CN105680684A - Method for increasing switching converter gain based on parameter perturbation method - Google Patents

Abstract

The invention discloses a method for increasing switching converter gain based on a parameter perturbation method. The method comprises the steps of establishing a discrete time iteration model of the switching converter xn+1 is equal to F(xn, pn); choosing a discrete state variable xn and a control variable pn, determining circuit parameters; enabling the switching converter to be in a chaos state, and calculating the unsteady balance point at the current moment: a formula is as shown in the specification; sampling each state variable by a sensor before each period starts; sending the sampling result to an A/D converter, and converting an analog quantity into a digital quantity; calculating a control variable disturbance quantity pn' in each period in a digital control computer; adding the disturbance variable to the control variable to obtain an expected control variable pn* and outputting and sending the expected control variable to a D/A converter to convert the digital quantity into an analog quantity; comparing the expected control variable with the state variable, and sending the comparison result to a reset end of an RS trigger, and adopting the generated PWM waveform to control a switch tube of the switching converter. According to the method, the working section of the switching converter can be expanded, so that the gain of the switching converter can be further increased.

Description

A kind of method improving switch converters gain based on parameter perturbation technique

Technical field

The present invention relates to non-linear power electronics and chaos controlling field, refer in particular to a kind of method improving switch converters gain based on parameter perturbation technique.

Background technology

Along with constantly application and the development of the green energy resource such as photovoltaic generating system and fuel cell, the DC-DC converter with high-gain receives research and the concern of Chinese scholars more and more. For obtaining the boost capability of high multiple, having higher efficiency and power density concurrently, switched inductors is suggested simultaneously, and in order to improve boost capability and the conversion efficiency of system, has higher researching value.

Owing to parameter value scope limits the operation interval of changer, if beyond this interval, changer arising that various nonlinear dynamic phenomenon, thus preventing changer to reach higher output gain, making voltage conversion efficiency reduce. Utilize the control program of parameter perturbation, can make to work in the changer under chaos state, from many running, track is fixed on dutycycle ideal cycle-1 track, from the operation interval substantially expanding this DC-DC converter, improves the gain of DC-DC converter further.

Summary of the invention

It is an object of the invention to overcome the shortcoming and defect of prior art, it is provided that a kind of method improving switch converters gain based on parameter perturbation technique, it is possible to expand the operation interval of switch converters, improve its gain further.

For achieving the above object, technical scheme provided by the present invention is: a kind of method improving switch converters gain based on parameter perturbation technique, comprises the following steps:

1) the discrete time iterative model x of switch converters is set up_n+1=F (x_n,p_n), selected discrete state variable x_nWith control variable p_n, it is determined that circuit parameter, make switch converters be in chaos state, calculate now unstable equilibrium point

2) when each cycle starts, with sensor, each state variable is sampled, including inductive current, capacitance voltage;

3) sampled result is sent into A/D converter, analog quantity is converted to digital quantity;

4) in digital control computer, below equation the control variable disturbance quantity in each cycle is calculated:

4.1) by system at equilibrium point trackNeighborhood in, linear approximation is expressed as:

$x_{n+1}-\stackrel{\‾}{x}=A(x_n-\stackrel{\‾}{x})+B(p_n-\stackrel{\‾}{p})---\left(1\right)$

Wherein

4.2) linear approximation expression formula (1) iteration is obtained for twice:

$x_{n+2}=A^2(x_n-\stackrel{\‾}{x})+\left[\begin{array}{cc}AB& B\end{array}\right]\left[\begin{array}{c}{p}_n-\stackrel{\‾}{p}\\ p_{n+1}-\stackrel{\‾}{p}\end{array}\right]+\stackrel{\‾}{x}---\left(2\right)$

4.3) order:

$\left[\begin{array}{c}{p}_n\\ p_{n+1}\end{array}\right]={\left[\begin{array}{cc}AB& B\end{array}\right]}^{-1}{A}^2(\stackrel{\‾}{x}-x_n)\left[\begin{array}{c}\stackrel{\‾}{p}\\ \stackrel{\‾}{p}\end{array}\right]---\left(3\right)$

Make M=[ABB]^-1A², obtain control variable disturbance quantity expression formula:

${p_n}^{\′}=\left[\begin{array}{cc}M(1,1)& M(1,2)\end{array}\right](\stackrel{\‾}{x}-x_n)---\left(4\right)$

Then each cycle desired control variable is:

$p_n*=\left[\begin{array}{cc}M(1,1)& M(1,2)\end{array}\right](\stackrel{\‾}{x}-x_n)+\stackrel{\‾}{p}---\left(5\right)$

5) output desired control variable p_n ^*, send into D/A converter, digital quantity be converted into analog quantity;

6) compare desired control variable and state variable, result is sent into the reset terminal of rest-set flip-flop, the PWM waveform of generation is used for controlling the switching tube of switch converters.

The present invention compared with prior art, has the advantage that and beneficial effect:

1, expand the working range of switched inductors Boost, make switched inductors Boost rework in cycle-1 state from chaos state.

