SU1279028A1 - D.c.voltage-to-d.c.voltage converter - Google Patents

Abstract

The invention relates to electrical engineering and can be used in secondary power supply systems. The purpose of the invention is to increase the efficiency and reduce the level of high-frequency interference by eliminating voltage surges on the collector of the regulating transistor when it is switched. When the control transistor (PT) I is connected, the voltage on the collector is close to zero, and the secondary winding of the power transformer produces a voltage that unlocks and a power diode 3. The inductance of the saturation droplets 7 is close to zero. The closing diode 4 is closed, the throttle current 5 increases and energy is transferred to the load. When the PT 1 is turned off, the collector current decreases to zero. The shunt capacitor (K) 8 is charged by the current accumulated by the trans iQ transformer during the stage of energy transfer to the load. Diode 4 is opened under (L by self-induction emf of drossel 5, diode 3 is closed. Introduced saturation inductor 7 and K 8 with reverse diode 9, connected in parallel with PT 1, increase the frequency of the oscillatory discharge K 8 and reduce the collector current to nuch l. A subdivision of the demagnetizing coil connected to the diode 10 increases the reliability by recovering a part of the energy into the load. 1 з. п.ф-лы, 2ш1. СХ)

Description

The invention relates to electrical engineering and can be used in secondary sources of direct voltage with a transformerless input. The aim of the invention is to increase the efficiency and reduce the level of high-frequency interference by eliminating the voltage spikes on the collector of the control transistor when it is switched.

Fig. 1 is a schematic diagram of the device; FIG. 2 shows timing diagrams explaining its operation. The device contains a regulating transistor 1 connected to a negative, input terminal of the power source and connected in series with the primary winding of the power transformer 2, the start associated with the positive input terminal. The beginning of the secondary winding of the power transformer 2 is connected to the anode of the rectifying diode 3, and the end to the anode of the closing diode 4 connected to the input of the smoothing LC filter containing a cumulative choke 5 and a capacitor 6, the choke is connected between the cathodes of the rectifying and closing diodes satin 7, and in parallel with the regulating transistor 1 is connected a shunt capacitor 8, a reverse diode 9, an anode connected to the negative input terminal. The beginning of the demagnetizing winding of the power transformer 2 is connected to the negative plate of the capacitor .6, and the end to the anode will limit the U1 diode 10, the cathode connected to the positive plate of the capacitor 6,

The device works as follows.

When the control transistor is turned on (the time interval t, on the period of Fig. 25), the voltage across its collector is close to zero (Fig. 2a). The primary winding of the transformer 2 is connected to the power supply, and the secondary winding produces a voltage unlocking the rectifying diode 3. The inductance of the saturation drops 7 in the specified time interval is already close to zero. The closing diode 4 is closed, the current accumulative throttle 5 and the collector current (Fig. 25) increase, the energy of the power source is transferred to the load of the converter.

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At time t t, the switching signal is applied to the base of the transistor, and the current through it decreases abruptly to zero (FIG. 2). The capacitor that shunt the transistor starts charging with the current accumulated by the transformer at the stage of energy transfer to the load. Diode 4 is opened by the action of self-induction emf of throttles 5 and snaps the current of throttles 5 through the load. The rectifying diode 3 is closed. At the time t t corresponding to the equality of the voltage on the demagnetizing winding to the output voltage, the limiting diode 10 turns on. In the time t t t when the diode 10 is open, part of the energy accumulated by the transformer is transferred to the load. Since the number of turns of the demagnetizing winding is chosen to be less than or equal to twice the number of turns of the secondary winding, the voltage on the collector of the control transistor is limited to a level greater than or equal to twice the voltage of the power source E (U |

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 2E) in FIG. 2a, in the case

the greater number of turns of the demagnetizing winding, the limitation of the collector voltage occurs at the level of max. 2E, With skz; 1 pulses of the collector voltage equal to two, this leads to the appearance of a constant component of the transformer primary winding, i.e. - to unlimited accumulation of energy, as a result of which the device loses its working capacity.

At the time t t, the diode 10 is closed and the oscillating recharge of the capacitor 8 starts through 1 magnetizing behavior of the transformer 2. As a result, the voltage on the collector of transistor I decreases. At the point in time when it reaches the supply source voltage, the voltage on the primary and therefore on the secondary winding of the transformer 2 becomes zero, the rectifying diode 3 opens, and, since the closing diode 4 also remains open, the choke It is connected in parallel with the secondary winding of the transformer. At the same time, the voltage at the collector continues to decrease with increased

speed, as the frequency of the oscillating discharge of the capacitor 8 increases. If the inductance of throttle saturation is large enough. Compared with the magnetizing inductance of a transformer, then at a certain point in time (Fig. 2a) the voltage across the collector reaches zero. In this case, the turn-on reverse diode 9 closes the inductance current of the transformer magnetizing, and the voltage on the collector remains zero. At time t t, the current of diode 9 reaches zero

level, and the tanzistor opens with an input signal and remains open until time t tg (Fig. 2a, 5) when a blocking signal arrives at its base. Further, all the described processes are repeated.

The inclusion of the throttles, nascen 7, in the circuit of the rectifying diode 3, as well as the reverse diode 9 and the shunt capacitor 8, makes it possible to completely eliminate surges in the collector voltage and the power loss associated with them.

Connecting a disconnecting winding connected to a limiting diode to the output of the converter allows you to further increase the efficiency of the device by recovering part of the excess energy accumulated by the transformer into the load (and not the source, as in the known device) and increase reliability by limiting the voltage level transistor collector. By eliminating the voltage spikes on the collector of the control transistor and, therefore, at the input of the smoothing filter, the proposed converter provides a reduced level of noise at the output.

