Disclosure of Invention
The invention aims to provide an inverter control method, an inverter control device, electronic equipment and a computer readable storage medium based on a cascade repetitive controller, so as to effectively improve the dynamic performance and the steady-state performance of the output of an inverter at the same time.
In order to solve the technical problem, in one aspect, the present application discloses an inverter control method based on a cascaded repetitive controller, including:
acquiring a reference output voltage and an actual output voltage of the inverter to calculate an actual deviation of the reference output voltage and the actual output voltage;
calculating a first control signal based on the actual deviation with a repetitive controller;
summing the first control signal and the actual deviation to obtain a corrected deviation;
performing PI control based on the correction deviation by using a PI double closed-loop controller cascaded with the repetitive controller to calculate a second control signal;
and generating a corresponding pulse signal based on the second control signal to drive a switching tube of the inverter so as to regulate the output voltage of the inverter.
Optionally, the calculating, with the repetitive controller, a first control signal based on the actual deviation includes:
filtering the actual deviation by using a filter with a delay element to calculate a filtering deviation;
summing the actual deviation and the filtering deviation to obtain a combined deviation;
and sequentially delaying and compensating the merging deviation by utilizing a cascaded delay link and a cascaded compensation link to acquire the first control signal.
Optionally, the filter with the delay element in the repetitive controller is specifically a low-pass filter.
Optionally, the compensation element in the repetitive controller specifically includes phase compensation and amplitude compensation.
Optionally, the expression of the transfer function of the compensation link is krzkS(z);
Wherein k isrIs the gain of the compensation stage; z is a radical ofkFor phase compensation; s (z) is amplitude compensation, specifically a second-order link.
Optionally, the performing PI control based on the corrected deviation by using a PI double closed-loop controller cascaded with the repetitive controller to calculate a second control signal includes:
calculating a current control amount based on the correction deviation by using a PI controller of a voltage outer ring;
the current control quantity is differed with the filter capacitor current of the inverter to obtain a current deviation;
summing the product of the current deviation and a current loop scaling parameter with a reference output voltage of the inverter to obtain the second control signal.
Optionally, the inverter is embodied as a single-phase H6 bridge inverter.
In another aspect, the present application also discloses an inverter control device based on a cascaded repetitive controller, including:
the acquisition module is used for acquiring the reference output voltage and the actual output voltage of the inverter;
a repetitive control module for calculating an actual deviation of the reference output voltage from the actual output voltage; calculating a first control signal based on the actual deviation with a repetitive controller; summing the first control signal and the actual deviation to obtain a corrected deviation;
a PI control module for performing PI control based on the correction deviation by using a PI double closed-loop controller cascaded with the repetitive controller to calculate a second control signal;
and the driving module is used for generating a corresponding pulse signal based on the second control signal to drive a switching tube of the inverter so as to regulate the output voltage of the inverter.
In another aspect, the present application also discloses an electronic device, including:
a memory for storing a computer program;
a processor for executing the computer program to implement the steps of any of the cascade repetitive controller based inverter control methods described above.
In yet another aspect, the present application further discloses a computer readable storage medium having a computer program stored therein, which when executed by a processor is used to implement the steps of any one of the cascade repetitive controller based inverter control methods described above.
The inverter control method, the inverter control device, the electronic equipment and the computer-readable storage medium based on the cascading repetitive controllers have the advantages that: according to the method and the device, cascade control is performed by sequentially utilizing the repetitive controllers and the PI controllers, dynamic performance and stable performance of voltage output of the inverter are effectively balanced based on the cascade repetitive controllers, and the parameter design of a cascade structure is simple, so that the method and the device have wider system stability and are beneficial to improving the waveform quality of output voltage.
Detailed Description
The core of the application is to provide an inverter control method, an inverter control device, electronic equipment and a computer-readable storage medium based on a cascade repetitive controller, so as to effectively improve the dynamic performance and the steady-state performance of the output of an inverter at the same time.
In order to more clearly and completely describe the technical solutions in the embodiments of the present application, the technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. 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 application.
