SU1365302A1 - A.c. to d.c. voltage converter with transformer-less input - Google Patents

Abstract

The invention relates to the field of electrical engineering and can be used as a source of secondary power supply. transformerless input. The purpose of the invention is to improve the electromagnetic compatibility of the converter with the power supply network and improve its weight and size parameters. The converter contains three conversion channels, the inputs of which are connected to the power supply network having a zero output, and the outputs form the output outputs of the converter. Each channel of the converter consists of a voltage divider 1 connected between (L

Description

with a

ate

input channel inputs, droplets 2, shunt 3, rectifier 4, transistor 6 with control circuit 5, diode 7, capacitor 8 connected to the input of the inverter 9. The output of the inverter 9 is connected to the output rectifier 11. through the high-frequency transformer. output voltage is connected between output terminals. Its output is connected to the control inputs of voltage divider 1 of all channels. The transistor 6 is connected to the output of the rectifier 4, the input of which through the inductor 2 and the shunt 3 is connected to the voltage divider 1. The inputs of the control circuit 5 are connected to the output of the voltage divider 1 and the input of the rectifier

5302

Cluster 4 connected to shunt 3. The introduction of a controlled voltage divider 1, transistor 6 with control circuit 5, droplets 2, shunt 3 and sensor 12 ensures the consumption of currents from each phase, the shape of which almost repeats the shape of the applied sinusoidal voltage. It does not require the use of low-frequency filter elements, since the instantaneous power at both the input and output of the converter is not dependent on time, additional devices for matching with the supply network and load, as well as means of protecting the network from the influence of electromagnetic interference. 3 il.

The invention relates to electrical engineering and can be used to create sources of secondary power supply (IHEP) with transformerless input.

The purpose of the invention is to improve the electromagnetic compatibility of the converter with the power supply network and improve its weight and size parameters.

Figure 1 presents the structural diagram of the proposed Converter; Fig. 2 shows timing diagrams explaining the operation of the converter; FIG. 3 shows an embodiment of the control circuit of the power transistor of one of the converter channels.

The converter contains a controlled divider 1, input voltage, high frequency choke 2, shunt 3, rectifying bridge 4, power transistor control circuit 5, semiconductor diode 7, smoothing high frequency capacitor 8, voltage inverter 9, high frequency transformer 10, output voltage the driver 11, the output voltage sensor 12, the input terminals 13 and 14 of the converter channels controlling the input 15, the output terminals 16 and 17 of the channels.

Figure 2 shows the time diagrams of changes in the instantaneous values of the phase to the voltage Uo, a three-phase network.

0

five

0

five

0

DC, Ug, and Uc, phase load currents and nv ns corresponding phase powers Rd, P, and R., total powers P, load current voltage on the load Uyi. The control circuit of the power transistor of one of the converter channels contains circuits 18 and 19 of the selection of the modules of the standard U signals, for example, the voltage and the signal proportional to the input current connected to the inputs of the reference circuit 20, to the output of which the amplifying element 21 is sequentially connected, the gain factor k, , relay element 22 and power amplifier 23.

The Converter (figure 1) consists

 of three channels, each of which

: it is supplied with two entrance 13 and 14 and two output 16 and 17 conclusions,

 one input terminals of the same name 13

connected to the mains phases, other inputs of the same name

 14 - to the zero wire of the network, the same output pins 16 and 17 are interconnected to form the output pins of the converter, between the input pins 13 and 14 of each channel the controlled divider 1 of the input voltage is connected, the high-frequency choke 2 is connected to the input pins 13 and 14 and shunt 3,

connected to the AC leads of the rectifying bridge 4, between the DC terminals of the latter is turned on the power transistor 6, with the control circuit 5, the inputs of which are connected to the output of the controlled divider 1 and connected to the AC shunt output of the rectifying bridge 4 In addition, the positive DC output of the rectifying bridge 4 through the semiconductor diode 7 is connected to the smoothing capacitor 8 and the input of the voltage inverter 9, the other terminals of which are connected to the negative. the DC output of the rectifying bridge 4, the outputs of the inverter 9 are connected via high-frequency transformer 10 to the inputs of the high voltage rectifier 11, and between the output terminals 16 and 17, an output voltage sensor 12 is connected, the output of which is connected to the control inputs 15 of the input divisors 1 voltage of each channel.

