Dead-time compensation control method for single-stage isolated high-frequency DC / AC converter

Abstract

The application discloses a single-stage isolated high-frequency DC / AC converter dead-time compensation control method, which comprises the following steps: obtaining a converter operating parameter; calculating a theoretical phase-shifting angle D I under a current working condition based on the converter operating parameter; calculating a current value of a secondary side switch tube switching time under the current working condition based on the theoretical phase-shifting angle D I ; judging whether the current value of the secondary side switch tube switching time is less than zero; if yes, taking a difference between the theoretical phase-shifting angle D I and a secondary side dead-time proportion D dt as an open-loop feedforward phase-shifting angle; if not, taking the theoretical phase-shifting angle D I as the open-loop feedforward phase-shifting angle; outputting a compensation phase-shifting angle ΔD for compensating a static error of a parameter according to an off-grid voltage loop or a grid-connected current loop, and adding the open-loop feedforward phase-shifting angle D F to the compensation phase-shifting angle ΔD to output a given phase-shifting angle D; and performing phase-shifting control on a switch tube in the converter according to the given phase-shifting angle D. The application can improve the influence of an excessively large dead-time proportion on output current and voltage under high frequency, and improve output power quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter. BACKGROUND

[0002] DAB-type single-phase DC / AC converters generally use single-stage power conversion, do not require intermediate bus electrolytic capacitors, have advantages such as bidirectional energy flow, high efficiency, and high power density, and have important applications in photovoltaic storage integration, distributed power grids, and electric vehicle grid connection.

[0003] Existing DAB-type single-phase DC / AC converters generally use single-stage or quasi-single-stage structures, have various topologies, and usually use phase-shift control. By controlling the phase shift between different bridge arm drive signals, two-level or three-level terminal voltages are generated on the primary and secondary sides of the transformer. The power flow and size are adjusted by controlling the phase shift angle between the primary and secondary side terminal voltages. According to different phase shift methods, it can be divided into single phase shift, extended phase shift, double phase shift, and triple phase shift control.

[0004] With the development of household micro inverters, vehicle bidirectional charging piles, and energy routers towards miniaturization and portability, high frequency is an important development trend for DAB-type single-phase DC / AC converters. Since the dead-time cannot be infinitely reduced, as the switching frequency increases, the dead-time ratio continues to rise, which has a serious impact on the output power quality and efficiency of the converter. The impact of dead-time cannot be ignored.

[0005] In high-frequency applications, the large dead-time ratio causes the power transmission of the DAB-type DC / AC converter to deviate, which in turn affects the output power quality of the converter. Generally, this problem can be improved by increasing the bandwidth of the closed-loop control. However, due to the limitation of control accuracy at high switching frequencies, and the high performance requirements for the controller, it is difficult to achieve improvement in output power quality.

[0006] In related technologies, the patent application document with publication number CN111371326A improves the dynamic performance of the DAB-DC / DC converter by adding dead-time compensation control based on the introduction of load feedforward compensation system, but this scheme does not consider the impact of dead-time on power deviation. The patent application document with publication number CN117674608A proposes to combine PI regulation and trajectory control to improve the dynamic performance of the series resonant DAB-DC / DC converter, but this scheme also does not consider the impact of dead-time on power deviation. The patent application document with publication number CN110401350A focuses on the phase-shift control method for full-load range ZVS of the DAB-DC / DC converter, mainly focusing on phase-shift angle calculation, and also does not consider the impact of dead-time. SUMMARY

[0007] The technical problem to be solved by the present application is how to improve the influence of the large dead time ratio on the output current and voltage at high frequency, reduce the bandwidth requirement of the control system, and improve the output power quality.

