RU2465711C1 - Transistor voltage converter - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: transistor voltage converter, comprising a power transformer (PT), a load, a magnetisation current sensor (MCS), the first and second supply inputs, the first and second power switches (PS), emitters of which are connected with the first supply input, there is a threshold device (TD) introduced, a converter output voltage sensor (OVS) magnetically coupled with the PT, the first and second summator, a peak detector (PD), an integrator, besides, the OVS output is coupled with the first inlet of the first summator, the outlet of which is connected via the integrator with the first inlet of the second summator, the outlet of which is coupled via the TD by control inlets of the first and second PS, at the same time the MCS outlet via the PD is coupled with the second inlet of the first summator, and also with the second inlet of the second summator, the first and second inlets of MCS are coupled accordingly with the end of the first and start of the second windings of the PT, the third and fourth inlets of the MCS are connected accordingly with the start of the third PT winding and the load, the fifth and sixth inlets of the MCS are coupled accordingly with the outlet of the first and second PS, the end of the third PT winding is coupled with the load, the start of the first and end of the second PT windings are coupled with the second inlet of supply, the start of the converter OVS winding is connected with the first supply inlet.

EFFECT: higher efficiency of a converter through reduction of magnetisation current.

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Description

The invention relates to a conversion technique and can be used in DC power converters and secondary power sources.

A device for controlling magnetic induction when converting the supply voltage (RF patent No. 2134012) containing a Hall sensor located in the gap of the inverter power transformer is known. The Hall sensor controls the duration and duty cycle of the pulses supplied to the power switches of the converter, fixing the degree of saturation of the core. With a glut, the duty cycle of the pulses increases.

This device has a low accuracy of balancing when working on the saturation border of a power transformer (CT) converter. At the moment of saturation of the core of the CT converter, when the relative magnetic permeability μ decreases from 2000 ... 3000 (ferrites) to 1, a small change in the induction B, according to the private magnetization reversal loop, corresponds to a large increase in the magnetization current i ₀ (field strength in the core N):

Where

l is the length of the midline of the core, m;

w is the number of turns, pcs.

This leads to large magnetization current pulses at the moments of switching the power switches of the inverter and, consequently, to a decrease in the efficiency of the converter.

A device for balancing [a.s. No. 1495963] CT inverter with a sinusoidal output voltage obtained using pulse-width modulation, which, in addition to correcting the pulse width of the pulse-width modulator by the magnitude of the magnetic circuit induction, uses a signal of the difference of the average for the period of the primary currents proportional to the magnetization current.

This technical solution leads to a decrease in the efficiency of the inverter or its failure for the following reasons:

1. The correction signal for the bias current is calculated as the average value for the period and, therefore, the balancing circuit has a speed that is insufficient to maintain small values of the magnetization current in transients, which reduces the efficiency.

2. With bilateral saturation of the core, the inverter efficiency will also decrease, because the correction signal for the bias current in this mode is 0.

3. When generating a correction signal for the bias current, the secondary current of the inverter CT is not taken into account, which reduces the accuracy of balancing, and therefore, the efficiency of the inverter, in particular with an asymmetric load.

Known voltage converters [US Pat. RF №2331961] with balancing ST on the current of the primary winding. In such converters, the maximum value of the magnetization current is equal to the maximum value of the reduced load current, which reduces the efficiency of the converter, in particular with a variable load.

Known transistor voltage Converter [Glibitsky MM, Mezenina N.S. Method for limiting one-sided saturation of transistor transformer transformer. // Electronic technology in automation. Ed. Yu.I. Koneva. - M.: Soviet Radio, 1978. - issue. No. 10. - p.122-124], taken as a prototype, with the limitation of saturation of the CT converter using a magnetization current signal measured by a transformer with three primary windings according to the expression:

Where

i ₁ is the current of the primary winding ST, A;

- приведенный ток вторичной обмотки, А.

- reduced current of the secondary winding, A.

The disadvantage of the prototype is that when the magnetizing current exceeds the maximum value in one arm, the duration of the on state of the transistor in the other arm is not adjusted, which reduces the efficiency of the converter.

The aim of the invention is to increase the efficiency of the Converter by reducing the magnetization current.

