SU655047A1 - Static voltage converter - Google Patents

Description

pi, the second input is with a voltage source, and the output is with an input, a key management unit and an auxiliary circuit of two series-connected resistors, one of which is diode bounded, and a capacitor connected to the base of the additional transistor, the emitter-collector junction bypasses the capacitor / C-circuit, the latter being connected to the secondary winding of the transformer via a rectifier.

In those cases where galvanic isolation between the load and the control circuits is necessary, the rectifier whose output is connected to the integrating / C-circuit is connected to the third winding of the transformer.

FIG. 1 is a schematic diagram of a static converter; in fig. 2 - time diagrams of voltage at characteristic points of the circuit.

The static converter contains power semiconductor elements 1 (transistors or thyristors), commuting the primary winding circuit of a single-phase transformer 2.

As an example, given pavement scheme. A full-wave rectifier 4 is connected to the secondary winding of transformer 2 parallel to the load 3, to the output of which an integrating circuit consisting of resistor 5 and capacitor 6 is connected. A collector and an ejector transistor 7 are connected to capacitor 6. One of the terminals of capacitor 6 is connected to the first input of the threshold device 8. The second input is connected to the source 9 of the reference voltage. The output of the threshold device 8 is connected to a serial circuit of two resistors 10 and 11 and a capacitor 12. One of the resistors is bounded by a diode 13. One output of the capacitor 12 is connected to a common point of the circuit, the other is connected to the base of the transistor 7. In addition, the output of the threshold device 8 is connected with the input of the device 14 control power switching elements 1.

FIG. 2 denotes the voltage 15 on the integrating capacitor 6, the voltage 16 of the reference source 9, the voltage 17 at the output of the threshold element 8, the voltage 18 on the capacitor 12, the switching level 19 of the transistor 7, the voltage 20 on the load 3; t is the moment the threshold device 8 is turned on, / 2 is the moment the transistor 7 is turned on, ts is the moment the threshold device 8 is turned off, / 4 is the moment the transistor 7 is turned off.

The Converter operates as follows.

After switching on the voltage switching element 1 to the primary winding of the transformer 2, a rectangular voltage 20 appears at the load 3. The rectifier 4 detects it and the voltage of the integrating capacitor 6 increases according to a law close to linear. At time I, when the voltage 15 of the integrating capacitor is equal to the voltage level 16, the threshold device 8 is triggered and a voltage 17 appears at its output, which enters the control device and causes the switching elements of the converter to switch. On load, the voltage changes polarity.

The voltage at the output of the threshold device causes a charge on the capacitor 12 through the diode 13 and the resistor 10.

After some time, determined by the constant charge time, the voltage 18 on the capacitor 12 reaches the switching level 19 of the transistor 7 (time t), which, being saturated, provides the discharge of the integrating capacitor 6. At the time a / s. when the decreasing voltage 15 of the capacitor 6 is comparable to the level of the reference voltage 16 of source 9, the threshold element 8 switches and releases the voltage

17 from the input of the control device 14 and the charging chain of the capacitor 12. The latter begins to discharge through the series-connected resistors 10 and 11. The resistor 11 is mounted to limit the discharge

the capacitor current 12. At time t, the transistor 7 switches to the cut-off mode. At this point, the integrating capacitor 6 is completely discharged and the next cycle of its charge begins.

Thus, in the converter, the amplitude value of the voltage on the integrating capacitor is stabilized, which is normal to the average value of the output voltage

converter The latter, in turn, is proportional to the amplitude value of induction in the core of the transformer 2. All information processing is performed

in low-power control circuits using semiconductor elements that allow the use of methods of hybrid-film technology. This significantly reduces the size of the device and

loss in converter. Switching of power elements occurs at nominal currents, therefore, the reliability of the proposed converter is higher. Improving reliability also affects

power reduction by the circuit.

Claims (2)

Invention Formula A static voltage converter containing power switches associated with a control unit integrating the / C circuit associated with the secondary winding of the transformer and the source of the reference voltage, characterized in that in order to reduce losses and reduce dimensions, it is equipped with a normative element, the first input of which is connected to the capacitor of the / C-circuit, the second input to the source of voltage, and the output to the input of the control unit and an auxiliary chain of two series-connected resistors of which is shunted by a diode, and a capacitor connected to the base of an additionally inserted transistor, the emitter-collector junction of which is connected in parallel to the capacitor J of the C circuit, the latter being connected to the secondary winding transformer through rectifier. Sources of information taken into account in the examination of 1 USSR author's certificate N ° 352355, cl. H 02 M 7/12, 1975. 2. Patent of England X ° 1322009, NRT, 1974. f cpus.Z