[0008] The present application solves the above technical problems by the following technical means:

[0009] The present application provides a single-stage isolated high-frequency DC / AC converter dead-time compensation control method, which comprises the following steps:

[0010] Based on the operating parameters of the converter, the theoretical phase shift angle value D under the current working condition is calculated I , wherein the operating parameters include circuit hardware and software parameters and sampling control parameters;

[0011] Based on the theoretical phase shift angle D I , the current value at the switching time of the secondary side switch tube under the current working condition is calculated, and the influence of the dead time on the output power quality of the converter is determined;

[0012] When the current value at the switching time of the secondary side switch tube is less than zero, the difference between the theoretical phase shift angle D I and the secondary side dead time ratio D dt is taken as the open-loop feedforward phase shift angle D F ;

[0013] When the current value at the switching time of the secondary side switch tube is greater than or equal to zero, the theoretical phase shift angle D I is taken as the open-loop feedforward phase shift angle D F ;

[0014] The off-grid voltage loop or grid-connected current loop compensation link outputs a compensation phase shift angle ΔD for compensating the parameter static difference, and PI, PR or QPR controller can be used;

[0015] The open-loop feedforward phase shift angle and the output compensation phase shift angle ΔD are summed to output a given phase shift angle D;

[0016] According to the given phase shift angle D, the switch tube in the converter is controlled by phase shift.

[0017] Further, the circuit hardware and software parameters include the transformer secondary primary side ratio n, the transformer leakage inductance L k and the half-bridge capacitor C HB ;

[0018] The sampling control parameters include the switching frequency f s , the sampling input direct current voltage u dc , the output alternating current voltage u ac , the output current i ac and the secondary side dead time ratio D dt .

[0019] Further, the theoretical phase shift angle calculation formula of DAB single phase shift modulation is:

[0020]

[0021] In the formula, D I is the actual phase shift angle, M is the output current unit value, t is the time, I TN is the DAB converter current reference value, n is the transformer secondary side primary side ratio, u dc is the sampling input DC voltage, f s is the switching frequency, L k is the transformer leakage inductance, I ac is the ideal AC output current effective value.

[0022] Further, the current value of the secondary side switch tube switching time calculated is :

[0023]

[0024] In the formula, u ac is the AC voltage effective value, u dc is the sampling input DC voltage, f s is the switching frequency, n is the transformer secondary side primary side ratio, L k is the transformer leakage inductance, D I is the theoretical phase shift angle.

[0025] Further, the relationship formula for determining the influence of the dead time on the power quality of the converter output based on the operating parameters is:

[0026] The grid-connected output current i o waveform expression is:

[0027]

[0028] The off-grid output voltage u o waveform expression is:

[0029]

[0030] In the formula, u ac is the AC voltage effective value, P ac is the average output power, ω is the AC voltage angular frequency, D dt is the secondary side dead time ratio, I TN is the DAB converter current reference value, M is the output current unit value, t is the time.

[0031] Further, the output current io The actual impact is:

[0032]

[0033] Theoretical calculations revealed that in DC / AC conversion, only the secondary-side switch exhibits a hard-switching phase. Therefore, the hard-switching condition i of the secondary-side switch is determined. Lk If (t1) < 0, determine whether to perform phase angle compensation.

[0034] Furthermore, determine the current i at the moment the secondary transistor switches. Lk Whether (t1) is less than zero, and thus the given phase shift angle is corrected:

[0035] Furthermore, determine the secondary-side transistor current i. Lk (t1)<0, the secondary switch is a hard switch, and the open-loop feedforward phase shift angle D F =D I -D dt ;

[0036] Furthermore, determine the secondary-side transistor current i. Lk (t1)>0, the secondary side tube can achieve ZVS, and the open-loop feedforward phase shift angle D F =D I ;

[0037] The open-loop feed-forward phase angle D F The output current i o The expression is:

[0038]

[0039] Eliminating dead time affects output current i o This mitigates the impact of dead time and compensates for it.

[0040] This invention proposes a dead-time compensation control system for a single-stage isolated high-frequency DC / AC converter, the system comprising:

[0041] The parameter acquisition module is used to acquire the converter's operating parameters, which include circuit hardware and software parameters and sampling control parameters.

[0042] The theoretical phase shift angle calculation module calculates the theoretical phase shift angle value D under the current operating conditions based on the converter's operating parameters. I ;

[0043] The current value calculation module is used to calculate the current value based on the theoretical phase shift angle D. I Calculate the current value of the secondary switch at the switching moment under the current operating conditions;

[0044] a open-loop feedforward phase-shift angle calculation module, configured to calculate the theoretical phase-shift angle D I as the open-loop feedforward phase-shift angle; and configured to calculate the theoretical phase-shift angle D I as the open-loop feedforward phase-shift angle when the current value at the switching time of the secondary-side switch is greater than or equal to zero.