This is achieved by the fact that a threshold device, an output voltage sensor, magnetically coupled, are introduced into the transistor voltage converter containing a power transformer, a load, a magnetization current sensor, first and second power inputs, first and second power switches, the emitters of which are connected to the first power input with a power transformer, the first and second adders, a peak detector, an integrator, and the output of the output voltage sensor is connected to the first input of the first adder, the output of which is connected via an integrator nen with the first input of the second adder, the output of which through a threshold device is connected to the control inputs of the first and second power switches, while the output of the magnetization current sensor through a peak detector is connected to the second input of the first adder, as well as to the second input of the second adder, the first and second inputs magnetization current sensors are connected respectively to the end of the first and the beginning of the second windings of the power transformer, the third and fourth inputs of the magnetization current sensor are connected respectively to the beginning of the third the windings of the power transformer and the load, the fifth and sixth inputs of the magnetization current sensor are connected respectively to the outputs of the first and second power switches, the end of the third winding of the power transformer is connected to the load, the beginning of the first and the end of the second windings of the power transformer are connected to the second power input, the beginning of the output sensor winding voltage is connected to the first power input.

Figure 1 presents a diagram of the inventive transistor voltage Converter, figure 2 - waveforms of his work.

The transistor voltage Converter (figure 1) contains CT 1, load 2, magnetization current sensor (DTN) 3, the first negative and second positive power inputs, the first 4 and second 5 power switches (SC), the emitters of which are connected to the first power input, threshold device (PU) 6, output voltage sensor (DVN) 7, magnetically coupled to CT 1, first 8 and second 9 adders, peak detector (PD) 10 and integrator 11, the output of DVN 7 of the converter connected to the first input of the first 8 adder whose output is connected through an integrator 11 with the first Odom second adder 9, whose output is connected via IP 6 to the control inputs of the first 4 and second 5 SC SC, the output 3 through the DST PD 10 is connected to a second input of the first adder 8, and also to a second input of the second adder 9; the first and second inputs of DTN 3 are connected respectively to the end of the first and the beginning of the second windings CT 1, the third and fourth inputs of DTN 3 are connected respectively to the beginning of the third winding of ST 1 and load 2, the fifth and sixth inputs of DTN 3 are connected respectively to the output of the first 4 SK and the second 5 SK, the end of the third winding CT 1 is connected to the load 2, the beginning of the first and the end of the second winding CT 1 are connected to the second power input, the beginning of the winding DVN 7 is connected to the first power input.

The transistor voltage Converter operates as follows. Conversion of the DC voltage of the power source into alternating voltage supplied to the load 2 is carried out by changing the polarity of the voltage applied to the CT 1, by switching the first 4 SK and the second 5 SK. The duration of switching on the first 4 SK and the second 5 SK is set by PU 6, and the presence of a pulse at the output of PU 6 corresponds to switching on the first 4 SK, pause to turning on the second 5 SK.

Consider the formation of control pulses at the output of PU 6 (Uout1, figure 2). PU 6, made, for example, in the form of a Schmitt trigger, has a relay characteristic with hysteresis. The pulses at its output are formed in such a way that when the core of CT 1 is saturated, the polarity of the voltage applied to CT 1 changes, i.e. magnetization direction ST 1 along the hysteresis loop. For this, the output signals of DVN 7 and PD 10 are summed by the first 8 adder, integrated by the integrator 11, the integration result from the output of the integrator 11 is added to the output signal of the DTN 3 using the second 9 adder. The output signal of the second 9 adder is compared with the threshold voltage set by the PU 6. If the threshold voltage and the total signal from the output of the second 9 adder are equal, the state at the output of the PU 6 changes and the first 4 SK and second 5 SK switch corresponding to this change. There is a change in the polarity of the voltage applied to ST 1 and the direction of magnetization changes.

Consider the switching control of the first 4 SC and the second 5 SC by induction of the field in the core CT1. At the output of DVN 7 (Uout2) a signal is generated proportional to the output voltage of the converter. The phase matching of the DVN 7 and DTH 3 signals is provided by connecting the beginning of the DVN 7 winding to the first power input. The output signal DVN 7 is supplied to the first input of the first 8 adder, and from its output to the input of the integrator 11. At the output of the integrator 11, a signal is generated proportional to the magnetic induction in the core CT 1:

where S is the cross-sectional area of the core ST 1, m ² ;

u _DVN (t) - alternating voltage at the output of DVN 7, V;

U ₀ - residual voltage at the output of the integrator 11, V;

w ₁ - the number of turns of each of the primary half windings CT 1, pcs;

k _DVN - transmission coefficient DVN 7, defined as follows:

where w _DVN - the number of turns of the winding DVN 7, pcs.

