CN103905017B - A kind of new chaotic spread spectrum SPWM ripple generates method - Google Patents

Abstract

nullA kind of new chaotic spread spectrum SPWM ripple generates method，1、Determine the constant interval of the chaos variable element of the double chaos sequence of mutual variable element，2、The fixing chaotic parameter of Logistic chaos sequence and Tent chaos sequence is replaced with chaos variable element，3、Chaos variable element is utilized to generate chaos sequence，4、Calculate the slope coefficient of chaos triangular wave，5、Utilize the double chaos sequence of mutual variable element by chaotization for chaos triangular wave slope，6、The external clock utilizing SPWM ripple generation module counts to get chaos triangle wave number，7、When chaos triangular wave count value reaches 0，Repeat above step，I.e. can get chaos triangular wave，It is interior in case calling that its value is stored in TRG，8、Obtain from controller and need the sinusoidal wave parameter of modulation，Generate sine table，9、Calculate sine table and update step-length，10、Update sinusoidal wave number，11、Obtain the value of sine wave，It is stored in SIN interior in case calling，12、TRG with SIN is compared，Output chaos SPWM waveform；The present invention has quick, real-time, the feature of low harmony wave.

Description

A kind of new chaotic spread spectrum SPWM ripple generates method

Technical field

The present invention relates to the generation technique field of SPWM ripple, be specifically related to a kind of new chaotic spread spectrum SPWM Ripple generates method.

Background technology

The circuit of converter is typically made up of rectification, intermediate DC link, inversion and control, and voltage is output as PWM (Pulse width modulation, PWM) waveform.PWM is exactly pulse width modulation, namely accounts for The empty variable impulse waveform of ratio, in reality exports, different dutycycles is equivalent to different output levels, Such that it is able to reach to be equivalent to the effect of analog voltage output by regulation dutycycle.PWM control technology with This conclusion is theoretical basis, is controlled the turn-on and turn-off of semiconductor switch device, makes outfan obtain A series of amplitudes are equal and the unequal pulse of width, with these pulses replace sine wave or other required for Waveform.By certain rule, the width of each pulse is modulated, both can change inverter circuit output voltage Size, it is possible to change output frequency.

By sine wave modulation be PWM ripple be exactly SPWM ripple, converter generally used now is substantially directly The electric power apparatus such as direct-driving motor, transformator is carried out with SPWM ripple.SPWM ripple is easy to use, it is easy to real Existing, but the harmonic spike that SWPM ripple comprises is very big, and the especially switching frequency at semiconductor switch device is attached Closely, a high harmonic spike can be formed.Harmonic wave can cause electromagnetic interference in the operation of power equipment, The quality of impact output electric energy；If transducer drive is motor, it is also possible to cause mechanical resonant to make System cisco unity malfunction, and reduce motor service life.

In field of power electronics, chaos sequence is used for the chaos spread spectrum of triangular wave to modulate SPWM ripple, Minimizing electromagnetic interference (electromagnetic interference, EMI) and elimination mechanical resonant had substantially effect Really.In SPWM modulates, higher hamonic wave can concentrate near the multiple of switching frequency and switching frequency, And reach the highest peak value, triangular wave is carried out chaos spread spectrum switching frequency can be made to be become certain from fixed value Successive value in interval, the distribution of corresponding higher hamonic wave is also become continuous from discrete, thus reduces harmonic wave The purpose of peak value.A this method major issue when application is to produce chaos sequence real-time, and In digital control, chaos sequence is affected by numerical calculation precision, inherently deteriorates to periodic sequence.With Periodically sequence pair triangular wave spreads, and can be formed about at the product of sequence period and triangular wave cycle One higher harmonic wave.

Summary of the invention

In order to solve the problem that above-mentioned prior art exists, it is an object of the invention to provide a kind of new chaotic Spread spectrum SPWM ripple generates system and method, has quick, real-time, the feature of low harmony wave.

