阅读说明：本技术 用于逆变器的多目标协同控制输出电压谐波抑制的方法 (Method for multi-target cooperative control of output voltage harmonic suppression for inverter ) 是由 唐伟 刘洪良 于 2021-08-05 设计创作，主要内容包括：本发明公开了用于逆变器的多目标协同控制输出电压谐波抑制的方法。步骤一：将发电机输送的交流电通过整流电路整流,变为脉动直流电,并输出到直流母线电路；直流母线电路将脉动直流电滤除交流成分后输送到逆变电路；步骤二：控制电路产生的PWM波通过驱动电路控制逆变电路,得到脉冲电压波形,再经过滤波电路后产生逼近正弦的纯净交流电,并将纯净交流电输出到EMC电路；步骤三：在EMC电路中降低传导和辐射干扰后输出负载。本发明在保证系统稳定的基础上,能够无静差跟踪参考信号,实现突加、突卸负载时有快速的动态性能以及对母线电压波动、滤波器参数变化等系统参数摄动有较强的鲁棒性能。(The invention discloses a method for multi-target cooperative control of output voltage harmonic suppression of an inverter. The method comprises the following steps: rectifying alternating current transmitted by a generator through a rectifying circuit to obtain pulsating direct current, and outputting the pulsating direct current to a direct current bus circuit; the direct current bus circuit filters alternating current components of pulsating direct current and then transmits the alternating current components to the inverter circuit; step two: PWM waves generated by the control circuit control the inverter circuit through the drive circuit to obtain pulse voltage waveforms, pure alternating current close to sine is generated after the pulse voltage waveforms pass through the filter circuit, and the pure alternating current is output to the EMC circuit; step three: the output load after conductive and radiated interference is reduced in an EMC circuit. On the basis of ensuring the stability of the system, the invention can track the reference signal without static error, and realizes the rapid dynamic performance when suddenly adding and suddenly unloading the load and the strong robust performance for the perturbation of system parameters such as the voltage fluctuation of a bus, the parameter change of a filter and the like.)

1. The method for the harmonic suppression of the multi-target cooperative control output voltage of the inverter is characterized by comprising the following steps:

the method comprises the following steps: rectifying the alternating current transmitted by the generator through a rectifying circuit with a three-phase bridge circuit to obtain pulsating direct current, and outputting the pulsating direct current to a direct current bus circuit; the direct current bus circuit filters alternating current components of the pulsating direct current and then transmits the alternating current components to the inverter circuit;

step two: PWM waves generated by the control circuit control the inverter circuit through the drive circuit to obtain pulse voltage waveforms, pure alternating current close to sine is generated after the pulse voltage waveforms pass through the filter circuit, and the pure alternating current is output to the EMC circuit;

step three: by arranging the common-mode inductor, the capacitor X and the capacitor Y in the EMC circuit, the output load after conduction and radiation interference is reduced.

2. The method for harmonic suppression of output voltages of multi-target cooperative control of inverters according to claim 1, wherein the control circuit in the second step comprises an LMI method solving controller, the LMI method solving controller comprises a plurality of servo compensators, a sliding mode controller and an LMI stabilizing controller, an inner film of a signal to be tracked is embedded in the servo compensator, disturbance consistent with the control input direction is contained in the inner film, and the servo compensator sends the signal to the sliding mode controller; and the sliding mode controller eliminates the interference matched with the system and then outputs the interference, and the interference is stabilized by the LMI stabilizing controller and then outputs the stable power frequency voltage.

3. The method according to claim 2, wherein a protection circuit is further provided in the second step, the protection circuit is electrically connected to the control circuit, and the protection circuit includes a short-circuit protection circuit, an input over-voltage and under-voltage protection circuit, an output over-current protection circuit, a temperature protection circuit, and an auxiliary power supply circuit.

4. The method for multi-target cooperative control of output voltage harmonic suppression for inverters according to claim 3, wherein the driving circuit in the second step includes an IGBT module, and after the PWM signal sent by the control circuit passes through a reverse Schmitt trigger, a steeper square wave is obtained and output to the inverter.

Technical Field

The invention belongs to the technical field of inverters, and particularly relates to a multi-target cooperative control output voltage harmonic suppression method for an inverter.

