Improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter

Abstract

The invention discloses an improved Lorenz chaos spread spectrum EMI (Electro-Magnetic Interference) reduction method based on a Buck converter, which relates to an electronic switching power supply technical method, and adopts a switching tube driving signal of an improved Lorenz chaos spread spectrum modulation method converter to control. And electromagnetic noise energy concentrated at the switching frequency and the frequency doubling position is dispersed to a wider frequency band, so that the conducted electromagnetic interference noise of the Buck converter is reduced. A new chaotic system is designed by changing a nonlinear term of a classical Lorenz system, a chaotic spread spectrum circuit is designed, a PWM signal generated by the chaotic circuit serves as a spread spectrum signal, a switching tube driving signal of a Buck converter is controlled, and chaotic spread spectrum EMI noise suppression is achieved. According to the Buck converter, the noise peak value of the Buck converter at the switching frequency and the frequency doubling position can be reduced, so that the conduction electromagnetic interference of the Buck converter is reduced, the circuit is easy to build, and the EMI reduction effect is obvious.

Description

Technical Field

[0001] The present invention relates to a technical method for an electronic switching power supply, and more particularly to an improved Lorenz chaotic spread spectrum EMI reduction method based on a Buck converter. Background Art

[0002] In recent years, with the miniaturization and high-frequencyization of electronic information devices, the fluctuations of switching noise propagate in a wide frequency range, making the electromagnetic interference problem particularly prominent. The high di / dt and du / dt characteristics during the operation of a switching power supply make the electromagnetic interference problem more obvious. Excessive electromagnetic interference will seriously affect the performance of electronic devices, leading to problems such as equipment failure, shortened lifespan, or damage.

[0003] Adopting shielding technology can reduce the EMI noise of a switching converter, but it increases the volume and cost of the switching converter and is difficult to implement in mass production; using periodic spread spectrum modulation technology can reduce the EMI noise of a switching converter, but the suppression effect is not good; in recent years, some scholars have studied chaotic spread spectrum modulation technology, using some classical chaotic circuits or multi-scroll chaotic circuits as modulation signals to reduce the electromagnetic noise of a switching power supply.

[0004] Classical chaotic circuits such as the Chua's chaotic circuit have obvious effects in EMI suppression, but due to the presence of inductance coils, the system has strict requirements for the experimental environment, and the modulation frequencies of other multi-scroll chaotic circuits are relatively low, resulting in a slower response speed. Summary of the Invention

[0005] The purpose of the present invention is to provide an improved Lorenz chaotic spread spectrum EMI reduction method based on a Buck converter. This method designs a chaotic system by changing the non-linear term of the classical Lorenz system, improves the Lorenz chaotic spread spectrum modulation method to control the switching tube drive signal of the Buck converter, disperses the electromagnetic noise energy concentrated at the switching frequency point and its harmonics to a wider frequency band, thereby reducing the conducted electromagnetic interference noise of the Buck converter, and its suppression effect is obvious.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An improved Lorenz chaotic spread spectrum EMI reduction method based on a Buck converter, the method includes a chaotic system designed by changing the non-linear term of the classical Lorenz system. This system includes a power supply part and a control part. The power supply part is a Buck converter topology structure, and the control part includes a comparator, a compensation circuit, and a spread spectrum circuit. The spread spectrum signal in the spread spectrum circuit is a chaotic spread spectrum signal generated by an improved Lorenz chaotic system circuit;

[0008] Among them, the first integration circuit of the improved Lorenz chaotic circuit includes: multiplier MUL 1 , amplifier EA 1 , EA 2 , resistor R 1 , R 2 , R 3 , R 8 , R 9 , capacitor C 1 ; The output terminal of MUL 1 is connected to one end of R 3 , and the other end is connected in parallel with R 1 , R 2 and then connected to the inverting input terminal of EA 1 . Both ends of C 1 are respectively connected to the inverting input terminal and the output terminal of EA 1 . The output terminal of EA 1 is connected to R 8 and then connected to the inverting input terminal of EA 2 . Both ends of R 9 are respectively connected to the inverting input terminal and the output terminal of EA 2 . The non-inverting input terminals of EA 1 , EA 2 are grounded, and the output terminals are respectively denoted as x, -x;

