RU2767315C1 - Power supply system of pulse power amplifier - Google Patents

Abstract

FIELD: power electronics.

SUBSTANCE: invention relates to the field of power electronics and can be used for power supply of power amplifiers of pulse modes of operation in transmitting devices of sonar stations for illumination of a nearby situation. A power supply system for a pulsed power amplifier with voltage stabilization and current limitation for forward and reverse power transmission is proposed, which contains a charger (1), a capacitive storage (2), a key converter (3), a filter (4) along the power supply buses of a pulse amplifier (7), a current sensor (8), also a voltage feedback circuit (6), a current feedback circuit (9) and a control circuit (5). The control circuit includes a pulse-width converter (5.1), a balanced adder (5.2), threshold amplifier (5.3) of the current feedback signal, a subtractor (5.4) providing comparison of control signals and voltage feedback, the output of which is connected through a two-sided limiter (5.5) to the direct input of a balanced adder connected by an inverse input to the output of the threshold amplifier (5.3), and the output through a pulse-width converter (5.1) with the control input of the reverse key amplifier. The use of voltage and current feedbacks with specified modes of a double-sided limiter and a threshold amplifier when using a reversible key amplifier with pulse-width modulation made it possible to minimize energy losses, including with dynamic control of the voltage level of the power supply of the pulse amplifier. This ensures voltage stabilization in the nominal operating mode and eliminates the extreme modes of overcharging the capacitive storage and filter by limiting the maximum current.

EFFECT: limiting the maximum value of the overcharge current and excluding extreme impulse currents that affect the decrease in the reliability of the power supply system.

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Description

The invention relates to the field of power electronics and can be used mainly for the power supply of power amplifiers of pulsed modes of operation in transmitters of sonar stations (SLS) for illumination of the near situation (NBO).

It is known that the high requirements for the tactical, technical and operational performance of modern GLS OBO should be ensured by the use of complex probing signals generated by hydroacoustic phased antenna arrays (PAR) in pulsed operating modes [Aleksandrov V.A., Smirnov V.A., Ermolaeva E.Yu., Ignatiev K.V. Digital generator devices for sonar lighting stations in the near area // Hydroacoustics 2018, No. 33, p. 70-77]. At the same time, the output power of the PAR excitation can reach units and tens of kW, with a duration of emission cycles of a unit and tens of ms, which makes it possible to use capacitive energy storage devices to minimize the maximum power consumption and dimensions of the transmitting equipment. The frequency range of the GLS OBO, as a rule, is tens of kHz with a relative bandwidth of no more than an octave. Accordingly, pulsed power amplifiers of this mode should be equipped with a capacitive filter on the power supply buses, the presence of which is a necessary condition for their operation, especially with the essentially reactive nature of the impedance of hydroacoustic emitters with an active power factor of not more than 0.3-0.5.

The technical requirements for the GLS transmitting equipment are in many ways similar to the requirements for radio transmitters of radar circuits (RLS), which also use capacitive energy storage devices to provide pulsed operating modes [Shumilin M.S., Golovin O.V., Sevalnev V.P. and other radio transmitting devices. M.: Higher school, 1981, RF patent No. 2465627. Constant voltage stabilizer. Published October 27, 2012].

However, the power supply of a pulsed power amplifier directly from a capacitive storage device has a number of significant drawbacks, namely: a decrease in the power supply voltage level and, accordingly, the output signal level in the radiation cycle, the inability to dynamically control the level and shape of the output signal envelope by changing the power supply voltage. The latter circumstance significantly limits the dynamic range of regulation of the output power of the pulse amplifier and can lead to noticeable energy losses in the transmitting equipment in the nominal modes of PAR excitation.

