RU2779631C1 - Method for controlling a charger of a capacitive energy storage device with a series bridge resonant inverter - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering, in particular, to methods for controlling converters of a capacitive energy storage charger with a series bridge resonant inverter with a transformer, to the secondary winding of which an output rectifier is connected, to the output of which a capacitive energy storage is connected, and can be used in electrophysical installations of various destination, in particular, with high operating voltage. In a method for controlling a charger of a capacitive energy storage device with a series bridge resonant inverter, in addition to the main control pulses, on odd clock periods, additional control pulses are sent to the upper transistors of the inverter racks, and on even clock periods, to the lower rack transistors, which lag behind the main pulses by the sum of the half-cycle durations natural oscillations of the resonant power circuit and the half-cycle of natural oscillations of the resonant circuit formed by the inductance of the power circuit and the reduced capacitance of the secondary winding of the high-voltage transformer.

EFFECT: introduction of additional control pulses makes it possible to reduce the energy intensity, weight, dimensions and cost of the resonant circuit elements, increase the efficiency of the charger and the reliability of its operation.

1 cl, 7 dwg, 1 tbl

Description

The invention relates to the field of electrical engineering, in particular, to methods for controlling a charger of a capacitive energy storage device with a series bridge resonant inverter, a high-voltage transformer, to the output of which a rectifier is connected to the output of which a capacitive energy storage device is connected, and can be used in electrophysical installations for various purposes, with operating voltage of one to tens of kilovolts.

A known method of controlling a charger of a capacitive energy storage device with a series bridge resonant inverter [1, 2, 3], having two racks of two series-connected upper and lower transistors with freewheeling diodes, and an output transformer, to the secondary winding of which an output rectifier is connected, to the output which is connected to a capacitive energy storage device, according to which control pulses with a duration equal to the half-cycle of the natural oscillations of the power resonant circuit of the inverter are simultaneously fed to the control electrodes of the transistors of one diagonal pair of bridge racks, and then, after a clock half-cycle, to the control electrodes of the transistors of another diagonal pair.

The disadvantage of this method is that when the clock frequency decreases in the mode of stabilization of the output voltage of the charger, the induction in the transformer core increases and it saturates. Saturation of the core is accompanied by an increase in the currents of the inverter transistors above operating values, an increase in the voltage on the elements of the resonant circuit and unstable operation of the device. Due to this, the reliability of the chargers with a series bridge resonant inverter that implements this control method is reduced, and their functionality is limited.

This disadvantage is eliminated by the control method [4], according to which, in order to exclude the saturation mode and current overload of power transistors in the voltage stabilization mode of the capacitive energy storage, additional control pulses are applied to the lower transistors of both racks of the bridge resonant inverter with a shift relative to the main ones by half the period corresponding to its nominal clock frequency.

The disadvantage of the known control methods is that in the mode of charging a capacitive energy storage device to a predetermined voltage value, the voltage amplitude on the capacitor of the resonant circuit is twice the voltage of the power source, [2], which increases its energy intensity, weight, dimensions and cost.

In addition, in the current consumed by the bridge resonant inverter, there are intervals of reverse polarity, which leads to an increase in the effective value of the variable component of this current. Since the chargers of capacitive energy storage devices of powerful electrophysical installations are powered from a three-phase industrial network through a three-phase bridge rectifier with a smoothing L - C filter, this increase causes an increase in losses in the filter capacitor, through which the variable component of the consumed current flows. The resource of the filter capacitor is also reduced, the efficiency of the charger and the reliability of its operation are reduced.

These shortcomings are eliminated by the proposed solution.

The problem solved by the proposed method is to reduce the energy consumption, weight, dimensions and cost of the resonant circuit capacitor, as well as reduce losses in the filter capacitor, increase its resource, increase the efficiency of the charger with a series bridge resonant inverter and its reliability.

