Non-intrusive parameter identification method for single-phase PWM inverter circuit

Abstract

A non-intrusive parameter identification method for a single-phase PWM inverter circuit comprises the following steps: establishing a PWM inverter circuit model, listing a space state equation set of the PWM inverter circuit model, and calculating the value of the space state equation set by using a four-order Runge-Kutta method; establishing an evaluation function, using an optimized particle swarm optimization algorithm to carry out optimization, finding the minimum value of the evaluation function frmse when the coordinate dimension of particles is 4, finding out the particle coordinates corresponding to the minimum value of the evaluation function, and updating the coordinates into the identified circuit parameters in the state.

Description

Technical Field

[0001] The invention relates to the technical field of single-phase PWM inverter circuits, and in particular to a non-intrusive parameter identification method for a single-phase PWM inverter circuit. Background Art

[0002] Inverters play a vital role in modern power systems and power electronics. Studies have shown that power semiconductor devices and capacitors are the most prone to failure in inverters. These components will be subjected to complex and frequent electrical and thermal stresses during long-term operation, causing reliability reduction and directly affecting the safe and stable operation of the system. Summary of the invention

[0003] The present invention provides a non-intrusive parameter identification method for a single-phase PWM inverter circuit, which provides a non-intrusive, low-cost and accurate solution for predictive maintenance and life assessment of a single-phase PWM inverter system.

[0004] A non-intrusive parameter identification method for a single-phase PWM inverter circuit, wherein:

[0005] The single-phase PWM inverter circuit is a single-phase two-level PWM inverter circuit, and the circuit includes a DC power supply side, a power switch device T1 and a power switch device T2, and an AC output side, wherein:

[0006] The DC power supply side includes capacitors C1 and C2 for voltage division and connected in series.

[0007] The power switch device T1 and the power switch device T2 are connected in parallel with the capacitor C1 and the capacitor C2 respectively, and the power switch device T1 and the power switch device T2 form a series relationship;

[0008] The power switch device T1 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on1 ;

[0009] The power switch device T2 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on2 ;

[0010] A DC voltage source with a voltage of V and a resistance of R s The line resistance of the capacitor C1 and the capacitor C2 are connected in parallel after the two are connected in series.

[0011] From the series connection of capacitor C1 and capacitor C2, and the series connection of power switch device T1 and power switch device T2, the AC output side is led out, where:

[0012] The AC output side uses inductor L for filtering, and the load is resistor R L, where the inductance L and the resistance R L Form a series relationship;

[0013] The method comprises the following steps:

[0014] S1: respectively collect the voltage u of capacitor C1 C1 , the voltage u of capacitor C2 C2 And the output voltage u on the load at the AC output side L , output current i L =u L / R L ,

[0015] The voltage u C1 、Voltage u C2 , output current i L As the observation quantity of the physical circuit to be identified, it is denoted as u C1_real 、u C2_real 、i L_real, ,

[0016] The control signal is collected by the controller, and the switching signals of the power switch device T1 and the power switch device T2 are recorded as S1 and S2 respectively, where S i =1 or 0, 1 represents on, 2 represents off, i=1,2, signal S is used to represent the switch signal, the switch signal S1 is S, then the switch signal S2=1-S, where S=0 or 1;

[0017] S2: Determine the spatial state equations of the single-phase PWM inverter circuit model;

[0018] S3: Use the 4th-order Runge-Kutta method to calculate the values ​​of the spatial state equations;

[0019] S4: Construct an evaluation function using the real system model and the digital twin model as a comparison;

[0020] S5: Use the particle swarm optimization algorithm to find the optimal solution. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, R on1 , R on2 , in order to find the evaluation function f rmse The minimum value of the evaluation function is obtained, and the particle coordinates corresponding to the minimum value of the evaluation function are found, and the coordinates are updated to the circuit parameters C1, C2, R in this state. on1 , R on2 , to monitor the health status of the voltage-dividing capacitors and power switching devices;

[0021] in,

[0022] The two R at the power switch device T1 on1 Among the resistors, the first Ron1 The resistor is connected in series between the power switch device T1 and the load resistor R L and connected in series between the power switch device T1 and the power switch device T2; the second R on1 After the resistor is connected in series with the first diode, it is further connected in series with the first R on1 The resistor and the power switch device T1 form a parallel relationship;

[0023] The two R at the power switch device T2 on2 Among the resistors, the first R on2 The resistor is connected in series between the power switch device T2 and the capacitor C2; the second R on2 After the resistor is connected in series with the second diode, it is further connected in series with the first R on2 The resistor and the power switch device T2 form a parallel relationship.