When controlling the inverter to output voltage, a dual closed-loop control structure based on a PI controller is mostly adopted at present, and includes a voltage outer loop and a current inner loop with voltage feedforward, and the specific structure of the dual closed-loop control structure can be seen in fig. 1.
Wherein, the first and the second are digital control parts, the third is an equivalent transfer function of the main circuit of the inverter, vrefIs a reference output voltage, voFor the actual output voltage of the inverter, there are two control parameters in the voltage loop PI controller, namely the proportionality coefficient kvpAnd integral coefficient kviIc is the filter capacitor current, kcIs the current loop proportionality coefficient, kPWMFor PWM gain, VdcIs the DC bus voltage of the inverter, L is the filter inductor, C is the filter capacitor, iLFor filtering inductor current, R is parasiticAnd (4) resistance.
Aiming at the difficulty in balancing the dynamic performance and the steady-state performance of the voltage output of the inverter by simple PI control, the application provides an inverter control scheme based on a cascade type repetitive controller, and the technical problem can be effectively solved.
Referring to fig. 2, an embodiment of the present application discloses an inverter control method based on a cascaded repetitive controller, which mainly includes:
s101: and acquiring the reference output voltage and the actual output voltage of the inverter to calculate the actual deviation of the reference output voltage and the actual output voltage.
Let the reference output voltage be vrefThe actual output voltage is denoted voThe actual deviation is denoted verrThe method specifically comprises the following steps: v. oferr=vref-vo。
S102: a first control signal is calculated based on the actual deviation with a repetitive controller.
It is noted that the present application uses a PI controller and a repetitive controller in particular in combination. Specifically, the basic idea of repetitive control stems from the inner membrane principle in control theory, which requires a feedback system with good ability to track commands and cancel disturbances. The method and the device have the advantages that the repetitive control and the PI controller are cascaded to effectively inhibit periodic disturbance and ensure that a system keeps good steady-state performance, so that the steady-state performance and the dynamic performance of the output of the inverter are further improved.
S103: the first control signal is summed with the actual deviation to obtain a corrected deviation.
Denote the first control signal as yrpThe actual deviation is denoted verrThe correction deviation is noted as ycrThen y iscr=yrp+verr。
S104: and performing PI control based on the correction deviation by using a PI double closed-loop controller cascaded with the repetitive controller to calculate a second control signal.
S105: and generating a corresponding pulse signal based on the second control signal to drive a switching tube of the inverter so as to regulate the output voltage of the inverter.
In particular, the repetitive controllers and PI controllers used in conjunction with the present application are specifically in a cascade relationship (i.e., a series relationship) rather than a parallel relationship. It should be noted that in the parallel type structure, the PI controller and the repetitive controller operate in parallel, as shown in fig. 3: the repetitive controller and the PI controller share one output error signal, and the result of adding the output of the repetitive controller and the output of the PI controller is transmitted to the controlled object. However, the parallel structure has the defect of complex control design process, and according to simulation verification analysis, the parallel structure has complex parameter design and a small system stability range, and is not beneficial to the design of the inverter.
Therefore, the cascade structure is adopted, the output signal of the repetitive controller is processed to be used as the input signal of the PI controller, and the result of PI control is output to the main circuit of the inverter to complete cascade control. The overall cascade structure can be seen in fig. 4: the repetitive controller will generate the first control signal yrpOutputting, and summing with the actual deviation to obtain the corrected deviation ycrAnd input to PI double closed-loop controller, which can generate second control signal y after correlation calculationcuSo as to modulate and generate a corresponding pulse signal u to drive a switching tube in the main circuit of the inverter, thereby achieving the purpose of adjusting the output voltage of the inverter.
Wherein g (z) represents a related control structure in the PI double closed-loop structure, and the specific PI double closed-loop control structure can be similar to that shown in fig. 1, and only the input signal needs to be replaced by the correction deviation y in the present applicationcrThen the method is finished; and the specific structure of the repetitive controller can refer to fig. 6.
According to simulation verification analysis, the cascade structure adopted by the method is simple in parameter design, can keep the advantages of the parallel repetitive controllers, has wider system stability, improves the waveform quality of output voltage, and has better dynamic performance and steady-state performance than the parallel repetitive controllers.