Converter with transformerless input works as follows.

The principle of building a converter is based on the forced formation of symmetric and sinusoidal input currents that coincide in phase with the network voltages, for which each channel of the converter contains a converter based on a downstream type of current regulator containing (FIG. 1) voltage divider 1 , high frequency choke 2, shunt 3, rectifying bridge 4, key element (transistor) 6 with control circuit 5, diode 7, smoothing capacitor 8. Expressions for instantaneous values of currents generated at input The transducer under consideration can be obtained on the basis of the instantaneous values of the phase voltages of the DC, Ug and Uc network and the equivalent system resistance source – load R

9UA

g-smut;

g-sin ();

Uc, - 4.

--sin (cot + -).

The instantaneous power in the input circuits of the converter is determined by

711

P (t) 4 sin2at + 2-sin (cot + i -) + 5-

R,

R,

R

4t.

(2)

X sin (cot + r-).

The effective value of the power consumed during the mains voltage period is determined from (2) as

t (t) (). (3)

oE

on the other hand, where P is the load power.

H

Equal to, find the value of R.

R Y1 + Y1 + and

E 9TT t,

(four)

For symmetrical three-phase network.

R, 2G-f .- (5)

,

Substituting (5) into (1), we find:. 2i1n.

A-zi; -

i, sin (Qt4-f);

30 gg 40 45

. 2in1n. (, 4 ir

 "((6)

50

55

From (6) it follows that the amplitude of the current consumed is directly proportional to the load current, and the instantaneous value of the phase current is proportional to the instantaneous value of the phase voltage. This determines the need to control the power supply in two dimensions — the level of the output voltage and the shape of the current consumption curve.

The instantaneous power consumption for a symmetrical three-phase network according to (2) and (5) is:

P (t) 2U Jl | sin2a) t + sin4cot + |) +

+ sin2 (cot + -.-) j - -i 3-cos2at-cos (+ - | i) -cos (2ut4 |), I, - y ii cos2ut-cos2Qt cos- - sin2G3t sin- + + cos2at cos- - sin2cot --i-FcosZut- | cos2ait + sin2ut 1

- rcos2cot- -2-sin2G) t and, 1c.

(7)

It follows from expression (7) that the instantaneous powers at both the input and output do not depend on time, i.e. energy reserve, which is 10

The principle of operation of the converter is based on the accumulation of energy in the magnetic field of the core of the input throttle 2 with the subsequent transfer of the accumulated energy to the load. At the same time, due to a change in the ratio of the duration of the accumulation intervals and

The proposed converter is equal to zero, while the low-frequency ripple of the output voltage is absent, which is ideal from the viewpoint of matching with the load-energy return, it can be achieved and good mass and energy flow control can be achieved. as a non-thrashing network and converter output. The presence of throttle on the input circuit. causes a continuous current consumption of 20, as required for the operation of the converter.

The input control circuit of the power transistor 6 receives signals about

The use of additional filtering elements is in place. The presence of reactive circuit elements — chokes of capacitors and transformers operating at an increased frequency (10-20 kHz) has practically no effect on the weight and size of the power supplies. The consumption of sinusoidal currents and the absence of low-frequency pulsations in the output voltage cause good electromagnetic compatibility of the power supply with the mains and the load.