[0045] a off-grid voltage loop module, configured to output a compensation phase-shift angle ΔD for compensating for static errors of parameters, and add the open-loop feedforward phase-shift angle to output a given phase-shift angle.

[0046] a phase-shift control module, configured to perform phase-shift control on the switches in the converter according to the given phase-shift angle.

[0047] The present application has the following advantages:

[0048] (1) The present application determines the influence of the dead-time on the output power quality of the DAB single-phase DC / AC converter, and calculates the control phase-shift angle by feedforward compensation. By introducing the feedforward calculation link of the phase-shift angle, the influence of the dead-time on the output power is compensated in the feedforward link, the influence of the dead-time on the total harmonic distortion THD is actively improved by feedforward open-loop calculation, the output voltage and current distortion problem caused by the excessive dead-time ratio at high switching frequency is significantly improved, the output power quality of the DAB-DC / AC converter is actively improved, the requirements for the closed-loop control bandwidth and control accuracy are reduced, which is helpful for the control loop design at high frequency and reduces the complexity of the controller.

[0049] Additional aspects and advantages of the present application will be made apparent by the following description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a flowchart of a single-stage isolated high-frequency DC / AC converter dead-time compensation control method according to an embodiment of the present application;

[0051] Figure 2 is a feedforward open-loop dead-time optimization control block diagram according to an embodiment of the present application;

[0052] Figure 3 is a specific control block diagram of the feedforward open-loop link according to an embodiment of the present application;

[0053] Figure 4 is a topological structure diagram of a DAB single-phase DC / AC converter according to an embodiment of the present application;

[0054] Figure 5 is a voltage and current waveform diagram of different stages in an output voltage period according to an embodiment of the present application;

[0055] Figure 6 is an AC output voltage waveform diagram of an embodiment of the present application, wherein (a) is an AC output voltage waveform diagram obtained without using the method of the present application, and (b) is an AC output voltage waveform diagram obtained using the method of the present application;

[0056] Figure 7 is a structural schematic diagram of a dead-time compensation control system of a single-stage isolated high-frequency DC / AC converter according to an embodiment of the present application. DETAILED DESCRIPTION

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0058] As shown in Figures 1 to 3 , the first embodiment of the present application proposes a dead-time compensation control method of a single-stage isolated high-frequency DC / AC converter, which comprises the following steps:

[0059] S10, obtaining a converter operating parameter, wherein the operating parameter comprises a circuit hardware and software parameter and a sampling control parameter;

[0060] S20, calculating a theoretical phase shift angle D I under a current working condition based on the converter operating parameter;

[0061] S30, calculating a current value of a secondary side switch tube switching time under the current working condition based on the theoretical phase shift angle D I ;

[0062] S40, judging whether the current value of the secondary side switch tube switching time is less than zero, if yes, executing step S50, and if no, executing step S60;

[0063] S50, taking a difference between the theoretical phase shift angle D I and a secondary side dead-time time proportion D dt as an open-loop feedforward phase shift angle;

[0064] S60, taking the theoretical phase shift angle D I as the open-loop feedforward phase shift angle;

[0065] S70, outputting a compensation phase shift angle ΔD for compensating a static error of a parameter according to an off-grid voltage loop or a grid-connected current loop, and combining with the open-loop feedforward phase shift angle DF The addition output is given a phase shift angle D.

[0066] S80, phase shift control is performed on the switch tube in the transformer according to the given phase shift angle D.

[0067] The embodiment adopts feedforward open-loop calculation to actively improve the influence of the dead time on the harmonic distortion rate THD, can significantly improve the output voltage and current distortion problem caused by the too large proportion of the dead time at high switching frequency, and reduces the requirement on the control bandwidth and control accuracy of the closed-loop control, is helpful for the control loop design at high frequency, and reduces the complexity of the controller.