[0009] Its second integration circuit includes: multiplier MUL 2 , amplifier EA 3 , resistor R 4 , R 5 , capacitor C 2 ; The output terminal of MUL 2 is connected to one end of R 4 , and the other end is connected in parallel with R 5 and then connected to the inverting input terminal of EA 3 . Both ends of C 2 are respectively connected to the inverting input terminal and the output terminal of EA 3 . The non-inverting input terminal of EA 3 is grounded, and the output terminal is denoted as y;

[0010] Its third integration circuit includes: multiplier MUL 3 , amplifier EA 4 , resistor R 6 , R 7 , capacitor C 3 ; The output terminal of MUL 3 is connected to one end of R 6 , and the other end is connected in parallel with R 7 and then connected to the inverting input terminal of EA 4 . Both ends of C 3 are respectively connected to the inverting input terminal of EA4 The inverting input terminal and the output terminal of EA 4 The non-inverting input terminal of is grounded, and the output terminal is denoted as z.

[0011] The improved Lorenz chaos spread spectrum EMI reduction method based on a Buck converter, the integration circuit. In the first integration circuit, the multiplier MUL 1 The input terminal is connected to z and y, and the resistor R 1 and R 2 The left ends of are respectively connected to y and -x; in the second integration circuit, the multiplier MUL 2 The input terminal is connected to -x and z, and the resistor R 5 The left end of is connected to y; in the third integration circuit, the multiplier MUL 3 The input terminal is connected to -x and y, and the resistor R 7 The left end of is connected to z.

[0012] The improved Lorenz chaos spread spectrum EMI reduction method based on a Buck converter, the improved Lorenz chaos circuit. Its chaos system has 7 non-linear terms. The model of the improved Lorenz chaos system is:

[0013]

[0014] The improved Lorenz chaos spread spectrum EMI reduction method based on a Buck converter, the control part of the circuit includes an improved Lorenz chaos circuit, a reference voltage V base , a voltage-controlled oscillator VCO, a sawtooth wave generator, a comparator Comp, an amplifier EA, a reference voltage V ref , a resistor R 12 , R 13 , R 14 , R 15 , and capacitors C 5 , C 6 ;

[0015] Among them, the amplifier EA, the reference voltage V ref , the resistor R 12 , R 13 , R 14 , R 15 , and capacitors C 5 , C 6 form a compensation loop. V ref is grounded negatively and connected to the non-inverting input terminal of the amplifier EA positively. R 15 is in series with C 6 and then in parallel with R 14 . The two ends are respectively connected to the output terminal and the inverting input terminal of the amplifier EA. R 12 is in series with C5 After being connected in series and then with R 13 in parallel, the two ends are respectively connected to the inverting input terminal of the amplifier EA and the output terminal of the Buck converter;

[0016] The chaotic signal generated by the improved Lorenz chaotic circuit is used as a modulation signal and connected to a voltage-controlled oscillator. The voltage-controlled oscillator VCO outputs to a sawtooth wave generator to generate a chaotic sawtooth wave signal. The chaotic sawtooth wave signal is connected to the inverting input terminal of the comparator Comp, and the output terminal of the amplifier EA is connected to the non-inverting input terminal of the comparator Comp. The output terminal of the comparator Comp generates a chaotic PWM signal, and this signal controls the switch of the Buck converter.

[0017] In the described improved Lorenz chaotic spread spectrum EMI reduction method based on a Buck converter, the chaotic spread spectrum circuit generates a PWM signal and connects it to the Buck converter to achieve EMI noise suppression. An improved Lorenz chaotic circuit, a chaotic spread spectrum circuit, and a Buck converter topology circuit are built using simulation software. The chaotic PWM signal generated by the chaotic spread spectrum circuit is connected to the Buck converter topology circuit, and through simulation experiments, it is verified that the EMI noise of the Buck converter is suppressed.

[0018] In the described improved Lorenz chaotic spread spectrum EMI reduction method based on a Buck converter, the Buck converter topology circuit includes an input voltage V in , a switch S W , a freewheeling diode D, an inductor L 1 , a capacitor C 4 , a load resistor R LOAD , an equivalent series resistance R 10 、R 11 , a feedback voltage-dividing resistor R FB1 、R FB2 .