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Claims (2)

The invention relates to electrical engineering and can be used in secondary sources of direct voltage with a transformerless input. The aim of the invention is to increase the efficiency and reduce the level of high-frequency interference by eliminating voltage spikes on the collector of the control transistor when it is switched. Fig. 1 is a schematic diagram of the device; FIG. 2 shows timing diagrams explaining its operation. The device contains a regulating transistor 1 connected to a negative, input terminal of a power source and connected in series with the primary winding of a power transformer 2, the beginning of which is connected to a positive input terminal. The beginning of the secondary winding of the power transformer 2 is connected to the anode of the rectifying diode 3, and the end to the anode of the closing diode 4 connected to the input of the smoothing LC filter containing the accumulator choke 5 and identifier 6, the choke is connected between the cathodes of the rectifying and closing diodes satin 7, and in parallel with the regulating transistor 1 is connected a shunt capacitor 8, a reverse diode 9, an anode connected to the negative input terminal. The beginning of the demagnetizing winding of the power transformer 2 is connected to the negative capacitor plate .6, and the end to the anode will limit the diode 10, the cathode connected to the positive plate of the capacitor 6, the device operates as follows. When the control transistor is turned on (the time interval t, on the period of Fig. 25), the voltage across its collector is close to zero (Fig. 2a). The primary winding of the transformer 2 is connected to the power supply, and the secondary winding produces a voltage unlocking the rectifying diode 3. The inductance of the saturation terminals 7 in the specified time interval is already close to zero. The closing diode 4 is closed, the current accumulative throttle 5 and the collector current (Fig. 25) increases, the energy of the power source is transferred to the load on the converter. At time t t, the switching signal is applied to the base of the transistor, and the current through it decreases abruptly to zero (FIG. 2). The capacitor that shunt the transistor starts charging with the current accumulated by the transformer at the stage of energy transfer to the load. Diode 4 is opened by the action of self-induction emf of throttles 5 and snaps the current of throttles 5 through the load. The rectifying diode 3 is closed. At the time t t corresponding to the equality of the voltage on the demagnetizing winding to the output voltage, the limiting diode 10 turns on. In the time t t t when the diode 10 is open, part of the energy accumulated by the transformer is transferred to the load. Since the number of turns of the demagnetizing winding is chosen to be less than or equal to twice the number of turns of the secondary winding, the voltage on the collector of the control transistor is limited to a level greater than or equal to twice the voltage of the power source E (U | 2E) in FIG. 2a. In the case of a larger number of turns, the demagnetizing winding limiting the collector voltage occurs at the level of max 2E, With skz; 1 of the pulses of the collector voltage equal to two, this leads to the appearance of a constant component of the voltage on the primary transformer winding, i.e. - to unlimited accumulation of energy, as a result of which the device loses its working capacity. At the time t t, the diode 10 is closed and the oscillating recharge of the capacitor 8 starts through 1 magnetizing behavior of the transformer 2. As a result, the voltage on the collector of transistor I decreases. At the point in time when it reaches the supply source voltage, the voltage on the primary and, therefore, on the secondary winding of transformer 2 becomes zero, the rectifying diode 3 opens, and since the closing diode 4 also remains open, the throttle is switched on parallel to the secondary winding of the transformer. At the same time, the voltage on the collector continues to decrease with increased speed, as the frequency of the oscillating discharge of the capacitor 8 increases. If the inductance of throttle saturation is large enough. Compared with the magnetizing inductance of a transformer, then at a certain point in time (Fig. 2a) the voltage across the collector reaches zero. In this case, the turn-on reverse diode 9 closes the inductance current of the transformer magnetizing, and the voltage on the collector remains zero. At time t t, the current of diode 9 reaches zero, and the tanzistor opens with an input signal and remains open until time t tg (Fig. 2a, 5) when a blocking signal arrives at its base. Further, all the described processes are repeated. The inclusion of the throttles, nascen 7, in the circuit of the rectifying diode 3, as well as the reverse diode 9 and the shunt capacitor 8, makes it possible to completely eliminate surges in the collector voltage and the power loss associated with them. Connecting a disconnecting winding connected to a limiting diode to the output of the converter allows the device to be further improved by recovering part of the excess energy stored by the transformer into the load (and not the source, as in the known device) and increasing reliability by limiting the voltage level on the transistor collector. By eliminating the voltage spikes on the collector of the regulating transistor and, therefore, at the input of the smoothing filter, the proposed converter provides a reduced level of noise at the output. Claim 1. A DC / DC converter containing a -1 Y power transformer with primary and secondary windings, a control transistor connected in series with the primary winding and input terminals, and a secondary winding with a rectifying diode connected in parallel to the closed diode and the input LC filter, made on a cumulative choke and capacitor, characterized in that, in order to increase efficiency and reduce the level of high-frequency interference by eliminating voltage surges on the collector regulates the switching transistor when it is, administered .shuntiruyuschy capacitor, and diode reverse saturation throttle, wherein the throttle saturation included between the same terminals and the locking vtr mitelnogo diodes and parallel-connected capacitor shuntiruyush 1st and reverse diode connected in anti-parallel force transfer regulating transistor. I 2. The converter according to claim 1, characterized in that, in order to increase the efficiency and limit the voltage level on the collector of the regulating transistor by recovering the energy of the transformer, the demagnetizing coil is introduced by start to the negative output, and to the anode of the limiting diode, whose cathode is connected to a positive input I output, and the number of turns of the demagnetizing winding is chosen to be less than or equal to twice the number of turns of the secondary winding. d about t