A power supply device is known, including a charger, a capacitive storage device and an adjustable pulse converter [Kushnerev N.A. Power supply device for a pulsed solid-state transmitter with high specific performance // Radio engineering. 2009. No. 5]. The advantage of this scheme is the ability to regulate the power supply voltage of the power amplifier during the radiation cycle, regardless of the change in voltage on the capacitive storage. As a result, a large discharge is allowed, which makes it possible to significantly reduce the capacitive dimensions of storage capacitors while reducing energy losses in the pulse amplifier. A disadvantage of the known device is the limited rate of reduction of the power supply voltage. Taking into account a very small current in the pause between radiation cycles, limiting the rate of decrease in the power supply voltage prevents a dynamic decrease in the power level, which significantly worsens the performance characteristics of the GLS.

The closest technical solution, chosen as a prototype, is the power supply system of a pulse amplifier described in RF patent 2629788, published in BI No. 1 on 09/01/2017. In the prototype device, in contrast to the previously given analogue for powering a switching power amplifier from a capacitive storage, it is proposed to use a reverse switching voltage converter that provides forced discharge of the filter's dynamic capacitance, which fundamentally improves the dynamic characteristics of regulation.

The prototype device (Fig. 1) contains a charger 1 (memory 1), a capacitive storage 2 (EN 2), a key converter 3, a low-pass filter 4 (LPF 4), a control circuit 5, a voltage feedback circuit 6 (OSN 6) and a pulse power amplifier 7 (PA 7). Moreover, the key converter 3 is made on power switches that provide a controlled charge and discharge of the capacitance of the low-pass filter 4 in accordance with the signal at the output of the control circuit 5 from the condition of stabilizing the power supply voltage of the PA 7 at a level determined by the signal coming from the control bus. Thus, in the prototype device, a given level of power supply voltage of the switching power amplifier is provided with the possibility of a rapid rise and fall of the voltage with a wide range of voltage changes of the EH 2 capacitive storage.

At the same time, the dynamic control of the power supply voltage in the prototype device is associated with an almost unlimited amplitude of the charge and discharge current, which leads to a decrease in reliability and a deterioration in the energy efficiency of the known power supply system of a switching power amplifier.

The identified shortcomings are due to transient processes of dynamic change in the filter capacitance voltage.

However, in this case, despite the increase in energy losses, in the prototype device, there is a multiple excess of the amplitude of the output current of the key converter 3 compared to the maximum current consumption of the PA 7. Especially critical is the long time required to discharge the filter capacitance for the transmitting equipment of the GLS , where a significant level of power of the channels of pulse amplifiers that provide excitation of hydroacoustic phased arrays is combined with stringent requirements for overall dimensions with significant margins for the use of power switches in terms of current.

The objective of the invention is to improve the reliability and energy efficiency of the power supply system of a pulsed power amplifier while expanding the area of use.

The technical result of the invention is to limit the maximum value of the overcharge current, and the exclusion of extreme pulsed currents that affect the decrease in the reliability of the power supply system.

The technical result is achieved by the fact that in a known power supply system of a switching power amplifier, containing a charger connected by input to the power supply bus, and by output through a capacitive storage to the input of the key converter, the output of which is connected to the input of the low-pass filter, and the control input of the key converter is connected to the output of the control circuit, the control input of which is connected through a voltage feedback circuit to the output of the low-pass filter and to the power supply bus of the switching power amplifier, and the input is connected to the control bus, by means of the fact that new features have been introduced into its composition, namely: a current sensor is introduced, and the control circuit contains a pulse-width converter, a balanced adder, a threshold amplifier, a subtractor and a two-way limiter, and the L-input of the low-pass filter is connected through the current sensor to the output of a key converter made on a reversible key power amplifier, in the over In turn, the output of the current sensor through the current feedback circuit is connected to an additional control input of the control circuit, connected through a threshold amplifier to the first input of the balanced adder, the output of which is connected to the input of the pulse-width converter, and the second input is connected to the output of the subtractor through a two-way limiter. device, the first input of which is connected to the control input of the control circuit, and the second input - to the input of the control circuit, the output of which is connected to the output of the pulse-width converter.