[0068] In the embodiment, the single-stage isolated high-frequency DC / AC converter takes the full-bridge-half-bridge type DAB single-stage DC / AC converter as shown in the figure. Figure 4 The primary side is composed of a full-bridge circuit of four switch tubes S1-S4, and the secondary side is composed of a half-bridge circuit of two anti-series switch tubes Q1, Q2 (Q3, Q4).

[0069] Among them, the primary side full-bridge driving mode is that the same bridge arm switch tubes S1, S2 or S3, S4 are complementary on for 50% duty ratio, and the switch tubes S1, S4 (S2, S3) are turned on and off at the same time.

[0070] The secondary side half-bridge driving mode is that the output alternating voltage u ac is positive half-wave, Q1, Q3 are complementary on for 50% duty ratio, and Q2, Q4 are always on; the output alternating voltage u ac is negative half-wave, Q2, Q4 are complementary on for 50% duty ratio, and Q1, Q3 are always on.

[0071] The phase shift ratio between the driving signals of the primary side switch tube S1 and the secondary side switch tube Q1 is D, which is the ratio of the phase shift time to the whole switching period T s ; and in order to prevent the bridge arm from being directly connected, the driving signals of the switch tubes S1-S4 and Q1-Q4 need to pass through the dead time module to be turned on, so the actual phase shift D between the falling edges of the driving signals of the primary side switch tube S1 and the secondary side switch tube Q1 is the phase shift.

[0072] It should be understood that the topology of the single-stage isolated high-frequency DC / AC converter can also be other three arbitrary combinations of the primary side full-bridge (half-bridge) and the secondary side full-bridge (half-bridge): half-bridge-half-bridge structure, half-bridge-full-bridge structure, and full-bridge-full-bridge structure, which are not limited in the embodiment.

[0073] Further, in the step S10, the obtained circuit software and hardware parameters include the transformer secondary side-primary side ratio n, the transformer leakage inductance L k , and the half-bridge capacitor C HB .

[0074] The obtained sampling control parameters include the switching frequency fs Sampling input DC voltage u dc Output AC voltage u ac Output current i ac and the percentage of time spent in the secondary dead zone D dt .

[0075] Further, in step S20, the formula for calculating the actual phase shift angle of DAB single-phase modulation is:

[0076]

[0077] In the formula, D I Where M is the actual phase shift angle and M is the per-unit value of the output current. t is time, I TN This is the current reference value for the DAB converter. n is the transformer ratio on the primary side of the transformer, u dc To sample the input DC voltage, f s L is the switching frequency. k For transformer leakage inductance, I ac This represents the effective value of the ideal AC output current.

[0078] Further, in step S30, the current value at the switching moment of the secondary-side switch is calculated. for:

[0079]

[0080] In the formula, u ac u is the effective value of AC voltage. dc To sample the input DC voltage, f s Where n is the switching frequency, n is the primary turns ratio of the transformer secondary side, and L is the switching frequency. k For transformer leakage inductance, D I This is the theoretical phase shift angle.

[0081] like Figure 5 As shown, the process of controlling the converter output current using the method of this embodiment of the invention is as follows: based on the characteristics of the output voltage and current of the single-phase inverter, one output voltage cycle is divided into three stages: step-down light load stage, step-down heavy load stage, and step-up heavy load stage.

[0082] u ac <2nu dc ,and When the circuit operates in the step-down light load stage, the primary side transistor achieves soft switching, while the secondary side transistor does not. The dead time of the secondary side affects the phase shift angle, which in turn affects the output voltage and current waveform of the inverter.

[0083] u ac <2nu dc ,and When the circuit works in the step-up heavy load stage, it is determined that the primary and secondary switch tubes achieve soft switching, and the determination of the primary and secondary dead time has no effect on the phase shift angle.

[0084] u ac = 2nu dc When the circuit works at the voltage matching point, the primary and secondary switch tubes achieve soft switching, and the determination of the primary and secondary dead time has no effect on the phase shift angle.

[0085] u ac > 2nu dc , and When the circuit works in the step-up heavy load stage, it is determined that the primary and secondary switch tubes achieve soft switching, and the determination of the primary and secondary dead time has no effect on the phase shift angle.