The specific analysis process is as follows:
for the above two control structures, to make the system have better performance, the bandwidth of the voltage loop is designed as follows:
500Hz=10*fo≤ωbv≤0.1*fs=2kHz (1)
wherein, ω isbvIs the resonant frequency, foAt fundamental frequency, fsIs the sampling frequency. Substituting the above formula (1) into the following formula (2):
the value range of the voltage ring proportionality coefficient can be obtained as the following formula (3):
0.063≤kvp≤0.208 (3)
system-based transfer function equation (4):
the characteristic equation of formula (4) can be obtained as shown in formula (5):
LCs3+(CR+Ckc)s2+kvpkcs+kvikc=0 (5)
the condition that system stability can be obtained according to the Ross criterion is equation (6):
the combination of equations (3) and (6) can obtain a stable value range of the controller, i.e. the region a + B in fig. 5. On the basis, the Baud diagram analysis of the equivalent transfer function is respectively carried out on the cascade structure and the parallel structure of the repetitive controller and the PI controller, and the transfer function of the parallel structure has the turning frequency. Therefore, the turning frequency of the parallel structure is required to be lower than the fundamental frequency by 50Hz during design, that is:
from this calculation:
kvi<100πkvp (8)
thus, the stable value range of the parallel repetitive controller can be obtained by combining equations (3), (6) and (8), i.e., region B in fig. 5. And because the bode graph of the cascade structure is a relatively smooth curve in the whole low-frequency band, has no turning frequency and is not limited by the formula (8), the area A + B is the stable value range of the cascade repetitive controller. The comparison shows that the stability range of the cascade repetitive controller is wider, and the parameter design is more facilitated.
Therefore, the inverter control method based on the cascade repetitive controllers carries out cascade control by successively utilizing the repetitive controllers and the PI controllers, effectively balances the dynamic performance and the steady-state performance of the voltage output of the inverter based on the cascade repetitive controllers, has simple parameter design of a cascade structure, has wider system stability, and is beneficial to improving the waveform quality of the output voltage.
As a specific embodiment, the inverter control method based on a cascaded repetitive controller provided in the embodiments of the present application, based on the above, uses the repetitive controller to calculate the first control signal based on the actual deviation, and includes:
filtering the actual deviation by using a filter with a delay link to calculate a filtering deviation;
summing the actual deviation and the filtering deviation to obtain a combined deviation;
and sequentially delaying and compensating the combined deviation by utilizing a cascaded delay link and a cascaded compensation link so as to obtain a first control signal.
Further, as a specific embodiment, the filter with a delay element in the repetitive controller is specifically a low-pass filter; the compensation step in the repetitive controller specifically includes phase compensation and amplitude compensation. Specifically, the transfer function expression of the compensation link may be krzkS (z); wherein k isrThe gain of the compensation link is obtained; z is a radical ofkFor phase compensation; s (z) is amplitude compensationThe body is a second-order link.
Referring to fig. 6 in particular, fig. 6 is a schematic structural diagram of a repetitive controller disclosed in the embodiment of the present application. Wherein v iserrIs the input signal of the repetitive controller, i.e. the actual deviation; q (z) is a filter; z is a radical of-NA delay link is adopted; v. oferr_cIs the filtering deviation; v. ofeMerging the deviations; k is a radical ofrzkS (z) as a whole is a compensation element, which includes phase compensation and amplitude compensation, krFor the gain of the repetitive controller, zkFor phase compensation, s (z) is amplitude compensation. Through calculation and simulation verification, Q (z) is designed to be a low-pass filter, and S (z) is designed to be a second-order link.
As a specific embodiment, the inverter control method based on a cascaded repetitive controller provided in the embodiments of the present application, based on the above, performs PI control based on a correction deviation by using a PI dual closed-loop controller cascaded with the repetitive controller to calculate a second control signal, including:
calculating a current control quantity based on the correction deviation by using a PI controller of the voltage outer ring;
the current control quantity is differed with the filter capacitor current of the inverter to obtain current deviation;
and summing the product of the current deviation and the current loop proportion parameter with the reference output voltage of the inverter to obtain a second control signal.