In the proposed power supply system (PSS), the implementation of the claimed technical result is provided by a set of newly introduced blocks and connections. The increase in reliability is achieved by limiting the maximum value of the direct and reverse current of the charge and discharge of the filter capacitance while maintaining deep feedback on the output voltage in nominal operating modes through the use of a subtractor, a two-way limiter of the difference signal in voltage and feedback in current through a threshold amplifier, and as well as a balanced adder that generates the resulting signal for controlling the pulse-width converter in the voltage stabilization and current limiting modes of the key converter. In this case, the reduction of energy losses is achieved by performing a key converter on a highly efficient reversible key signal power amplifier with pulse-width modulation. In turn, the increase in the reliability and energy efficiency of the PSS makes it possible to extend the applicability of the proposed technical solution for high-power transmission paths used in the SFS OBO.

The essence of the invention is illustrated in Fig. 1-4, which shows a block diagram of the claimed prototype device (Fig. 1), a block diagram of the claimed device (Fig. 2) and timing diagrams explaining its operation (Fig. 3, Fig. 4) with discrete control of the signal level of a pulse amplifier power.

The structural diagram of the proposed device (Fig. 2) contains a charger 1 (memory 1), a capacitive storage (EN 2), a key power amplifier 3, a current sensor 8 (DT 8), a low-pass filter 4 (LPF 4), a control circuit 5 , including a subtractor 5.4 (VU 5.4), a pulse-width converter 5.1 (SHIP 5.1), a balanced adder 5.2 (BS 5.2), a threshold amplifier 5.3 (PU 5.3), a two-way limiter 5.5 (TO 5.5), as well as a feedback circuit 6 voltage (OSN 6), current feedback circuit 9 (OST 9) and switching power amplifier 7 (PA 7).

To explain the principle of operation of the proposed technical solution in the mode of forming the envelope signal PA 7 in Fig. 3 illustrates the timing diagrams of signals with the following symbols:

U _OC - signal circuit OSN 6, given to the first input VU 5.4;

V _OC - signal at the output of the two-way limiter 5.5 with a limit threshold V _{OC max} and V _{OC min} maximum and minimum levels;

i _OC - circuit signal OST 9, reduced to the input of the threshold amplifier PU 5.3 sensitivity thresholds I _{OC max} and I _{OC min} for positive and negative signal values;

I _OC - signal at the output of the threshold amplifier PU 5.3 with a dead zone: at I _{OC max} > i _OC > I _{OC min} , I _OC = 0;

U _p - the resulting difference signal at the output of the balanced adder BS 5.2;

V _p - reference sawtooth voltage of the clock frequency ƒ _t in PWM 5.1 to form a sequence of pulses based on the result of comparison with the signal U _p ;

V _PWM - a sequence of voltage pulses with pulse-width modulation PWM, generated at the output of the KUM 3, the amplitude of which is determined by the voltage E of the capacitive storage.

U - power supply voltage UM 7.

In the timing diagrams shown in Fig. 4, the following signal designations are accepted:

V _y - control signal with discrete levels V ₁ , V ₂ , V ₃ ;

E - the voltage of the capacitive carrier 2, changing relative to the nominal value of E ₀ from the minimum E _min to the maximum E _max values;

U - power supply voltage of the pulse power amplifier 7;

U _HF - the voltage of the output high-frequency signal of a discrete level U1, U ₂ , U ₃ generated PA 7 to excite the channel of the radiating antenna;

i is the output current of the KUM 3 in radiation cycles with discrete values of I ₁ , I ₂ , I ₃ and in the intervals for recharging the capacitor LPF 4 through the input inductor when the level U changes with a maximum current limit I _m (without limitation - dotted lines).

All structural blocks included in the proposed SEP are performed according to known rules, and their combined use leads to the claimed technical results.

The charger 1 is performed in the same way as in the prototype device with the mode of limiting the charge current and stabilizing the maximum voltage on the capacitive storage 2. When power is supplied from the site network, it is advisable to perform the charger on the basis of key voltage converters with transformer isolation, for example, made according to bridge circuit, or half-bridge circuit.