[0019] The advantages and effects of the present invention are:

[0020] Based on an improved Lorenz chaotic system, the present invention proposes a Buck converter capable of reducing EMI. A new chaotic system and a chaotic circuit are designed and built, and they are used as frequency modulation signals to generate chaotic PWM signals to control the on and off of the driving signal of the switch tube of the Buck converter. The method of the present invention suppresses the conducted noise of the Buck converter, has a good suppression effect, and the implementation method is simple, which is beneficial to industrial applications. Description of the Drawings

[0021] Figure 1 is the circuit schematic diagram of the improved Lorenz chaotic system of the present invention;

[0022] Figure 2This is the time-domain signal waveform diagram of the chaotic circuit of the present invention, where (a) is the x port, (b) is the y port, and (c) is the z port;

[0023] Figure 3 This is the phase diagram of the chaotic circuit of the present invention, where (a) is the xy phase diagram, (b) is the xz phase diagram, and (c) is the yz phase diagram;

[0024] Figure 4 This is the schematic diagram of the improved Lorenz chaotic spread spectrum based on the Buck converter of the present invention;

[0025] Figure 5 This is the PWM spectrum diagram of the application of the improved Lorenz chaotic system of the present invention;

[0026] Figure 6 This is the schematic diagram of the system composition principle of the present invention. Detailed implementation manners

[0027] The following further describes the implementation manners of the present invention with reference to the accompanying drawings, so that relevant personnel in the field can refer to and implement it. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention described in the accompanying drawings can be arranged and designed by various different types of devices.

[0028] The present invention controls the switching tube drive signal of the Buck converter through chaotic spread spectrum technology, realizes the reduction of the EMI of the Buck converter, and has obvious effects and application value.

[0029] The embodiment of the present invention provides a Buck converter capable of reducing electromagnetic interference. This converter includes: a power supply part and a control part. Among them, the power supply part is the Buck converter topology structure, which consists of an input voltage V in , a switch S W , a freewheeling diode D, an inductor L 1 , a capacitor C 4 , a load resistor R LOAD , an equivalent series resistance R 10 , R 11 , a feedback voltage dividing resistor R FB1 , R FB2 ; the control part includes a comparator, a compensation circuit and a spread spectrum circuit. The compensation circuit consists of an amplifier EA, a reference voltage V ref , a resistor R 12 , R 13 , R 14 , R 15 , a capacitor C 5 , C 6 ; the spread spectrum circuit consists of an improved Lorenz chaotic circuit, a reference voltage V base, consisting of a voltage-controlled oscillator VCO and a sawtooth wave generator.

[0030] Build the topology of the Buck converter and its output voltage compensation circuit, so that the output voltage of the Buck converter is compensated and amplified, and compared with the spread-spectrum sawtooth wave generated by the improved Lorenz chaotic circuit to generate a chaotic spread-spectrum pulse code control signal;

[0031] According to the model of the improved Lorenz chaotic system, using Kirchhoff's theorem, design three integral circuits with multipliers, amplifiers, resistors, and capacitors, and then connect the three integral circuits together by connecting the same ends to generate a chaotic signal and use it as a spread-spectrum signal to access the spread-spectrum circuit;

[0032] Design a spread-spectrum circuit using a reference voltage, a voltage-controlled oscillator, and a sawtooth wave generator, and connect the y port of the improved Lorenz chaotic system to the spread-spectrum circuit to make the sawtooth wave generator output a chaotic sawtooth wave signal with a changing chaotic frequency;

[0033] Connect the compensated and amplified output voltage signal and the chaotic sawtooth wave signal frequency-modulated using the improved Lorenz chaotic system to the non-inverting input terminal and the inverting input terminal of the comparator respectively to generate a chaotic PWM signal and connect it to the Buck converter to control the power switch S W , realizing the reduction of the electromagnetic noise of the Buck converter.

[0034] The above description only briefly expounds the content of the invention. The technical means of the present invention can be understood in detail below through the description in combination with the drawings.

[0035] Embodiment

[0036] Figure 1 Shows the circuit schematic diagram of the improved Lorenz chaotic system designed by the present invention. By analyzing the model (1) of the system, the following equations can be obtained according to Kirchhoff's theorem:

[0037]

[0038] Through simulation experiments, the resistance and capacitance values in the chaotic circuit can be obtained, where R 1 =R 2 =500Ω, R 3 =R 4 =R 6 =1kΩ, R 5 =310Ω, R 7 =2.5kΩ, R 8 =R 9 =10kΩ, C 1 =C 2 =C 3= 1 uF, and the gain of the multiplier is 0.1 V for all.