2, expand the duty cycle range of switched inductors Boost steady operation, and then improve the gain of changer.

3, owing to disturbance parameter calculates programmable, different circuit parameters can quickly draw disturbance parameter, and it is convenient to calculate.

4, Ability of Resisting Disturbance is strong, and within the specific limits, under the disturbance of load input voltage E, under the disturbance of load resistance R, system can be changed into cycle-1 state from chaos state.

5, control program has general applicability, at traditional DC-DC converter such as Boost, One Buck-Boost converter body, Cuk changer, Sepic changer, Zeta changer, and in the DC-DC converter such as forward converter and circuit of reversed excitation with isolation, can use according to same approach.

Accompanying drawing explanation

Fig. 1 is the switched inductors Boost basic circuit diagram that current-mode controls.

Fig. 2 is with reference current I_refBifurcation graphs for sensitive parameter.

Fig. 3 is that parameter perturbation technique is in order to improve transducer gain implementation schematic diagram.

Fig. 4 is that parameter perturbation technique is in order to improve transducer gain implementation block diagram.

Fig. 5 a is Matlab numerical simulation inductive current time domain beamformer.

Fig. 5 b is Matlab numerical simulation inductive current time domain waveform enlarged drawing.

Fig. 5 c is Matlab numerical simulation capacitance voltage time domain beamformer.

Detailed description of the invention

Below in conjunction with specific embodiment, the invention will be further described.

As it is shown in figure 1, be switched inductors Boost in a current mode control, including switched inductors structure, voltage source E, electric capacity C, load resistance R, power switch tube S. Switched inductors structure is by two equal-sized inductance L₁、L₂And 3 diode D₁、D₂、D₁₂Constitute.

The method improving switch converters gain based on parameter perturbation technique described in the present embodiment, its concrete condition is as follows:

1) the discrete time iterative model x of switch converters is set up_n+1=F (x_n,p_n), selected discrete state variable x_nWith control variable p_n, it is determined that circuit parameter, make switch converters be in chaos state, calculate now unstable equilibrium point

Power taking inducing current i_L1With capacitance voltage u_CFor state variable, i.e. x=[i_L1,u_C]^T, reference current I_refFor control variable p_n. If the n-th cycle is at first, inductance L₁Electric current i_L1With electric capacity C voltage u_CInitial value is i respectively_nAnd u_n, obtain discrete time iterative model under continuous current mode pattern (CCM).

$\left\{\begin{array}{c}{i}_{n+1}\left(t\right)=e^{-\mathrm{\α}t}\[\frac{2\mathrm{\α}L(I_{ref}-\frac{E}{R})+E-u_n{e}^{-2{\mathrm{\αt}}_n}}{2\mathrm{\ω}L}\sin \left({{\mathrm{\ωt}}_n}^{\′}\right)+(Iref-\frac{E}{R})\cos \left({{\mathrm{\ωt}}_n}^{\′}\right)\]+\frac{E}{R}\\ u_{n+1}\left(t\right)=-e^{-\mathrm{\α}t}\[2L(-\mathrm{\α}\frac{2\mathrm{\α}L(I_{ref}-\frac{E}{R})+E-u_n{e}^{-2{\mathrm{\αt}}_n}}{2\mathrm{\ω}L}-(Iref-\frac{E}{R})\mathrm{\ω})\sin \left({{\mathrm{\ωt}}_n}^{\′}\right)+(-u_n{e}^{-2{\mathrm{\αt}}_n}+E)\cos \left({{\mathrm{\ωt}}_n}^{\′}\right)\]+E\end{array}\right.$

Wherein

Choose cycle T=100 μ s, inductance L=L₁=L₂=1mH, load resistance R=10 Ω, electric capacity C=10 μ F, DC source E=20V, make inductive current as shown in Figure 2 with reference current I_refThe bifurcation graphs of change.Choose sensitive parameter I_ref=25A, now changer is in chaos state. Make x_n+1=x_n, try to achieve unstable equilibrium point

2) when each cycle starts, with sensor, each state variable (inductive current, capacitance voltage) is sampled.

3) sampled result is sent into A/D converter, analog quantity is converted to digital quantity.

4) in digital control computer, the control variable disturbance quantity in each cycle is calculated, as follows:

4.1) by system at equilibrium point trackNeighborhood in, linear approximation is expressed as:

$x_{n+1}-\stackrel{\‾}{x}=A(x_n-\stackrel{\‾}{x})+B(p_n-\stackrel{\‾}{p})---\left(1\right)$

Wherein

4.2) linear approximation expression formula (1) iteration is obtained for twice:

$x_{n+2}=A^2(x_n-\stackrel{\‾}{x})+\left[\begin{array}{cc}AB& B\end{array}\right]\left[\begin{array}{c}{p}_n-\stackrel{\‾}{p}\\ p_{n+1}-\stackrel{\‾}{p}\end{array}\right]+\stackrel{\‾}{x}---\left(2\right)$

4.3) order:

