RU2497266C2 - Voltage converter control method, and device for its implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in the proposed method based on pulse width modulation of supply voltage with a key element, an error signal is calculated, a saw-tooth signal of sweep with amplitude proportional to difference of voltages on inductance of a filter throttle before and after switching of the key element and offset by the value proportional to voltage on inductance of the filter throttle after switching of the key element is shaped; a control signal is shaped from sum of the error signal and the sweep signal; the key element is switched by synchronising and control signals, and the error signal is shaped proportional to energy balance between current value of energy stored by the filter and its value at the specified output voltage. In the proposed device there is a sweep unit, a key element, a summation assembly and an RS trigger; an error unit and current sensors are introduced.

EFFECT: performing high quick action and non-periodic nature of a transient process in a voltage converter with pulse width modulation.

2 cl, 2 dwg

Description

The present invention relates to electrical engineering and is intended for use in sources of secondary power supply devices of radio engineering, automation and computer technology.

A known relay method for controlling a voltage converter, which consists in switching the key element by changing the sign of the energy balance between the current value of the energy stored by the filter and its value at a given output voltage [1].

Moreover, the law of switching control of the key element corresponds to the expression

$$\begin{array}{l}{F}_{\mathrm{uh}}=C\left(U_n^2-U_{\mathrm{about}P}^2\right)+L{\left(I_L-I_n\right)}^{2}SGN\left(I_L-I_n\right);\left(\mathrm{one}\right)\\ F_{\mathrm{to}}=\{\begin{array}{c}\mathrm{one}PR\mathrm{and}{F}_{\mathrm{uh}}+\alpha <0{\dot{F}}_{\mathrm{uh}}<0\\ 0PR\mathrm{and}{F}_{\mathrm{uh}}-\alpha >0{\dot{F}}_{\mathrm{uh}}>0\end{array}\end{array}$$

where F _e - control signal; U _n , U _op - output and specified voltage; L, C is the inductance of the inductor and the capacitance of the filter capacitor; (I _L -I _n ) is the capacitor current; I _L is the inductor current; I _n - output current; α is the hysteresis value; F _to - a signal that controls the state of the key element (when F _to = 1 is on, when F _to = 0 off).

The regulator of the voltage converter that implements the known relay control method comprises a summing unit and two nodes for calculating the current values, respectively, the energy of the pulsating component of the current of the filter choke and the energy required by the filter capacitor to achieve a given output voltage.

The first input of the first calculation node is connected to the output of the current sensor included in the filter reactor circuit, the second input of the first calculation node is connected to the output of the current sensor included in the load circuit, the first input of the second calculation node is connected to the output terminal of the voltage converter, the second input of the second calculation node connected to the output voltage of the job, the outputs of both nodes of the calculation are connected to the inputs of the summation node, the output of the summation node is connected to the control input of the key element of the voltage converter I [1].

In the known device, the switching of the key element is carried out in accordance with the sign of the current value of the equation of the energy balance of energy stored in the elements of the LC filter, and its value at a given voltage, which ensures the minimum duration and aperiodic nature of the transition process.

However, since the energy balance values are proportional to the second degree of the voltage and current of the filter capacitor, the switching frequency of the key element varies over a wide range, which affects the electromagnetic compatibility of the equipment.

The closest technical solution, selected as a prototype, is a method of controlling a DC-voltage converter based on pulse-width modulation of the supply voltage with a key element, namely, that a mismatch signal is calculated as the difference between the system output signal and the reference signal, and a sawtooth scan signal is generated with an amplitude proportional to the voltage difference across the inductance of the filter inductor before and after switching the key element and offset by the voltage at the inductance of the filter inductor after switching the key element, the control signal is formed from the sum of the mismatch signal and the sweep signal, the switching of the key element is carried out by synchronizing and control signals [2].

