SU1677701A1 - Constant voltage regulator - Google Patents

Abstract

The invention relates to secondary power sources of various radio equipment. The aim of the invention is to improve the quality of stabilization by improving the conditions for switching off the power transistors while at the same time increasing the efficiency. This is achieved by introducing an additional transformer 10 and rectifier 13 with a capacitive filter 15. This ensures shunting of the transistor control element 1 when it is turned off by the filter capacitor 15. This reduces the voltage rise rate on the collectors of the transistors in the control element 1 during the shutdown process. The excess energy accumulated in the capacitor is transferred to the load, which provides an increase in efficiency. 1 il.

Description

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AND

The invention relates to electrical engineering and can be used to power general-purpose radio electronic equipment, in particular computer units.

The aim of the invention is to improve the quality of stabilization by improving the conditions for switching off the power transistors while at the same time increasing the efficiency.

The drawing shows a diagram of the stabilizer.

The DC voltage regulator contains a key transistor regulating element 1, a main power transformer 2 with a primary 3 and a secondary 4 windings, a main power rectifier 5 consisting of a diode bridge 6 and a filter 7, there are also a comparison element 8 and a control unit 9.

An additional power transformer 10 with primary 11 and secondary 12 windings and an additional power rectifier 13, consisting of a diode bridge 14 with a capacitive filter 15 at the output, are brought into the stabilizer.

In this case, the regulating element 1 is connected in series with the primary winding 3 of the transformer 2 between the terminals 16, 17 for connecting an alternating current source. The input of the main power rectifier 5 (i.e., the diagonal of the alternating current of bridge 6) is connected to the secondary winding 4 of the transformer 2. The input of the comparison element 8 is connected to the terminals 18, 19 for connecting the load. The output of the element 8 through the unit 9 of the comparison is connected to the control input of the regulating element 1

ABOUT

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Unlike the prototype, the input of the rectifier 13 (i.e., the diagonal of the alternating current of the bridge 14) is connected to the secondary winding 12 of the transformer 10, the primary winding 11 of which is connected parallel to the regulating element 1. At the same time, the outputs of rectifiers 5 and 13 are connected in series and agree between pins 18, 19 for connecting the load.

The regulating element 1 can be made on the basis of any known circuit design. For example, it can contain two power transistors 20, 21, diodes 22-25, a transformer 26 with windings 27, 28, 29, a diode bridge 30, a control transistor 31 and resistors 32, 33. Filter 7 has an inductive input.

Comparison element 8 may be made based on any known circuit design. Thus, it may contain a EB 34 output sensor 34, existing at the outputs 18, 19, a differential amplifier 35, a voltage divider 36, and a diode 37.

The control unit 9 may be executed on the basis of any known circuit design. For example, it may contain a voltage supply sensor 38 of the EP power supply, consisting of a transformer 39 and a full-wave rectifier 40 without a filter, a comparator 41, a current limiting resistor 42 and a diode 43,

The stabilizer works as follows.

At the beginning of the positive half-cycle of the supply voltage Еп (plus on the bus 16), the transistor 31 is locked and the transistor 20 is saturated under the action of a positive polarity applied to its base from the left end section of the winding 27 of the transformer 26. The transformer 21 is locked. At the same time, a voltage App is applied to the winding 28 through the current limiting resistor 32. The current from pin 16 flows through the transistor 20, the middle section of the winding 27, the diode 23 and the winding 3 to the output 17. The winding 11 of the transformer 10 is almost short-circuited, so the voltage on the winding 12 is close to zero.

The winding sections 27 of transformer 26 are turned on according to, therefore, due to the positive feedback, the base current of transistor 20 is proportional to the current flowing through the winding 3 of transformer 2 and through the middle winding section 27. This ensures the so-called current-proportional control of transistor 20 (during the negative half-cycle of the voltage En is similarly controlled by the transistor 21).