In order to reach object above, the present invention adopts the following technical scheme that

A kind of new chaotic spread spectrum SPWM ripple generates method, comprises the steps:

Step 1: the change of the chaos variable element of the double chaos sequence of the mutual variable element of variable element ratio-dependent as required Changing interval, the double chaos sequence of described mutual variable element is combined raw by Logistic chaos sequence and Tent chaos sequence Become,

y_n/K₁ (1)

x_n/K₂ (2)

In formula: x_nFor Logistic chaos sequence value；y_nFor Tent chaos sequence value；Subscript n is sequence sequence Number, represent the n-th value in chaos sequence；K₁、K₂For set variable element ratio, by changing it Size may determine that the constant interval of chaos variable element；

Step 2: after obtaining the constant interval of chaos variable element, by Logistic chaos sequence and Tent chaos sequence The fixing chaotic parameter of row replaces with chaos variable element, obtains shown in chaos variable element such as formula (3), formula (4):

${\stackrel{\‾}{K}}_x=K_x-y_n/K_1---\left(3\right)$

${\stackrel{\‾}{K}}_y=K_y-x_n/K_2---\left(4\right)$

In formula: K_xFor the original fixing chaotic parameter of Logistic set, K_yTent for setting is original fixing Chaotic parameter, calculated Logistic chaos variable elementWith Tent chaos variable elementIn given interval Inside present chaos change；

Step 3: utilize chaos variable element to generate chaos sequence: for realizing rapid computations, by Logistic chaos Sequential value x_nWith Tent chaos sequence value y_nExpansion rounds, and calculates with integer form, 16 binary system essences Under degree, taking excursion is (0,60000), makes Logistic and Tent two kinds map the chaos sequence produced and exists Chaos change is presented, using formula (3), formula (4) as Logistic and Tent chaos in the range of (0,60000) The new chaotic parameter of mapping formula, is iterated computing according to formula (5) and obtains chaos sequence in case calling；

$\left\{\begin{array}{c}{x}_{n+1}={\stackrel{\‾}{K}}_x\·x_n(60000-x_n)/60000\\ y_{n+1}={\stackrel{\‾}{K}}_y\·\min (y_n,60000-y_n)\end{array}\right.---\left(5\right)$

Step 4: obtain the parameter i.e. maximum amplitude of chaos triangular wave, frequency and chaos frequency conversion ratio from controller, The slope coefficient P of chaos triangular wave is calculated according to the parameter obtained₀, shown in its calculating formula such as formula (6):

P₀=2DNF_sin/F_clk (6)

In formula: P₀For the ratio of slope coefficient i.e. external clock frequency Yu chaos triangular wave count frequency, D is Chaos triangular wave maximum amplitude, N is the ratio of modulated triangular wave and sine wave freuqency, F_sinFor sine to be modulated Wave frequency, F_clkFor external clock frequency；

Step 5: utilize the double chaos sequence of mutual variable element by chaotization for chaos triangular wave slope, select Logistic Chaos sequence value x_n, obtain chaos frequency conversion ratio K from controller₃, then utilize formula (7) by oblique for chaos triangular wave Rate is chaotization:

P=P₀(1-K₃+2K₃·x_n/60000) (7)

In formula: P be chaotization after chaos triangular wave slope coefficient, chaotization after the triangular wave slope that obtains exist (1-K₃P₀, 1+K₃P₀Presenting chaos change in), i.e. triangular wave frequency is at (1-K₃F_sin, 1+K₃F_sin) In the range of present chaos change, but its equivalent frequency is F_sin；

Step 6: utilize the external clock of SPWM ripple generation module to count to get chaos triangle wave number, with TRG Represent triangular wave currency, COUNTER_trgRepresent external clock enumerator；Then each external clock cycle Inside make COUNTER_trg=COUNTER_trg+ 1, and chaos triangle wave number TRG is by count value COUNTER_trg It is multiplied by slope P to obtain；

TRG=COUNTER_trg*P (8)

Step 7: when chaos triangle wave number TRG reaches maximum D, become subtracting counting from counting up, meter Numerical value COUNTER_trgResetting, slope remains as P, i.e. makes in each external clock cycle COUNTER_trg=COUNTER_trg+ 1, and chaos triangle wave number TRG is deducted count value by maximum D COUNTER_trgIt is multiplied by slope P to obtain；

