RU2474948C1 - Stabilised voltage converter - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: result is achieved due to application of a voltage controlled generator (VCG), pulse shapers with phases 0° and 180°, current drivers for switching of power transistor switches, introduction of a precision voltage controller and a load current sensor. Continuous tracking of an output voltage value and a load current value makes it possible to automatically control frequency of pulses of a control generator (VCG), providing for accuracy of an output voltage value at any value of load current.

EFFECT: higher reliability by simplification of a control circuit of transistor switches, high-quality stabilisation of output voltage at zero and maximum load current.

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Description

The invention relates to the field of electrical engineering, in particular to converters of DC voltage to DC voltage (DC / DC), receiving input power in a wide range, and can be used in secondary power sources for consumers of various industrial and military purposes.

A known power supply unit having a self-oscillating serial resonance converter (RF patent No. 2330373, Н02М 3/338, dated 07.05.2004) containing a diode bridge circuit, two transistors (TR1, TR2), a control transformer (T1), a coil (L1 ) inductors, capacitor (C4), transformer T2, electromagnet T3, discharge capacitors (C6, C7), control generator (GNR).

In the known voltage converter, the processes are substantially dependent on the magnitude of the load current. In particular, due to the use of a magnetic amplifier, it is impossible to achieve the complete adjustment of the converter with the time-varying value of the consumed load current from its maximum value to zero.

Known stabilized voltage Converter (RF patent No. 2396686, Н02М 3/338, dated 03.07.2008), selected as a prototype, containing two transistor switches, antiparallel diodes, a primary power source, power transformer, output winding of a power transformer, push-pull rectifier , smoothing LC filter, load, primary winding of the power transformer, filtering capacitor, first driver, second driver, starting resistors, error signal amplifier, voltage reference, elem galvanic isolation element, the first additional winding of the transformer, the second additional winding of the transformer, time-lag RC circuit, auxiliary rectifier, voltage detector.

The known stabilized voltage converter has the disadvantage of using a complex circuit for controlling the switching of transistor switches using an RC timing circuit, shapers, a mismatch amplifier, a transformer with a significant number of windings, which makes it technologically difficult to ensure its reliability.

The technical task of the invention is to increase reliability by simplifying the control circuit of transistor switches.

To solve this problem, a stabilized voltage converter is proposed, containing the first and second transistor switches, a primary power source, a power transformer, a push-pull rectifier, a smoothing LC filter, a load, a first and second pulse shaper, galvanic isolation, the drain of the first transistor switch and the source of the second transistor of the key are connected to the bipolar terminals of the primary power source, the source of the first transistor switch and the drain of the second transistor switch are connected to the primary winding of a power transformer, the secondary winding of which is connected through a push-pull rectifier to a smoothing LC filter, to the output of which a load is connected to the output of the transformer secondary winding and the first and second linear transistor stabilizers, a voltage-controlled generator, the first and second current drivers are connected , capacitor, bypass diode, inductor, current sensor, precision voltage regulator, capacitive voltage divider, resistive voltage divider, and the generator output, controlled by voltage, connected to the input of the first pulse shaper with a phase of 0 °, the output of which through galvanic isolation is connected to the input of the first driver of current, the output of which is connected to the gate of the first transistor switch, the source of which is connected to the transformer primary winding, the inductor, the current sensor is connected to the midpoint of the capacitive voltage divider, and the drain is connected to the positive bus of the primary power source, and with the input of the second pulse shaper with a phase of 180 °, the output of which is connected to the input the house of the second current driver, the output of which is connected to the gate of the second transistor switch, the drain of which is connected to the source of the first transistor switch, and the source is connected to a common negative bus, the outputs of the precision output voltage regulator and load current sensor are connected to the gate of additional transistors, the drain of which is connected to the midpoint of the resistive voltage divider and the input of the voltage-controlled generator, and the source to the common negative bus, the input of the first and second linear transistor stabilization OV is connected to the positive bus of the primary power source, the output of the first linear transistor stabilizer is connected to the power bus of the voltage-controlled generator, the first and second pulse shapers, the second current driver, the first part of the galvanic isolation, the output of the second linear transistor stabilizer is connected to the power bus of the second part of the galvanic decoupling and the first current driver.

Figure 1 shows the structural diagram of a stabilized voltage Converter.

Figure 2 shows the timing diagram of the formation of control pulses with a minimum output voltage and maximum load current.

Figure 3 shows a timing diagram of the formation of control pulses at an output voltage different from the minimum and a load current different from the maximum.

Figure 1 shows:

1 - primary power source;

2 - voltage controlled oscillator (VCO) (for example, a CD74HC4046AM96 chip, Texas. ~ Instruments);

3 - pulse shaper with a phase of 0 ° (for example, a chip 74HC123D f. NXP);

4 - a pulse shaper with a phase of 180 ° (for example, a chip 74NS1230 f. NXP);

5 - linear transistor stabilizer with an output voltage of +5 V, +10 V;

6 - linear transistor stabilizer with an output voltage of -5 V, -10 V;

7 - galvanic isolation (for example, chip ADuM1100BR f. Analog ~ Devices);

8, 9 - gate current driver of a field-effect transistor (for example, a MIC4452BM microcircuit f. Micrel);

10 - the first transistor switch is a P-channel field effect transistor (for example, IXTR90P20P f. IxyS);

11 - the second transistor switch is an N-channel field effect transistor (for example, IRFP4668PbF f. IRF);

12 - capacitor;

13 - power transformer;

14, 15 - push-pull rectifier (for example, diode SBR40U200CT f. Diodes Incorporated);

16 - bypass diode (for example, diode SBR40U200CT f. Diodes Incorporated);

17 - a throttle;

18, 19 - smoothing LC filter;

20 - current sensor;

21 - precision voltage regulator;

22 - load;

23, 24 - capacitive voltage divider;

25 - resistive voltage divider;

26, 27 - two additional transistors - N-channel field effect transistors (for example, transistor ZXMN2B14FH f. Zetex Semiconductors).