The output signal of the integrator 11 is supplied to the first input of the second 9 adder, from the output of which the signal is fed to the input of the control unit 6 (Uout3 - voltage at the input of the control unit 6). With symmetrical operation of the converter, the time interval during which the core CT 1 is magnetized is reversed from the induction value -B _max to + B _max is equal to half the period of operation of the converter;

Where

U _m - the amplitude of the alternating voltage at the output of the DVN 7, Century

Thus, the voltage at the output of the integrator 11 during the T / 2 should change by an amount equal to the difference between the switching levels of the PU 6. The optimal value of the upper switching level of the PU 6 (U1) should correspond to the value of the magnetic induction + B _max , the lower switching level of the PU 6 ( U2) - the value of the magnetic induction -B _max . The voltage at the output of the integrator 11 changes linearly when exposed to a rectangular signal DVN 7. When it reaches the value U1, PU 6 switches to the state "log 1" (time t ₂ , t ₄ ). If the voltage at the output of the integrator 11 is less than U2, the control unit 6 switches to the “log 0” state (time instants t ₃ , t ₅ ). At the moment of changing the polarity of the voltage applied to the primary winding of CT 1, the sign of the voltage at the output of DVN 7 is reversed by switching the first 4 SK and second 5 SK converter. The voltage at the output of the integrator 11 starts to fall if the PU 6 has switched to the state "log 0", or to increase if the PU 6 has switched to the state "log 1".

Thus, at the output of PU 6, a train of pulses is formed that determines the duration of the first 4 SK and second 5 SK.

An additional correction of the balancing of the operating mode of CT 1 is carried out by introducing into the feedback loop the measured value of the magnetization current, proportional to the field strength in the core of CT 1, which is formed at the output of DTN 3 (Uout4). The formation at the output of the DTN 3 signal proportional to the magnetization current is ensured by the fact that the first and second inputs of the DTN 3 are connected respectively to the end of the first and the beginning of the second windings CT 1, the third and fourth inputs of the DTN 3 are connected respectively to the beginning of the third winding CT 1 and load 2 , the fifth and sixth inputs of DTN 3 are connected respectively to the outputs of the first 4 SK and the second 5 SK.

. Далее на интервале

напряжение на выходе интегратора 11 будет уменьшаться под действием напряжения ДВН7.The signal from the output of the DTN 3 is fed to the second input of the second 9 adder and added to the output voltage of the integrator 11. If there is a signal at the output of the accident 3, the PU 6 switches before the measured induction reaches ± B _max . Let, for example, by the time moment t _2, CT 1 core enter saturation, and a signal will appear at the output of DTN 3, the amplitude of which will be enough to increase the voltage at the input of PU 6 to the value U1. This will cause the switching of PU 6 and will lead to a change in the direction of magnetization CT 1, the output of CT 1 from saturation and a decrease in the magnetization current, and, consequently, a decrease in the signal at the output of DTN 3 to the state “log. 0 ”by time

. Further on the interval

the voltage at the output of the integrator 11 will decrease under the action of the voltage DVN7.

Consider the operation of a transistor voltage converter taking into account PD 10. PD 10 has a discharge time constant equal to 2 ... 3T and a dead zone of width ΔU, due to the presence of a threshold voltage of diodes from the composition of PD 10. The input of the PD 10 receives the instantaneous value of the magnetization current from the output of DTN 3 The output signal of the PD 10 (Uout5) is added to the output signal of the DVN 7 using the first 8 adder, and the total signal is fed to the input of the integrator 11. At the output of the PD 10, a signal is generated that regulates the duration of the half-periods of operation photoelectret depending on the maximum period for the magnetizing current.