TRG=D-COUNTER_trg*P (9)

Step 8: when chaos triangular wave count value reaches 0, repeats above step, i.e. can get chaos triangle Ripple, it is interior in case calling that its value is stored in TRG；

Step 9: obtain from controller and need the sinusoidal wave parameter of modulation: amplitude A_sin, frequency F_sinJust Beginning phase place P_sin, generate sine table sina [] according to amplitude and phase place；

Step 10: according to sine table precision, sine wave freuqency calculates sine table and updates step-length N_sinIf, precision It is 2 °, when i.e. sine table includes 180 data, calculating formula such as formula (10):

N_sin=F_clk/(F_sin*180) (10)

Step 11: utilize the external clock of SPWM ripple generation module to calculate sinusoidal wave number, with COUNTER_sin Represent the sine table position that current sinusoidal wave number is corresponding, represent sinusoidal wave value with SIN, according to external clock To COUNTER_sinCounting, counting often expires N_sinSecondary make COUNTER_sin=COUNTER_sin+ 1 and update just String wave number SIN, i.e. SIN=sina [COUNTER_sin]；

Step 12: when sine table reads last value, return sine table heading, i.e. when COUNTER_sinWhen=180, reset COUNTER_sin=0, repeat the 9th to the 12nd step the most available Sinusoidal wave value, is stored in SIN in case calling；

Step 13: compared by TRG with SIN, exports chaos SPWM waveform.

Described combination by Logistic chaos sequence and Tent chaos sequence generates the double chaos sequence of mutual variable element Method is as follows:

The primitive form of described Logistic chaos sequence and Tent chaos sequence is as follows:

x_n+1=K_xx_n(1-x_n),K_x∈(3.5 699 456,4),x∈(0,1) (11)

y_n+1=K_y min(y_n,1-y_n),K_y∈(1,2),y∈(0,1) (12)

Wherein K_xFor the chaotic parameter of Logistic chaos sequence, K_yFor the chaotic parameter of Tent chaos sequence, x_nFor Logistic chaos sequence value, y_nFor Tent chaos sequence value, often perform an iteration computing, sequential value Change once, obtains Logistic chaos sequence value x after interative computation_n+1With Tent chaos sequence value y_n+1, Obtain sequential value for the chaos sequence in (0,1) interval；

For avoiding the computing of floating number, do not use normalized chaos generation mapping equation, but with integer shape Formula calculates.Expand sequence span for this, but keep chaotic parameter constant.By chaos sequence value x_n、y_n's Constant interval expands to (0,60000), then formula (11) and formula (12) can be changed into formula (13) and formula (14):

The mapping equation of Logistic chaos sequence is

x_n+1=K_xx_n(60 000-x_n)/60 000,x_n∈(0,60 000) (13)

The mapping equation of Tent chaos sequence is

y_n+1=K_ymin(y_n,60 000-y_n),y_n∈(0,60 000) (14)

In formula: x_nFor Logistic chaos sequence value；y_nFor Tent chaos sequence value；K_xLogistic for formula (13) Chaotic parameter, K_yFor the Tent chaotic parameter of formula (14), the chaos sequence that both mapping equations produce is (0,60 000) chaos change is presented in the range of；

Chaotic parameter K with the Logistic chaos sequence in Tent chaos sequence result change formula (13)_xValue, Change the chaotic parameter K of Tent chaos sequence with Logistic chaos sequence result simultaneously_yValue；

For this by formula (15) by the Logistic chaotic parameter K in formula (13)_xReplace with the Logistic after improvement to mix Ignorant variable elementLogistic chaos variable element after improvementFor

${\stackrel{\‾}{k}}_x=K_x-y_n/\left(1000K_1\right)---\left(15\right)$

In formula: y_nFor Tent chaos sequence value in formula (14)；K₁For the variable element ratio set；K_xFor former The chaotic parameter that chaos sequence sets；Chaos variable elementChaos change is presented in the excursion set；