The technical result of using the proposed method is to reduce the voltage amplitude on the resonant capacitor, equalize the current load of the semiconductor devices of the resonant inverter, reduce the effective value of the current flowing through the charger input filter capacitor, simplify the control device that implements a single inverter control algorithm in all operating modes memory.

This result is achieved by the fact that in the method of controlling the charger of a capacitive energy storage device with a series bridge resonant inverter, having two racks of two series-connected upper and lower transistors with freewheeling diodes, and an output transformer, to the secondary winding of which an output rectifier is connected, to the output of which a capacitive energy storage device is connected, according to which, in all operating modes of the charger, the main control pulses with a duration equal to the duration of the half-cycle of natural oscillations of the power resonant circuit of the inverter are simultaneously fed to the control electrodes of the transistors of one diagonal pair of bridge racks, then, after a clock half-cycle, to the control electrodes of the transistors of another diagonal pair , in addition, at odd clock periods, an additional control pulse is applied to the upper transistor of each rack, which lags behind the main pulse applied to the upper transit side of the other rack, and at even periods of the clock frequency, an additional control pulse is applied to the lower transistor of each rack, which lags behind the main pulse applied to the lower transistor of the other rack, and the lag duration is equal to the sum of the durations of the half-cycle of natural oscillations of the resonant power circuit and the half-period of natural oscillations of the resonant the circuit formed by the inductance of the power circuit and the capacitance of the secondary winding of a high-voltage transformer, reduced to its primary winding.

In FIG. 1 shows the electrical circuit of the charger, where: 1, 2, 3, 4 - transistors; 5, 6, 7, 8 - reverse shunt diodes; 9 - resonant circuit capacitor; 10 - choke of the resonant circuit; 11 - high voltage transformer; 12 - output rectifier; 13 - capacitive energy storage; 14 - self-capacitance of the secondary winding of the high-voltage transformer. In FIG. 1 mains rectifier and L-C smoothing filter not shown.

In FIG. Figure 2 shows diagrams of the operation of the converter with the proposed control method.

- диаграмма тока первичной обмотки трансформатора 11, а также резонансного контура;

- диаграмма напряжения конденсатора 9;

- диаграмма напряжения конденсатора 14;

- диаграмма тока, потребляемого резонансным инвертором;

,

- диаграммы импульсов управления, соответственно, транзисторами 1 и 2 инвертора, образующими первую стойку инвертора;

,

- диаграммы импульсов управления, соответственно, транзисторами 3 и 4, образующими вторую стойку инвертора.The diagrams show:

- current diagram of the primary winding of the transformer 11, as well as the resonant circuit;

- capacitor voltage diagram 9;

- capacitor voltage diagram 14;

- diagram of the current consumed by the resonant inverter;

,

- control pulse diagrams, respectively, by transistors 1 and 2 of the inverter, forming the first rack of the inverter;

,

- diagrams of control pulses, respectively, by transistors 3 and 4, forming the second rack of the inverter.

мкФ; индуктивность дросселя 10 резонансного контура с учетом рассеяния обмоток трансформатора -

мкГн; коэффициент трансформации трансформатора 11 -

; емкость конденсатора 13 -

мкФ; емкость конденсатора 14 -

нФ; тактовая частота преобразователя -

кГц.In FIG. Figure 3 shows diagrams of a charger with a known method for controlling transistors of a resonant inverter, obtained on its simulation model in the MATLAB Simulink environment. The diagrams were obtained with the following model parameters: supply voltage - 500V; capacitor capacitance 9 -

uF; choke inductance 10 of the resonant circuit, taking into account the scattering of the transformer windings -

µH; transformer ratio 11 -

; capacitor capacitance 13 -

uF; capacitor capacity 14 -

nF; converter clock frequency -

kHz.