[0039] Figure 2 It shows the time-domain signal waveform diagram of the chaotic circuit designed by the present invention. According to Figure 1 the circuit schematic diagram shown, use Multisim software to build Figure 1 the chaotic circuit shown, and set the parameters of each component. Connect the x, y, and z output terminals in the schematic diagram to an oscilloscope, and the time-domain signal waveform diagrams of x, y, and z can be obtained.

[0040] Figure 3 It shows the phase diagram of the chaotic circuit designed by the present invention. Using a dual-channel oscilloscope, introduce the three groups of signals of x, y, x, z, and y, z into the dual-channel oscilloscope respectively, and the phase diagrams of x-y, x-z, and y-z can be obtained. It can be seen from the phase diagrams that the chaotic circuit has complex and rich nonlinear dynamic behaviors Figure 4 It shows the schematic diagram of the improved Lorenz chaotic spread spectrum based on a Buck converter. This diagram is divided into a power supply part and a control part. The power supply part is a Buck converter topology, and the figure includes power supply V IN , power switch S W , diode D, energy storage inductor L 1 , filter capacitor C 4 , equivalent series resistance R 10 , R 11 , feedback voltage-dividing resistors R FB1 , R FB2 , load resistor R LOAD , and the voltage across the load is denoted as output voltage V OUT . Utilize the unidirectional conduction principle of the diode and the charge and discharge principles of the capacitor and inductor, and maintain the normal operation of the Buck converter by controlling the conduction and turn-off of the power switch S W . When S W conducts, diode D turns off, and V IN charges L 1 and load resistor R LOAD ; when S W disconnects, diode D conducts, and L 1 charges load resistor R LOAD , and capacitor C 4 mainly plays a role in voltage stabilization and filtering.

[0041] In the control part, connect the output voltage of the Buck converter to the control part. After compensation and amplification, connect it to the non-inverting input terminal of the comparator, and Figure 1The chaotic y-time domain signal generated by the middle circuit is used as a modulation signal and connected to the spread spectrum circuit. After frequency modulation by the voltage-controlled oscillator, it enters the sawtooth wave generator to generate sawtooth wave signals with the same slope but different periods. The sawtooth wave signal generated by the chaotic signal is connected to the inverting input terminal of the comparator (Comp). By comparing it with the voltage ΔV at the non-inverting input terminal of the comparator, when the voltage at the non-inverting input terminal is greater than the voltage at the inverting input terminal, the comparator outputs a high level; when the voltage at the non-inverting input terminal is less than the voltage at the inverting input terminal, the comparator outputs a low level, thus generating a chaotic PWM signal to control the on and off of the switch S W to reduce the EMI of the Buck converter.

[0042] Figure 5 Fig. shows the PWM spectrum diagram of the present invention applying the improved Lorenz chaotic system. The circuit is built using SIMPLIS simulation software, and the fast Fourier transform is performed on the chaotic PWM signal of the circuit to obtain the PWM spectrum diagram. As can be seen from the figure, the EMI noise of the Buck converter at the switching frequency of the fundamental frequency 500KHZ is 402mV.

[0043] The above is only one of the embodiments of the present invention. The power supply part can be changed to the topological structure of other converters, and the component models and values in the circuit can be changed to reduce the electromagnetic noise of other boost and buck-boost converters. The specific operation can be understood by referring to the description of the embodiments and will not be described in detail here. It should be noted that these examples only show the technical solutions of the present invention and do not constitute a limitation thereto. Although the above examples elaborate on the various steps of the present invention in detail, those skilled in the art should recognize that the technical solutions in these examples can be adjusted, or some or all of the technical features therein can be equivalently replaced. In addition, any modification or substitution of the present invention that does not deviate from the essence of the present invention falls within the protection scope of the present invention.