$\left[\begin{array}{c}{p}_n\\ p_{n+1}\end{array}\right]={\left[\begin{array}{cc}AB& B\end{array}\right]}^{-1}{A}^2(\stackrel{\‾}{x}-x_n)+\left[\begin{array}{c}\stackrel{\‾}{p}\\ \stackrel{\‾}{p}\end{array}\right]---\left(3\right)$

Make M=[ABB]^-1A², obtain control variable disturbance quantity expression formula:

${p_n}^{\′}=\left[\begin{array}{cc}M(1,1)& M(1,2)\end{array}\right](\stackrel{\‾}{x}-x_n)---\left(4\right)$

Then each cycle desired control variable is:

$p_n*=\left[\begin{array}{cc}M(1,1)& M(1,2)\end{array}\right](\stackrel{\‾}{x}-x_n)+\stackrel{\‾}{p}---\left(5\right)$

By (1) Shi Ke get

By (3) Shi Ke get:

$\left[\begin{array}{c}{I}_{ref1}\\ I_{ref2}\end{array}\right]=\left[\begin{array}{cc}-0.6863062& -0.001521289\\ 0.1201498& 0.001032846\end{array}\right]\left(\left[\begin{array}{c}{i}_{Lf}\\ u_{Cf}\end{array}\right]-\left[\begin{array}{c}{i}_{L1}\\ u_C\end{array}\right]\right)+\left[\begin{array}{c}25\\ 25\end{array}\right]$

NamelyTake a=-0.6863, b=-0.0015, obtain disturbance quantity I as shown in Figure 3_ref', and this cycle control variable I_ref*。

I_ref'=a (i_Lf-i_L1)+b(u_Cf-u_C)

I_ref*=I_ref'+I_ref

5) output expection control variable I_ref', send into D/A converter, digital quantity is converted into analog quantity.

6) compare control variable and state variable, result is sent into the reset terminal of rest-set flip-flop, the PWM waveform of generation is used for controlling the switching tube of switch converters.

Previous step 2) to 6) the process that realizes as shown in Figure 4.

By Matlab numerical simulation, obtain the capacitance voltage time domain beamformer shown in the inductive current time domain waveform enlarged drawing shown in inductive current time domain beamformer as shown in Figure 5 a, Fig. 5 b, Fig. 5 c. Can show that the control program of the switch converters based on parameter perturbation can expand the operation interval of switch converters, improve the conclusion of its gain, be i.e. the effectiveness of this scheme.

The examples of implementation of the above are only the preferred embodiments of the invention, not limit the practical range of the present invention with this, therefore all changes made according to the shape of the present invention, principle, all should be encompassed in protection scope of the present invention.

Claims (1)

1. the method improving switch converters gain based on parameter perturbation technique, it is characterised in that comprise the following steps:

1) the discrete time iterative model x of switch converters is set up_n+1=F (x_n,p_n), selected discrete state variable x_nWith control variable p_n, it is determined that circuit parameter, make switch converters be in chaos state, calculate now unstable equilibrium point

2) when each cycle starts, with sensor, each state variable is sampled, including inductive current, capacitance voltage;

3) sampled result is sent into A/D converter, analog quantity is converted to digital quantity;

4) in digital control computer, below equation the control variable disturbance quantity in each cycle is calculated:

4.1) by system at equilibrium point trackNeighborhood in, linear approximation is expressed as:

$x_{n+1}-\stackrel{\‾}{x}=A(x_n-\stackrel{\‾}{x})+B(p_n-\stackrel{\‾}{p})---\left(1\right)$

Wherein

4.2) linear approximation expression formula (1) iteration is obtained for twice:

$x_{n+2}=A^2(x_n-\stackrel{\‾}{x})+\left[\begin{array}{cc}AB& B\end{array}\right]\left[\begin{array}{c}{p}_n-\stackrel{\‾}{p}\\ p_{n+1}-\stackrel{\‾}{p}\end{array}\right]+\stackrel{\‾}{x}---\left(2\right)$

4.3) order:

$\left[\begin{array}{c}{p}_n\\ p_{n+1}\end{array}\right]={\left[\begin{array}{cc}AB& B\end{array}\right]}^{-1}{A}^2(\stackrel{\‾}{x}-x_n)+\left[\begin{array}{c}\stackrel{\‾}{p}\\ \stackrel{\‾}{p}\end{array}\right]---\left(3\right)$

Make M=[ABB]^-1A², obtain control variable disturbance quantity expression formula:

${p_n}^{\′}=\left[\begin{array}{cc}M\left(1,1\right)& M\left(1,2\right)\end{array}\right](\stackrel{\‾}{x}-x_n)---\left(4\right)$

Then each cycle desired control variable is:

$p_n*=\left[\begin{array}{cc}M\left(1,1\right)& M\left(1,2\right)\end{array}\right](\stackrel{\‾}{x}-x_n)+\stackrel{\‾}{p}---\left(5\right)$

5) output desired control variable p_n ^*, send into D/A converter, digital quantity be converted into analog quantity;

6) compare desired control variable and state variable, result is sent into the reset terminal of rest-set flip-flop, the PWM waveform of generation is used for controlling the switching tube of switch converters.