выходное напряжение ПД 10, изменяя наклон выходного напряжения интегратора 11, задерживает уменьшение выходного напряжения интегратора 11 до значения U2 на время

а на интервале времени

ускоряет увеличение выходного напряжения интегратора 11 до значения U1 на время

. Таким образом, выходной сигнал ПД 10 регулирует длительность полупериодов работы преобразователя. При этом длительность следующего за насыщением СТ 1 полупериода увеличивается, длительность полупериодов, в которых наблюдалось насыщение СТ 1, сокращается. Ток намагничивания СТ 1 становится более симметричным, потери в преобразователе уменьшаются.Consider the time t ₂ . The voltage pulse at the output of DTN 3 charges a capacitor from the composition of PD 10. The total effect of the output voltages of DTN 3 and PD 10 leads to an increase in the output voltage of the integrator 11 to the value U2. This causes the switching of PU 6, a change in the direction of magnetization CT 1, the output of CT 1 from saturation, a decrease in the magnetization current, and, consequently, a decrease in the signal at the output of the accident 3. At the time interval

the output voltage of the PD 10, by changing the slope of the output voltage of the integrator 11, delays the decrease in the output voltage of the integrator 11 to the value U2 for a while

and in the time interval

accelerates the increase in the output voltage of the integrator 11 to the value of U1 for a while

. Thus, the output signal PD 10 regulates the duration of the half-cycles of the Converter. In this case, the duration of the half-period following the saturation of CT 1 increases; the duration of the half-periods in which CT 1 is saturated is reduced. The magnetization current CT 1 becomes more symmetrical, the losses in the converter are reduced.

.In the absence of PD 10, the magnetization current, for example, in the interval t ₃ -t ₄ would increase to a larger value than in the interval t ₂ -t ₃ , since the core saturation state exited at a time

.

Thus, increasing the accuracy of balancing is achieved by the fact that PD 10, remembering the pulses of the magnetization current, “expands” them, raises the gain of the circuit, reducing the error in balancing the magnetization current, and, as a result, the efficiency of the transistor converter increases.

Introduction to the transistor converter of the control loop by induction of the field in the core of CT 1 increases the efficiency of the transistor converter and the accuracy of balancing, since the switching of the PU 6 occurs according to the sum of the induction signals and the magnetization current, i.e. at lower magnetization currents. At the same time, the speed of the converter increases, since the switching of power switches takes place in a shorter time.

DTN 3 measures the magnetization current CT 1 and can be performed, for example, according to [Glibitsky MM, Mezenina N.S. Method for limiting one-sided saturation of transistor transformer transformer. // Electronic technology in automation. Ed. Yu.I. Koneva. - M.: Soviet Radio, 1978. - issue. No. 10. - p.122-124]. In this version, DTN 3 is a transformer with three primary windings. The first and second primary windings of DTN 3 are connected in series with one of the primary half-windings of CT 1 so that the current of the first 4 SC flows through the first primary winding of DTN 3 during one half-cycle, and the current of the second 5 through the second primary winding of DTN 3 during the second half-cycle SK. The third primary winding of DTN 3 is connected in series with the secondary winding of CT 1. The first and second primary windings of DTN 3 contain one turn, the number of turns of the third primary winding of DTN 3 is equal to the transformation coefficient CT 1.

DVN 7 can be made in the form of a winding CT 1.

PD 10 can be implemented, for example, according to [Gusev V.G., Gusev Yu.M. Electronics. M .: Higher. Shk., 1991 - p.622, Fig.6.53b].

This transistor voltage converter was manufactured at the enterprise and passed tests with positive results.

Claims (1)

A transistor voltage converter comprising a power transformer, a load, a magnetization current sensor, first and second power inputs, first and second power switches, the emitters of which are connected to the first power input, characterized in that a threshold device, an output voltage sensor, a magnetic connected to the power transformer, the first and second adders, a peak detector, an integrator, and the output of the output voltage sensor is connected to the first input of the first adder, the output of which is through the integrator is dined with the first input of the second adder, the output of which through a threshold device is connected to the control inputs of the first and second power switches, while the output of the magnetization current sensor through a peak detector is connected to the second input of the first adder, as well as to the second input of the second adder, the first and second inputs magnetization current sensors are connected respectively to the end of the first and the beginning of the second windings of the power transformer, the third and fourth inputs of the magnetization current sensor are connected respectively to the beginning of the third the windings of the power transformer and the load, the fifth and sixth inputs of the magnetization current sensor are connected respectively to the outputs of the first and second power switches, the end of the third winding of the power transformer is connected to the load, the beginning of the first and the end of the second windings of the power transformer are connected to the second power input, the beginning of the sensor winding output voltage is connected to the first power input.

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