The functioning of the stabilized voltage Converter is as follows.

The voltage of the primary power source 1 includes a circuit containing a linear transistor stabilizer with an output voltage (+5 V, +10 V) 5, a linear transistor stabilizer with an output voltage (-5 V, -10 V) 6, which generate a supply voltage for the control circuit immediately after turning on. The control circuit, consisting of a voltage controlled oscillator (VCO), 2, generates a control voltage U _gong (Fig. 2) in the form of a meander with a frequency of about 50 kilohertz. The frequency from the voltage-controlled oscillator (VCO) is simultaneously fed to a pulse shaper with a phase of 0 ° 3 and a pulse shaper with a phase of 180 ° 4. A pulse sequence with a phase of 0 ° U1 (Fig. 2) through galvanic isolation 7 controls the current driver 8 for opening the first transistor switch - the P-channel field effect transistor 10, the load of which is the primary winding of the power transformer 13, the first output of which through the inductor 17, the current sensor 20 is connected to the midpoint of the capacitive divider 23, 24, the second output through the cond The sensor 12, an open P-channel field-effect transistor 10 is connected to the positive bus of the primary power source. The pulse sequence with a phase of 180 ° U2 (Fig. 3) controls the current driver 9 to open the second transistor switch - the N-channel field-effect transistor 11, the load of which is the primary winding of the power transformer 13, the second output of which is through the capacitor 12, an open N-channel field transistor 11 is connected to a common negative bus. Capacitors 23, 24 of a sufficiently large and identical capacity form a capacitive divider (the voltage of the primary power source is divided in half), at the same time they perform the function of a smoothing high-frequency filter of the primary power source. As a result of switching the transistor switches 10, 11, pulse emfs are induced in the secondary windings of the power transformer 13, which are then rectified by a push-pull rectifier 14, 15, smoothed by an LC filter 18, 19, the output of which is connected to the load 22. The bypass diode 16, having a low resistance, opens at the stage of pauses of the operation of field-effect transistors 10, 11, thus, losses are reduced by reducing the path of the inductor current. The value of the output voltage is monitored by a precision voltage regulator 21, if the value of the output voltage is exceeded, the precision regulator opens an additional transistor 26, the input of the voltage-controlled oscillator (VCO) 2 is pulled to a common negative bus, thereby reducing the frequency of control pulses U _gun (Fig. 3), the pause time t of the _{pause of the} operation of field-effect transistors increases. At the same time, the consumed load current is monitored, for this, a current sensor 20 is connected in series with the primary winding of the power transformer 13, in case of exceeding the permissible load current, the current pulses flowing through the primary winding of the transformer are converted to voltage, which opens an additional transistor 27, the voltage-controlled generator input ( VCO), 2 is attracted to the common negative bus - the frequency of the control pulses decreases U _gong (Fig. 3), the pause time t the _pause operation of the field effect transistors is growing. Thus, the switching frequency of power transistors is controlled by a minimum number of elements, which improves the overall mass characteristics and the reliability of a stabilized voltage converter.

The capacitor 12, the inductor 17 smooth out the pulse voltage that occurs when switching field effect transistors 10, 11, due to the slowdown of the slew rate of the current in the primary winding at the stage of turning on the transistor with a relatively smooth rise in voltage at the drain.

One of the advantages of this stabilized voltage converter through the use of a voltage control generator (VCO) 2 is the possibility of miniaturizing the power switch control circuit. In addition, it provides simultaneous regulation of the generator frequency depending on the output voltage and load current.

Claims (1)

A stabilized voltage converter containing the first and second transistor switches, a primary power source, a power transformer, a push-pull rectifier, a smoothing LC filter, a load, the first and second pulse shapers, galvanic isolation, the drain of the first transistor switch and the source of the second transistor switch are connected to bipolar leads the primary power source, the source of the first transistor switch and the drain of the second transistor switch are connected to the primary winding of the power transformer, WTO the secondary winding of which is connected through a push-pull rectifier to a smoothing LC filter, the output of which is connected to the output and to the midpoint of the secondary winding of the transformer, characterized in that the first and second linear transistor stabilizers, a voltage-controlled generator, the first and second current drivers are inserted into it, capacitor, bypass diode, inductor, current sensor, precision voltage regulator, capacitive voltage divider, resistive voltage divider, the output of a voltage controlled oscillator, connected to the input of the first pulse shaper with a phase of 0 °, the output of which through galvanic isolation is connected to the input of the first current driver, the output of which is connected to the gate of the first transistor switch, the source of which is connected through the capacitor, the primary winding of the transformer, the inductor to the midpoint of the capacitive a voltage divider, and the drain is connected to the positive bus of the primary power source, and with the input of the second pulse shaper with a phase of 180 °, the output of which is connected to the input of the second current driver, in the output of which is connected to the gate of the second transistor switch, the drain of which is connected to the source of the first transistor switch, and the source is connected to a common negative bus, the outputs of the precision output voltage regulator and load current sensor are connected to the gate of additional transistors, the drain of which is connected to the midpoint of the resistive voltage divider and the input of the voltage-controlled generator, and the source to the common negative bus, the input of the first and second linear transistor stabilizer is connected to the positive by the bus of the primary power source, the output of the first linear transistor stabilizer is connected to the power bus of the voltage-controlled generator, the first and second pulse shaper, the second current driver, the first part of the galvanic isolation, the output of the second linear transistor stabilizer is connected to the power bus of the second galvanic isolation and the first current driver.

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