мкФ; индуктивность дросселя 10 резонансного контура с учетом рассеяния обмоток трансформатора -

мкГн; коэффициент трансформации трансформатора 11 -

; емкость конденсатора 13 -

мкФ; емкость конденсатора 14 -

нФ; тактовая частота преобразователя -

кГц.In FIG. Figure 4 shows diagrams of the charger with the proposed method for controlling the inverter transistors, obtained on its simulation model in the MATLAB Simulink environment. The diagrams were obtained with the following model parameters: supply voltage - 500V; capacitor capacitance 9 -

uF; choke inductance 10 of the resonant circuit, taking into account the scattering of the transformer windings -

µH; transformer ratio 11 -

; capacitor capacitance 13 -

uF; capacitor capacity 14 -

nF; converter clock frequency -

kHz.

A capacitive energy storage charger with a series bridge resonant inverter with the proposed control method according to the description is characterized by the order of operation of transistors and diodes, presented in table 1.

The order of operation of transistors and diodes with the proposed control method

Table 1 Period half cycle Interval 1 Interval 2 Interval 3 Interval 4 Odd 1st fourteen 5, 8 3, 5 - 2nd 2, 3 6, 7 1, 7 - Honest 1st fourteen 5, 8 2, 8 - 2nd 2, 3 6, 7 4, 6 -

To identify the main regularities of the proposed control method, consider the operation of the charger in the first half-cycle of an odd clock period.

Within the considered half-cycle in the operation of the charger in accordance with the table. 1, in the general case, there are four characteristic intervals.

на фиг. 2). Проводят транзисторы 1, 4 и под действием напряжения питания

резонансного инвертора происходит перезарядка конденсатора 9 с начального уровня

до конечного значения

в полярности, показанной на фиг. 2, и зарядка емкостного накопителя 13. Процесс изменения во времени тока

резонансного контура и тока

имеет колебательный характер с собственной круговой частотой

, где L и C - величина индуктивности дросселя 10 и емкости 9, соответственно.First interval (

in fig. 2). Conduct transistors 1, 4 and under the action of the supply voltage

resonant inverter, capacitor 9 is recharged from the initial level

to final value

in the polarity shown in Fig. 2, and charging the capacitive storage 13. The process of changing the current with time

resonant circuit and current

has an oscillatory character with its own circular frequency

, where L and C - the value of the inductance of the inductor 10 and capacitance 9, respectively.

равно напряжению

конденсатора 13. Интервал завершается при достижении током

нулевого значения.Capacitor 14 through open diodes of output rectifier 12 is connected in parallel with capacitor 13 and its voltage

equal to voltage

capacitor 13. The interval ends when the current reaches

zero value.

The mathematical description of the processes in the 1st interval corresponds to the equivalent circuit in Fig. 5.

In the absence of losses in the power circuit, the processes occurring in it in the first interval " j " of the half-cycle of the charger are described by the equation

- величина емкости конденсатора 13, приведенная к первичной обмотке трансформатора 11;

- начальное напряжение конденсатора 9 на 1-м интервале «j» полупериода работы;

- напряжение ЕНЭ, которое на «j» периоде тактовой частоты почти неизменно, так как на практике выполняется соотношениеwhere

- the value of the capacitance of the capacitor 13, reduced to the primary winding of the transformer 11;

- the initial voltage of the capacitor 9 on the 1st interval " j "half-cycle;

- the voltage of the CES, which is almost unchanged on the “ j ” period of the clock frequency, since in practice the relation is fulfilled

- величина емкости конденсатора 14, приведенная к первичной обмотке трансформатора 11.where

- the value of the capacitance of the capacitor 14, reduced to the primary winding of the transformer 11.

Equation (1) can be converted to the form

в контуре и напряжения конденсаторов 9 и 13Solving equation (3), we find the expressions for the current

in the circuit and the voltage of capacitors 9 and 13

,

,

- круговая частота собственных колебаний силового контура на 1-м интервале;

- эквивалентная емкость силового контура, определяемая из выраженияwhere

- circular frequency of natural oscillations of the power circuit in the 1st interval;

- equivalent capacity of the power circuit, determined from the expression

- относительное значение емкости конденсатора 13.

- the relative value of the capacitance of the capacitor 13.

и

.When condition (2) is satisfied, the equalities

and

.