Background

The inverter is a high-performance converter power supply matched with a generator system, and is mainly used for converting alternating current with unstable frequency and voltage output by the permanent magnet generator into power frequency single-phase alternating current with stable frequency and voltage so as to provide power frequency power for task equipment.

The output waveform of the existing inverter has rapid dynamic performance when the output waveform is subjected to sudden input and sudden load unloading, and has lower robustness on system parameter perturbation such as bus voltage fluctuation, filter parameter change and the like.

Disclosure of Invention

The invention aims to provide a method for suppressing harmonic waves of output voltage by multi-target cooperative control of an inverter, which solves the existing problems.

In order to solve the technical problems, the invention is realized by the following technical scheme:

the invention discloses a method for suppressing harmonic waves of output voltage by multi-target cooperative control of an inverter, which comprises the following steps:

the method comprises the following steps: rectifying the alternating current transmitted by the generator through a rectifying circuit with a three-phase bridge circuit to obtain pulsating direct current, and outputting the pulsating direct current to a direct current bus circuit; the direct current bus circuit filters alternating current components of the pulsating direct current and then transmits the alternating current components to the inverter circuit;

step two: PWM waves generated by the control circuit control the inverter circuit through the drive circuit to obtain pulse voltage waveforms, pure alternating current close to sine is generated after the pulse voltage waveforms pass through the filter circuit, and the pure alternating current is output to the EMC circuit;

step three: by arranging the common-mode inductor, the capacitor X and the capacitor Y in the EMC circuit, the output load after conduction and radiation interference is reduced.

Preferably, the control circuit in the third step includes an LMI method solving controller, the LMI method solving controller includes a plurality of servo compensators, a sliding mode controller and an LMI stabilizing controller, an inner film of a signal to be tracked is embedded in the servo compensator, disturbance consistent with the control input direction is included in the inner film, and the servo compensator sends the signal to the sliding mode controller; and the sliding mode controller eliminates the interference matched with the system and then outputs the interference, and the interference is stabilized by the LMI stabilizing controller and then outputs the stable power frequency voltage.

Preferably, a protection circuit is further arranged in the second step, the protection circuit is electrically connected with the control circuit, and the protection circuit comprises a short-circuit protection circuit, an input over-voltage and under-voltage protection circuit, an output over-current protection circuit, a temperature protection circuit and an auxiliary power supply circuit.

Preferably, the driving circuit in the second step includes an IGBT module, and the PWM signal sent by the control circuit passes through the reverse schmitt trigger to obtain a steeper square wave, and is output to the inverter.

The invention has the following beneficial effects:

1. on the basis of ensuring the stability of the system, the invention can track the reference signal without static error, and realize the rapid dynamic performance when suddenly adding and suddenly unloading the load and the strong robust performance for the perturbation of system parameters such as the voltage fluctuation of a bus, the parameter change of a filter and the like;

2. the invention comprehensively considers the multi-mode energy flow characteristics of the main loop of the inverter, reduces the influence of the capacitance-capacitance value of the direct current bus on the damping characteristics of the system, adopts a control strategy for improving the damping characteristics of the direct current side and expanding the attraction domain of the system by utilizing power self-adaptation, and realizes the stable and high-performance control of the closed-loop system under the condition of not increasing passive elements;

3. the invention adopts a control method for inhibiting the low-order harmonic of the output voltage of the electrolytic capacitor-free intermediate frequency inverter, and solves the optimal controller for stable operation and harmonic inhibition under the nonlinear load condition by combining a sliding mode control method and a robust multi-resonance servo control method.

