integration.

When this voltage reaches the value Uy, Ug 0 is obtained at the output of the first PE 9, Un 0 being obtained, the power switch is switched to the state corresponding to U i 0. A voltage pulse of duration T2 at the output of the power switch 1 is formed.

Since the average voltage Ui is

12

Ui

T

/ Ui (t) dt,

ti

(6)

one

t

t / ui (t) .dt,

ln n

(7)

as well as Un (t2) Uy, from expressions (6) and (7)

get

Ui

Tp

Uy,

(eight)

t - y

those. the average per cycle value of the voltage Ui, as in the prototype, does not depend on the power supply voltage Un and is determined by the value of the control signal Uy. In the static mode, the output voltage of the converter is fully invariant to the supply voltage, which is typical

for astatic systems that create an integrating link in the feedback loop. In this case, feedback is provided on the output voltage of the power switch. If necessary, a general feedback on the output voltage of the converter can be introduced, for which the control voltage Uy should be made a function of the deviation of the voltage UH from the specified value.

However, the dynamic accuracy due to the correction of the position of the leading edge of the voltage pulse Ui in the proposed device is significantly higher than that of the prototype.

Example. Take TP T, then Ui Uy. If during the interval TI Un const, then from expressions (6), (7) have

T2 (9)

Un or when Ui UH Uy,

(YU)

rt UH T2 T ttUn

Then from relations (10) and (4) with Un 30 V, UH 20 V, L Gn, t 0.167x ,, 66 10 s.

The current during the interval l changes with speed

(dii uhnn

 dt L 111J

The current increment for L equals

(

dlL

d t

Tv

(12)

From expressions (11) and (12) D 0.33 A.

The current increment during TI D it2 is 0.66 A. Since r3 0.167 n, the increment in current IL over the interval r3 is also 0.33 A.

Since the voltage pulse Ui is in the middle of a cycle (lz) and the increment of the current IL during l and tz are equal, in the steady state the values of the current IL at the clock points of time are equal to the average value of the throttle current, i.e. load current {see figz). After a jump in the supply voltage up to Un 40, B from the same ratios, we get n 0.25 s, TI 0.5 s, tz 0.25 KG4 s, | A1c1 I DY 0.5 A,

D it2 1 A. In this case, the average value of the current IL on the period has not changed, t, e. the voltage jump Un is not accompanied, as in the prototype, by noticeable transient processes, where the input voltage jump leads to a change in the constant component of the inductance current of the throttle 2, i.e. to the emergence of the transition process,

Claims (1)

Invention Formula A pulse voltage converter containing a power switch and a smoothing filter sequentially connected between the input and output pins, a clock pulse generator, an integrator whose input is connected to the output of the power switch, and the first threshold element, one input of which is connected to the output of the integrator and the other connected to the output of a control voltage source, characterized in that, in order to increase the dynamic stability of the output voltage during disturbances of the input voltage, to it A sawtooth voltage generator is introduced, the clock input of which is connected to the output of the clock generator, an analog voltage divider, one input of which is connected to the output a control voltage source, another is connected to the input terminal, a two-input analog adder, the inverting input of which is connected to the output of the analog voltage divider, and the non-inverting one is connected to the output of the inputted voltage source, the value of which is proportional to the switching period by the power switch, second threshold element, inputs which are connected to the outputs of the two-input analog adder and sawtooth generator, and logic element 2I, whose inputs are connected to the outputs of the first and second threshold elements, and the output --epes the matching unit is connected to the control input of the power switch, and the integrator is equipped with an input zeroing connected to the output of the clock generator. rvvV. . . V4Ki FIG. I