CN102647076B - Method for reducing output voltage ripples of Boost power electronics inverter - Google Patents

Abstract

The invention provides a method for reducing output voltage ripples of a Boost power electronics inverter. The method comprises the following steps of: firstly calculating a current reference value Iref and then calculating a voltage reference value Vref; then calculating a minimal load resistance value Rmin and determining a ripple voltage Vripple; and finally on the premise that the load resistance of the convertor is greater than the Rmin, controlling a switch of the convertor as follows: measuring an output voltage vC, measuring an inductive current iL, and when the vC is less than the reference voltage Vref and the iL is less than or equal to zero, controlling the switch to be switched on; and measuring the inductive current iL, and when the iL is greater than the reference current Iref, controlling the switch to be switched off. The method provided by the invention has the beneficial effects of quickening the output voltage response speed of the convertor and reducing the output voltage ripples of the convertor.

Description

Reduce the method for Boost converters output voltage ripple

Technical field

The invention belongs to electrical energy changer field, relate to a kind of converters method for handover control, in order to reduce converters output voltage ripple under switching controls.

Background technology

Electric energy is the most important energy form of modern society, and converters is realized electric energy and converted, and is the key device that electric energy effectively utilizes.Converters had both had the discrete event that switching device turns on and off, has again in switch continually varying state variable during in particular state, and be a typical hybrid system.Hybrid system refers to by continuous variable system and discrete event dynamic system and interacts and the unified dynamical system that forms.Under each switching state, circuit may be linear, nonlinear but the switching of switch becomes whole system.Traditional converters control adopts and small signal linearization method average based on state to obtain ignoring the model of on off state mostly, realize again the control of switch converters according to modelling controller, this method for designing tries hard to ignore the switching of switch, can not truly reflect the operating state of real system, in the time of signal wide variation, can there will be unstable.The modeling that utilizes Hybrid System Theory to carry out converters can truly reflect the operating state of variator, and according to the hybrid model CONTROLLER DESIGN explicit physical meaning of converter, controller is relatively simple.But the switch controller according to Hybrid System Theory design is generally open loop control, and control performance has much room for improvement.

Summary of the invention

The present invention has provided a kind of method of utilizing feedback thought to reduce Boost converters switching controls output voltage ripple, to overcome the large shortcoming of existing control method control output voltage ripple.

The technical solution adopted in the present invention, a kind of method that reduces Boost converters output voltage ripple, the method based on Boost converters comprise input DC power E, inductance L, diode D, switch S, capacitor C and load R; The positive pole of input DC power E is by the first resistance r of series connection _lmeet respectively the second resistance r with inductance L _dwith the 3rd resistance r _s, the 3rd resistance r _sconnect with switch S, switch S connects the negative pole of input DC power E, the second resistance r _dd connects with diode, and the negative pole of diode D meets respectively the 4th resistance r _cwith one end of load R, the 4th resistance r _cconnect with capacitor C, the negative pole of another termination input DC power E of the negative pole of capacitor C and load R;

Reduce the method for Boost converters output voltage ripple, concrete steps are:

Step 1, calculates current reference value I _ref, its formula is as follows:

$I_{\mathrm{ref}}=\sqrt{\frac{2C}{L}{V}_d{v}_{\mathrm{ripple}}}$

Wherein, the capacitance that C is electric capacity, the inductance value that L is inductance, V _dfor the expectation voltage of output, v _ripplefor voltage ripple value;

Step 2, computing reference magnitude of voltage V _ref, its formula is as follows:

$V_{\mathrm{ref}}={2V}_d-V_d\exp \left(\frac{-{\mathrm{LI}}_{\mathrm{ref}}}{E(R+r_C)C}\right)-\frac{v_{\mathrm{<figure-callout\; id="2"\; label="ripple"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">ripple</figure-callout>}}}{2}$

Wherein, the input direct voltage value that E is input DC power, the resistance value that R is load, r _cfor capacitances in series resistance value;

Step 3, computational load resistance minimum value R _min, its formula is as follows:

$R_{\min }=\frac{1}{\sqrt{\frac{2C}{L}(V_d-E)v_{\mathrm{ripple}}}}\frac{({2V}_d-E)V_d}{E}$

Step 4, determines ripple voltage v _ripple, its formula is

ν _ripple＝ν _ripple0+k _p*e+k _i*∫e _dt

Wherein, e=V _d-v _cfor the error of output voltage, v _ripple0for ripple voltage initialization, k _pfor proportionality coefficient, k _ifor integral coefficient, v _cfor output voltage values, t is the time;

Step 5, is greater than R at converter load resistance _minprerequisite under, converter switches is controlled as follows:

5.1 measure output voltage v _c, inductance measuring current i _l, work as v _cbe less than reference voltage V _refand i _lbe less than or equal at 1 o'clock, control switch closure;

5.2 inductance measuring current i _l, work as i _lbe greater than reference current I _reftime, control switch disconnects.