Of course, it is not necessary for any product in which the invention is practiced to achieve all of the above-described advantages at the same time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an inverter circuit topology diagram of the method of the present invention for multi-target coordinated control of output voltage harmonic suppression for an inverter;

FIG. 2 is a schematic block diagram of the inverter unit control of the present invention;

FIG. 3 is a driving circuit diagram of the present invention;

FIG. 4 shows the current I in the IGBT module of the invention_cVoltage drop V from collector to emitter_ceA corresponding relationship diagram;

FIG. 5 is a diagram of pole placement areas;

FIG. 6 is a diagram of a sudden load simulation result of a single-phase inverter power supply controlled by a linear matrix inequality method;

FIG. 7 is a diagram of a sudden load shedding simulation result of a single-phase inverter power supply controlled by a linear matrix inequality method;

FIG. 8 is a graph of sudden load test results of a single-phase inverter controlled by a linear matrix inequality method;

fig. 9 is a graph of the sudden load shedding experimental result of the single-phase inverter power supply controlled by the linear matrix inequality method.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the present invention is a method for multi-target cooperative control output voltage harmonic suppression of an inverter, comprising the following steps:

the method comprises the following steps: rectifying the alternating current transmitted by the generator through a rectifying circuit with a three-phase bridge circuit to obtain pulsating direct current, and outputting the pulsating direct current to a direct current bus circuit; the direct current bus circuit filters alternating current components of pulsating direct current and then transmits the alternating current components to the inverter circuit;

step two: PWM waves generated by the control circuit control the inverter circuit through the drive circuit to obtain pulse voltage waveforms, pure alternating current close to sine is generated after the pulse voltage waveforms pass through the filter circuit, and the pure alternating current is output to the EMC circuit;

the inductance of the filter circuit requires that the switching frequency cannot be greater than the maximum switching frequency at which the IGBT can work; the switching frequency of the switching tube is shown as formula 1, wherein U_dIs the bus voltage of u_oFor output voltage, H is the set hysteresis value, L is the inductance value:

when the output voltage is half of the dc side voltage, the maximum switching frequency is obtained, and the formula is shown in formula 2:

f_max＝U_d/8HL formula 2

Wherein the maximum value of the bus voltage Ud is 620, H is set to be 2.8, L is inductance value, and the maximum switching frequency f allowed by the IGBT is set_maxAt 26kHz, as shown in equation 2, the inductance is 1.4mH, but the transient performance of the inverter unit is degraded due to the excessive inductance, and the output voltage THD is increased, so that the inductance is finally set to 1.58mH by comprehensive consideration in practical experiments.

Although too small inductance may cause the current error value to exceed the set threshold range, the switching frequency of the IGBT can be limited to 19.2kHz by setting the D flip-flop, and the IGBT switching loss will not be too large.

The hysteresis control characteristic exists, when the current is high, the switching frequency is low due to high output voltage, and the magnetic permeability of the magnetic core is reduced along with the increase of the magnetic field intensity, so that the inductance is reduced, and the formula is shown as formula 3:

therefore, a magnetic core with the inductance value which is not greatly changed along with the current needs to be selected, and the high-magnetic-flux NPF series of the POCO can meet the requirements; when the inductor is a magnetic core NPF226060, two magnetic cores are overlapped to form the inductor, and only one inverter unit in the filter circuit can form an LC filter circuit;

the value of the filter capacitor C can be determined by the cut-off frequency of the LC filter, the lowest harmonic of the output of the inverter is the switching frequency of the inverter, 1/10 in which the cut-off frequency of the LC low-pass filter is equal to or less than the lowest harmonic, that is, 1/10 of the switching frequency is adopted, the frequency of the hysteresis control is not fixed, but the frequency is a frequency division relation of 19.2kHz by adopting a D flip-flop, so that the average switching frequency is set to 10kHz, which can be obtained by equation 4:

the value of the output capacitor C is 16uH, and three capacitors of the Tanzhou macro-Dada CBB 25500V/6.8 uF are connected in parallel;

the driving circuit is formed by taking a driving optocoupler HCPL-316J of Agilent technologies as a core, the chip can drive an IGBT module with an ICE (integrated Circuit chip) of 150A and a VCE (Voltage control Unit) of 1600V, the driving peak current is 2A, the driving requirements of most medium and small power can be met, the functions of overcurrent protection, undervoltage protection and the like are realized, soft turn-off is carried out on the IGBT during protection, and a circuit diagram is shown in fig. 3;

after a PWM signal sent by the control circuit passes through the reverse Schmitt trigger, delay in transmission is removed, so that a square wave signal is steeper, the driving output of the optocoupler is connected with a diode in parallel, and the IGBT module is protected from being damaged due to overhigh input driving voltage; and is emphatically provided with R₃The resistance value of the resistor is expressed by the formula 5:

