SU1767647A1 - Voltage transformer - Google Patents

Description

one

(21) 4738469/07 (22) 09/18/89 (46) 10/07/92. Bul №37 (75) A.D. Artym

(56) USSR Copyright Certificate Ms 1279028, cl. H 02 M 3/335, 1986.

USSR Author's Certificate No. 1277324, cl. H 02 M 7/5395, 1986. (54) VOLTAGE CONVERTER

(57) Use: secondary power supplies. The essence of the invention: the converter contains a high-frequency transformer 1, two transistor

key 2, 3, two cumulative chokes 4, 5, high frequency choke 6, two additional chokes 7, 8 capacitors 9, 10, diodes 11, 12. At the moment of switching on the power supply Еп and collectors of transistors, the charge of capacitors 9 and 10 starts to charge through the windings chokes 4, 5, 7, 8. At the same time, the capacitor-14 is charged, the voltage of which unlocks the transistors 2 and 3, which provides self-excitation (start-up) of the converter due to positive feedback. 2 h.p.f. 4 il.

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The invention relates to electronics and can be used in electronic equipment.

A voltage transformer operating in class E is known, in which the switching of an active device occurs at voltages close to zero, blurs, which results in a decrease in the level of switching losses in a competitive location.

A disadvantage of devices of this type is relatively low reliability due to the effect of high peak voltages on an active device, several times higher than the voltage level of the power source.

The closest to the proposed device according to the technical essence and the achieved result is a key converter of constant voltage, made on the basis of a parallel resonant inverter with an overvoltage protection circuit (auth. USSR Ns 1277324, class Н02 М 7/5395, 1986 d).

It contains a resonant circuit consisting of parallel-connected high-frequency droplets and a capacitor connected between the collectors of two power transistors, the emitters of which are connected to the negative terminal of the power supply, the positive terminal of which is connected to the midpoint of the high-frequency choke, an additional choke, connected in parallel to the main choke with one output through a blocking capacitor, and the other through a power source, and No additional choke with a blocking capacitor is connected to the positive terminal of the power source through a diode connected in opposite to the voltage of the power source.

This device does not achieve a hard limiting voltage surge on the transistor, as a result of which its reliability decreases, it becomes necessary to reduce the supply voltage, which leads to a decrease in power and efficiency due to the high level of voltage applied to the transistors (3, 14EP) and current flowing through the elements of the oscillating circuit (in the number of times equal to the quality factor of the loaded circuit, exceeding the current consumed from the power source).

The aim of the invention is to increase efficiency and power by reducing the voltage amplitude at the transistors and currents in the reactive elements.

The invention is illustrated in FIGS. 1 to 4. Figure 1 is a schematic diagram of the invention.

It contains a high-frequency transformer 1, the secondary winding of which is connected to the input of the rectifier circuit, to the output of which are connected in parallel a filter capacitor and a load, two electronic transistor switches 2 and 3,

0 two cumulative throttles 4 and 5, connected by the beginning with a positive output of the power source, and the ends with the collectors of the corresponding transistors 2, 3, and a circuit consisting of parallel

5 connected primary windings of the transformer 1 and high-frequency droplets 6. The device also contains two additional chokes 7 and 8, the beginnings of which are connected to the negative terminal

0 power sources, and the ends to the first terminals of capacitors 9 and 10 and anodes of restrictive diodes 11 and 12, respectively. In this case, the cathodes of diodes 11 and 12 are connected to the positive terminal

5 power sources, and the second terminals of capacitors 9 and 10 are connected to the collectors of transistors 2 and 3, respectively.

The invention works as follows.

0 Transistors 2 and 3 (Fig. 1) are driven in anti-phase rectangular oscillations, as a result of which the total current lo inductors (Fig. 1) is alternately closed via each of the transistor switches.