The invention has the beneficial effects as follows, can accelerate the output voltage response speed of converter, and lowered converter output voltage ripple.

Brief description of the drawings

Fig. 1 is Boost converter circuit schematic diagram;

Inductive current waveform and output voltage waveforms when Fig. 2 is Boost converter stable state;

Fig. 3 is that Boost converter operating state is switched schematic diagram;

Fig. 4 adopts fixing ripple set point and the present invention to adopt the simulation result comparison diagram of feedback adjusting ripple set point method;

Fig. 5 is the experimental result comparison diagram that adopts respectively the fixing ripple establishing method of tradition and adopt the inventive method.

Embodiment

1) controlled device is described

As shown in Figure 1, circuit is by input power E for Boost converter circuit, and inductance L, diode D, switch S, capacitor C and load R form, wherein, and inductance L and equivalent the first resistance r _lseries connection, diode D and equivalent the second resistance r _dseries connection, switch S and equivalence the 3rd resistance r _sseries connection, capacitor C and equivalence the 4th resistance r _cseries connection.Can obtain the dynamical equation of Boost converter according to basic laws of circuit

$\stackrel{\&CenterDot;}{X}=A_{k}X+B_{k}U---\left(1\right)$

Wherein X=[x ₁x ₂] ^t=[i _lv _c] ^t, T is for representing vectorial transposition, i _lfor inductive current value, v _cfor output voltage values, A _k, B _kfor sytem matrix and input matrix, k=1,2,3, U=E, E is the input direct voltage value of input DC power E.

Pattern 1: switch S closure; Now converter has two independent loops, and first loop is by DC power supply E, inductance L, the first resistance r _l, closed switch S and the 3rd resistance r _sresistance forms, and in this loop, input DC power E charges to inductance L, inductive current i _lincrease inductance L storage power; Second loop is by capacitor C, the 4th resistance r _cform with load R, in this loop, capacitor C, to load R electric discharge, releases energy;

In pattern 1, sytem matrix and input matrix are respectively:

$A_1=\left[\begin{array}{cc}-\frac{r_L+{\mathrm{<figure-callout\; id="0"\; label="r\; S\; L"\; filenames="HDA0000454210330000021.png,HDA0000454210330000031.png"\; state="\{\{state\}\}">r</figure-callout>}}_S}{L}& 0\\ 0& -\frac{1}{(R+r_C)C}\end{array}\right],{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">B</figure-callout>}}_1\left[\begin{array}{c}\frac{1}{L}\\ 0\end{array}\right]---\left(2\right)$

Pattern 2: switch S disconnects, simultaneously inductive current i _lbe greater than 0; Now on diode D, have forward voltage, in conducting state, therefore the structure of circuit becomes by the capacitor C of connecting and the 4th resistance r _cafter in parallel with load R in again with diode D, the second resistance r _d, inductance L, the first resistance r _lform series loop with DC power supply E, this stage inductance L together with DC power supply E for capacitor C and load R provide energy, inductive current i _lbe reduced to gradually 0;

In pattern 2, sytem matrix and input matrix are respectively:

$A_2=\left[\begin{array}{cc}-\frac{1}{L}[\frac{{\mathrm{Rr}}_C}{R+r_c}+r_d+r_L]& -\frac{R}{R+r_L}\\ \frac{R}{(R+r_C)C}& -\frac{1}{R+r_C}\end{array}\right],{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">B</figure-callout>}}_2=\left[\begin{array}{c}\frac{1}{L}\\ 0\end{array}\right]---\left(3\right)$

Mode 3: switch S disconnects, simultaneously inductive current i _lequal 0; Now on diode D, bear reverse voltage and turn-off, by capacitor C, the 4th resistance r _cform loop with load R, in this loop, capacitor C continues the electric discharge to load R, releases energy, and capacitor C voltage reduces gradually, and this pattern is continued until next switch S closure;