The known control method performs switching of the key element of the Converter in accordance with the law of the form

$$\begin{array}{l}{F}_{\mathrm{at}}=x+K_{\mathrm{from}}{Y}_R;\\ Y_R=\frac{\mathrm{one}}{T}{\displaystyle \underset{0}{\overset{t}{\int }}\left(U_L^{\text{'}\text{'}}-U_L^{"}\right)}dt+U_L^{"};\left(2\right)\\ F_{\mathrm{to}}=\{\begin{array}{c}\theta PR\mathrm{and}t<t_{\mathrm{to}};\\ \overline{\theta }PR\mathrm{and}t>t_{\mathrm{to}},\end{array}\end{array}$$

, $$U_L^{"}$$

- напряжения на индуктивности дросселя до и после коммутации ключевого элемента; Т - длительность периода коммутации; F_к - сигнал, переключающий ключевой элемент (при F_к=1 включено, при F_к=0 выключено); t_к - момент коммутации ключевого элемента определяется корнем уравнения F_у=0 (при модуляции заднего фронта если $${\dot{F}}_{у}<0$$

, принимая $$U_L^{\text{'}}=U_{п}-U_{оп}$$

, $$U_L^{"}=-U_{оп}$$

, θ=1, при модуляции переднего фронта если $${\dot{F}}_{к}>0$$

, принимая $$U_L^{\text{'}}=-U_{оп}$$

, $$U_L^{"}=U_{п}-U_{оп}$$

, θ=0,); U_п - напряжение питания.where F _y is the control signal; x = U _n -U _op - the error signal; U _n , U _op - output and specified voltage; Y _p - scan signal; K _with - coupling coefficient;

, $$U_L^{"}$$

- voltage on the inductance of the inductor before and after switching the key element; T is the duration of the switching period; F _to - a signal that switches the key element (when F _to = 1 is on, when F _to = 0 off); t _to - the moment of switching of the key element is determined by the root of the equation F _y = 0 (when modulating the trailing edge if $${\dot{F}}_{\mathrm{at}}<0$$

, taking $$U_L^{\text{'}\text{'}}=U_P-U_{\mathrm{about}P}$$

, $$U_L^{"}=-U_{\mathrm{about}P}$$

, θ = 1, when modulating the leading edge, if $${\dot{F}}_{\mathrm{to}}>0$$

, taking $$U_L^{\text{'}\text{'}}=-U_{\mathrm{about}P}$$

, $$U_L^{"}=U_P-U_{\mathrm{about}P}$$

, θ = 0,); U _p - supply voltage.

The closest technical solution, selected as a prototype, is a voltage converter, the regulator of which contains a scan unit, a comparison unit, a summing unit and an RS-trigger, the scan unit has three inputs, the first input of the scan unit is connected to the voltage input of the voltage converter, the second input the scan unit is connected to the output of the reference signal, the third input of the scan unit is connected to the output of the synchronizing signal, the first input of the comparison unit is connected to the output of the voltage converter, sec the first input of the comparison node is connected to the output of the reference signal, the first input of the summation node is connected to the output of the scan unit, the second input of the summation node is connected to the output of the comparison node, the first input of the RS-trigger is connected to the output of the summation node, the second input of the RS-trigger is connected to the output of the synchronizing unit signal, the RS-trigger output is connected to the control input of the key element of the voltage converter [2].

The known control method is based on the criterion of equality to zero in the steady state of the average value of the voltage across the inductance of the filter inductor during the modulation period, which is realized by generating a scan signal proportional to the average value of the voltage across the inductance of the filter inductor for the modulation period, provided that the key element is switched at the current time, which provides in steady state switching of the key element with a zero value of the error signal in the entire control range.

A disadvantage of the known control method is that it does not guarantee the quality of dynamic characteristics.

The purpose of the invention is to provide high speed and aperiodic nature of the transition process in a voltage Converter with pulse-width modulation.

This goal is achieved due to the fact that in the control method of the DC-voltage converter, based on pulse-width modulation of the supply voltage, the key element, namely, that the mismatch signal is calculated, form a sawtooth sweep signal with an amplitude proportional to the voltage difference across the inductance of the filter inductor to and after switching the key element and offset by a value proportional to the voltage at the inductance of the filter inductor after switching the key of the element, from the sum of the mismatch signal and the scan signal, a control signal is generated, the key element is switched by synchronizing and control signals, while the mismatch signal is formed proportional to the energy balance between the current energy value stored by the filter and its value at a given output voltage, the voltage converter is controlled in accordance with the law of the form

$$\begin{array}{l}{F}_{\mathrm{at}}=F_{\mathrm{uh}}+K_{\mathrm{from}}{Y}_R;\\ F_{\mathrm{uh}}=C\left(U_n^2-U_{\mathrm{about}P}^2\right)+L{\left(I_L-I_n\right)}^{2}SGN\left(I_L-I_n\right);\\ Y_R=\frac{\mathrm{one}}{T}{\displaystyle \underset{0}{\overset{t_R}{\int }}\left(U_L^{\text{'}\text{'}}-U_L^{"}\right)}dt+U_L^{"};\left(3\right)\\ F_{\mathrm{to}}=\{\begin{array}{c}\theta PR\mathrm{and}t<t_{\mathrm{to}};\\ \overline{\theta }PR\mathrm{and}t>t_{\mathrm{to}},\end{array}\end{array}$$