By formula (16) by the K in formula (14)_yReplace withFor

${\stackrel{\‾}{k}}_y=K_y-y_n/\left(1000K_2\right)---\left(16\right)$

In formula: x_nFor Logistic chaos sequence value in formula (13)；K₂For the variable element ratio set；K_y Chaotic parameter for former chaos sequence；Equally, chaos variable elementChaos is presented in the excursion set Change；

Formula (15), formula (16) are substituted into formula (13), formula (14) respectively, obtains the double chaos sequence equation of mutual variable element For

$\left\{\begin{array}{c}{x}_{n+1}={\stackrel{\‾}{K}}_x\·x_n(60000-x_n)/60000=\[K_x-\\ y_n/\left(1000K_1\right)\]x_n(60000-x_n)/60000\\ y_{n+1}={\stackrel{\‾}{K}}_y\·\min (y_n,60000-y_n)=\[K_y-\\ x_n/\left(1000K_2\right)\]\min (y_n,60000-y_n)\end{array}\right.---\left(17\right)$

In formula: x_n、y_nIt is respectively the chaos sequence value of Logistic and Tent the n-th step, regulates K₁、K₂With And K_x、K_ySize, it is possible to corresponding regulation chaos variable elementExcursion；Same up-to-date style (17) It is generated as the two mutual variable element chaos sequences being listed in given interval.

Compared to the prior art, the invention have the advantages that

One, the double chaos sequence of this mutual variable element is compared with traditional Logistic chaos sequence, Tent chaos sequence, In the case of same computational accuracy, chaos cycle stretch-out more than 100 times.

Two, the double chaos sequence algorithm of this mutual variable element is highly suitable for the parallel arithmetic mode of FPGA, in reality Time computing in can reach the highest speed, and this algorithm have employed integer calculations form, computing on FPGA Shi Wuxu builds floating-point mould, takies resource few, and real-time is good.

Three, this algorithm designs with FPGA for operation platform, and the work of its major calculations is placed on FPGA, The hardware platform of FPGA collocation main control chip type can be saved the calculation resources of main control chip in large quantities, Improve the speed of service.

Accompanying drawing explanation

Fig. 1 is chaos triangular wave chaos spread spectrum principle schematic.

Fig. 2 is chaos SPWM ripple modulation principle schematic diagram, wherein: Fig. 2 (a) is sinusoidal pattern, and figure 2 (b) is chaos triangular wave figure, and Fig. 2 (c) is chaos SPWM ripple figure.

Fig. 3 is SPWM ripple frequency analysis result spectrogram, wherein: Fig. 3 (a) is constant frequency triangular modulation SPWM ripple frequency spectrum, Fig. 3 (b) is the chaos triangular wave after using conventional Logistic chaos sequence spread spectrum The SPWM ripple frequency spectrum of modulation, Fig. 3 (c) is the SPWM ripple frequency spectrum of the chaos triangular modulation of the present invention.

Fig. 4 is SPWM wave power analysis of spectrum result, wherein: Fig. 4 (a) is constant frequency triangular modulation SPWM wave energy is composed, and Fig. 4 (b) is the chaos triangular wave after using conventional Logistic chaos sequence spread spectrum The SPWM wave energy spectrum of modulation, Fig. 4 (c) is the SPWM wave energy spectrum of the chaos triangular modulation of the present invention.

Detailed description of the invention

With specific embodiment, the present invention is described in further details below in conjunction with the accompanying drawings.

Requiring one sine wave of modulation in the present embodiment, its parameter is as follows: amplitude 250, and frequency is 50Hz, Initial phase is 180 °.Modulation requires: carrier wave ratio 50, modulates ratio 1, and chaos variable frequency range is 50%.Outward The external clock of portion's hardware condition: FPGA is 10MHz.

Step 1: determine the constant interval of the chaos variable element of the double chaos sequence of mutual variable element, take K₁=2000 000, K₂=300 000.

y_n/2000000 (1)

x_n/300000 (2)

In formula: x_nFor Logistic chaos sequence value；y_nFor Tent chaos sequence value；Because of its span be (0, 60000) thus may determine that chaotic parameter constant interval be respectively (0,0.003) and (0,0.02).