In mode 3, sytem matrix and input matrix are respectively:

$A_3=\left[\begin{array}{cc}0& 0\\ 0& -\frac{1}{(R+r_C)C}\end{array}\right],{\mathrm{<figure-callout\; id="3"\; label="B"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">B</figure-callout>}}_3=\left[\begin{array}{c}0\\ 0\end{array}\right]---\left(4\right)$

In formula (2), formula (3) and formula (4), r _lbe the first resistance r _lresistance value, r _dbe the second resistance r _dresistance value, r _sbe the 3rd resistance r _sresistance value, r _cbe the 4th resistance r _cresistance value, the inductance value that L is inductance L, R is load R resistance value, C is capacitor C capacitance.

Boost converter is operated in pattern 1 situation, and power supply E charges to inductance L, inductive current i _lincrease, inductance L storage power, capacitor C, to load R electric discharge, releases energy; In pattern 2 inductance L together with input DC power E for capacitor C and load R provide energy, inductive current i _lbe reduced to gradually 0; Inductive current i in mode 3 _lbe zero, capacitor C continues the electric discharge to load R, releases energy, and capacitor C voltage reduces gradually.Inductive current i when stable state _lwith output voltage v _cwaveform as shown in Figure 2.

2) switching controls rule

Can sum up easily following several rules by the operating state under each pattern above and stable state inductive current waveform and output voltage waveforms: 1) as inductive current i _lbe greater than reference current I _ref(I _reffor inductive current reference value) time, switch disconnects, and electric route pattern 1 enters pattern 2; 2) as inductive current i _l=0 while output voltage v _cbe greater than V _ref(V _reffor capacitance voltage reference value) time, electric route pattern 2 enters mode 3; 3) as output voltage v _cbe less than V _reftime, switch closure, circuit enters pattern 1 by mode 3; 4) as inductive current i _lbe zero, output voltage v simultaneously _cbe less than V _reftime, switch closure, electric route pattern 2 directly turns back to pattern 1.Mutual switching between above-mentioned operating state and state can be described with Fig. 3.

Realize the turn-on and turn-off that only need control gate-controlled switch device when above-mentioned Boost transducer status is switched, therefore can obtain a kind of method for handover control: as output voltage v _cbe less than V _reftime, and inductive current i _lbe less than or equal to 0, switch closure; As inductive current i _lbe greater than I _reftime, switch disconnects.As long as measure output voltage and inductive current and just can realize converter switching controls by above-mentioned rule control switch.

3) in method for handover control inductive current reference value and output voltage reference value determine

According to conservation of energy principle, can calculate these reference values, concrete grammar is as follows:

In the time that switch is closed (pattern 1), inductive current i _lincrease, inductance L storage power, as inductive current i _lincrease to I _reftime, switch disconnects and enters pattern 2, and now, inductance L and input DC power E provide energy to capacitor C and load R simultaneously.

During pattern 1, the energy obtaining in inductance L is

$E_{\mathrm{inductor}}=\frac{1}{2}{\mathrm{LI}}_{\mathrm{ref}}^2---\left(5\right)$

The gross energy discharging in capacitor C is approximately

$E_{\mathrm{capaitor}}=\frac{1}{2}C(V_d^{{+}^2}-V_d^{{-}^2})={\mathrm{CV}}_d{v}_{\mathrm{ripple}}---\left(6\right)$

As shown in Figure 2,

be respectively peak and the minimum of capacitance voltage, v _ripplefor ripple size, its expression formula is as follows

$v_{\mathrm{ripple}}=(V_d^{+}-V_d^{-})=((V_d^{+2}-V_d^{-2})/{2V}_d)---\left(7\right)$

Wherein, V _dfor the expectation voltage of output, during pattern 1, can row conservation of energy equation by the conservation of energy

$E_{\mathrm{source}}+E_{\mathrm{inductor}}=E_{r_L}+E_{r_C}+E_{r_d}+E_{\mathrm{load}}+E_{\mathrm{capacitor}}---\left(8\right)$

E _sourthe gross energy providing for ce input voltage,

be the first resistance r _lthe energy consuming, E _rcbe the 4th resistance r _cthe energy consuming, E _rdbe the second resistance r _dthe energy consuming, E _loadfor the energy of load R consumption.

