Enhanced cascaded H-bridge inverter dead zone compensation method, system and product

Abstract

The invention relates to the technical field of power electronics, and provides an enhanced cascade H-bridge inverter dead-time compensation method, system and product, and the method comprises the steps: calculating the reference power grid current of a current sample according to the phase angle of the power grid voltage of the current sample, calculating the phase angle of the current sample, and calculating the phase angle of the current sample; predicting the phase angle of the next sample according to the phase angle of the current sample and predicting the phase angle of the power grid voltage of the next sample; calculating the reference power grid current of the next sample; detecting the polarity change of the simulated reference power grid current according to the reference power grid current of the front and back samples; calculating a polarity ratio according to the phase angles of the front and rear samples; and calculating an offset voltage for dead time compensation according to the polarity ratio, and adding the offset voltage to the dead time reference voltage to compensate the dead time. By predicting the reference current of the next sample and calculating the ratio of the polarity of the reference current, the compensation is more sufficient, and the method has better effects in the aspects of suppressing the current ZCD and reducing odd harmonics.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to an enhanced dead-time compensation method, system, and product for cascaded H-bridge inverters. Background Technology

[0002] CHB inverters employing phase-shift pulse width modulation (PS PWM) form their output voltage by accumulating the H-bridge voltage. Since there is a phase difference between the H-bridge voltages, the H-bridge voltage error caused by the dead time is also cumulative. Compared to two-level inverters, this results in relatively large current zero-crossing distortion (ZCD) in the grid current. Sufficient dead time compensation is required to achieve low harmonics.

[0003] The voltage error caused by the dead-time effect is related to the polarity of the grid current. If the gate current is positive, the voltage error is negative; if it is negative, the error is positive. Therefore, dead-time compensation is achieved by adding an offset voltage of the same magnitude but with the opposite sign to the original switching reference voltage. This means that applying an incorrect sign to the offset voltage can actually exacerbate the current ZCD. This can occur at the zero-crossing point of the grid current due to switching current ripple, as well as delays from the shadow register and communication.

[0004] Previous studies did not consider the delay in the switching reference voltage caused by the shadow register and the impact of current polarity changes within a control cycle. In an enhanced cascaded H-bridge (CHB) system, a DSP's shadow register is typically used to prevent vertical crossover (also known as leaky edge) in the PWM. It stores the switching reference voltage and then updates it at predetermined time points, typically at the minimum and maximum values ​​of the triangular carrier wave. Due to this update delay, near the zero-crossing point of the grid current, the offset voltage determined from previous samples is actually applied to the current sample, leading to incorrect compensation. Furthermore, when the current polarity changes within a control cycle, although the actual current is simulated, digital processors, including the DSP, only measure that current at the sampling point. This means that if the current polarity changes within a control cycle (i.e., between sampling points), the DSP cannot recognize the polarity change until the next sampling. For example, if the DSP currently samples a negative current, but the actual simulated current becomes positive shortly after sampling, assigning a negative sign to the offset voltage will result in incorrect compensation, which exacerbates the current ZCD.

[0005] Although there has been much research on dead-time compensation methods, existing studies have largely failed to consider the effects of the delay in the switching reference voltage caused by the shadow register and the changes in current polarity within a control cycle. This may lead to incorrect compensation and exacerbate the current ZCD. Summary of the Invention

[0006] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention provides an enhanced dead-time compensation method, system, and product for cascaded H-bridge inverters. It considers the adverse effects of the delay in the switching reference voltage caused by the shadow register and the change in current polarity within a control cycle. Specifically, assigning an incorrect symbol to the offset voltage leads to incorrect compensation and exacerbates current ZCD. This invention, by predicting the reference current of the next sample and calculating the ratio of the reference current polarity, makes the compensation more sufficient and has a better effect on suppressing current ZCD and reducing odd harmonics.

[0007] This invention provides an enhanced dead-time compensation method for cascaded H-bridge inverters, comprising: S1: Calculate the reference current in the stationary coordinate system of the current sample based on the phase angle of the current sample grid voltage and the reference current of the current sample, and obtain the reference grid current of the current sample based on the reference current in the stationary coordinate system of the current sample. S2: Calculate the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predict the phase angle of the next sample based on the phase angle of the current sample, and predict the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. S3: Calculate the reference current in the stationary coordinate system of the next sample based on the phase angle of the grid voltage of the next sample, and obtain the reference grid current of the next sample based on the reference current in the stationary coordinate system of the next sample. S4: Detect the polarity change of the simulated reference grid current based on the reference grid current of the current sample and the reference grid current of the next sample; calculate the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample; S5: Calculate the offset voltage for dead time compensation based on the polarity ratio; S6: Add the offset voltage for dead time compensation to the dead time reference voltage to compensate for the dead time.