Step 2: after obtaining the constant interval of chaos variable element, by Logistic chaos sequence and Tent chaos sequence The fixing chaotic parameter of row replaces with parameter variable element.Assignment Logistic original chaotic parameter K_x=3.9999, Tent chaos initial parameter K_y=1.9999, in order to represent with integer form, it is written as K_x=39999/10000, K_y=19999/10000.Obtain shown in chaos variable element such as formula (3), formula (4):

${\stackrel{\‾}{K}}_x=39999/10000-y_n/K_1---\left(3\right)$

${\stackrel{\‾}{K}}_y=19999/10000-x_n/K_2---\left(4\right)$

It is calculated chaos variable elementRespectively at given interval (3.9969,3.9999) and (1.9799,1.9999) chaos change is presented in.

Step 3: utilize chaos variable element to generate chaos sequence.Using formula (3), formula (4) as Logistic and Tent New chaotic parameter, be iterated computing according to formula (5) and obtain becoming chaos to become in (0,60000) is interval The chaos sequence changed is in case calling.

$\left\{\begin{array}{c}{x}_{n+1}={\stackrel{\‾}{K}}_x\·x_n(60000-x_n)/60000\\ y_{n+1}={\stackrel{\‾}{K}}_y\·\min (y_n,60000-y_n)\end{array}\right.---\left(5\right)$

Step 4: obtain the parameter of chaos triangular wave from controller, initializes according to the parameter obtained, three Angle ripple modulation principle is as shown in Figure 1:

Triangular wave frequency according to setting obtains slope coefficient P₀, shown in its calculating formula such as formula (6):

P₀=2DNF_sin/F_clk (6)

Now understanding triangular wave frequency is 50, and modulation ratio is 50, and maximum amplitude is 500.External clock is 10MHz, therefore its slope is P₀=2500Hz*1000/ (10MHz)=0.25.

Step 5: utilize the double chaos sequence of mutual variable element by chaotization for chaos triangular wave slope.Select Logistic Chaos sequence x_n, obtain chaos frequency conversion ratio K from controller₃, because the frequency conversion ratio required is 50%, then K₃=0.5. Triangular wave slope is chaotization to be had:

P=0.25 (0.5+x_n/60000) (7)

The triangular wave slope obtained after chaotization presents chaos change in (0.125,0.375), i.e. triangular wave Frequency presents chaos change in the range of (1.25kHz, 3.75kHz), but its average eguivalent frequency is 2.5kHz.

Step 6: utilize the external clock of SPWM ripple generation module to count to get chaos triangle wave number, with TRG Represent triangular wave currency, COUNTER_trgRepresent external clock enumerator.Then each external clock cycle Inside make COUNTER_trg=COUNTER_trg+ 1, and triangle wave number TRG is by count value COUNTER_trgIt is multiplied by Slope P obtains.

TRG=COUNTER_trg*P (8)

Step 7: when triangle wave number TRG reaches maximum 500, become subtracting counting from counting up, counting Value COUNTER_trgResetting, slope remains as P.The most then make in each external clock cycle COUNTER_trg=COUNTER_trg+ 1, and triangle wave number TRG is deducted count value by maximum is multiplied by slope and obtains Arrive.

TRG=500-COUNTER_trg*P (9)

Step 8: when triangular wave count value reaches 0, repeats above step, i.e. can get chaos triangle wave number According to.It is interior in case calling that its value is stored in TRG.

Step 9: obtained by controller and need the sine wave parameter of modulation, amplitude A_sin, frequency F_sin, initially Phase place P_sin.According to amplitude and initialisation phase sine table sina [].The amplitude of sine wave is set after initialization A_sin=250, frequency F_sin=50, and phase parameter P_sin=180.Sine table sina [] is initialized simultaneously, After initialization, sina [] represents that sine value is multiplied by A_sinAfter carry out being lifted on the occasion of result.This example takes sine wave Precision is twice, sine table is lifted on the occasion of, i.e. constant interval is lifted to (0,500) by (-250,250). Obtain sine table slightly.