Claims

1. An improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter, characterized in that: The method comprises changing a chaotic system designed by a nonlinear term of a classical Lorenz system, wherein the modified system comprises a power supply part and a control part, wherein the power supply part is a Buck converter topology structure, and the control part comprises a comparator, a compensation circuit and a spectrum spreading circuit, wherein a spectrum spreading signal in the spectrum spreading circuit is a chaotic spectrum spreading signal generated by an improved Lorenz chaotic system circuit; The first integration circuit of the improved Lorenz chaotic circuit includes: a multiplier MUL1, amplifiers EA1 and EA2, resistors R1, R2, R3, R8 and R9, and a capacitor C1; the output end of MUL1 is connected to one end of R3, the other end is connected in parallel with R1 and R2 and then connected to the inverting input end of EA1, the two ends of C1 are respectively connected to the inverting input end and the output end of EA1, the output end of EA1 is connected to R8 and then connected to the inverting input end of EA2, the two ends of R9 are respectively connected to the inverting input end and the output end of EA2, the in-phase input ends of EA1 and EA2 are grounded, and the output ends are respectively denoted as x and -x; The second integration circuit includes: a multiplier MUL2, an amplifier EA3, resistors R4 and R5, and a capacitor C2; the output end of MUL2 is connected to one end of R4, the other end is connected in parallel with R5 and then connected to the inverting input end of EA3, the two ends of C2 are respectively connected to the inverting input end and the output end of EA3, the non-inverting input end of EA3 is grounded, and the output end is denoted as y; Its third integrating circuit includes: multiplier MUL3, amplifier EA4, resistors R6, R7, capacitor C3; the output end of MUL3 is connected to one end of R6, and the other end is connected to the inverting input end of EA4 in parallel with R7, the two ends of C3 are respectively connected to the inverting input end and output end of EA4, the non-inverting input end of EA4 is grounded, and the output end is denoted as z.

2. The improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter according to claim 1 is characterized in that: The integration circuit, in the first integration circuit, the input end of the multiplier MUL1 is connected to z and y, and the left ends of the resistors R1 and R2 are connected to y and -x respectively; in the second integration circuit, the input end of the multiplier MUL2 is connected to -x and z, and the left end of the resistor R5 is connected to y; in the third integration circuit, the input end of the multiplier MUL3 is connected to -x and y, and the left end of the resistor R7 is connected to z.

3. The improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter according to claim 1 is characterized in that: The improved Lorenz chaotic circuit has a chaotic system with 7 nonlinear terms. The model of the improved Lorenz chaotic system is:

4. The improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter according to claim 1 is characterized in that: The control part of the circuit includes an improved Lorenz chaotic circuit, a reference voltage V base , voltage controlled oscillator VCO, sawtooth wave generator, comparator Comp, amplifier EA, reference voltage V ref , resistor R 12 , R 13 , R 14 , R 15 , capacitors C5 and C6; The amplifier EA, the reference voltage V ref , resistor R 12 , R 13 , R 14 , R 15 , capacitors C5 and C6 form a compensation loop, V ref The negative direction is grounded, and the positive direction is connected to the non-inverting input terminal of the amplifier EA. 15 Connect in series with C6 and then with R 14 Connect in parallel, and connect the two ends to the output and inverting input of amplifier EA respectively. 12 Connect in series with C5 and then with R 13 Connect in parallel, with the two ends connected to the inverting input of amplifier EA and the output of Buck converter respectively; The chaotic signal generated by the improved Lorenz chaotic circuit is connected to the voltage-controlled oscillator as a modulation signal. The voltage-controlled oscillator VCO outputs a chaotic sawtooth wave signal to the sawtooth wave generator, which is connected to the inverting input of the comparator Comp. The output of the amplifier EA is connected to the non-inverting input of the comparator Comp. The output of the comparator Comp generates a chaotic PWM signal, which controls the switch of the Buck converter.

5. The improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter according to claim 1 is characterized in that: The chaotic spread spectrum circuit generates a PWM signal which is connected to a Buck converter to achieve EMI noise suppression. Simulation software is used to build an improved Lorenz chaotic circuit, a chaotic spread spectrum circuit, and a Buck converter topology circuit. The chaotic PWM signal generated by the chaotic spread spectrum circuit is connected to the Buck converter topology circuit. Simulation experiments verify that the EMI noise of the Buck converter can be suppressed.

6. The improved Lorenz chaotic spread spectrum EMI reduction method based on Buck converter according to claim 1 is characterized in that: The Buck converter topology circuit includes an input voltage V in , switch S W , freewheeling diode D, inductor L1, capacitor C4, load resistor R LOAD , equivalent series resistance R 10 , R 11 , feedback voltage divider resistor R FB1 , R FB2。

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