SU1577013A1 - Secondary power supply source - Google Patents

Abstract

The invention relates to converter equipment and can be used in secondary power supply sources. The purpose of the invention is to increase reliability and simplify the design. The power supply containing a key converter with a power transformer at the output, two output channels and a control unit are entered into two current transformers 8 and 9, two load resistors 10 and 11 and a diode switch. Protective shutdown of the source is made both when the output channels are overloaded and when the key converter is overloaded. 6 Il.

Description

Phage.1

The invention relates to converter equipment and can be used in secondary power supply sources.

The purpose of the invention is to increase reliability and simplify the design.

FIG. 1 shows a secondary power supply circuit; in fig. 2 and 3 are diagrams of a diode switch for single-stroke and two-stroke inverters, respectively; in fig. 4 is a diagram explaining the principle of calculating currents in an assumed source; Fig. 5 is a diagram of the control unit with an overcurrent protection input; in fig. 6 - timing diagrams explaining the operation of the source using the example of a single-ended inverter.

On the timeline indicated; the current through the transistors of the inverter li (a), the current of the first secondary winding of the power transformer 2 (b), the current of its second secondary winding 1z (c), the control signal at the output of the pulse-width modulator (PWM) (g), the output signal zero - organ (H0) (d), and the voltage across the capacitor Uc (e).

The secondary power source (Fig. 1) contains an inverter 1 with a control unit 2 at the input and a power transformer 3 at the output, its first and second secondary windings through the first 4 and second 5 power supply channels, respectively, connected to the corresponding terminals 6 and 7 for connecting the load the first transformer 8 current, the primary winding is included in the primary circuit of the power transformer, the second transformer 9 current, the primary winding is included in the circuit of the second secondary winding of the power transformer, the first 10 and the second 11 nag ruznoe resistors, the first conclusions connected to the second output of the secondary winding of the first transformer 8 current and the first input 12 of the diode switch 13, the second input 14 of which is connected to the second output of the second load resistor 11 and the first output of the secondary winding of the second transformer 9 current, the third input 15 is connected with the second output of the first load resistor 10 and the first and second terminals of the secondary windings, respectively, of the first 8 and second 9 current transformers, the first output 16 is connected to the common wire, and the second output 17 - with current protection input of control unit 2, the negative feedback input of which is connected to terminals 6 for connecting the load of the first channel. When using a single-ended inverter, the diode switch (Fig. 2a) contains two diodes 18 and 19, anodes connected to the second output 17, and cathodes to the second 14

and the third 15 inputs, while the first input 12 and output 16 are interconnected. When using a push-pull inverter (FIG. 3), the diode switch contains three

the first diode 20, anodes connected to the second output 17, and the cathodes, respectively, with three inputs 12,14 and 15 and the anodes of the second three diodes 21, the cathodes connected to the first output 16. In FIG. four

current sources 22 and 23 replace current transformers 8 and 9; in fig. 5, the control unit 2 includes a PWM 24, an output connected to a control input of the inverter, a negative reverse input

connection - with the leads for connecting the load 6, and the blocking input - with the output of the null organ 25. The input of which through the first summing resistor 26 is connected to the capacitor 27 and the second output

17 of the diode switch through the second summing resistor 28 with the source 29 of the reference voltage, and through the third summing resistor 30 with leads 6 for connecting the load.

The secondary power source operates as follows.

The latitude-modulated pulses produced by control unit 2 (Fig. 5d) are amplified by inverter 1, released by power transformer 3, converted to constant voltage by supply channels 4 and 5, and fed to terminals 6 and 7 for connecting the load. In this case, if in the second feed channel a pulse stabilizer is used, then in. The second secondary winding of a power transformer current pulse will be shorter in duration than the voltage pulse on its windings.

The current of the primary winding of the power transformer (Fig. 6a)

l. + -Lia + la- -,

KT1Kt2

where i, la, 1h, KTI, Kt2 - respectively, the current

5 magnetizing, secondary currents and the transformation ratio of the power transformer, is transformed into the secondary winding of the first current transformer 8 with the transformation ratio Km

0

.1вКттН /.+ 1 | 2Ч- П | з.

CP

CT2

The current of the second secondary winding of the transformer 3 (Fig. 6c) is transformed into the secondary winding of the current transformer 9 with a KTT2 transformation ratio,

Gz-1z-Ktt2,

Since the secondary windings, representing in their first approximation the current sources (Fig. 4), are connected in parallel to the load resistor 10. then the current through it will be equal to the current source current difference

1, + 1 s КТТ11 + ш1зззКТТ2 + - 12. CTT2

CT1

When selecting the transformation ratios of current transformers that satisfy the ratio Ktp / Kp Ktt2, the current through the load resistor 10 will be proportional to the magnetizing current and the current in the first secondary winding.

The current through the load resistor-11 will be equal to the current of the secondary winding of the current transformer 8, in the circuit of which it is connected, and therefore proportional to the current of the second secondary winding of the power transformer.

The diode switch 13 extracts from the signals of the load resistors 10 and 11 larger in amplitude, rectifies it and supplies it to the current protection input of the control unit.

In the example of a specific embodiment (Fig. 5), the received signal is integrated by a capacitor 27 (Fig. Ba) and is compared at the input of the null organ 25 by summing resistors 26, 28 and 30 with the voltage of the reference voltage source 29 and the output voltage of the first channel (Fig. 6d, e). When the primary current of the power transformer of its first or current of the second secondary windings exceeds a certain value, the zero-body produces a blocking signal that limits the width of the inverter control pulse. In this case1, the current of the second secondary winding of the power transformer 3 (Fig. 6c) abnormally increases, which causes the voltage on the capacitor 27 to increase and the zero organ 25. triggers. The inverter control pulse is removed earlier than in normal mode

five

0

five

0

five

0 5 0 5

for a time At (Fig. 6d), and after a time corresponding to the turn-off time of the inverter's transistors t. Off, the current pulse of the inverter is removed (Fig. B.B.), also limited in duration by the time At. The voltage at the source output decreases and, due to a decrease in the current through the resistor 30 (Fig. 5), the overload current decreases. In the short circuit mode, the residual load current is determined by the current through the resistor 28.

Claims (1)

Invention Formula The secondary power supply source containing an inverter with a power transformer at the output, the first and second secondary windings of which through the output circuits are connected respectively to the first and second terminals, the control unit with a current protection input and a stabilizing input connected to the output of the first output circuit, and the output to the control input of the inverter, and the first current transformer with the first load resistor, which is due to the fact that. in order to improve reliability and simplification, a second current transformer is included in it, connected to the second secondary winding of the power transformer, a second load resistor and a diode switch, the first input of which is connected to the first terminals of the first and second load resistors and the second output of the secondary windings of the first current transformer , the primary winding of which is included in the primary winding circuit of a power transformer, the second input is with the first output of the secondary winding of the second current transformer, the second output is to Torah connected to a first terminal of the secondary winding of the first current transformer, a second terminal of the first load resistor and the third input of the diode switch, the first output of which is connected to the common bus, and the second - to an input overcurrent protection control unit. It 15 3 Rig. 2 G, 12 20 -k F- : 2 / -7rV / Yu . a