[0086] Further, the relationship that the dead time affects the quality of the output power of the converter based on the operating parameters is:

[0087] The waveform expression of the grid-connected output current i o is:

[0088]

[0089] The waveform expression of the off-grid output voltage u o is:

[0090]

[0091] In the formula, u ac is the effective value of the alternating voltage, P ac is the average output power, ω is the angular frequency of the alternating voltage, D dt is the proportion of the secondary dead time, I TN is the current reference value of the DAB converter, M is the output current unit value, and t is time.

[0092] Further, the actual effect of the dead time on the output current i o is:

[0093]

[0094] The essence of determining the effect of the dead time on the quality of the output power is that the dead time affects the actual phase shift angle under hard switching, causing power deviation. Through theoretical calculation, it is found that only the secondary switch tube exists in the hard switching stage under DC / AC conversion, so whether to compensate the phase shift angle is determined by judging the hard switching condition i Lk (t1)>0 of the secondary tube.

[0095] Further, in the step S40, whether to compensate the phase shift angle is determined by judging the current i LkWhether (t1) is less than zero, and thus the given phase shift angle is corrected:

[0096] Furthermore, in step S50, the secondary-side transistor current i is determined. Lk (t1)<0, the secondary switch is a hard switch, and the open-loop feedforward phase shift angle D F =D I -D dt ;

[0097] Furthermore, in step S60, the secondary-side transistor current i is determined. Lk (t1)≥0, ZVS can be achieved by the secondary side tube, and the open-loop feedforward phase shift angle D F =D I ;

[0098] In summary, the open-loop feedforward phase shift angle D is established. F and theoretical phase shift angle D I The relationship between these factors, and thus the control of the output current i o :

[0099]

[0100] It should be noted that the open-loop feedforward phase shift angle D proposed in this embodiment of the invention is used. F The calculation method and the method not proposed in this embodiment were used to perform phase shift control at high frequencies (switching frequency 500kHz, dead time 100ns), and the results are as follows. Figure 6 As shown, it can be seen that the open-loop feedforward phase shift angle D proposed in the embodiments of the present invention... F After phase-shift control was applied to the calculation method, the power quality was significantly improved.

[0101] like Figure 7 As shown, the second embodiment of the present invention proposes a single-stage isolated high-frequency DC / AC converter dead-time compensation control system, the system comprising:

[0102] The parameter acquisition module 10 is used to acquire the converter operating parameters, which include circuit hardware and software parameters and sampling control parameters.

[0103] Theoretical phase shift angle calculation module 20 calculates the theoretical phase shift angle D under the current operating conditions based on the converter's operating parameters. I ;

[0104] The current value calculation module 30 is used to calculate the current value based on the theoretical phase shift angle D. I Calculate the current value of the secondary switch at the switching moment under the current operating conditions;

[0105] The open-loop feedforward phase shift angle calculation module 40 is used to calculate the theoretical phase shift angle D when the current value at the switching moment of the secondary switch is less than zero.I The proportion of time spent in the secondary dead zone (D) dt The difference is used as the open-loop feedforward phase shift angle; and the theoretical phase shift angle D is used to adjust the current value at the switching moment of the secondary switch to be greater than or equal to zero. I As the open-loop feedforward phase shift angle;

[0106] The parameter static error compensation module 50 outputs a compensation phase shift angle ΔD based on the off-grid voltage loop or the grid-connected current loop to compensate for the static error of the parameters. It is added to the open-loop feedforward phase shift angle to output a given phase shift angle.

[0107] The phase-shift control module 60 is used to perform phase-shift control on the switching transistors in the converter according to the open-loop phase-shift angle.

[0108] It should be noted that other embodiments or implementation methods of the single-stage isolated high-frequency DC / AC converter dead-time compensation control system described in this invention can refer to the above-described method embodiments, and will not be repeated here.

[0109] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the 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.