[0008] Furthermore, in step S1, the calculation expression for the reference current in the current sample stationary coordinate system is: in, For the first Reference current in a stationary coordinate system for each sample For the first Each sample direct-axis reference current, For the first Each sample cross-axis reference current, For the first Phase angle of the grid voltage for each sample; in, For the first In the stationary coordinate system of a sample Quantity, For the first In the stationary coordinate system of a sample Quantity; In a stationary coordinate system in, For the first Direct-axis reference current in a stationary coordinate system for each sample; The reference grid current of the current sample is equal to the current sample's stationary coordinate system. Quantity.

[0009] Furthermore, in step S2, the expression for calculating the phase angle of the current sample based on the reference current in the current sample's stationary coordinate system is as follows: in, For the first Phase angle of each sample, For the first Direct-axis reference current in a sample stationary coordinate system For the first Cross-axis reference current in a sample stationary coordinate system It is the arctangent function.

[0010] Furthermore, the phase angle of the next sample is predicted based on the phase angle of the current sample, and the calculation expression is as follows: in, For the first Phase angle of each sample, The base frequency of the grid voltage supplied to the PLL. To control the cycle; The phase angle of the next sample grid voltage is predicted based on the phase angle of the current sample grid voltage. The calculation expression is as follows: in, For the first Phase angle of the grid voltage for each sample, For the first The phase angle of the grid voltage for each sample.

[0011] Furthermore, in step S4, the reference grid current of the current sample is used... and the reference grid current for the next sample Multiply to detect changes in the polarity of the simulated reference grid current; like If the polarity of the simulated reference grid current changes within one control cycle, the rate of change of the sample reference grid current relative to the phase angle is calculated using the following expression: in, The slope The reference current in the current sample's stationary coordinate system. This serves as the reference current in the next sample stationary coordinate system. For the first Phase angle of each sample, For the first The phase angle of each sample.

[0012] Furthermore, in step S4, the expression for calculating the polarity ratio is: in, It represents the polarity ratio.

[0013] Furthermore, in step S5, the expression for calculating the offset voltage for dead-time compensation is as follows: in, The offset voltage for dead time compensation. This refers to the DC voltage on the DC side of the inverter. Dead time, For carrier frequency, It represents the polarity ratio.

[0014] Furthermore, in step S6, when lie in and Between, Add to the reference offset voltage for dead time compensation to generate a normalized voltage command that compensates for dead time.

[0015] An enhanced dead-time compensation system for a cascaded H-bridge inverter, used to implement the aforementioned enhanced dead-time compensation method for a cascaded H-bridge inverter, includes: The current reference current calculation module calculates the reference current in the current sample stationary coordinate system based on the phase angle of the current sample grid voltage and the current sample reference current, and obtains the current reference grid current of the current sample based on the current sample stationary coordinate system. The phase angle prediction module calculates the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predicts the phase angle of the next sample based on the phase angle of the current sample, and predicts the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. The next reference current calculation module calculates the reference current in the next sample stationary coordinate system based on the phase angle of the next sample grid voltage. The polarity ratio calculation module detects the polarity change of the simulated reference grid current based on the reference current in the next sample stationary coordinate system and the reference current in the current sample stationary coordinate system; and calculates the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample. Offset voltage calculation module, which calculates the offset voltage for dead time compensation based on the polarity ratio; The compensation module adds the dead time compensation offset voltage to the dead time reference voltage to compensate for the dead time.

[0016] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the enhanced dead-time compensation method for a cascaded H-bridge inverter as described above.

[0017] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: This invention takes into account the adverse effects of the delay in the switching reference voltage caused by the shadow register and the change in current polarity within a control cycle. Specifically, assigning an incorrect symbol to the offset voltage leads to incorrect compensation and exacerbates the current ZCD. This invention makes the compensation more sufficient by predicting the reference current of the next sample and calculating the ratio of the reference current polarity, and has a better effect in suppressing current ZCD and reducing odd harmonics.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1This is a flowchart illustrating an enhanced dead-time compensation method for cascaded H-bridge inverters provided by the present invention.

[0021] Figure 2 This is an embodiment of the invention reflecting the polarity ratio. A schematic diagram illustrating the calculation of offset voltage for polarity change detection and dead time compensation.

[0022] Figure 3 This is a schematic diagram of the topology of a seven-level CHB inverter in a single-phase grid-connected system provided in an embodiment of the present invention.