Capacitive storage 2 is a set of electrolytic capacitors connected in series-parallel, the switching circuit of which provides adaptation to a given maximum voltage E _max at the required capacitance necessary for energy support of the operation of a pulsed power amplifier for a given duration t _and and signal power P _max in the radiation cycle in conditions of the established off-duty ratio of excitation of the radiating antenna. So, for example, for a rated voltage E=250 V with a permissible discharge ΔE=50 V under the conditions of the given values P _max =1 kW and t _{and rnax} =0.2 s, the storage capacity must be provided at least:

Moreover, with a decrease in the allowable discharge during the pulse, the required capacitance and, accordingly, the dimensions of the EH 2 storage device increase significantly.

Key Converter 3 is a circuit reversible key power amplifier (KUM), made, for example, on the rack of powerful field-effect transistors with their own freewheeling diodes included in the half-bridge circuit. A reversible AFB of this type has high energy efficiency at very high switching frequencies and functions as a pulsed voltage generator. At the same time, through the key converter 3, depending on the difference between the average value of the pulse voltage and the voltage on the capacitance of the low-pass filter 4, a current of various directions can be closed, both from the capacitive storage EH 2 through the low-pass filter 4 to the consumer PA 7, and from the capacitance of the low-pass filter 4 in EH 2 capacitive storage if it is necessary to quickly reduce the voltage E in conditions of energy recovery.

LPF 4 contains a choke with inductance L _f and a capacitor with capacitance c _f , the output of which is connected to the power supply bus PA 7, and L is the input (choke input L _f ) to the output of switching converter 3. The choice of capacitance LPF c _f is determined from the condition of effective short circuit of the variable current consumption of the pulsed power amplifier UM 7 For the GLS of the OBO mode with a minimum operating frequency ƒ _p of excitation of the channel of the hydroacoustic phased array at a maximum power consumption of 1.0 kW from a stabilized voltage E _c = E _min = 200 V, the capacitance of the low-pass filter 4 must be at least:

where ƒ _p =10 kHz - maximum operating frequency;

X _c =0.1E _c /i _prnax - output impedance of the LPF 4 at the operating frequency (i _pmax - the amplitude of the maximum AC consumption PA 7).

As a result, for i _prnax =P _max /E _c we get the value with _f =1 mF. It should be noted that the overcharging of such a capacitance with a change in the power supply voltage of the PA 7 in accordance with the control signal leads to significant transients with extreme current values through the key converter 3.

To limit the recharge currents, high-frequency control of the parameters of the pulsed voltage at the L-input of the low-pass filter 4 using pulse-width modulation (PWM) is used. At a PWM frequency ƒ ₀ significantly (more than 5 times) higher than the operating frequency ƒ _p UM 7, smooth regulation of the output voltage of the low-pass filter 4 can be ensured while limiting the high-frequency current of the filter inductor. The inductance of the inductor L _f ultimately determines the time constant τ _f LPF 4, limiting the dynamic characteristics of the PDS.

The minimum value of the inductance L _f is selected from the condition of limiting the maximum amplitude of the RF current through the inductor at the level:

For the accepted values: i _max =5 A; E _max =300 V; ƒ ₀ \u003d 100 kHz - we get the value L _min \u003d 150 μH, which corresponds to the time constant:

Accordingly, the cutoff frequency of the LPF-4 filter will be

The presented assessment of the capacitance and inductance parameters LC LPF 4 confirms the possibility of dynamic regulation of the voltage of the power supply PA 7 with the setting of the required value for 3-5 periods of the operating frequency, which is acceptable for the implementation of the GLS of the OBO mode. At the same time, the proposed technical solution implements restrictions on the extreme currents of recharging the capacitance c _f at an acceptable level exceeding the maximum current consumption of PA 7 by no more than (30-50)%. Such a limitation, which is an integral part of ensuring the reliable operation of the PDS, is achieved by the appropriate implementation of the control circuit 5 using newly introduced blocks (Fig. 2): PWM 5.1, BS 5.2, PU 5.3, VU 5.4, TO 5.5.