, $$U_L^{"}$$

- напряжения на индуктивности дросселя до и после коммутации ключевого элемента; Т - длительность периода коммутации; t_p=T{t/T} - временная координата для формирования сигнала развертки ({t/T} - дробная часть выражения t/T); F_к - сигнал, переключающий ключевой элемент (при F_к=1 включено, при F_к=0 выключено); t_к - момент коммутации ключевого элемента определяется корнем уравнения F_у=0 (при модуляции заднего фронта если $${\dot{F}}_{у}<0$$

, принимая $$U_L^{\text{'}}=U_{п}-U_{оп}$$

, $$U_L^{"}=-U_{оп}$$

, θ=1, при модуляции переднего фронта если $${\dot{F}}_{к}>0$$

, принимая $$U_L^{\text{'}}=-U_{оп}$$

, $$U_L^{"}=U_{п}-U_{оп}$$

, θ=0,); U_п - напряжение питания.where F _y is the control signal; F _e - the error signal; U _n , U _op - output and specified voltage; Y _p is the sweep signal; L, C is the inductance of the inductor and the capacitance of the filter capacitor; (I _L -I _n ) is the capacitor current; I _L is the inductor current; I _n - output current; $$U_L^{\text{'}\text{'}}$$

, $$U_L^{"}$$

- voltage on the inductance of the inductor before and after switching the key element; T is the duration of the switching period; t _p = T {t / T} - time coordinate for generating a sweep signal ({t / T} - fractional part of the expression t / T); F _to - a signal that switches the key element (when F _to = 1 on, when F _to = 0 off); t _to - the moment of switching of the key element is determined by the root of the equation F _y = 0 (when modulating the trailing edge if $${\dot{F}}_{\mathrm{at}}<0$$

, taking $$U_L^{\text{'}\text{'}}=U_P-U_{\mathrm{about}P}$$

, $$U_L^{"}=-U_{\mathrm{about}P}$$

, θ = 1, when modulating the leading edge, if $${\dot{F}}_{\mathrm{to}}>0$$

, taking $$U_L^{\text{'}\text{'}}=-U_{\mathrm{about}P}$$

, $$U_L^{"}=U_P-U_{\mathrm{about}P}$$

, θ = 0,); U _p - supply voltage.

The essence of the invention lies in the fact that the mismatch signal is formed proportional to the energy balance between the current value of the energy stored by the filter and its value at a given output voltage, and the stability of periodic modes at a pulse-width modulation frequency is ensured by the formation of a sawtooth sweep signal with a slope exceeding the slope of the change mismatch signal

, $${\frac{{\mathrm{BUT}}_R}{T}>\frac{d{F}_{\mathrm{uh}}}{dt}|}_m$$

,

where A _p is the amplitude of the signal K _with Y _p .

To implement the proposed control method, to the regulator of the voltage converter containing the scan unit, the summing unit and the RS-trigger, the first input of the scan unit is connected to the voltage input of the voltage converter, the second input of the scan unit is connected to the output of the reference signal, the third input of the scan unit is connected to the output of the clock signal, the second input of the summing node is connected to the output of the scanner, the first input of the RS-trigger is connected to the output of the summing node, the second input of the RS-trigger is connected to by means of a synchronizing signal, the RS-trigger output is connected to the control input of the key element of the voltage converter, an additional mismatch unit is introduced, which has four inputs, the first input of the mismatch unit is connected to the output of the current sensor included in the inductor circuit, the second input of the mismatch unit is connected to the sensor output the current included in the output circuit of the converter, the third input of the mismatch unit is connected to the output terminal of the voltage converter, the fourth input of the mismatch unit is connected nen a reference signal output, the error output of the unit connected to the first input of the summing node.