Suppose that the energy consuming in dead resistance is very little, can obtain equation

E _source+E _inductor＝E _load+E _capacitor (9)

Under ideal state, the gross energy that input voltage provides equals the upper energy consuming of load R,

E _source＝E _load (10)

Can obtain,

$\frac{1}{2}{\mathrm{<figure-callout\; id="2"\; label="LI\; ref"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">LI</figure-callout>}}_{\mathrm{ref}}^{}={\mathrm{CV}}_d{v}_{\mathrm{ripple}}---\left(11\right)$

Solve an equation (11) must be with reference to inductive current

$I_{\mathrm{ref}}=\sqrt{\frac{2C}{L}{V}_d{v}_{\mathrm{ripple}}}---\left(12\right)$

Reference voltage level can be by comparing trough and the desired value of output voltage ripple, and the trough desired value of output voltage is

$V_{d\left(\mathrm{ideal}\right)}^{-}=(V_d-(v_{\mathrm{ripple}}/2))---\left(13\right)$

In pattern 1, voltage drop is extremely lower than V _d, current equation is

$\frac{{\mathrm{dv}}_C}{\mathrm{dt}}=-\frac{v_C}{(R+r_C)C}---\left(14\right)$

Wherein, t is the time;

Integration obtains the actual value of the trough of output voltage

$V_{d\left(\mathrm{actual}\right)}^{-}=V_d\exp \left(\frac{-{\mathrm{LI}}_{\mathrm{ref}}}{E(R+r_C)C}\right)---\left(15\right)$

The reference value of voltage is

$V_{\mathrm{ref}}=V_d-(V_{d\left(\mathrm{actual}\right)}^{-}-V_{d\left(\mathrm{ideal}\right)}^{-})={2V}_d-V_d\exp \left(\frac{{-\mathrm{LI}}_{\mathrm{ref}}}{E(R+r_C)C}\right)-\frac{v_{\mathrm{ripple}}}{2}---\left(16\right)$

So far obtain voltage reference value (as shown in (16) formula) and current reference value (as shown in (12) formula), can realize switching controls by the method for handover control shown in Fig. 3.

Can reach desired value V in order to ensure capacitor C terminal voltage _d, load R resistance should be more than or equal to minimum value R _min, can calculate this value by offering the maximum energy value of load R, wherein mode 3 does not provide energy, therefore the energy that the mode 3 stage obtains is 0,

$R_{\min }=\frac{{2\mathrm{<figure-callout\; id="2"\; label="V\; d"\; filenames="HDA0000454210330000012.png,HDA0000454210330000021.png"\; state="\{\{state\}\}">V</figure-callout>}}_d^{}}{{\mathrm{EI}}_{\mathrm{ref}\left(\max \right)}}---\left(17\right)$

Wherein maximum current reference value

$I_{\mathrm{ref}\left(\max \right)}=\sqrt{(2C/L)(V_d-E)v_{\mathrm{ripple}}}+(V_d/R_{\min })---\left(18\right)$

Obtain

$R_{\min }=\frac{1}{\sqrt{\frac{2C}{L}(V_d-E)v_{\mathrm{ripple}}}}\frac{({2V}_d-E)V_d}{E}---\left(19\right)$

4) utilize feedback adjusting ripple voltage set point

Method regulates by the thought of feedback the v originally fixing below _ripplecan reduce actual ripple voltage, improve response speed simultaneously.Concrete method is as follows:

Ripple value is set by original fixed value v _ripplefor:

v _ripple＝v _ripple0+u _pi (20)

Wherein v _ripple0to be equivalent to original v _ripplea ripple initialization,

u _pi＝k _p*e+k _i*∫e _dt (21)

e＝V _d-v _C (22)

K _pfor proportionality coefficient, k _ifor integral coefficient, t is the time.

Below in conjunction with accompanying drawing and a specific embodiment, the present invention is further detailed.

For the Boost circuit shown in Fig. 1, parameter is as follows: E=5V, C=2000 μ F, L=50mH, r _c=0.33 Ω, r _s=0.023 Ω, r _l=1.4 Ω, the fixing ripple voltage of conventional method is set v _ripple=0.2, the present invention utilizes and feeds back in the ripple voltage formula (20) and formula (21) obtaining, v _ripple0=0, k _p=0.5, k _i=0.2, the comparative result that adopts feedback to obtain ripple voltage method in the fixing ripple set point method of contrast and the present invention is shown in Fig. 4.