Referring similarly to FIG. 1, in particular, the PI controller is based on correcting the offset ycrCalculating to obtain a current control quantity ir,irAnd the filter capacitor current icDifferencing to obtain a current deviation ierrAnd further calculates the second control signal ycu=ierr·kc-vref. Thus, based on the second control signal ycuAnd modulating to obtain a pulse signal u so as to drive the inverter main circuit to work.
As a specific embodiment, in the inverter control method based on the cascaded repetitive controller provided by the embodiment of the present application, on the basis of the above content, the inverter is specifically a single-phase H6 bridge inverter.
In particular, an H6 bridge topology circuit is a novel inverter topology provided for solving the problem of common-mode leakage current of an inverter. The H6 bridge inverter embeds two unit freewheeling units between the full bridge inverter leg midpoints to obtain a freewheeling channel.
Among DC/AC inverter circuit topologies having various configurations, H4 topology has been widely studied because of its advantages such as small output voltage ripple, small filter inductance, and high utilization rate of the input-side DC voltage. However, the circuit topology generates a large common mode voltage, which results in a large leakage current. In order to suppress the common mode voltage and thus generate low leakage current, related research proposes an improved inverter topology-H6 topology. Therefore, the inverter in the present embodiment may be embodied as an H6 inverter.
Referring to fig. 7-11, fig. 7 is a structural topology diagram of an H6 inverter disclosed in the embodiments of the present application, and fig. 8-11 show 4 operation modes of PWM in an H6 inverter. Wherein, S1-S6 are switches, D1 and D2 are diodes, L is a filter inductor, and C is a filter capacitor. Compared to a conventional single-phase H4 inverter, the H6 inverter adds two additional diodes and two additional switches in order to provide a freewheeling path.
Specifically, in the operation mode 1, S1, S5, S4 are turned on; in the operation mode 2, S5 and D1 are conducted; in the operation mode 3, S3, S6 and S2 are turned on; in operation mode 4, S6 and D2 are turned on.
Common mode voltage of the H6 inverter is denoted ucomThen, the common mode voltage formula in the four modes is as follows:
it can be seen that in these four modes, the common mode voltage u of the H6 invertercomThe amplitude is kept constant all the time, so theoretically, the H6 inverter can effectively eliminate the influence of leakage current and improve the voltage output quality.
In order to further verify the beneficial effects of the inverter control method based on the cascade repetitive controller provided by the application, the application also provides simulation verification results of the inverter control method and the parallel structure in MATLAB/SIMULINK.
Specifically, fig. 12 is a dynamic waveform of output voltage and current based on a parallel-type repetitive controller under a linear load; fig. 13 shows dynamic waveforms of output voltage and current based on a cascade type repetitive controller under a linear load. It can be seen that the load switches into the system at 0.04 seconds, the output current starts to develop at 0.04 seconds, and is synchronized with the output voltage. By performing fourier analysis on the output voltages of the two structures, the Total Harmonic Distortion (THD) of the output voltage of the parallel repetitive controller is 0.82%, while the THD of the cascade controller is only 0.23%.
Similarly, the two configuration repetitive controllers were compared under nonlinear loading. FIG. 14 is a dynamic waveform of output voltage and current based on a parallel type repetitive controller under a nonlinear load; fig. 15 shows dynamic waveforms of output voltage and current based on the cascade type repetitive controller under a nonlinear load. By performing FFT analysis on the output voltage under the nonlinear load, the Total Harmonic Distortion (THD) of the output voltage of the parallel repetitive controller is 1.64%, while the THD of the cascade repetitive controller is only 0.71%.
Through simulation analysis, no matter linear load or nonlinear load, under the same design parameter, the output voltage waveform of the cascade repetitive controller has certain improvement effect compared with the output voltage waveform of the parallel repetitive controller, the THD of the output voltage is lower, and the dynamic performance is further improved.