[0024] Preferably, in step S2,

[0025] The spatial state equation group of the single-phase PWM inverter circuit model is:

[0026]

[0027] Right now:

[0028]

[0029] Where, L is the inductance value, S is the switching signal, R L is the load resistance value, f1~f3 are the functional relationships of various variables.

[0030] Preferably, in step S3,

[0031] Determine the initial conditions and solution interval according to the spatial state equations.

[0032] The solution interval is divided into n small intervals, and the time step of each interval is h. In each small interval, the approximate solution of several points in the small interval is calculated in sequence using the fourth-order Runge-Kutta iteration formula:

[0033]

[0034] in, , h is the interval step length, x i is the sampling time point,

[0035] The approximate solution at each step is weighted averaged to obtain the approximate solution of the entire solution interval as the value of the space state equation group.

[0036] Preferably, in step S4,

[0037] The digital twin model is a model solved using the Runge-Kutta method. The real system model is a physical inverter entity model. The load current i is obtained by measuring and sampling. L_real and capacitor voltage u C1_real ,u C2_real Data, using adaptive filtering algorithm to filter out noise, get the filtered measurement value i L_m , u C1_m , u C2_m , the digital twin model is used to calculate the i under a certain circuit parameter state L ,u C1 ,u C2 Data, and construct the evaluation function f rmse .

[0038] Preferably, in step S5,

[0039] The optimization using improved particle swarm algorithm includes:

[0040] Initialization: Randomly generate several groups of particles with a group dimension of 4, each particle contains 4 circuit parameters to be optimized, namely C1, C2, R on1 , R on2 ,

[0041] Calculate particle fitness: use the current particle parameters to calculate the evaluation function f rmse ,

[0042] Update individual optimal and global optimal: find the historical optimal parameters of each particle and the parameters of the current global optimal particle.

[0043] Speed ​​update and position update: Update the speed of particles according to the historical best positions of individuals and groups, and adjust the positions of particles, i.e. circuit parameters, according to the updated speed. The individual learning factor and group learning factor change dynamically to avoid falling into the local optimum and speed up the convergence speed.

[0044] Result evaluation: Under the circuit parameters represented by each particle, the evaluation function f between the model prediction value and the actual measured value is calculated rmse value,

[0045] When the evaluation function is minimum, the corresponding C1, C2, R on1 , R on2 , and it is considered that the closest parameters of the circuit parameters are obtained to realize the health status monitoring of the voltage-dividing capacitor and the power switching device.

[0046] In addition, the present invention also discloses a non-intrusive parameter identification system for a single-phase PWM inverter circuit, wherein:

[0047] The single-phase PWM inverter circuit is a single-phase two-level PWM inverter circuit, and the circuit includes a DC power supply side, a power switch device T1 and a power switch device T2, and an AC output side, wherein:

[0048] The DC power supply side includes capacitors C1 and C2 for voltage division and connected in series.

[0049] The power switch device T1 and the power switch device T2 are connected in parallel with the capacitor C1 and the capacitor C2 respectively, and the power switch device T1 and the power switch device T2 form a series relationship;

[0050] The power switch device T1 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on1 ;

[0051] The power switch device T2 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on2 ;

[0052] A DC voltage source with a voltage of V and a resistance of R s The line resistance of the capacitor C1 and the capacitor C2 are connected in parallel after the two are connected in series.

[0053] From the series connection of capacitor C1 and capacitor C2, and the series connection of power switch device T1 and power switch device T2, the AC output side is led out, where:

[0054] The AC output side uses inductor L for filtering, and the load is resistor R L , where the inductance L and the resistance R L Form a series relationship;

[0055] The system comprises:

[0056] The acquisition unit is used to respectively acquire the voltage u of the capacitor C1 C1 , the voltage u of capacitor C2 C2 And the output voltage u on the load at the AC output side L , output current i L =u L / R L ,

[0057] The voltage u C1 、Voltage u C2 , output current i L As the observation quantity of the physical circuit to be identified, it is denoted as u C1_real 、u C2_real 、i L_real, ,