Step 10: according to external clock, sine table precision, sine wave freuqency calculates sine table and updates step-length N_sin, If precision is 2 °, when i.e. sine table includes 180 data, calculating formula such as formula (10):

N_sin=F_clk/(F_sin*180) (10)

Being calculated renewal step-length is 10M/ (50*180)=1111.

Step 11: with COUNTER_sinRepresent the sine table position that current sinusoidal wave number is corresponding, with SIN table Show the value of sine wave.Because initial phase is 180 °, the COUNTER after initialization_sin=90.During according to outside Clock is to COUNTER_sinCounting, counting often expires N_sinEven if secondary COUNTER_sin=COUNTER_sin+ 1 and more New sinusoidal wave number SIN, i.e. SIN=sina [COUNTER_sin]。

Step 12: when sine table reads last value, returns heading, i.e. works as COUNTER_sin=180 Time, reset COUNTER_sin=0.Repeat the i.e. available sinusoidal wave value of the 9th to the 12nd step, storage It is stored in SIN in case calling.

Step 13: sine i.e. Fig. 2 (a) of wave number SIN and chaos triangle i.e. Fig. 2 (b) of wave number TRG is compared Relatively, output chaos SPWM waveform i.e. Fig. 2 (c).I.e. as SIN > TRG time output 1 otherwise export 0.

Algorithm effect:

PWM waveform after the PWM waveform generated is spread with tradition Logistic chaos sequence and constant frequency PWM waveform after triangular wave waveform spread spectrum is analyzed contrast.Show its harmonic content analysis and energy spectrum Analyze, as shown in Figure 3 and Figure 4.

From the figure 3, it may be seen that the higher hamonic wave of the SPWM ripple of constant frequency triangular modulation concentrate on switching frequency and Near the multiple of switching frequency, there is higher peak value.After triangular wave is carried out chaos spread spectrum, switching frequency Become continuous from discrete so that harmonic wave distribution is also become continuous from discrete, in the case of harmonic wave total amount is constant, Corresponding harmonic spike substantially reduces.Knowable to Fig. 3 (b), the harmonic spike of conventional Logistic chaos algorithm from 45% drops to 15%, and algorithm in this paper is relative to conventional Logistic chaos algorithm, can be by humorous for maximum Crest value is further lowered into 5% from 15%, and harmonic spike inhibition is more preferable.

As shown in Figure 4, in Fig. 4 (a), the harmonic power peak value of SPWM ripple is the highest and more discrete.In Fig. 4 (b), Power spectrum then becomes continuous, and harmonic power peak value drops to-30dB from-20dB, and new calculation in this paper Harmonic power peak value is reduced to-35dB by rule further.

Claims (2)

1. a new chaotic spread spectrum SPWM ripple generates method, it is characterised in that: comprise the steps:

Step 1: the change of the chaos variable element of the double chaos sequence of the mutual variable element of variable element ratio-dependent as required Changing interval, the double chaos sequence of described mutual variable element is combined raw by Logistic chaos sequence and Tent chaos sequence Become,

y_n/K₁ (1)

x_n/K₂ (2)

In formula: x_nFor Logistic chaos sequence value；y_nFor Tent chaos sequence value；Subscript n is sequence sequence Number, represent the n-th value in chaos sequence；K₁、K₂For set variable element ratio, by changing it Size may determine that the constant interval of chaos variable element；

Step 2: after obtaining the constant interval of chaos variable element, by Logistic chaos sequence and Tent chaos sequence The fixing chaotic parameter of row replaces with chaos variable element, obtains chaos variable element such as formula (3), formula (4) institute Show:

${\stackrel{\‾}{K}}_x=K_x-y_n/K_1---\left(3\right)$

${\stackrel{\‾}{K}}_y=K_y-x_n/K_2---\left(4\right)$

In formula: K_xFor the original fixing chaotic parameter of Logistic set, K_yTent for setting is original fixing Chaotic parameter, calculated Logistic chaos variable elementWith Tent chaos variable elementIn given interval Inside present chaos change；