Referring to fig. 16, an embodiment of the present application discloses an inverter control device based on a cascaded repetitive controller, which mainly includes:
an obtaining module 201, configured to obtain a reference output voltage and an actual output voltage of an inverter;
a repetitive control module 202 for calculating an actual deviation of the reference output voltage from the actual output voltage; calculating a first control signal based on the actual deviation with a repetitive controller; summing the first control signal and the actual deviation to obtain a corrected deviation;
a PI control module 203 for performing PI control based on the correction deviation by using a PI double closed-loop controller cascaded with the repetitive controller to calculate a second control signal;
and the driving module 204 is configured to generate a corresponding pulse signal based on the second control signal to drive a switching tube of the inverter, so as to regulate an output voltage of the inverter.
Therefore, the inverter control device based on the cascade repetitive controller disclosed by the embodiment of the application performs cascade control by sequentially using the repetitive controller and the PI controller, effectively balances the dynamic performance and the steady-state performance of the voltage output of the inverter based on the cascade repetitive controller, has simple parameter design of a cascade structure, has wider system stability, and is beneficial to improving the waveform quality of the output voltage.
For specific content of the inverter control device based on the cascaded repetitive controller, reference may be made to the detailed description of the inverter control method based on the cascaded repetitive controller, and details thereof are not repeated here.
As a specific embodiment, in the inverter control device based on the cascaded repetitive controller disclosed in the embodiment of the present application, on the basis of the foregoing, the repetitive control module 202 is specifically configured to:
filtering the actual deviation by using a filter with a delay link to calculate a filtering deviation; summing the actual deviation and the filtering deviation to obtain a combined deviation; and sequentially delaying and compensating the combined deviation by utilizing a cascaded delay link and a cascaded compensation link so as to obtain a first control signal.
As a specific embodiment, in the inverter control device based on the cascaded repetitive controller disclosed in the embodiments of the present application, on the basis of the above contents, the filter with the delay element in the repetitive controller is specifically a low-pass filter.
As a specific embodiment, in the inverter control device based on the cascaded repetitive controller disclosed in the embodiments of the present application, on the basis of the above contents, the compensation link in the repetitive controller specifically includes phase compensation and amplitude compensation.
As a specific embodiment, the embodiment of the present application disclosesBased on the contents, the inverter control device based on the cascade repetitive controller has a transfer function expression k of a compensation linkrzkS (z); wherein k isrThe gain of the compensation link is obtained; z is a radical ofkFor phase compensation; s (z) is amplitude compensation, specifically a second-order link.
As a specific embodiment, in the inverter control device based on the cascaded repetitive controller disclosed in the embodiment of the present application, on the basis of the above content, the PI control module 203 is specifically configured to:
calculating a current control quantity based on the correction deviation by using a PI controller of the voltage outer ring; the current control quantity is differed with the filter capacitor current of the inverter to obtain current deviation; and summing the product of the current deviation and the current loop proportion parameter with the reference output voltage of the inverter to obtain a second control signal.
As a specific embodiment, the inverter control device based on the cascaded repetitive controller disclosed in the embodiments of the present application is based on the above, and the inverter is specifically a single-phase H6 bridge inverter.
Referring to fig. 17, an embodiment of the present application discloses an electronic device, including:
a memory 301 for storing a computer program;
a processor 302 for executing the computer program to implement the steps of any of the cascade repetitive controller based inverter control methods described above.
Further, the present application also discloses a computer readable storage medium, in which a computer program is stored, and the computer program is used for implementing the steps of any one of the above-mentioned inverter control methods based on a cascaded repetitive controller when being executed by a processor.
For details of the electronic device and the computer-readable storage medium, reference may be made to the foregoing detailed description of the inverter control method based on the cascaded repetitive controller, and details thereof are not repeated here.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the equipment disclosed by the embodiment, the description is relatively simple because the equipment corresponds to the method disclosed by the embodiment, and the relevant parts can be referred to the method part for description.
It is further noted that, throughout this document, relational terms such as "first" and "second" are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Furthermore, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The technical solutions provided by the present application are described in detail above. The principles and embodiments of the present application are explained herein using specific examples, which are provided only to help understand the method and the core idea of the present application. It should be noted that, for those skilled in the art, without departing from the principle of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall into the protection scope of the present application.