The voltage on the winding 4 increases, which ensures the charging of the filter 7 through the rectifier 6. The voltage on the filter

7 via rectifier 14 is fed to pins 18, 19, to which an external load is connected. A portion of the output voltage EBi through the sensor 34 in the form of a divider is fed to the inverting input of the differential amplifier 35, where it is compared with the reference voltage e0 fed to a non-inverting input. The output of the amplifier 35 produces an error voltage E, which goes through the divider 36 V a voltage to the inverting input of the comparator 41. A voltage from the amplitude sensor 38 output proportional to the amplitude of the voltage EP is supplied to its non-inverting input. At the moment of equality of the voltages, a positive pulse E41 appears at the output of the comparator 31, which saturates the transistor 31. As a result, the winding 29 is short-circuited through the bridge 30 and the transistor 31 for the duration of the pulse E41.

As a result, the base-emitter junction of the transistor 20 is also short-circuited, which ensures its locking for the time T41. As a result, the voltage Ez on the winding 3 of the transformer 2 takes the form of a sinusoid with a central part cut out.

The locking of the transistor 20 causes the current flow through the regulating element 1 to stop. This current will now (during the time interval T4i) flow through the windings 11 and 3 of transformers 10 and 2 connected in series. The amplitude of the voltage Ez is less than the amplitude outside the interval T41. In order to transfer energy to the load in these conditions, it is necessary for filter 7 to have an inductive input.

The result is a reduction in the amplitude of the pulsations, since the frequency of the pulsations is six times higher than the frequency of the network. The voltage on the winding 11 of the transformer 10 after full-wave rectification in the rectifier 14 is fed to the filter capacitor 15.

So, at the moment of turning off the transistor 20, a capacitor 15 having a capacitance Cis is connected to it via a transformer 10 and the rectifier 14. The time constant T, at which the voltage across the collector of the latching transistor 20 rises, is defined as

 T NnS15PYu2, (1)

where RH is the load resistance;

nio - transformer transformation ratio 10.

To optimize the transistor off mode, the following conditions must be met:

T (5 ... 20) gVykl, where Gwikl - off time.

This is achieved by selecting the Cis value. The discharge of the capacitance Cis is carried out on the load, thus increasing the efficiency. In this way, the turn-off conditions of the transistor 20 are improved. the combination of the values of the collector current and the collector-emitter voltage at any given time does not go beyond the boundaries of the safe operation area specified in the technical conditions.

During the negative half-cycle of the supply voltage Eu, the processes described above repeat with the only difference that the current C through the winding 3 flows through the transistor 21 and the diode 22. The transistor 20 and the diode 23 are locked. Diodes 24, 25 limit the amplitude of the negative pulses at the bases of the transistors 20, 21.

When the transistor 21 is turned off during the negative half-period, the capacitor 15, similarly to the one described above, ensures the optimization of the off mode.

Stabilization of the output voltage of the Evy is achieved as follows. Let there be a tendency to increase the output voltage of the Euves relative to a given nominal value, for example, due to an increase in the supply voltage En.

Then the error voltage at the output of divider 36, proportional to the voltage at the output of amplifier 35, will begin to decrease. As a consequence, the duration T41 of the pulse E – n will begin to increase by

output of the comparator 41. This will reduce the amplitude of the voltage Ez. Correspondingly, the voltage of the Eves will decrease until it reaches

newly set face value. The transformation ratio of transformer 12 (the ratio of the number of turns of oTomok 11 and 12) must be 1.5-3 times higher than the transformation ratio of transformer 2.

Claims (1)

Claims of a DC Voltage Stabilizer Containing a Key Transistor a regulating element connected in series with the primary winding of the main power transformer between the leads for connecting an AC source, the main power rectifier input connected to the secondary winding of the main power transformer, leads for connecting the load to which the input of the comparison element is connected, the output of which is through the control unit connected to the control input of the regulating element, characterized in that, in order to improve the quality of stabilization by improving off conditions power transistors while increasing efficiency, an additional power transformer and rectifier with a capacitive filter are introduced into it, while the additional rectifier input is connected to the secondary winding of the additional transformer, the primary winding of which is connected in parallel to the regulating element, and the main power rectifier is equipped with LC filter, and the outputs of the main and additional rectifiers are connected in series and in accordance with and used as terminals for connection to loads. four hp i a and -13