Step 3: utilize chaos variable element to generate chaos sequence: for realizing rapid computations, by Logistic chaos Sequential value x_nWith Tent chaos sequence value y_nExpansion rounds, and calculates with integer form, 16 binary system essences Under degree, taking excursion is (0,60000), makes Logistic and Tent two kinds map the chaos sequence produced In the range of (0,60000), present chaos change, formula (3), formula (4) are mixed as Logistic and Tent The new chaotic parameter of ignorant mapping formula, is iterated computing according to formula (5) and obtains chaos sequence in case calling；

$\{\begin{array}{c}{x}_{n+1}={\stackrel{\‾}{K}}_x\·x_n(60000-x_n)/60000\\ y_{n+1}={\stackrel{\‾}{K}}_y\·\min (y_n,60000-y_n)\end{array}---\left(5\right)$

Step 4: obtain the parameter i.e. maximum amplitude of chaos triangular wave, frequency and chaos frequency conversion ratio from controller, The slope coefficient P of chaos triangular wave is calculated according to the parameter obtained₀, shown in its calculating formula such as formula (6):

P₀=2DNF_sin/F_clk (6)

In formula: P₀For the ratio of slope coefficient i.e. external clock frequency Yu chaos triangular wave count frequency, D is Chaos triangular wave maximum amplitude, N is the ratio of modulated triangular wave and sine wave freuqency, F_sinFor sine to be modulated Wave frequency, F_clkFor external clock frequency；

Step 5: utilize the double chaos sequence of mutual variable element by chaotization for chaos triangular wave slope: to select Logistic Chaos sequence value x_n, obtain chaos frequency conversion ratio K from controller₃, then utilize formula (7) by oblique for chaos triangular wave Rate is chaotization:

P=P₀(1-K₃+2K₃·x_n/60000) (7)

In formula: P be chaotization after chaos triangular wave slope coefficient, chaotization after the triangular wave slope that obtains exist (1-K₃P₀, 1+K₃P₀Presenting chaos change in), i.e. triangular wave frequency is at (1-K₃F_sin, 1+K₃F_sin) In the range of present chaos change, but its equivalent frequency is F_sin；

Step 6: utilize the external clock of SPWM ripple generation module to count to get chaos triangle wave number, with TRG Represent triangular wave currency, COUNTER_trgRepresent external clock enumerator；Then each external clock cycle Inside make COUNTER_trg=COUNTER_trg+ 1, and chaos triangle wave number TRG is by count value COUNTER_trg It is multiplied by slope P to obtain；

TRG=COUNTER_trg*P (8)

Step 7: when chaos triangle wave number TRG reaches maximum D, become subtracting counting from counting up, meter Numerical value COUNTER_trgResetting, slope remains as P, i.e. makes in each external clock cycle COUNTER_trg=COUNTER_trg+ 1, and chaos triangle wave number TRG is deducted count value by maximum D COUNTER_trgIt is multiplied by slope P to obtain；

TRG=D-COUNTER_trg*P (9)

Step 8: when chaos triangular wave count value reaches 0, repeats above step, i.e. can get chaos triangle Ripple, it is interior in case calling that its value is stored in TRG；

Step 9: obtain from controller and need the sinusoidal wave parameter of modulation: amplitude A_sin, frequency F_sinJust Beginning phase place P_sin, generate sine table sina [] according to amplitude and phase place；

Step 10: according to sine table precision, sine wave freuqency calculates sine table and updates step-length N_sinIf, precision It is 2 °, when i.e. sine table includes 180 data, calculating formula such as formula (10):

N_sin=F_clk/(F_sin*180) (10)

Step 11: utilize the external clock of SPWM ripple generation module to calculate sinusoidal wave number, with COUNTER_sin Represent the sine table position that current sinusoidal wave number is corresponding, represent sinusoidal wave value with SIN, according to external clock To COUNTER_sinCounting, counting often expires N_sinSecondary make COUNTER_sin=COUNTER_sin+ 1 and update just String wave number SIN, i.e. SIN=sina [COUNTER_sin]；

Step 12: when sine table reads last value, return sine table heading, i.e. when COUNTER_sinWhen=180, reset COUNTER_sin=0, repeat the 9th to the 12nd step the most available Sinusoidal wave value, is stored in SIN interior in case calling；

Step 13: compared by TRG with SIN, exports chaos SPWM waveform.