5 (Fig.2, a, c, b). The maximum voltages on the keys 2, 3 (Fig. 1) are fixed at the level of doubled power supply with the help of hard limiting circuits, including additional chokes 7, 8, capacitors 9,

0 10 and diodes 11,12 (fig, 1). As a result of this, as well as due to the equality of the volt-second Si areas and $ 2 in Fig. 2, c, d (see below), transistors 2,3 act as square-voltage voltages with an amplitude of 2EP

5 (FIG. 2, c, d). Due to the presence of chokes, the average voltages on the collectors are equal to En, therefore the volt-second areas Si and $ 2 in FIG. 2c, r are equal, since the voltage on the transistor is excellent in the open state

0 from zero, positive with respect to the level En of the half-wave of oscillations is slightly shorter than negative. A voltage equal to the voltage difference across the keys is applied to the high frequency choke 6. The form

5 of this voltage is shown in Fig. 2d, the current through the choke is shown in Fig. 2, e. The inductance of the droplets 6 has such a magnitude that for a certain period of time before turning off the transistor (Dt), it manages to accumulate all the current supplied to the winding

transformer main chokes 4 or 5. The rate of change of current in this inductance becomes zero, therefore, starting from the moment the current reaches ± 0/2 in the inductance, the voltage on the transformer and transistor winding to which the unlocking signal should go to zero ,

As a result, the inclusion of this transistor takes place at zero voltage across it (Fig. 2c, d).

The forms of currents in the windings of transformers and at the output of the rectifier are shown in figure 2, h.

Thus, the invention implements a mode of operation with a rectangular waveform on the collectors of transistors, the amplitude of which does not exceed the value of twice the supply voltage.

The chokes 4 and 5 (Fig. 1) are connected in parallel to the primary winding of the transformer, therefore this winding, made with a midpoint, can perform the functions of chokes 4 and 5. The chokes 7 and 8 are alternately connected to chokes 4 and 5, so as the drop in variable voltages on the capacitors 9 and 10 and on the power source E can be neglected, therefore, in order to improve the weight and size parameters of the output high-frequency transformer, main and additional chokes can be performed on a common magnetic core according to Asno fig.Z.

In order to increase the reliability of the device by automatically setting the switching mode of the transistors, additional chokes can be connected to the negative output of the power source through a circuit consisting of parallel-connected additional capacitor 14 and the diode 13 of which is connected to the negative output of the power supply, additional chokes are made with outlets, moreover, the tap from the drossel 7 of the first circuit is connected through the first current-setting resistor 15 to the control input of the second transistor 3, and the tap from the core Sells 8 of the second circuit with the control input of the first transistor 2, as shown in Fig. 4, thereby providing positive feedback in the converter.

At the moment of switching on the power supply Ep of the collectors of the transistors, the capacitors 9 and 10 begin to charge through the windings of the chokes 4, 5, 7, 8. At the same time, the capacitor 14 is charged, the voltage of which transistors 2 and 3 are opened, which ensures self-excitation (starting) of the converter due to positive feedback.

Claims (3)

1. A voltage converter containing two transistors, the collectors of which are interconnected through a high-frequency choke, and the emitters are connected to the negative output of the power source, as well as the first circuit including the main choke connected by one output to the positive output of the power supply, and the second through a capacitor with a diode anode and one of the outputs of the additional choke, and the cathode The diode is connected to the positive terminal of the power source, and Another output of the additional drossel is with a negative input of the power source, characterized in that, in order to increase efficiency and power by reducing the amplitude of the voltage on the transistors and currents in the reactive elements, the second terminal of the main throttle of the first circuit is connected to the collector of one transistor; circuit, the second output of the main throttle of which is connected to the collector of the other transistor, and also an output transformer is introduced, the primary winding of which is connected in parallel with the high-frequency choke , and a rectifier input is connected to the secondary winding, the output of which includes a filter capacitor and a load circuit connected in parallel. 2. The converter according to claim 1, of which is an output transformer, main and additional chokes are made on a common magnetic core. 3. The transducer according to claim 1, about tl and h and yushi and the fact that additional chokes connected to the negative output of the power source through a circuit consisting of an additional capacitor connected in parallel and a diode whose anode is connected to the negative output of the power source; additional chokes are made with outlets, removing the throttles from the first circuit through the first current supply resistor connected to the control input the second transistor, and the tap from Drossel of the second circuit through the second current setting resistor - with the control input of the first transistor. W, T / 2 i IIZT h) J.U. X t 3V2 2T 2EG Fig.Z I St.npfiMileco Fi Fi Plesch chain ± P T / 6 &