определяется из условия

, в соответствии с которым согласно (4) получаемAngular duration of the first interval

determined from the condition

, according to which, according to (4), we obtain

The voltages on capacitors 9 and 13 by the end of the first interval will take on the values

на фиг. 2). (Проводят диоды 5 и 8) К моменту времени

сумма напряжений (

) превышает напряжение источника питания

и при снижении тока

до нуля отпираются обратные диоды 5, 8. Под действием суммы напряжений (

) происходит колебательный процесс перезарядки конденсатора 14 через дроссель 10, конденсатор 9 и цепь питания инвертора. При этом токи

и

меняют свою полярность. Напряжение конденсатора 14 на этом интервале изменяется от напряжения

до напряжения

, равного

.Second interval (

in fig. 2). (Conduct diodes 5 and 8) By the time

sum of stresses (

) exceeds the power supply voltage

and with decreasing current

reverse diodes 5, 8 are unlocked to zero. Under the action of the sum of voltages (

) there is an oscillatory process of recharging the capacitor 14 through the inductor 10, the capacitor 9 and the inverter power circuit. At the same time, the currents

and

change their polarity. The voltage of the capacitor 14 in this interval varies from the voltage

up to voltage

equal to

.

круговая частота процесса определяется по формуле

. Так как с момента начала перезарядки конденсатора 14 его напряжение становится менее напряжения конденсатора 13, то диоды выпрямителя 12 закрыты, и ток через конденсатор 13 на данном интервале не протекает.On condition

the circular frequency of the process is determined by the formula

. Since from the moment the capacitor 14 begins to recharge, its voltage becomes less than the voltage of the capacitor 13, the rectifier diodes 12 are closed, and the current through the capacitor 13 does not flow in this interval.

ток

снижается до нуля, а сумма напряжений (

) становится меньше напряжения источника питания

, и второй интервал заканчивается.At the point in time

current

decreases to zero, and the sum of stresses (

) becomes smaller than the power supply voltage

, and the second interval ends.

The second interval " j " of the half-cycle of the charger corresponds to the equivalent circuit in Fig. 6 and the following differential equation

Solving equation (11), under conditions (2) and (10), we obtain

- круговая частота собственных колебаний силового контура на 2-м интервале.where

- circular frequency of natural oscillations of the power circuit in the 2nd interval.

определяется из условия

, в соответствии с которым согласно (12) получаемAngular duration of the second interval

determined from the condition

, according to which, according to (12), we obtain

и

на конденсаторах 9, 13 и 14 к концу второго интервала при условии (2) примут значенияVoltage

and

on capacitors 9, 13 and 14 by the end of the second interval under condition (2) will take on the values

отпирают транзистор 3, и начинается 3-й интервал работы ЗУ.At the end of the 2nd interval at time

transistor 3 is unlocked, and the 3rd interval of the memory operation begins.

на фиг. 2). (Проводит транзистор 3 и диод 5). На 3-м интервале происходит колебательный разряд конденсатора 9 с начального напряжения

до напряжения

с круговой частотой

по контуру (фиг.1), включающему в себя элементы 9 - 5 - 3 - 11 - 10 - 9, и подзарядка конденсатора 13. Напряжение

конденсатора 14 при этом равно

. В момент времени

ток

колебательного контура достигает нуля и интервал завершается. На третьем интервале ток

, потребляемый инвертором, равен нулю.Third interval (

in fig. 2). (Conducts transistor 3 and diode 5). On the 3rd interval, an oscillatory discharge of the capacitor 9 occurs from the initial voltage

up to voltage

with circular frequency

along the contour (figure 1), which includes elements 9-5-3-eleven-ten-9, and recharging the capacitor 13. Voltage

capacitor 14 is equal to

. At the point in time

current

the oscillatory circuit reaches zero and the interval ends. On the third interval, the current

consumed by the inverter is zero.

The replacement circuit of the memory at the 3rd continuity interval is given in Fig. 7.

