SU995236A1 - Two-cyclic voltage converter - Google Patents

Description

one

The device relates to converter technology and can be used in secondary power supply systems.

Circuits of transistor converters with saturating power transformer 1 are known.

However, in these circuits, the start of switching of the transistors is determined by the output from the saturation state of the previously open transistor. In this case, the collector current rises to a value equal to the product of the base current and the static current gain in a common emitter circuit. Since the amplitude of the current pulse cannot exceed the maximum permissible value for the transistor, the rated collector current cannot be greater than the product of the allowable pulse collector current by the ratio of the minimum to maximum static transistor gains in a common emitter circuit. The latter circumstance sometimes causes significant under-utilization of transistors by the average value of the collector current, or it forces them to select transistors with close gain factors. The efficiency of the device is relatively low due to unnecessary losses in the core (since the working induction will be equal to the induction of saturation) and in the power transistors.

Transistor converter circuits are known that contain switching power transistors associated with an output transformer in which forced switching of power transistors with the onset of transformer 2 is provided.

ten

However, these circuits are rather complicated due to the presence of transistors of various types of conductivities. In addition, the losses on the resistor current sensor, which is connected in series to the power supply, decrease 5 times the efficiency of the device.

Also known is a push-pull transistor converter, made according to an oscillator circuit, containing two power transistors connected to an output transformer, a positive reverse circuit

20 communication, time master circuits 3.

However, this device is significantly complicated, since the timing of the drive circuits implies the presence of an additional coiled product (saturable throttle), in addition, the output transformer has auxiliary feedback windings.

Closest to the present invention is a push-pull voltage converter containing in each arm power transistors, the control transitions of which are connected to auxiliary transistors and additional circuits consisting of a series-connected capacitor, a diode and a resistor connected to the windings of the positive feedback 4 .

A disadvantage of the known device is its complexity due to the presence of transistors of different conductivity types in the circuit.

The purpose of the invention is to simplify the design of the device.

The goal is achieved by the fact that in each of the arms the power circuit of the auxiliary transistor, the conductivity type of which is identical to the power one, is connected in series with the positive feedback winding and ground by the input reverse diodes, and the base of this transistor is connected to the junction point of the diode and the additional circuit capacitor.

The drawing shows a circuit diagram of a voltage converter.

The circuit contains the power transistors 1 and 2 connected to the transformer 3, the auxiliary transistor 4, (5), the power terminals connecting the base resistor 6 and 7 to the base of the transistor 1 (2). The timing of the capacitor 8 (9) and the resistor 10 (11) are connected in series and connect the base of the transistor 4 (5) to the connection point of the base resistor 6 (7) and the winding 12 (13). A diode 14 (15) is connected between the base of the transistor 4 (5) and the emitter of the transistor 1 (2) in the same direction as their control transitions. Diodes 16 and 17 are shunted in the opposite direction by transistors 4 and 5, respectively.

The device works as follows.

The two-stroke auto-generator circuit with transformer feedback has two states of quasi-stable equilibrium. Consider one of these states.

Let, for example, the transistor is open and saturated, and the transistor 2 is closed. The circuit is maintained in this state for some time due to the effect of the positive feedback signal. The capacitor 9 tends to charge up to the voltage on the base winding 13 along the circuit: the lower terminal of the winding 13 (plus a charging voltage source), the anode-cathode of the diode 15, the capacitor 9, the resistor And, the upper terminal of the winding 13 (minus the charging source voltage wives). The previously charged capacitor 8 (on the left facing-plus, on the right minus) tends to be recharged to the voltage on the base winding 12 along the circuit: the upper terminal of the winding 12 (plus voltage source), the resistor 10, the capacitor 8, the transistor control transition 4, the control transition of the transistor 1, the lower terminal of the winding 12 (minus the voltage source). The recharge current of capacitor 3 (it is also the base current of transistor 4) decreases as the capacitor 8 recharges. At the same time, due to the appropriate choice of resistor 10, transistor 4 is in a saturated state for some time. The voltage between the collector and the emitter of the saturated transistor 4 is close to zero and it has no practical effect on the base current of the transistor 1, which is mainly determined by the voltage; On the winding 12 and the resistance value of the resistor 6. The resistance of the resistors 6 and 7 is selected from the saturation condition of the power transistors 1 and 2. A decrease in the base current of the transistor 4 at some moment will cause the transistor 4 to go out of the saturation state. In this case, the resistance in the base circuit of transistor 1 will sharply increase, which leads to the release of the latter from the saturation state. When transistor 1 is out of saturation, a regenerative process will occur, as a result of which transistor 2 will fall into saturation region. Then the polarities of the voltages on the windings 12 and 1-3 will be reversed and the transistor 1 will be locked. The circuit will switch to the second state of quasi-stable equilibrium.

The recharge circuit of the capacitor 8 (9) is a circuit that determines the time the circuit is in a state of quasistable equilibrium. The constant recharge time of capacitor 8 (9) is mainly determined by the capacitance values of the capacitor 8 (9) and the resistance of resistor 10 (11) and Bijj6H is such that the circuit breaks down before the saturation of the output transformer 3 occurs.

Diodes 16 and 17 close the positive feedback circuit, which ensures quick locking of the vigor from the saturation of the power transistor i and 2, respectively, by changing the polarity of the voltage on the windings 12 and 13.

The push-pull voltage converter can be constructed using any known transformer feedback circuit.

Thus, the proposed device is simpler than the known one, since it uses transistors of the same conductivity type.

Claims (4)

1. Moin, V.S., et al., “Stabilized DC Converters, M.,“ Energie, 1972, p. 311. 2. USSR author's certificate number 834821, cl. H 02 M 7/537, 1981. 3. USSR author's certificate number 157407, cl. H 02 M 7/48, 1963. 4. USSR author's certificate number 634438, cl. H 02 M 7/537, 1977. / gg fj