In Fig. 4 (a) and (b) be respectively the phase-plane diagram that adopts fixing ripple set point and adopt feedback adjusting ripple set point method of the present invention, wherein abscissa is inductive current (unit is A), and ordinate is output voltage (unit is V); In Fig. 4 (c) and (d) be respectively the response process figure that powers on that adopts fixing ripple set point and adopt feedback adjusting ripple set point method of the present invention, wherein abscissa is that the time, (unit was s), and ordinate is output voltage (unit is V); In Fig. 4 (e) and (f) be respectively the stable state output voltage enlarged drawing that adopts fixing ripple set point and adopt feedback adjusting ripple set point method of the present invention, wherein abscissa is that the time, (unit was s), and ordinate is output voltage (unit is V).Comparison diagram 4 results are visible, adopt the inventive method than the output fast response time of fixing ripple establishing method, and stable state output voltage ripple is little.

In order further to verify effect of the present invention, the hardware circuit of Boost shown in design drawing 1, and adopt MC9S12DG128MPVE single-chip microcomputer as core controller, and carry out experimental study, be fixed the switching controls effect of ripple establishing method and the inventive method as shown in Figure 5.In Fig. 5, (a) (b) is respectively and adopts the fixing ripple establishing method of tradition and adopt the inventive method output voltage dynamic response curve, and in Fig. 5, (c) (d) is respectively and adopts the fixing ripple establishing method of tradition and adopt the inventive method stable state output voltage waveforms.Contrast and experiment is known, adopts the inventive method compared with adopting fixing ripple establishing method, and the output voltage adjusting time reduces 49ms, and steady state ripple voltage reduces 0.2V.Further verify that the inventive method has the advantages that to reduce output ripple voltage and improve response speed.

Claims (1)

1. reduce a method for Boost converters output voltage ripple, the method based on Boost converters comprise input DC power (E), inductance (L), diode (D), switch (S), electric capacity (C) and load (R); The positive pole of input DC power (E) is by the first resistance (r of series connection _l) and inductance (L) meet respectively the second resistance (r _d) and the 3rd resistance (r _s), the 3rd resistance (r _s) connect with switch (S), switch (S) connects the negative pole of input DC power (E), the second resistance (r _d) connect with diode (D), the negative pole of diode (D) meets respectively the 4th resistance (r _c) and one end of load (R), the 4th resistance (r _c) connect with electric capacity (C), the negative pole of another termination input DC power (E) of the negative pole of electric capacity (C) and load (R);

It is characterized in that, described in reduce the method for Boost converters output voltage ripple, concrete steps are:

Step 1, calculates current reference value I _ref, its formula is as follows:

$I_{\mathrm{ref}}=\sqrt{\frac{2C}{L}{V}_d{v}_{\mathrm{ripple}}}$

Wherein, C is the capacitance of electric capacity (C), and L is the inductance value of inductance (L), V _dfor the expectation voltage of output, v _ripplefor voltage ripple value;

Step 2, computing reference magnitude of voltage V _ref, its formula is as follows:

$V_{\mathrm{ref}}={2V}_d-V_d\exp \left(\frac{-{\mathrm{LI}}_{\mathrm{ref}}}{E(R+r_C)C}\right)-\frac{v_{\mathrm{ripple}}}{2}$

Wherein, E is the input direct voltage value of input DC power (E), and R is the resistance value of load (R), r _cfor electric capacity (C) series impedance;

Step 3, computational load resistance minimum value R _min, its formula is as follows:

$R_{\min }=\frac{1}{\sqrt{\frac{2C}{L}(V_d-E)v_{\mathrm{ripple}}}}\frac{({2V}_d-E)V_d}{E}$

Step 4, determines ripple voltage v _ripple, its formula is

ν _ripple＝ν _ripple0+k _p*e+k _i*∫e _dt

Wherein, e=V _d-v _cfor the error of output voltage, v _ripple0for ripple voltage initialization, k _pfor proportionality coefficient, k _ifor integral coefficient, v _cfor output voltage values, t is the time;

Step 5, is greater than R at converter load resistance _minprerequisite under, converter switches is controlled as follows:

5.1 measure output voltage v _c, inductance measuring current i _l, work as v _cbe less than reference voltage V _refand i _lbe less than or equal at 1 o'clock, control switch closure;

5.2 inductance measuring current i _l, work as i _lbe greater than reference current I _reftime, control switch disconnects.

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