wherein V_DIs the voltage drop of a diode, V_CESetting the on-state voltage drop of the over-current value for the IGBT, wherein the current I of the IGBT module_cVoltage drop V from collector to emitter_ceThe corresponding relationship of (a) is shown in fig. 4: when the IGBT module is turned on, the current from the constant current source flows out of the chip to generate voltage drop on the resistor R3, the diodes V1, V2 and V3, and the voltage drop V of the module is added_ceIf it is greater than 7V, then V_outThe output is changed to be low, the IGBT module is switched off and locked in a soft switch mode, the current flowing through the IGBT is prevented from further rising, and the IGBT module is protected;

after protection, REST signals (low level is effective) can be given within 3ms, and the IGBT is allowed to be turned on again;

as shown in fig. 2, the hysteresis control is implemented by a hardware circuit and a software circuit, the control circuit adopts PI, P and hysteresis control, and various controls ensure that the inverter unit obtains stable power frequency voltage required by output;

according to the internal model principle, the internal model of the signal to be tracked is embedded in the mathematical model of the servo compensator, so that the selected reference signal can be accurately tracked, matching (consistent with the control input direction) disturbance contained in the internal model can be completely eliminated once the sliding mode surface of the sliding mode controller enters, and if the robust control method is combined, the robust performance of the system can be improved; the servo compensator has the functions of realizing system asymptotic tracking and disturbance suppression, the sliding mode controller has the functions of eliminating system matching type disturbance, and the stabilizing controller has the functions of ensuring the stability of the closed-loop system under the conditions of parameter perturbation and multi-working-condition operation and enabling the influence of external disturbance d on the closed-loop system to be minimum.

The pole allocation method is one of effective ways to improve the dynamic performance of the closed-loop system, however, in an actual control system, the parameters of the controlled object often have uncertainty, so it is difficult to allocate all closed-loop poles at very accurate positions,it is common practice to arrange them in a designated area. If the poles are arranged in the shaded area as shown in FIG. 5, it is ensured that the closed loop system has the minimum damping ratio ε and the maximum natural frequency ω_nFurther, it can be ensured that dynamic performance indexes (such as overshoot, rise time and regulation time) do not exceed the regulation indexes of epsilon and omega_nThe upper bound of the decision.

Step three: by arranging the common-mode inductor, the capacitor X and the capacitor Y in the EMC circuit, the output load after conduction and radiation interference is reduced.

The control circuit in the second step comprises an LMI method solving controller, the LMI method solving controller comprises a plurality of servo compensators, a sliding mode controller and an LMI stabilizing controller, an inner membrane of a signal to be tracked is embedded in each servo compensator, disturbance consistent with the control input direction is contained in each inner membrane, and the servo compensators send the signal to the sliding mode controller; and the sliding mode controller eliminates the interference matched with the system and outputs the interference, and the stable power frequency voltage is output after the interference is stabilized by the LMI stabilizing controller.

And the driving circuit in the second step comprises an IGBT module, and the PWM signal sent by the control circuit is processed by a reverse Schmitt trigger to obtain a steeper square wave and output the wave to the inverter.

Referring to the simulation diagrams and the experimental diagrams shown in fig. 6-9, the uncertainty of the system model parameters is considered, and an LMI solution method is adopted, so that the closed-loop system can simultaneously satisfy the following conditions:

firstly, within all uncertain parameter ranges, a closed loop system can meet internal stability;

secondly, the influence of the interference signal omega on the expected output y is minimum;

thirdly, a closed loop system pole is configured in a given D area so as to meet the requirements of the system on tracking performance, dynamic performance, damping ratio and the like; the closed-loop system has faster dynamic response speed and better robust performance.

It should be noted that, in the above system embodiment, each included unit is only divided according to functional logic, but is not limited to the above division as long as the corresponding function can be implemented; in addition, specific names of the functional units are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention.

In addition, it can be understood by those skilled in the art that all or part of the steps in the method for implementing the embodiments described above can be implemented by instructing the relevant hardware through a program, and the corresponding program can be stored in a computer-readable storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, or the like.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.