[0023] Figure 4 This is an embodiment of the present invention. A diagram showing the distortion comparison.

[0024] Figure 5 This is an embodiment of the present invention. A comparative diagram of FFT.

[0025] Figure 6 This is an embodiment of the present invention. A schematic diagram comparing the transient responses to a step change.

[0026] Figure 7 This is a schematic diagram of an enhanced dead-time compensation system for a cascaded H-bridge inverter provided by the present invention.

[0027] Figure label: 101. Current reference current calculation module; 102. Phase angle prediction module; 103. Next reference current calculation module; 104. Polarity ratio calculation module; 105. Offset voltage calculation module; 106. Compensation module. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but cannot be used to limit the scope of this invention.

[0029] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0030] The following is combined Figures 1 to 7 This invention describes an enhanced dead-time compensation method, system, and product for cascaded H-bridge inverters.

[0031] like Figure 1 As shown, an enhanced dead-time compensation method for cascaded H-bridge inverters includes: S1: Calculate the reference current in the stationary coordinate system of the current sample based on the phase angle of the current sample grid voltage and the reference current of the current sample, and obtain the reference grid current of the current sample based on the reference current in the stationary coordinate system of the current sample. The formula for calculating the reference current in the current sample stationary coordinate system is: in, For the first Reference current in a stationary coordinate system for each sample For the first In the stationary coordinate system of a sample Quantity, For the first In the stationary coordinate system of a sample Quantity, For the first Each sample direct-axis reference current, For the first Each sample cross-axis reference current, For the first Phase angle of the grid voltage for each sample; In a stationary coordinate system ; The reference grid current of the current sample is equal to the current sample's stationary coordinate system. Quantity, therefore: in, This is the reference grid current for the current sample.

[0032] By replacing the measured value with a reference grid current, false detections of current polarity caused by noise and switching current ripple are avoided.

[0033] S2: Calculate the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predict the phase angle of the next sample based on the phase angle of the current sample, and predict the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. The expression for calculating the phase angle of the current sample based on the reference current in the current sample stationary coordinate system is as follows: in, For the first Phase angle of each sample, For the first Direct-axis reference current in a sample stationary coordinate system For the first Cross-axis reference current in a sample stationary coordinate system It is the arctangent function.

[0034] The phase angle of the next sample is predicted based on the phase angle of the current sample. The calculation expression is as follows: in, For the first Phase angle of each sample, The base frequency of the grid voltage supplied to the PLL. To control the cycle; The phase angle of the next sample grid voltage is predicted based on the phase angle of the current sample grid voltage. The calculation expression is as follows: in, For the first Phase angle of the grid voltage for each sample, For the first The phase angle of the grid voltage for each sample.

[0035] S3: Calculate the reference current in the stationary coordinate system of the next sample based on the phase angle of the grid voltage of the next sample, and obtain the reference grid current of the next sample based on the reference current in the stationary coordinate system of the next sample. in, For the first Reference current in a stationary coordinate system for each sample For the first In the stationary coordinate system of a sample Quantity, For the first In the stationary coordinate system of a sample Quantity, For the first Each sample direct-axis reference current, For the first Each sample cross-axis reference current, For the first Phase angle of the grid voltage for each sample; In a stationary coordinate system ; No. The reference grid current for each sample is equal to the current in the sample's stationary coordinate system. Quantity, therefore: in, For the first The reference grid current for each sample.

[0036] S4: Detect the polarity change of the simulated reference grid current based on the reference grid current of the current sample and the reference grid current of the next sample; calculate the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample; By using the reference grid current of the current sample and the reference grid current for the next sample Multiply to detect changes in the polarity of the simulated reference grid current; like Then refer to the grid current The polarity changes within a control cycle, requiring determination of whether the reference grid current is increasing or decreasing. This is determined by calculating the rate of change of the reference grid current relative to the phase angle, expressed as: in, The slope The reference grid current is in the current sample's stationary coordinate system. This is the reference grid current in the next sample stationary coordinate system. For the first Phase angle of each sample, For the first The phase angle of each sample.

[0037] Scenes such as Figure 2 As shown in Figure (a), Scenes such as Figure 2 As shown in Figure (b), During this period, reference grid current The negative time proportion is defined as the polarity ratio. Reference grid current A positive time proportion is defined as .

[0038] In this invention, It is a simulated value, and These are discrete values.

[0039] polarity ratio It can also be calculated as the ratio of phase angles. Time auxiliary variables for , Time auxiliary variables for The expression for calculating the polarity ratio is: in, It represents the polarity ratio.