[0058] The control signal is collected by the controller, and the switching signals of the power switch device T1 and the power switch device T2 are recorded as S1 and S2 respectively, where S i =1 or 0, 1 represents on, 2 represents off, i=1,2, signal S is used to represent the switch signal, the switch signal S1 is S, then the switch signal S2=1-S, where S=0 or 1;

[0059] A determination unit, which is used to determine a spatial state equation group of a single-phase PWM inverter circuit model;

[0060] A calculation unit, which is used to calculate the value of the spatial state equation group using a 4th-order Runge-Kutta method;

[0061] An evaluation function construction unit, which is used to construct an evaluation function using a real system model and a digital twin model as a comparison;

[0062] The optimization unit is used to optimize using the particle swarm optimization algorithm. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, R on1 , R on2 , in order to find the evaluation function f rmse The minimum value of the evaluation function is obtained, and the particle coordinates corresponding to the minimum value of the evaluation function are found, and the coordinates are updated to the circuit parameters C1, C2, R in this state. on1 , R on2 , to monitor the health status of the voltage-dividing capacitors and power switching devices;

[0063] in,

[0064] The two R at the power switch device T1 on1 Among the resistors, the first R on1 The resistor is connected in series between the power switch device T1 and the load resistor R L and connected in series between the power switch device T1 and the power switch device T2; the second R on1 After the resistor is connected in series with the first diode, it is further connected in series with the first R on1 The resistor and the power switch device T1 form a parallel relationship;

[0065] The two R at the power switch device T2 on2 Among the resistors, the first R on2 The resistor is connected in series between the power switch device T2 and the capacitor C2; the second R on2 After the resistor is connected in series with the second diode, it is further connected in series with the first R on2 The resistor and the power switch device T2 form a parallel relationship.

[0066] Preferably, for the determination unit, wherein,

[0067] The spatial state equation group of the single-phase PWM inverter circuit model is:

[0068]

[0069] Right now:

[0070]

[0071] Where, L is the inductance value, S is the switching signal, R L is the load resistance value, f1~f3 are the functional relationships of various variables.

[0072] Preferably, for the computing unit, wherein,

[0073] Determine the initial conditions and solution interval according to the spatial state equations.

[0074] The solution interval is divided into n small intervals, and the time step of each interval is h. In each small interval, the approximate solution of several points in the small interval is calculated in sequence using the fourth-order Runge-Kutta iteration formula:

[0075]

[0076] in, , h is the interval step length, x i is the sampling time point,

[0077] The approximate solution at each step is weighted averaged to obtain the approximate solution of the entire solution interval as the value of the space state equation group.

[0078] Preferably, for the evaluation function construction unit, wherein,

[0079] The digital twin model is a model solved using the Runge-Kutta method. The real system model is a physical inverter entity model. The load current i is obtained by measuring and sampling. L_real and capacitor voltage u C1_real ,u C2_real Data, using adaptive filtering algorithm to filter out noise, get the filtered measurement value i L_m , u C1_m , u C2_m , the digital twin model is used to calculate the i under a certain circuit parameter state L ,u C1 ,u C2 Data, and construct the evaluation function f rmse .

[0080] Preferably, for the optimization unit,

[0081] The optimization using improved particle swarm algorithm includes:

[0082] Initialization: Randomly generate several groups of particles with a group dimension of 4, each particle contains 4 circuit parameters to be optimized, namely C1, C2, R on1 , R on2 ,

[0083] Calculate particle fitness: use the current particle parameters to calculate the evaluation function f rmse ,

[0084] Update individual optimal and global optimal: find the historical optimal parameters of each particle and the parameters of the current global optimal particle.

[0085] Speed ​​update and position update: Update the speed of particles according to the historical best positions of individuals and groups, and adjust the positions of particles, i.e. circuit parameters, according to the updated speed. The individual learning factor and group learning factor change dynamically to avoid falling into the local optimum and speed up the convergence speed.

[0086] Result evaluation: Under the circuit parameters represented by each particle, the evaluation function f between the model prediction value and the actual measured value is calculated rmse value,

[0087] When the evaluation function is minimum, the corresponding C1, C2, R on1 , R on2 , and it is considered that the closest parameters of the circuit parameters are obtained to realize the health status monitoring of the voltage-dividing capacitor and the power switching device.

[0088] In addition, the present invention also discloses a computer storage medium, wherein the storage medium includes computer instructions, and when the computer is run on the computer, the computer executes any of the methods described above.