Pulse-width converter SHIP 5.1 must ensure the formation of a sequence of pulses V _PWM with a frequency of ƒ ₀ to control the key converter 3. A typical implementation of SHIP 5.1 is based on the use of a sawtooth symmetrical reference voltage generator V _p comparator, which provides the formation of a PWM signal based on the result of comparing voltage V _p frequency ƒ ₀ with the resulting difference signal U _p (Fig. 3), including dynamic changes in the control signal V _y , taking into account the feedback signals for voltage U _OC and current i _OC (Fig. 3).

The subtractor 5.4, which provides the formation of the signal difference U _OC as the difference between the signals V _y and u _OC (Fig. 3), VU 5.4 is performed on a differential amplifier, the gain K _U of which determines the depth of the voltage feedback.

When the signal U _OC exceeds the set limits for changing U _OCrnax and U _OCmin , the signal level is limited, as illustrated in FIG. 3. This limiting function is performed by a two-sided limiter 5.5, which can be performed, for example, on two zener diodes connected through a limiting resistor in parallel with the output of VU 5.4. The nature of limiting the output signal of VU 5.4 during the formation of a difference voltage signal at the signal output of DO 5.5 is illustrated in Fig. 3 and corresponds to the following condition:

where U _OCmax , U _OCmin - the limits of the maximum and minimum limits TO 5.5.

Threshold amplifier 5.3 is designed to transmit a feedback signal for current i _OC when its level exceeds the maximum allowable values of the forward current I _OCmax and reverse I _OCmin directions. PU 5.3 can be performed on a typical operational amplifier with a gain K _I with sequential switching off of limiting stabilizers. In this case, the output signal I _OC of the threshold amplifier is determined by the relation:

The principle of operation of CP 5.3 is illustrated by the timing diagrams of the signals at the input i _OC and at the output I _OC shown in Fig. 3.

Balance adder 5.2 is designed to generate the resulting difference signal U _p in accordance with the expression:

BS 5.2 can be implemented on a differential amplifier with a gain K _p . If necessary, BS 5.2 input signals can be transmitted through resistive dividers that change the resulting feedback signal transmission coefficients for voltage K _OCU and current K _OCI :

where K _ΔI , K _ΔU - division ratios of the signals U _OC and I _OC at the inputs of the BS 5.2.

The description of the blocks from the composition of the declared PSS of a pulsed power amplifier confirms the practical feasibility of the proposed technical solution.

The claimed device works as follows.

The voltage of the power supply through the charger 1 provides the charge of the capacitive storage 2 to the nominal value of the voltage E _n =E ₀ in the preparation of the MIND 7 to work. At the same time, the input control signal V _y is supplied through the subtractor 5.4 and the two-way limiter in the form of a signal U _OC to the direct input of the balanced adder 5.2. As a result, at the input of the pulse-width converter 5.1, a signal U _p of a large level is generated, which leads to switching of the key converter 3 in accordance with the signal V _PWM . At the same time, through the current sensor 8 and the inductor L _f LPF 4, the current of the capacitor charge c _f is closed. As the voltage U increases at the output of the low-pass filter 4, the signal u _OC increases at the output of the OOS circuit, which leads to a decrease in the signal U _OC and, accordingly, U _p to the level of stabilization of the output voltage of the low-pass filter

where β _U is the transmission coefficient of the OSN 6 circuit.

The accuracy of the stabilization of the output voltage of the LPF 4 is determined by the depth of the voltage feedback, which is set by the value of K _OCU , usually reaching 20-30 dB. At the same time, in the nominal mode of operation under conditions i _OC <I _OCmax (i _OC >I _OCmin ), the current feedback does not affect the formation of the resulting difference signal (the signal at the output of the threshold amplifier I _OC = 0), which makes it possible to increase the voltage stability under conditions changes in the output current of the key converter 3.