[0040] S5: Calculate the offset voltage for dead time compensation based on the polarity ratio; The formula for calculating the offset voltage for dead time compensation is: in, The offset voltage for dead time compensation. This refers to the DC voltage on the DC side of the inverter. Dead time, For carrier frequency.

[0041] S6: Add the offset voltage for dead time compensation to the dead time reference voltage to compensate for the dead time.

[0042] when lie in and Between, Add to China and Israel produced Compensation for dead zone time, in, The reference offset voltage for dead time compensation. This is a normalized voltage command.

[0043] In traditional dead zone compensation: in, The offset voltage is used for traditional dead time compensation.

[0044] The enhanced dead-time compensation method for cascaded H-bridge inverters of this invention was verified using an experimental setup with a seven-level CHB inverter. The topology of the seven-level CHB inverter in a single-phase grid-connected system is as follows: Figure 3As shown, there is a sampling communication delay between the motherboard and daughterboard of the experimental setup. This invention solves the sampling communication delay by using two-sample prediction.

[0045] In all experiments , , and Grid current Controlled During shading control, conventional methods produce completely negative values ​​when the polarity changes. ,like Figure 4 As shown, the present invention A slight increase in the positive direction. (In, for example...) Figure 4 As shown in Figure (a), in the conventional method It shows a large number of ZCD values, approximately and ,like Figure 4 As shown in Figure (b), the method of the present invention Without ZCD, therefore, The distortion is relatively small.

[0046] like Figure 5 The FFT comparison shown indicates that, compared to traditional methods, the method of this invention exhibits lower odd harmonics. Specifically, as... Figure 5 As shown in Figure (a), the third harmonic of the traditional method is The fifth harmonic is The seventh harmonic is ,like Figure 5 As shown in Figure (b), the third harmonic of the method of the present invention is The fifth harmonic is The seventh harmonic is Compared with traditional methods, the method of this invention reduces the third harmonic by about 42%, the fifth harmonic by about 42%, and the seventh harmonic by about 67%.

[0047] like Figure 6 The figure shows Comparison of transient responses to step changes Figure 6 Figure (a) shows the traditional method. Transient response to a step change, Figure 6 Figure (b) shows the application of this invention. The transient response to a step change, where, from Change to Because this invention uses The reference value is used, so there is still some distortion, but compared with the traditional method, the present invention shows a superior compensation effect.

[0048] Through comparative experiments, it was found that in traditional dead-time compensation methods, incorrect compensation occurs due to changes in the shadow register and current polarity within the control cycle. However, this invention predicts the reference current of the next sample and calculates the ratio of the reference current polarity, resulting in sufficient compensation. This invention can alleviate ZCD (Zero-Current Distortion). Experimental results demonstrate that this invention has good effects in suppressing current ZCD and reducing odd harmonics.

[0049] like Figure 7 As shown, an enhanced dead-time compensation system for a cascaded H-bridge inverter is used to implement an enhanced dead-time compensation method for a cascaded H-bridge inverter, comprising: The current reference current calculation module 101 calculates the reference current in the current sample stationary coordinate system based on the phase angle of the current sample grid voltage and the reference current, and obtains the reference grid current of the current sample based on the reference current in the current sample stationary coordinate system. The phase angle prediction module 102 calculates the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predicts the phase angle of the next sample based on the phase angle of the current sample, and predicts the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. The next reference current calculation module 103 calculates the reference current in the next sample stationary coordinate system based on the phase angle of the next sample grid voltage. The polarity ratio calculation module 104 detects the polarity change of the simulated reference grid current based on the reference current in the next sample stationary coordinate system and the reference current in the current sample stationary coordinate system; and calculates the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample. The offset voltage calculation module 105 calculates the offset voltage for dead time compensation based on the polarity ratio; The compensation module 106 adds the offset voltage of the dead time compensation to the dead time reference voltage to compensate for the dead time.

[0050] Through the coordinated work of the above modules, this invention predicts the reference current of the next sample and calculates the ratio of the reference current polarity, making the compensation more sufficient and achieving better results in suppressing current ZCD and reducing odd harmonics.

[0051] On the other hand, the present invention also provides a computer program product, the computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions, and when the program instructions are executed by a computer, the computer is able to execute an enhanced dead-time compensation method for cascaded H-bridge inverters provided by the above methods.

[0052] In another aspect, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to perform the aforementioned enhanced dead-time compensation method for cascaded H-bridge inverters.