[0089] In addition, the present invention also discloses an electronic device, wherein the electronic device comprises:

[0090] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0091] When the processor executes the program, any of the methods described above is implemented.

[0092] Compared with the prior art, the present invention has the following advantages:

[0093] Since the solution of the present invention is implemented by signal processing based on the collected electrical parameters and control signals without any expensive hardware costs, the present invention is non-invasive and low-cost. In addition, the present invention also has the characteristics of high recognition accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0094] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0095] In the attached picture:

[0096] Figure 1 It is a circuit diagram of a non-intrusive parameter identification method of a single-phase PWM inverter circuit in one embodiment of the present invention;

[0097] Figure 2 It is a schematic diagram of a current reference positive direction of a circuit of a non-intrusive parameter identification method for a single-phase PWM inverter circuit in one embodiment of the present invention;

[0098] Figure 3 It is a flow chart of a non-intrusive parameter identification method of a single-phase PWM inverter circuit in one embodiment of the present invention;

[0099] Figure 4 The diagram is a schematic diagram of the iterative convergence speed of an objective function of a non-intrusive parameter identification method for a single-phase PWM inverter circuit in one embodiment of the present invention.

[0100] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0101] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0102] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0103] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0104] like Figures 1 to 4 As shown, the non-intrusive parameter identification method of a single-phase PWM inverter circuit includes the following steps:

[0105] S1: Establish a PWM inverter circuit model, in which the DC power supply is connected in series with the line resistor Rs, capacitor C1 and capacitor C2, the power switch device T1 is connected in series with the inductor L and the load resistor RL, and the two sections of the capacitor C1 are connected in series. The power switch device T2 is connected in series with the inductor L and the load resistor RL, and the two sections of the capacitor C2 are connected in series. The AC output end is formed by the inductor L and the resistor RL in series, and the output voltage is provided by the load resistor RL. The switching signals of the power switch device T1 and the power switch device T2 are generated by PWM, which are respectively recorded as S1 and S2, and represented by the signal S. The relationship is:

[0106] (1)

[0107] Where, Si=1 or 0 (1 represents on, 2 represents off, i=1,2);

[0108] S2: Write the spatial state equations of the PWM inverter circuit model, which are:

[0109] ;

[0110] S3: 4th-order Runge-Kutta method to calculate the value of the spatial state equations;

[0111] S4: Construct an evaluation function, build a real system model and a digital twin model for comparison. The real system model is a physical inverter entity model. The load current iL_rs and capacitor voltage uc1_rs, uc2_rs data are obtained by measuring and sampling. The adaptive filtering algorithm is used to filter out the noise and obtain the filtered measurement values ​​iL_m, uc1_m, uc2_m. The iL, uC1, uC2 data under a certain circuit parameter state are calculated through the DT model. Based on the above data, the evaluation function frmse is constructed:

[0112] (2)

[0113] S5: Use the particle swarm optimization algorithm to search for the best solution. The coordinate dimension of the particle is 4. Each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, Ron1, and Ron2. Find the minimum value of the evaluation function frmse, find the particle coordinate corresponding to the minimum value of the evaluation function, and update this coordinate to the identified circuit parameter in this state.

[0114] In one embodiment, Figure 1 It is a single-phase two-level PWM inverter, where T1 and T2 are power switching devices. The DC power supply side is divided by two capacitors, C1 and C2, and Rs represents the line resistance. The AC output end is composed of an inductor L and a resistor RL in series, and the output voltage is provided by the load resistor RL. The switching device here is an IGBT. Since it is necessary to monitor the aging of the IGBT, considering that the health status parameter Vce of the IGBT is approximately linearly related to the current, the ideal IGBT model is replaced by a model containing an equivalent on-resistance Ron, such as Figure 2 As shown. Figure 2 In , the reference positive direction of each branch current is specified.

[0115] The switching signals of power devices T1 and T2 are generated by PWM and are denoted as S1 and S2 respectively. The relationship between them is represented by signal S:

[0116] (3)

[0117] Where Si=1 or 0 (1 represents on, 2 represents off, i=1,2)

[0118] According to the switch signal S, draw the circuit operation diagram in two states, such as Figure 2 As shown. Figure 2 Given two circuit states, write the circuit equations using capacitor voltages uc1, uc2 and load current iL, unify the equations using the S signal, and reorganize them into the form of a differential equation system:

[0119]

[0120] Right now:

[0121] 2. Calculate the value of the differential equation. Since the sampling signal is discrete and the switch signal is not differentiable, the fourth-order Runge-Kutta method can be used to solve the differential equation group to complete the discrete modeling of the circuit model. The Runge-Kutta method has higher calculation accuracy and faster speed.