A kind of new chaotic spread spectrum SPWM ripple the most according to claim 1 generates method, its feature It is: described combination by Logistic chaos sequence and Tent chaos sequence generates the double chaos sequence of mutual variable element Method as follows:

The primitive form of described Logistic chaos sequence and Tent chaos sequence is as follows:

x_n+1=K_xx_n(1-x_n),K_x∈(3.5 699 456,4),x∈(0,1) (11)

y_n+1=K_ymin(y_n,1-y_n),K_y∈(1,2),y∈(0,1) (12)

Wherein K_xFor the chaotic parameter of Logistic chaos sequence, K_yFor the chaotic parameter of Tent chaos sequence, x_nFor Logistic chaos sequence value, y_nFor Tent chaos sequence value, often perform an iteration computing, sequential value Change once, obtains sequential value for the chaos sequence in (0,1) interval；x_n+1For the Logistic after interative computation Chaos sequence value, y_n+1For the Tent chaos sequence value after interative computation；

By chaos sequence value x_n、y_nConstant interval expand to (0,60000), then formula (11) and formula (12) can be changed into Formula (13) and formula (14):

The mapping equation of Logistic chaos sequence is

x_n+1=K_xx_n(60 000-x_n)/60 000,x_n∈(0,60 000) (13)

The mapping equation of Tent chaos sequence is

y_n+1=K_ymin(y_n,60 000-y_n),y_n∈(0,60 000) (14)

In formula: x_nFor Logistic chaos sequence value；y_nFor Tent chaos sequence value；K_xLogistic for formula (13) Chaotic parameter, K_yFor the Tent chaotic parameter of formula (14), the chaos sequence that both mapping equations produce is (0,60 000) chaos change is presented in the range of；

Chaotic parameter K with the Logistic chaos sequence in Tent chaos sequence result change formula (13)_xValue, Change the chaotic parameter K of Tent chaos sequence with Logistic chaos sequence result simultaneously_yValue；For this with formula (15) By the Logistic chaotic parameter K in formula (13)_xReplace with the Logistic chaos variable element after improvementImprove After Logistic chaos variable elementFor

${\stackrel{\‾}{K}}_x=K_x-y_n/\left(1000K_1\right)---\left(15\right)$

In formula: y_nFor Tent chaos sequence value in (14) formula；K₁For the variable element ratio set；K_xFor former The chaotic parameter that chaos sequence sets；Chaos variable elementChaos change is presented in the excursion set；

By formula (16) by Tent chaotic parameter K in formula (14)_yReplace with the Tent chaos variable element after improvement Tent chaos variable element after improvementFor

${\stackrel{\‾}{K}}_y=K_y-x_n/\left(1000K_2\right)---\left(16\right)$

In formula: x_nFor Logistic chaos sequence value in formula (13)；K₂For the variable element ratio set；K_y Chaotic parameter for former chaos sequence；Equally, chaos variable elementChaos is presented in the excursion set Change；

Formula (15), formula (16) are substituted into formula (13), formula (14) respectively, and obtaining the double chaos sequence equation of mutual variable element is

$\left\{\begin{array}{c}{x}_{n+1}={\stackrel{\‾}{K}}_x\·x_n(60000-x_n)/60000=\[K_x-\\ y_n/\left(1000K_1\right)\]x_n(60000-x_n)/60000\\ y_{n+1}={\stackrel{\‾}{K}}_y\·\min (y_n,60000-y_n)=\[K_y-\\ x_n/\left(1000K_2\right)\]\min (y_n,60000-y_n)\end{array}\right.---\left(17\right)$

In formula: x_n、y_nIt is respectively the chaos sequence value of Logistic and Tent the n-th step, regulates K₁、K₂With And K_x、K_ySize, it is possible to corresponding regulation chaos variable elementExcursion；Formula (17) Generate the two mutual variable element chaos sequences being listed in given interval.