[0053] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0054] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An enhanced dead-time compensation method for cascaded H-bridge inverters, characterized in that, include: S1: Calculate the reference current in the stationary coordinate system of the current sample based on the phase angle of the current sample grid voltage and the reference current of the current sample, and obtain the reference grid current of the current sample based on the reference current in the stationary coordinate system of the current sample. S2: Calculate the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predict the phase angle of the next sample based on the phase angle of the current sample, and predict the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. S3: Calculate the reference current in the stationary coordinate system of the next sample based on the phase angle of the grid voltage of the next sample, and obtain the reference grid current of the next sample based on the reference current in the stationary coordinate system of the next sample. S4: Detect the polarity change of the simulated reference grid current based on the reference grid current of the current sample and the reference grid current of the next sample; calculate the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample; S5: Calculate the offset voltage for dead time compensation based on the polarity ratio; S6: Add the offset voltage for dead time compensation to the dead time reference voltage to compensate for the dead time.

2. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 1, characterized in that, In step S1, the expression for calculating the reference current in the current sample stationary coordinate system is: in, For the first Reference current in a stationary coordinate system for each sample For the first Each sample direct-axis reference current, For the first Each sample cross-axis reference current, For the first Phase angle of the grid voltage for each sample; in, For the first In the stationary coordinate system of a sample Quantity, For the first In the stationary coordinate system of a sample Quantity; In a stationary coordinate system in, For the first Direct-axis reference current in a stationary coordinate system for each sample; The reference grid current of the current sample is equal to the current sample's stationary coordinate system. Quantity.

3. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 1, characterized in that, In step S2, the expression for calculating the phase angle of the current sample based on the reference current in the current sample's stationary coordinate system is as follows: in, For the first Phase angle of each sample, For the first Direct-axis reference current in a sample stationary coordinate system For the first Cross-axis reference current in a sample stationary coordinate system It is the arctangent function.

4. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 3, characterized in that, The phase angle of the next sample is predicted based on the phase angle of the current sample. The calculation expression is as follows: in, For the first Phase angle of each sample, The base frequency of the grid voltage supplied to the PLL. To control the cycle; The phase angle of the next sample grid voltage is predicted based on the phase angle of the current sample grid voltage. The calculation expression is as follows: in, For the first Phase angle of the grid voltage for each sample, For the first The phase angle of the grid voltage for each sample.

5. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 1, characterized in that, In step S4, the reference grid current of the current sample is used. and the reference grid current for the next sample Multiply to detect changes in the polarity of the simulated reference grid current; like If the polarity of the simulated reference grid current changes within one control cycle, the rate of change of the sample reference grid current relative to the phase angle is calculated using the following expression: in, The slope The reference current in the current sample's stationary coordinate system. This serves as the reference current in the next sample stationary coordinate system. For the first Phase angle of each sample, For the first The phase angle of each sample.

6. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 5, characterized in that, In step S4, the expression for calculating the polarity ratio is: in, It represents the polarity ratio.

7. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 1, characterized in that, In step S5, the formula for calculating the offset voltage for dead time compensation is: in, The offset voltage for dead time compensation. This refers to the DC voltage on the DC side of the inverter. Dead time, For carrier frequency, It represents the polarity ratio.

8. The enhanced dead-time compensation method for a cascaded H-bridge inverter according to claim 7, characterized in that, In step S6, when lie in and Between, Add to the reference offset voltage for dead time compensation to generate a normalized voltage command that compensates for dead time.

9. An enhanced dead-time compensation system for a cascaded H-bridge inverter, characterized in that, To perform an enhanced dead-time compensation method for a cascaded H-bridge inverter as described in any one of claims 1 to 8, comprising: The current reference current calculation module calculates the reference current in the current sample stationary coordinate system based on the phase angle of the current sample grid voltage and the current sample reference current, and obtains the current reference grid current of the current sample based on the current sample stationary coordinate system. The phase angle prediction module calculates the phase angle of the current sample based on the reference current in the current sample stationary coordinate system, predicts the phase angle of the next sample based on the phase angle of the current sample, and predicts the phase angle of the grid voltage of the next sample based on the phase angle of the grid voltage of the current sample. The next reference current calculation module calculates the reference current in the next sample stationary coordinate system based on the phase angle of the next sample grid voltage. The polarity ratio calculation module detects the polarity change of the simulated reference grid current based on the reference current in the next sample stationary coordinate system and the reference current in the current sample stationary coordinate system; and calculates the polarity ratio based on the polarity change of the simulated reference grid current, the phase angle of the next sample, and the phase angle of the current sample. Offset voltage calculation module, which calculates the offset voltage for dead time compensation based on the polarity ratio; The compensation module adds the dead time compensation offset voltage to the dead time reference voltage to compensate for the dead time.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements an enhanced dead-time compensation method for a cascaded H-bridge inverter as described in any one of claims 1 to 8.

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