[0122] 3. Construct an evaluation function. For the target circuit that needs to be identified, we constructed a real system model and a digital twin model as a comparison. The real system model is a physical inverter entity model. We obtain the load current iL_rs and capacitor voltage uc1_rs, uc2_rs data through measurement sampling, and use the adaptive filtering algorithm to filter out the noise to obtain the filtered measurement values ​​iL_m, uc1_m, uc2_m. The iL, uC1, uC2 data under a certain circuit parameter state are calculated through the DT model, and the evaluation function frmse is constructed based on the above data:

[0123] (4)

[0124] 4. Use the particle swarm optimization (PSO) algorithm for optimization. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely (C1, C2, Ron1, Ron2). Under the given algorithm strategy, find the minimum value of the evaluation function frmse, find the particle coordinates corresponding to the minimum value of the evaluation function, and update this coordinate to the identified circuit parameters in this state. The specific flow chart is as follows Figure 3 shown.

[0125] In addition, the present invention also discloses a non-intrusive parameter identification system for a single-phase PWM inverter circuit, wherein:

[0126] The single-phase PWM inverter circuit is a single-phase two-level PWM inverter circuit, and the circuit includes a DC power supply side, a power switch device T1 and a power switch device T2, and an AC output side, wherein:

[0127] The DC power supply side includes capacitors C1 and C2 for voltage division and connected in series.

[0128] The power switch device T1 and the power switch device T2 are connected in parallel with the capacitor C1 and the capacitor C2 respectively, and the power switch device T1 and the power switch device T2 form a series relationship;

[0129] The power switch device T1 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on1 ;

[0130] The power switch device T2 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on2 ;

[0131] A DC voltage source with a voltage of V and a resistance of R s The line resistance of the capacitor C1 and the capacitor C2 are connected in parallel after the two are connected in series.

[0132] From the series connection of capacitor C1 and capacitor C2, and the series connection of power switch device T1 and power switch device T2, the AC output side is led out, where:

[0133] The AC output side uses inductor L for filtering, and the load is resistor R L , where the inductance L and the resistance R L Form a series relationship;

[0134] The system comprises:

[0135] The acquisition unit is used to respectively acquire the voltage u of the capacitor C1 C1 , the voltage u of capacitor C2 C2 And the output voltage u on the load at the AC output side L , output current i L =u L / R L ,

[0136] The voltage u C1 、Voltage u C2 , output current i L As the observation quantity of the physical circuit to be identified, it is denoted as u C1_real 、u C2_real 、i L_real, ,

[0137] The control signal is collected by the controller, and the switching signals of the power switch device T1 and the power switch device T2 are recorded as S1 and S2 respectively, where S i =1 or 0, 1 represents on, 2 represents off, i=1,2, signal S is used to represent the switch signal, the switch signal S1 is S, then the switch signal S2=1-S, where S=0 or 1;

[0138] A determination unit, which is used to determine a spatial state equation group of a single-phase PWM inverter circuit model;

[0139] A calculation unit, which is used to calculate the value of the spatial state equation group using a 4th-order Runge-Kutta method;

[0140] An evaluation function construction unit, which is used to construct an evaluation function using a real system model and a digital twin model as a comparison;

[0141] The optimization unit is used to optimize using the particle swarm optimization algorithm. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, R on1 , R on2 , in order to find the evaluation function f rmse The minimum value of the evaluation function is obtained, and the particle coordinates corresponding to the minimum value of the evaluation function are found, and the coordinates are updated to the circuit parameters C1, C2, R in this state. on1 , R on2 , to monitor the health status of the voltage-dividing capacitors and power switching devices;

[0142] in,

[0143] The two R at the power switch device T1 on1 Among the resistors, the first R on1 The resistor is connected in series between the power switch device T1 and the load resistor R L and connected in series between the power switch device T1 and the power switch device T2; the second R on1 After the resistor is connected in series with the first diode, it is further connected in series with the first R on1 The resistor and the power switch device T1 form a parallel relationship;

[0144] The two R at the power switch device T2 on2 Among the resistors, the first R on2 The resistor is connected in series between the power switch device T2 and the capacitor C2; the second R on2 After the resistor is connected in series with the second diode, it is further connected in series with the first R on2 The resistor and the power switch device T2 form a parallel relationship.