The mathematical description of the 3rd interval has the form

также определяется из условия

, в соответствии с которым и формулой (19) получаемThe duration of the third interval

is also determined from the condition

, according to which and formula (19) we obtain

The voltages on the capacitors 9, 14 by the end of the third interval reach the values

Expressions (23), (24) taking into account (2) will take the form

на фиг. 2). Здесь полупроводниковые приборы ток не проводят и напряжения

и

сохраняют свои значения:

,

. Этот интервал завершает первый полупериод

тактовой частоты. Длительность бестоковой паузы определяется значением тактовой частоты зарядного устройства. При выборе тактовой частоты из условияFourth interval 4 (

in fig. 2). Here, semiconductor devices do not conduct current and voltage

and

keep their values:

,

. This interval completes the first half cycle

clock frequency. The duration of the dead time is determined by the value of the clock frequency of the charger. When choosing a clock frequency from the condition

,

- частоты собственных колебаний силового контура на 1-м и 2-м интервале, бестоковая пауза отсутствует.where

,

- frequencies of natural oscillations of the power circuit on the 1st and 2nd intervals, there is no dead pause.

, на первом интервале которого проводят транзисторы 2 и 3, затем диоды 6 и 7, потом транзистор 1 и диод, 7 и затем после очередной бестоковой паузы первый (нечетный) период тактовой частоты завершается.Next, in the operation of the charger, the second clock half-cycle follows.

, on the first interval of which transistors 2 and 3 are conducted, then diodes 6 and 7, then transistor 1 and diode 7 , and then after the next dead pause, the first (odd) period of the clock frequency ends.

After that, the second (even) clock period begins, the processes at the intervals of which are of an identical nature, and the order of operation of transistors and diodes corresponds to Table 1.

The voltage on capacitor 9 by the end of the first clock half-cycle, taking into account formulas (9), (16), (25), will take on the value

From expressions (28) and (9) we find the initial and amplitude on the clock half-cycle voltage of the capacitor 9

равное

. При этом полярность напряжения

противоположна полярности напряжения

в начале этого интервала (фиг. 2).According to expressions (17) and (30), the voltage of the capacitor 14 at the end of the 2nd interval is

equal

. In this case, the polarity of the voltage

opposite voltage polarity

at the beginning of this interval (Fig. 2).

It follows from formula (30) that with the proposed control method, the voltage amplitude across the capacitor 9 of the resonant circuit does not depend on the voltage of the capacitive energy storage and is equal to the voltage of the power source, which is two times less than with the known control method.

The largest average value of the consumed current over the period of natural oscillations of the power circuit, excluding the relatively short duration of the 2nd interval and the absence of a dead pause at the highest clock frequency, is determined by the formula

- ток, протекающий в контуре на 1-м интервале «j» полупериода работы ЗУ, величина которого определяется из выражения (4).where

- the current flowing in the circuit at the 1st interval " j " of the half-cycle of the memory, the value of which is determined from expression (4).

By integrating, we get

Substituting expression (29) into (32), we find the final expression for calculating the average value of the input current of the charger

The highest average value of the reduced output current of the charger (capacitive energy storage charging current) is calculated by the formula

- ток, протекающий в контуре на 3-м интервале «j» полупериода работы ЗУ, величина которого определяется из выражения (19).where

- the current flowing in the circuit on the 3rd interval " j " of the half-cycle of the memory, the value of which is determined from the expression (19).

From expressions (33) and (34) it follows that the memory with the proposed control method, as well as with the known method [1, 2, 3], is a source of direct current, the value of which is determined by the supply voltage and the parameters of the power circuit.

The nature of the time dependences of the smooth (averaged over a half-cycle values) components of the current and voltage of the CES is identical to the same dependences with a known control method [2, 3].