[0110] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0111] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter, characterized in that, The method includes: Obtain the converter operating parameters, which include circuit hardware and software parameters and sampling control parameters; Based on the converter operating parameters, calculate the theoretical phase shift angle D under the current operating conditions. I ; Based on the theoretical phase shift angle D I Calculate the current value of the secondary switch at the switching moment under the current operating conditions; Determine whether the current value at the moment the secondary switch is switched is less than zero; If so, the theoretical phase shift angle D I The proportion of time spent in the secondary dead zone (D) dt The difference is used as the open-loop feedforward phase shift angle; If not, then the theoretical phase shift angle D will be... I As the open-loop feedforward phase shift angle; Based on the off-grid voltage loop or the grid-connected current loop, the output compensation phase shift angle ΔD is used to compensate for the static error of the parameters, and is compared with the open-loop feedforward phase shift angle D. F The summation outputs the given phase shift angle D; The switching transistors in the converter are phase-shifted according to the given phase-shift angle D.

2. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, The circuit hardware and software parameters include the transformer secondary primary winding ratio n and the transformer leakage inductance L. k and half-bridge capacitor C HB ; The sampling control parameters include the switching frequency f. s Sampling input DC voltage u dc Output AC voltage u ac Output current i ac and the percentage of time spent in the secondary dead zone D t .

3. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, The calculated theoretical phase shift angle is: In the formula, D I Where M is the actual phase shift angle and M is the per-unit value of the output current. t is time, I TN This is the current reference value for the DAB converter. n is the transformer ratio on the primary side of the transformer, u dc To sample the input DC voltage, f s L is the switching frequency. k For transformer leakage inductance, I ac This represents the effective value of the ideal AC output current.

4. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, Dead time affects output current i o The actual impact is: In the formula, u dc To sample the input DC voltage, D I f is the theoretical phase shift angle. s L is the switching frequency. k For transformer leakage inductance, i Lk (t1) is the secondary tube current, D dt This represents the percentage of time spent in the secondary dead zone.

5. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, The calculated current value at the switching moment of the secondary switch. for: In the formula, u ac u is the effective value of AC voltage. dc To sample the input DC voltage, f s Where n is the switching frequency, n is the primary turns ratio of the transformer secondary side, and L is the switching frequency. k For transformer leakage inductance, D I This is the theoretical phase shift angle.

6. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, Open-loop feedforward phase shift angle D F for: Determine the secondary transistor current i Lk (t1)>0, the secondary switch is a hard switch, and the open-loop feedforward phase shift angle D is... F =D I -D dt ; Determine the secondary transistor current i Lk (t1)<0, the secondary side tube can achieve ZVS, and the open-loop feedforward phase shift angle D F =D I .

7. The dead-time compensation control method for a single-stage isolated high-frequency DC / AC converter as described in claim 1, characterized in that, The single-stage topology of the converter is either a full-bridge-half-bridge structure, a half-bridge-half-bridge structure, a half-bridge-full-bridge structure, or a full-bridge-full-bridge structure.

8. A single-stage isolated high-frequency DC / AC converter dead-time compensation control system, characterized in that, The system includes: The parameter acquisition module is used to acquire the converter's operating parameters, which include circuit hardware and software parameters and sampling control parameters. The theoretical phase shift angle calculation module is used to calculate the theoretical phase shift angle D under the current operating conditions based on the converter's operating parameters. I ; The current value calculation module is used to calculate the current value based on the theoretical phase shift angle D. I Calculate the current value of the secondary switch at the switching moment under the current operating conditions; The open-loop feedforward phase shift angle calculation module is used to calculate the theoretical phase shift angle D when the current value at the switching moment of the secondary switch is less than zero. I The proportion of time spent in the secondary dead zone (D) dt The difference is used as the open-loop feedforward phase shift angle; and the theoretical phase shift angle D is used to adjust the current value at the switching moment of the secondary switch to be greater than or equal to zero. I As the open-loop feedforward phase shift angle; The parameter static error compensation module is used to output a compensation phase shift angle ΔD based on the off-grid voltage loop or grid-connected current loop to compensate for the static error of the parameters, and is related to the open-loop feedforward phase shift angle D. F The summation outputs the given phase shift angle D; The phase-shift control module is used to perform phase-shift control on the switching transistors in the converter according to the given phase-shift angle D.

Images