Therefore, the task of creating a power supply with improved electromagnetic compatibility and

the reference voltage U ,, 25 is proportional to the phase voltage of the supply mains U, which is removed from the voltage divider 1, as well as signals proportional to the input current ig |, rn, from the shunt 3. 30 Control circuit (Fig. 3) contains 18 and 19 allocation circuits of the reference voltage and voltage proportional to the input current, the comparison circuit 20, the amplifying element

the reference voltage U ,, 25 is proportional to the phase voltage of the supply mains U, which is removed from the voltage divider 1, as well as signals proportional to the input current ig |, rn, from the shunt 3. 30 Control circuit (Fig. 3) contains 18 and 19 allocation circuits of the reference voltage and voltage proportional to the input current, the comparison circuit 20, the amplifying element

By using high weight and size parameters, using the structural scheme-35, the gain factor kj, remo (figure 1) can be reduced to the ground element 22, the power amplifier 23.

The circuits, 18 and 19, implemented, for example, on the basis of operational amplification of individual semiconductor converters, for each phase of the network, implementing the required law

changes in the input current with a constant voltage, make the module modulate the resulting voltage on the output signals that are received during the course. The shape of the output component at the inputs of the comparison circuit 20, and the current in such a converter (the current signal goes to the subtracter, for phase A) is the expression input. A differential signal 11 is generated at the output of the comparison circuit 45

/ and, I - / igj Gsch | arriving at the input of the amplifying element 21, the output of the latter has a difference signal and (1i, | -fie, r, /) - k, by which, consequently, the operation of the relay element 22 the transfer characteristic of which must have a hysteresis. Relay output

Rsh 1 Gin1n, t L 1n /,

n p: l-з-- - ° J t -cos2 (ot). (8)

Each separate converter almost repeats the nature of the instantaneous power change at the input. The addition of three currents, taking into account the phase shift, gives a nonmemical value of both the power and the load current. Fig. 2 shows the curves of the phase voltage of the network, constituting the load currents, the consumed phases of the network, the instantaneous

55

element, a signal is formed, the temporal ratios of the pulse and pauses of which are proportional to the magnitude of the difference signal Uj, the matching of the high-resistance output of the relay element with the input circuit of the power transistor

53026

power of network phases, as well as total values of load currents, voltage and load power. The latter are constant.

The Converter operates as follows.

The principle of operation of the converter is based on the accumulation of energy in the magnetic field of the core of the input throttle 2 with the subsequent transfer of the accumulated energy to the load. At the same time, due to a change in the ratio of the duration of the accumulation intervals and

With the energy output, it is possible to control the flow of energy between the supply network and the output of the converter. The presence of throttle on the input circuit. causes a continuous current consumption of 20, as required for the operation of the converter.

the reference voltage U ,, proportional to the phase voltage of the supply mains U, which is removed from the voltage divider 1, as well as signals proportional to the input current ig |, rn, from the shunt 3. The control circuit (Fig. 3) contains circuits 18 and 19 allocation of reference voltage and voltage modules proportional to the input current, comparison circuit 20, amplifying element

  a gain factor kj ,, a relay element 22, a power amplifier 23.

55

element, a signal is formed, the temporal relationship of the pulse and pause is proportional to the magnitude of the difference signal Uj. The high-impedance output of the relay element is matched with the input circuit of the power transistor by means of a power amplifier.

Let at some instant of time the instantaneous value of the input current becomes less than the magnitude of the reference voltage and., From divider 1. In this case, a positive differential signal is generated at the output of the comparison circuit and causing the power to unlock the transformer with the network and

transistor 6 (Fig.1 and 3), which leads to an increase in the input current of the converter and the accumulation of energy in the magnetic field Drossel 2.

When the current signal exceeds the reference voltage at the output of the comparison circuit, a negative difference signal -U is generated, which causes the power transistor 6 to lock up. In this case, the energy accumulated in the magnetic field of the throttles 2 causes the current to flow, charging the smoothing capacitor 8. Diode 7 serves prevention of damage

load due to consumption from each phase of a network of currents, the shape of which practically repeats the shape of the applied sinusoidal voltage. In addition, in the proposed converter, the use of low-frequency filter elements is not required due to the fact that the instantaneous power at both the input and output

The 20 converter does not depend on time. At the same time, there is no need for additional devices for matching with the supply network and the load, or network protection means (filters) against the influence of

the capacitor 8 through the power transis-25 electromagnetic interference arising

torus 6 on the intervals of its open state.