и согласно (34) определяется по формулеThe maximum value of the charging power occurs at the end of the charge cycle under the condition

and according to (34) is determined by the formula

The average value of the charging power per cycle will be

согласно (36) требуется вдвое увеличить емкость конденсатора 9 и с учетом того, что

, вдвое уменьшить индуктивность дросселя 10.From expressions (35) and (36) it follows that the average value of the charging power with the proposed control method is two times lower than in the known control method [2]. To maintain the same average value of the charging power at the same value of the circular frequency

according to (36), it is required to double the capacitance of the capacitor 9 and taking into account the fact that

, halve the inductance of the inductor 10.

When implementing the known control method, the energy capacity of the capacitor 9, according to what is stated in [2], is equal to

With the same average value of the charging power in the case of the implementation of the proposed control method, the required energy capacity of the capacitor 9 will be

Comparison of expressions (37) and (38) shows that the proposed control method makes it possible to halve the required energy capacity of the resonant circuit capacitor compared to the known method.

, что и при известном способе управления [3]. Так как требуемая индуктивность дросселя при предлагаемом способе управления меньше в два раза, чем при известном способе, то энергоемкость дросселя 10 резонансного контура, рассчитываемая по формулеUnder these conditions, according to (4) and (29), the largest amplitude of the current of the power circuit has the same value equal to

, as with the known control method [3]. Since the required inductance of the choke with the proposed control method is two times less than with the known method, the energy capacity of the choke 10 of the resonant circuit, calculated by the formula

with the proposed method of control is also reduced by half.

According to expressions (4), (12), (29), (30) the ratio of the amplitudes of the currents (figure 2) in the second and first interval (figure 2) is determined by the formula

which, according to condition (2), implies the inequality

From inequality (41), as well as from the diagrams in Fig. 4 it follows that the current consumed by the inverter is practically unidirectional, which reduces the effective value of its variable component and reduces losses in the input filter capacitor. This reduces the heating of this capacitor, increases its resource and increases the reliability of the memory.

Sources of information

1. Kopelovich E.A., Vanyaev V.V., Troitsky M.M., Khvatov S.V., Flat F.A. Transistor-capacitor chargers for megajoule capacitive energy storage // Electrical Engineering, No. 7, 2010. - p. 11-16.

2. Oh J. S., Jang S. D., Son Y. G., Cho M. H. Development and application of an inverter charging supply to a pulse modulator // Proc. of LINAC Gyeongju, Korea 2002. pp. 207-209.

3.H.R. Hafezi, S.J. Mousavi, M. Barati, and M.H. Rahdan Design and Construction of 30 kV Capacitor Charger Using of Series Resonant Converter // Pulsed Power Technology. pp. 296 - 299.

4. Vanyaev V.V., Kopelovich E.A. Electromagnetic processes in a charger based on a series resonant inverter // Electrical Engineering, No. 9, 2021.- p.73-79.

Claims (1)

A method for controlling a charger of a capacitive energy storage device with a series bridge resonant inverter having two racks of two series-connected upper and lower transistors with freewheeling diodes, and an output transformer, to the secondary winding of which an output rectifier is connected, to the output of which a capacitive energy storage device is connected, according to which in the charging mode, the main control pulses with a duration equal to the duration of the half-cycle of natural oscillations of the power resonant circuit of the inverter are simultaneously fed to the control electrodes of the transistors of one diagonal pair of bridge racks, then through a clock half-cycle to the control electrodes of the transistors of another diagonal pair, and in the voltage stabilization mode of the capacitive storage energy, the inverter transistors are supplied with additional control pulses with a duration equal to the duration of the main pulses, characterized in that in all modes of operation of the chargers and on odd clock periods, an additional control pulse is applied to the upper transistor of each rack, which lags behind the main pulse applied to the upper transistor of another rack, and on even clock periods, an additional control pulse is applied to the lower transistor of each rack, which lags behind the main pulse supplied to the lower transistor of another rack, and the duration of the lag is equal to the sum of the durations of the half-cycle of natural oscillations of the resonant power circuit and the half-cycle of natural oscillations of the resonant circuit, formed by the inductance of the power circuit and the capacitance of the secondary winding of the high-voltage transformer, reduced to its primary winding.

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