[0145] Preferably, for the determination unit, wherein,

[0146] The spatial state equation group of the single-phase PWM inverter circuit model is:

[0147]

[0148] Right now:

[0149]

[0150] Where, L is the inductance value, S is the switching signal, R L is the load resistance value, f1~f3 are the functional relationships of various variables.

[0151] Preferably, for the computing unit, wherein,

[0152] Determine the initial conditions and solution interval according to the spatial state equations.

[0153] The solution interval is divided into n small intervals, and the time step of each interval is h. In each small interval, the approximate solution of several points in the small interval is calculated in sequence using the fourth-order Runge-Kutta iteration formula:

[0154]

[0155] in, , h is the interval step length, x i is the sampling time point,

[0156] The approximate solution at each step is weighted averaged to obtain the approximate solution of the entire solution interval as the value of the space state equation group.

[0157] Preferably, for the evaluation function construction unit, wherein,

[0158] The digital twin model is a model solved using the Runge-Kutta method. The real system model is a physical inverter entity model. The load current i is obtained by measuring and sampling. L_real and capacitor voltage u C1_real ,u C2_real Data, using adaptive filtering algorithm to filter out noise, get the filtered measurement value i L_m , u C1_m , u C2_m , the digital twin model is used to calculate the i under a certain circuit parameter state L ,u C1 ,u C2 Data, and construct the evaluation function f rmse .

[0159] Preferably, for the optimization unit,

[0160] The optimization using improved particle swarm algorithm includes:

[0161] Initialization: Randomly generate several groups of particles with a group dimension of 4, each particle contains 4 circuit parameters to be optimized, namely C1, C2, R on1 , R on2 ,

[0162] Calculate particle fitness: use the current particle parameters to calculate the evaluation function f rmse ,

[0163] Update individual optimal and global optimal: find the historical optimal parameters of each particle and the parameters of the current global optimal particle.

[0164] Speed ​​update and position update: Update the speed of particles according to the historical best positions of individuals and groups, and adjust the positions of particles, i.e. circuit parameters, according to the updated speed. The individual learning factor and group learning factor change dynamically to avoid falling into the local optimum and speed up the convergence speed.

[0165] Result evaluation: Under the circuit parameters represented by each particle, the evaluation function f between the model prediction value and the actual measured value is calculated rmse value,

[0166] When the evaluation function is minimum, the corresponding C1, C2, R on1 , R on2 , and it is considered that the closest parameters of the circuit parameters are obtained to realize the health status monitoring of the voltage-dividing capacitor and the power switching device.

[0167] In addition, the present invention also discloses a computer storage medium, wherein the storage medium includes computer instructions, and when the computer is run on the computer, the computer executes any of the methods described above.

[0168] In addition, the present invention also discloses an electronic device, wherein the electronic device comprises:

[0169] A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein:

[0170] When the processor executes the program, any of the methods described above is implemented.

[0171] In another more specific embodiment,

[0172] A two-level single-phase inverter simulation platform was built. The inverter adopted a sinusoidal pulse width modulation control algorithm. The DC voltage V was 200V, the control switching frequency fsw was 4kHz, the carrier frequency f0 was 50Hz, the load inductance L was 5mH, the load resistance RL was 1Ω, the DC side capacitance values ​​C1 and C2 were both 76mF, and the line resistance Rs was approximately 0.1Ω.

[0173] The table shows five groups of inverter parameters with different aging degrees. The parameter identification method in this paper is used under these working conditions. These parameter combinations cover the cases where the IGBT on-resistance increases by 0~5% and the capacitance decays by 0~5%, as shown in Table 1. The results are shown in Table 2. The convergence speed is Figure 4 shown.