Figure 1 shows a diagram of a voltage Converter with a device that implements the proposed control method; figure 2 - time diagrams of signals proportional to the current values of the output voltage U _n , the current of the inductor I _L , the signal switching the key element F _to and the error signal F _e when starting the converter from zero initial conditions and detailed diagrams of the beginning of the slip section (t = 0 , 26-0.36 ms) and steady state (t = 1.9-2.0 ms).

The power part of the voltage Converter (figure 1) consists of a key element 1, inductor 2, diode 3, a capacitor 4, and two current sensors 5 and 6, the second output of the key element 1, the first output of the inductor 2 and the second output of the diode 3 are interconnected , the conclusions of the capacitor 4 are connected to the output bus U _n and to the common bus U ₀ , the current sensor 5 is connected to the inductor circuit 2, the current sensor 6 is connected to the converter output circuit, the control input of the key element 1 is connected to the switching signal bus F _to , the sensor output current 5 is the output I _L , the output of the current sensor 6 - terminal I _n , the first terminal of the key element 1 is connected to the input power bus U _p , the first terminal of the diode 3 is connected to the common bus U ₀ , the second terminal of the inductor is the 2nd output bus U _n .

A device that implements the proposed control method (Fig. 1) consists of a mismatch unit 7 calculating a mismatch signal F _e , a scan unit 8 generating a sawtooth scan signal Y _p , a summing unit 9 that generates a control signal F _y and a trigger 10 that generates a signal F _k , the switching key element 1. The first two inputs of the mismatch unit 7 are connected to the outputs I _L and I _{n of the} current sensors 5 and 6, the third input of the mismatch unit 7 is connected to the output bus U _{n of the} converter, the fourth input of the mismatch unit 7 and p the first input of the scanner 8 is connected to the output voltage setting bus U _op , the second input of the scanner 8 is connected to the input power bus U _p , the third input of the scanner 8 is connected to the synchronization bus F _c , the inputs of the summing unit 9 are connected to the outputs of blocks 7 and 8 , the first input of the trigger 10 is connected to the output of the summing unit 9, the second input of the trigger 10 is connected to the synchronization bus F _c , the output of the trigger 10 is connected to the bus of the switching signal F _to .

The voltage Converter with a device that implements the proposed control method operates as follows: the mismatch unit 7 generates a mismatch signal F _e in accordance with the expression

, $$F_{\mathrm{uh}}=C\left(U_n^2-U_{\mathrm{about}P}^2\right)+L{\left(I_L-I_n\right)}^{2}SGN\left(I_L-I_n\right)$$

,

which is proportional to the energy balance between the current value of the energy stored by the filter and its value at a given output voltage.

The scan unit 8 generates a sawtooth scan signal Y _p in accordance with the expression

, $$Y_R=\frac{\mathrm{one}}{T}{\displaystyle \underset{0}{\overset{t_R}{\int }}\left(U_L^{\text{'}\text{'}}-U_L^{"}\right)}dt+U_L^{"}$$

,

, $$U_L^{"}=-U_{оп}$$

) преобразуют к видуwhich in voltage converters with pulse-width modulation of the trailing edge (for which $$U_L^{\text{'}\text{'}}=U_P-U_{\mathrm{about}P}$$

, $$U_L^{"}=-U_{\mathrm{about}P}$$

) transform to

, $$Y_R=\frac{U_P{t}_R}{T}-U_{\mathrm{about}P}$$

,

, $$U_L^{"}=U_{п}-U_{оп}$$

) - к видуand in voltage converters with pulse-width modulation of the leading edge (for which $$U_L^{\text{'}\text{'}}=-U_{\mathrm{about}P}$$

, $$U_L^{"}=U_P-U_{\mathrm{about}P}$$

) - to the form

. $$Y_R=\frac{-U_P{t}_R}{T}+\left(U_P-U_{\mathrm{about}P}\right)$$

.

At the output of the summing unit 9, a control signal F _{y is formed} in accordance with the expression

F _y = F _e + K _with Y _p ,

wherein K _{s is} selected by condition

, $${\frac{{\mathrm{BUT}}_R}{T}>\frac{d{F}_{\mathrm{uh}}}{dt}|}_m$$

,

where A _p is the amplitude of the signal K _with Y _p .

The trigger 10 turns on the key element 1 when the clock pulse F _c appears and turns it off when the control signal F _{y is} positive.