Thus, in the converter circuit of each channel, the current consumed from the mains is monitored continuously, the form of which, due to the high switching frequency of the power transistor 6, practically repeats the shape of the reference voltage.

The output DC outputs of the converters of each of the channels through the high-frequency inverter 9, transformer 10 and rectifier 11 are connected to the output pins 16 and 17 of the converter. At the same time, due to the mains consumption of each of the sinusoidal input currents by the converter, low-frequency pulsations are absent in the output voltage and current. High-frequency pulsations are smoothed with capacitor B.

To stabilize the output voltage, an output voltage sensor 12 is used, connected between output terminals 16 and 17. When the output voltage deviates from the nominal values, the sensor

thirty

35

with the consumption of impulse currents, which significantly improves the mass and mass parameters and allows to significantly improve the network operation mode, power factor, power quality parameters, and favorably affects the work of other power consumers.

Claims (1)

Invention Formula A constant-voltage converter with a transformerless input, containing three 40 channel channels, each of which It is equipped with two input and two output terminals, while the same input terminals are connected to the corresponding three-phase phases 45 of the network, other similar input terminals are connected to the zero wire of the network, and the same output terminals of the channels are interconnected to form output terminals of the converter, each of the channels contains a rectifying bridge, the negative DC terminal of which is connected to the smoothing capacitor to which the input 12 are connected, forms electrically, gg, the outputs of the voltage inverter, the output of the output outputs, the signals of which are controlled, through a high-frequency transformer, are connected to the inputs of the output rectifier, the DC outputs of which form none that go to the control inputs of 15 dividers 1 voltage of all channels, cause a change in the value the reference voltage, in accordance with the expression (6) changes the value of current and power consumed from the network. Thus, the use of additional elements and circuits in each channel of the converter makes it possible to significantly improve the electromagnetic load by consuming from each phase a network of currents, the shape of which practically repeats the shape of the applied sinusoidal voltage. In addition, in the proposed converter, the use of low-frequency filter elements is not required due to the fact that the instantaneous powers at both the input and output the converter is not time dependent. At the same time, there is no need for additional devices for matching with the supply network and the load, or network protection means (filters) against the influence of with the consumption of impulse currents, which significantly improves the mass and mass parameters and allows to significantly improve the network operation mode, power factor, power quality parameters, and favorably affects the work of other power consumers. Invention Formula A constant-voltage converter with a transformerless input, containing three channels, each of which It is equipped with two input and two output terminals, while the same input terminals are connected to the corresponding three-phase phases networks, other like input pins are connected to the zero wire of the network, and the same output pins of channels are interconnected to form the output pins of the converter, each of the channels containing a rectifying bridge, the negative DC terminal of which is connected to the smoothing condensate pins of the channel, different the fact that, in order to improve the electromagnetic compatibility of the converter with the power supply network and improve its mass and size parameters, each channel is additionally equipped with a control an input voltage divider connected between the input terminals of the channel, a high frequency choke and a shunt, each of which is connected between the corresponding input channel output and the AC output of the rectifying bridge, a power transistor with a control circuit connected between the DC terminals of the rectifying bridge, moreover, the inputs of the control circuit are connected respectively. R f tffCp RAI-NL and. with the output of the controlled input voltage divider connected to the shunt, the output of a rectifying bridge and the output of the control circuit is connected to the base of the power transistor, by a semiconductor diode connected in the conductive direction between the positive DC output of the rectifying bridge and the other output of the smoothing capacitor, while the converter is additionally equipped with a common for all channels output voltage sensor connected between the output terminals of the converter, the sensor output being connected to the control inputs of the input voltage divider of each channel. rAW e () l / w (rig 2. srig.Z