[0174] Table 1 Parameters of different aging degrees

[0175]

[0176] Table 2 Identification results of the present invention

[0177]

[0178] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A non-intrusive parameter identification method for a single-phase PWM inverter circuit, characterized in that: The single-phase PWM inverter circuit is a single-phase two-level PWM inverter circuit, and the circuit includes a DC power supply side, a power switch device T1 and a power switch device T2, and an AC output side, wherein: The DC power supply side includes capacitors C1 and C2 for voltage division and connected in series. The power switch device T1 and the power switch device T2 are connected in parallel with the capacitor C1 and the capacitor C2 respectively, and the power switch device T1 and the power switch device T2 form a series relationship; The power switch device T1 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on1 ; The power switch device T2 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on2 ; The DC voltage source with voltage V and resistance R s The line resistance of the capacitor C1 and the capacitor C2 are connected in parallel after the two are connected in series. From the series connection of capacitor C1 and capacitor C2, and the series connection of power switch device T1 and power switch device T2, the AC output side is led out, where: The AC output side uses inductor L for filtering, and the load is resistor R L , where the inductance L and the resistance R L Form a series relationship; The method comprises the following steps: S1: respectively collect the voltage u of capacitor C1 C1 , the voltage u of capacitor C2 C2 And the output voltage u on the load at the AC output side L , output current i L =u L / R L , The voltage u C1 、Voltage u C2 , output current i L As the observation quantity of the physical circuit to be identified, it is denoted as u C1_real 、u C2_real 、i L_real, , The control signal is collected by the controller, and the switching signals of the power switch device T1 and the power switch device T2 are recorded as S1 and S2 respectively, where S i =1 or 0, 1 represents on, 2 represents off, i=1,2, signal S is used to represent the switch signal, the switch signal S1 is S, then the switch signal S2=1-S, where S=0 or 1; S2: Determine the spatial state equations of the single-phase PWM inverter circuit model; S3: Use the 4th-order Runge-Kutta method to calculate the values ​​of the spatial state equations; S4: Construct an evaluation function using the real system model and the digital twin model as a comparison; S5: Use the particle swarm optimization algorithm to find the optimal solution. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, R on1 , R on2 , in order to find the evaluation function f rmse The minimum value of the evaluation function is obtained, and the particle coordinates corresponding to the minimum value of the evaluation function are found, and the coordinates are updated to the circuit parameters C1, C2, R in this state. on1 , R on2 , to monitor the health status of the voltage-dividing capacitors and power switching devices; in, The two R at the power switch device T1 on1 Among the resistors, the first R on1 The resistor is connected in series between the power switch device T1 and the load resistor R L and connected in series between the power switch device T1 and the power switch device T2; the second R on1 After the resistor is connected in series with the first diode, it is further connected in series with the first R on1 The resistor and the power switch device T1 form a parallel relationship; The two R at the power switch device T2 on2 Among the resistors, the first R on2 The resistor is connected in series between the power switch device T2 and the capacitor C2; the second R on2 After the resistor is connected in series with the second diode, it is further connected in series with the first R on2 The resistor and the power switch device T2 form a parallel relationship.

2. The method according to claim 1, wherein: Preferably, in step S2, The spatial state equation group of the single-phase PWM inverter circuit model is: ； Right now: ； Where, L is the inductance value, S is the switching signal, R L is the load resistance value, f1~f3 are the functional relationships of various variables.

3. The method according to claim 1, wherein: In step S3, Determine the initial conditions and solution interval according to the spatial state equations. The solution interval is divided into n small intervals, and the time step of each interval is h. In each small interval, the approximate solution of several points in the small interval is calculated in turn using the fourth-order Runge-Kutta iteration formula: ； in, , h is the interval step length, x i is the sampling time point, The approximate solution at each step is weighted averaged to obtain the approximate solution of the entire solution interval as the value of the spatial state equation group.

4. The method according to claim 1, wherein: In step S4, The digital twin model is a model solved using the Runge-Kutta method. The real system model is a physical inverter entity model. The load current i is obtained by measuring and sampling. L_real and capacitor voltage u C1_real ,u C2_real Data, using adaptive filtering algorithm to filter out noise, get the filtered measurement value i L_m , u C1_m , u C2_m , the digital twin model is used to calculate the i under a certain circuit parameter state L ,u C1 ,u C2 Data, and construct the evaluation function f rmse .