Figure 2 shows the operation of the control device and the voltage Converter with pulse-width modulation of the trailing edge and with the following parameters: supply voltage U _p = 35 V, a given voltage U _op = 27 V, load resistance R _n = 2.7 Ohm, capacitor capacitance 4-1000 μF, inductor inductance 2-0.1 mH, the amplitude of the sawtooth sweep signal And _p = 1.9 V (K _s = 1.9 / U _p ), the duration of the period of the sweep signal T = 20 μs.

, выходное напряжение $$U_{н}={27}_{+\mathrm{0,005}}^{+0}В$$

, текущее значение энергетического баланса $$F_{э}=-{\mathrm{0,2}}_{-\mathrm{0,005}}^{+\mathrm{0,02}}В$$

, длительность периода модуляции во всех режимах Т=20 мкс.When starting the voltage Converter from zero initial conditions (figure 2) on the plot t from 0 to 265 μs, the current I _{L of the} inductor 2 increases from 0 to 79 A, the output voltage U _n increases from 0 to 11 V, the key element 1 is on (F _k = 1), the current value of the energy balance F _e varies from -0.729 to 0.0012 V; on the plot t from 0.265 to 0.66 ms, the current I _{L of the} inductor 2 decreases from 79 to 9.3 A, the output voltage U _n increases from 11 to 27 V, the amplitude of the change in the current values of the energy balance F _e varies from 6.5 V ( in the range t = 0.34 ÷ 0.36 ms) to 0.13 V (in the section t = 1.14 ÷ 1.16 ms), in the steady state (t> 1.18 μs) the inductor current 2 $$I_L={10}_{-0.7}^{+0.7}A$$

, output voltage $$U_n={27}_{+0.005}^{+0}\mathrm{AT}$$

, the current value of the energy balance $$F_{\mathrm{uh}}=-{0.2}_{-0.005}^{+0.02}\mathrm{AT}$$

, the duration of the modulation period in all modes T = 20 μs.

Thus, the formation of a mismatch signal F _e proportional to the energy balance between the current energy value stored by the filter and its value at a given output voltage provides the minimum duration and aperiodic nature of the transition process in a pulse-width modulated voltage converter. In this case, the maximum value of the static mismatch between the output voltage of the converter and the specified voltage does not exceed the value of the ripple of the output voltage.

LITERATURE

1. Kazantsev Yu.M., Lekarev A.F. The formation of control by the balance of the necessary and accumulated energy in the system // Devices and Systems. Management, control, diagnostics. 2009. No5. S.17-20.

2. RF patent No. 2216764, G05F 1/56, publ. 11/20/2003, Bull. Number 32.

Claims (2)

1. A method for controlling a DC-voltage converter based on pulse-width modulation of the supply voltage by a key element, namely, that a mismatch signal is calculated, a sawtooth waveform with an amplitude proportional to the voltage difference across the inductance of the filter inductor before and after switching the key element is generated, and offset by a value proportional to the voltage at the inductance of the filter inductor after switching the key element, from the sum of the error signal and the signal and the sweeps form a control signal, the switching of the key element is carried out by synchronizing and control signals, characterized in that the mismatch signal is formed proportional to the energy balance between the current energy value stored by the filter and its value at a given output voltage. 2. The control device of the voltage converter, containing a scan unit, a summing unit and an RS-trigger, the scan unit of which has three inputs, the first input of the scanner is connected to the input of the voltage supply of the voltage converter, the second input of the scanner is connected to the output of the reference signal, the third input of the block the sweep is connected to the output of the synchronizing signal, the second input of the summing unit is connected to the output of the scanner, the first input of the RS-trigger is connected to the output of the summing unit, the second input of the RS-trigger is connected with the output of the synchronizing signal, the output of the RS-trigger is connected to the control input of the key element of the voltage converter, to implement the control method according to claim 1, an additional mismatch unit is introduced, which has four inputs, the first input of the mismatch unit is connected to the output of the current sensor included in the inductor circuit , the second input of the mismatch unit is connected to the output of the current sensor included in the output circuit of the converter, the third input of the mismatch unit is connected to the output terminal of the voltage converter, the fourth input of the mismatch unit is connected to the output of the reference signal, the output of the mismatch unit is connected to the first input of the summing unit.

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