At the same time, when recharging the capacitor c _f LPF 4, there is an increase in the direct or reverse output current of the KUM of the set values: i _OC >I _OCmax - for direct current; i _OC <I _OCmin ^_ for reverse current. In this case, a signal I _OC is generated at the output of the threshold amplifier, which is fed to the inverse input of the BS 5.2 and changes the level U _p (Fig. 4: decrease when the capacitor is charged under conditions i _OC >I _OCmax ; increase when the capacitor is discharged under conditions i _OC <I _OCmin ). Accordingly, when the control signal V _y changes, the voltage U _OC at the output of the subtractor device changes sharply, however, its value is limited by the two-sided limiter 5.5 and then does not affect the formation of the resulting difference signal U _p , which allows switching to the mode of limiting the output current of the switching converter 3.

Следует отметить, что передача и возврат энергии между емкостным накопителем и емкостью c_ф ФНЧ 4 через ключевой преобразователь 3 и дроссель L_ф осуществляется без существенных переходных процессов и потерь энергии при высоких динамических характеристиках регулирования напряжения U электропитания импульсного усилителя 7 мощности в соответствии с сигналом управления V_y (фиг. 4). Причем быстрый спад напряжения U достигается в том числе и во время паузы импульсов излучения U_ВЧ (фиг. 4).The output current feedback depth in this mode is determined by the K _OCI value and is at least 30 dB. This achieves the limitation of the output current I _OC (Fig. 4) in the forward and reverse directions at the maximum allowable level. As a result, the recharge time t _p of the capacitor c _f LPF 4 can be minimized in accordance with the filter time constant

It should be noted that the transfer and return of energy between the capacitive storage and the capacitance c _f LPF 4 through the key converter 3 and the inductor L _f is carried out without significant transients and energy losses with high dynamic characteristics of voltage regulation U of the power supply of the pulse power amplifier 7 in accordance with the control signal V _y (Fig. 4). Moreover, a rapid drop in voltage U is also achieved during a pause of radiation pulses U _RF (Fig. 4).

Thus, the proposed technical solution meets the requirements of dynamic control of the power supply voltage of the power amplifier in pulsed operating modes with discrete and continuous control of the excitation level of the radiating antenna. At the same time, unlike the prototype device, the proposed PDS achieves a limitation of the maximum value of the overcharge current, and excludes experimental pulsed currents that affect the decrease in reliability.

As shown in FIG. 4, the maximum level of recharging currents when stabilizing the output current of the CCM (solid lines) is a multiple of the pulse currents in the prototype device (dashed lines) and slightly exceeds the maximum output current I _C in radiation cycles by 20-30%. The relative energy losses in the claimed device are mainly determined by the losses in the key power amplifier and do not exceed 10% of the maximum power consumption of the switching power amplifier.

The achieved energy efficiency is significantly higher than in known devices, where the use of dissipative links to reduce transients can lead to relative losses of more than 20%.

Improving the energy efficiency and reliability of the proposed power supply system of a pulsed power amplifier is ensured by the introduction of the proposed technical solution in the transmission paths of the FLS of the OBO mode. At present, the enterprise has manufactured experimental samples of the power supply device for ultrasonic range power amplifiers of pulsed operating modes, the results of which confirmed the advantages of the proposed technical solution, which makes it possible to recommend the developed technical solution for use in prototypes of FLS OBO.

Claims (1)

The power supply system of a switching power amplifier, containing a charger connected by input to the power supply bus, and by output through a capacitive storage to the input of a key converter, the output of which is connected to the input of a low-pass filter, and the control input of the key converter is connected to the output of the control circuit, control input which, through a voltage feedback circuit, is connected to the output of the low-pass filter and to the power supply bus of the power amplifier, and the input is connected to the control bus, characterized in that a current sensor is introduced into its composition, and the control circuit contains a pulse-width converter, a balanced adder, a threshold amplifier, a subtracting device and a two-sided limiter, and the L-input of the low-pass filter is connected through a current sensor to the output of a key converter made on a reversible key power amplifier, in turn, the output of the current sensor through a current feedback circuit is connected to an additional control device control circuit connected through a threshold amplifier to the first input of a balanced adder, the output of which is connected to the input of a pulse-width converter, and the second input through a two-way limiter is connected to the output of a subtractor, the first input of which is connected to the control input of the control circuit, and the second input - to the input of the control circuit, the output of which is connected to the output of the pulse-width converter.

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