5. A non-intrusive parameter identification system for a single-phase PWM inverter circuit, characterized in that: The single-phase PWM inverter circuit is a single-phase two-level PWM inverter circuit, and the circuit includes a DC power supply side, a power switch device T1 and a power switch device T2, and an AC output side, wherein: The DC power supply side includes capacitors C1 and C2 for voltage division and connected in series. The power switch device T1 and the power switch device T2 are connected in parallel with the capacitor C1 and the capacitor C2 respectively, and the power switch device T1 and the power switch device T2 form a series relationship; The power switch device T1 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on1 ; The power switch device T2 is connected in series with an equivalent conduction resistance R at the forward conduction point and the reverse diode point respectively. on2 ; The DC voltage source with voltage V and resistance R s The line resistance of the capacitor C1 and the capacitor C2 are connected in parallel after the two are connected in series. From the series connection of capacitor C1 and capacitor C2, and the series connection of power switch device T1 and power switch device T2, the AC output side is led out, where: The AC output side uses inductor L for filtering, and the load is resistor R L , where the inductance L and the resistance R L Form a series relationship; The system comprises: The acquisition unit is used to respectively acquire the voltage u of the capacitor C1 C1 , the voltage u of capacitor C2 C2 And the output voltage u on the load at the AC output side L , output current i L =u L / R L , The voltage u C1 、Voltage u C2 , output current i L As the observation quantity of the physical circuit to be identified, it is denoted as u C1_real 、u C2_real 、i L_real, , The control signal is collected by the controller, and the switching signals of the power switch device T1 and the power switch device T2 are recorded as S1 and S2 respectively, where S i =1 or 0, 1 represents on, 2 represents off, i=1,2, signal S is used to represent the switch signal, the switch signal S1 is S, then the switch signal S2=1-S, where S=0 or 1; A determination unit, which is used to determine a spatial state equation group of a single-phase PWM inverter circuit model; A calculation unit, which is used to calculate the value of the spatial state equation group using a 4th-order Runge-Kutta method; An evaluation function construction unit, which is used to construct an evaluation function using a real system model and a digital twin model as a comparison; The optimization unit is used to optimize using the particle swarm optimization algorithm. The coordinate dimension of the particle is 4, and each coordinate represents a parameter to be monitored in the circuit, namely C1, C2, R on1 , R on2 , in order to find the evaluation function f rmse The minimum value of the evaluation function is obtained, and the particle coordinates corresponding to the minimum value of the evaluation function are found, and the coordinates are updated to the circuit parameters C1, C2, R in this state. on1 , R on2 , to monitor the health status of the voltage-dividing capacitors and power switching devices; in, The two R at the power switch device T1 on1 Among the resistors, the first R on1 The resistor is connected in series between the power switch device T1 and the load resistor R L and connected in series between the power switch device T1 and the power switch device T2; the second R on1 After the resistor is connected in series with the first diode, it is further connected in series with the first R on1 The resistor and the power switch device T1 form a parallel relationship; The two R at the power switch device T2 on2 Among the resistors, the first R on2 The resistor is connected in series between the power switch device T2 and the capacitor C2; the second R on2 After the resistor is connected in series with the second diode, it is further connected in series with the first R on2 The resistor and the power switch device T2 form a parallel relationship.

6. The system according to claim 5, wherein: For the determination unit, The spatial state equation group of the single-phase PWM inverter circuit model is: ； Right now: ； Where, L is the inductance value, S is the switching signal, R L is the load resistance value, f1~f3 are the functional relationships of various variables.

7. The system according to claim 5, wherein: For the computational unit, Determine the initial conditions and solution interval according to the spatial state equations. The solution interval is divided into n small intervals, and the time step of each interval is h. In each small interval, the approximate solution of several points in the small interval is calculated in turn using the fourth-order Runge-Kutta iteration formula: ； in, , h is the interval step length, x i is the sampling time point, The approximate solution at each step is weighted averaged to obtain the approximate solution of the entire solution interval as the value of the spatial state equation group.

8. The system according to claim 5, wherein: For the evaluation function construction unit, The digital twin model is a model solved using the Runge-Kutta method. The real system model is a physical inverter entity model. The load current i is obtained by measuring and sampling. L_real and capacitor voltage u C1_real ,u C2_real Data, using adaptive filtering algorithm to filter out noise, get the filtered measurement value i L_m , u C1_m , u C2_m , the digital twin model is used to calculate the i under a certain circuit parameter state L ,u C1 ,u C2 Data, and construct the evaluation function f rmse .

9. A computer storage medium, wherein: The storage medium includes computer instructions, which, when executed on a computer, enable the computer to execute the method according to any one of claims 1 to 4.

10. An electronic device, wherein: The electronic device comprises: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method according to any one of claims 1 to 4 is implemented.

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