Control method, storage medium and full-bridge inverter

Abstract

The invention provides a control method, a storage medium and a full-bridge inverter, and the control method is applied to the full-bridge inverter, and comprises the steps: switching and controlling the full-bridge inverter based on unipolar modulation and bipolar modulation; wherein the bipolar modulation covers an output zero crossing point of the full-bridge inverter; a compensation current value is obtained, and the compensation current value is a negative current change value of the full-bridge inverter in the switching process of unipolar modulation and bipolar modulation; and in the bipolar modulation process, compensating a preset extreme value of the inductive current of the full-bridge inverter based on the compensation current value. According to the control method provided by the embodiment of the invention, in the bipolar modulation process, the inductive current is compensated, so that the problem of current distortion caused by inconsistent volt-second balance during switching of unipolar modulation and bipolar modulation is avoided, the total distortion rate of current harmonics is reduced, and the current quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of full-bridge inverter control, and particularly relates to a control method, a storage medium and a full-bridge inverter. BACKGROUND

[0002] The full-bridge inverter is commonly used in electronic power systems to realize voltage conversion. The full-bridge inverter includes four switching tubes (Q1, Q2, Q3 and Q4), an inverter inductor (Ls), a resonant inductor (Lf) and a resonant capacitor (Cf). The full-bridge inverter converts a direct-current power supply U DC into an alternating-current power supply U AC .

[0003] In the control of the full-bridge inverter, the Triangular Current Mode TCM of the inductor Ls is used to realize soft switching of the switching tubes (by the conduction of the parasitic diodes of the switching tubes), so as to improve the efficiency of the inverter.

[0004] In addition, the full-bridge inverter includes two control methods, namely, single-polarity TCM modulation and bipolar TCM modulation. In the bipolar TCM modulation, both groups of bridge arms (Q1 and Q2, Q3 and Q4) work in a high-frequency switching mode, and the switching loss is large. In the single-polarity TCM modulation, the voltage difference across the inductor Ls is almost zero near the zero-crossing point, which leads to a too low frequency of the switching tubes and causes current waveform distortion. SUMMARY

[0005] The present application provides a control method, a storage medium and a full-bridge inverter, which are used to suppress current distortion, reduce the total harmonic distortion of the current and improve the quality of the current.

[0006] In a first aspect, the present application provides a control method applied to a full-bridge inverter, including: switching control of the full-bridge inverter based on single-polarity modulation and bipolar modulation, wherein the bipolar modulation covers the zero-crossing point of the output of the full-bridge inverter; obtaining a compensation current value, which is the negative current change value of the full-bridge inverter in the switching process of the single-polarity modulation and the bipolar modulation; and compensating a preset maximum value of the inductor current of the full-bridge inverter based on the compensation current value in the process of the bipolar modulation.

[0007] In some embodiments, the compensation of the preset maximum value of the inductor current of the full-bridge inverter based on the compensation current value includes: compensating the preset peak value of the inductor current based on the compensation current value in the positive-phase output stage and the negative-phase output stage of the full-bridge inverter.

[0008] In some embodiments, the step of compensating the inductor current of the full-bridge inverter based on the compensation current value to a preset maximum or minimum value includes: compensating the inductor current to a preset valley value based on the compensation current value during the positive phase output phase and the negative phase output phase of the full-bridge inverter.

[0009] In some embodiments, the step of compensating the inductor current of the full-bridge inverter based on the compensation current value to a preset maximum or minimum value includes: during the positive phase output phase of the full-bridge inverter, compensating the inductor current to a preset peak value based on the compensation current; and during the negative phase output phase of the full-bridge inverter, compensating the inductor current to a preset valley value based on the compensation current.

[0010] In some embodiments, the step of compensating the inductor current of the full-bridge inverter based on the compensation current value to a preset maximum or minimum value includes: during the positive phase output phase of the full-bridge inverter, compensating the inductor current to a preset valley value based on the compensation current; and during the negative phase output phase of the full-bridge inverter, compensating the inductor current to a preset peak value based on the compensation current.

[0011] In some embodiments, obtaining the compensation current value includes: obtaining the negative current change value during the switching process of the unipolar modulation and the bipolar modulation based on the volt-second balance principle.

[0012] In some embodiments, obtaining the negative current change value includes:

[0013]

[0014] Where ΔI is the change in the negative current, V DC V is the input voltage value of the full-bridge inverter. AC L represents the output voltage value of the full-bridge inverter. s Δt is the inductance value of the full-bridge inverter, and Δt is the delay time during the switching process between unipolar modulation and bipolar modulation.

[0015] In some embodiments, after compensating the inductor current of the full-bridge inverter based on the compensation current value, the control method further includes: obtaining the output current of the full-bridge inverter; obtaining the error current between the output current and the desired output current of the full-bridge inverter; and adjusting the preset maximum value of the inductor current based on the error current.

[0016] In some embodiments, the error current is the difference between the output current and the desired output current.

[0017] Secondly, this application provides a storage medium storing a plurality of instructions adapted for loading by a processor to execute the control method provided in the first aspect above.

[0018] Thirdly, this application provides a full-bridge inverter, including: a bridge arm circuit, and a control circuit connected to the bridge arm circuit; the control circuit is used to control the bridge arm circuit to perform the control method provided in the first aspect above.

[0019] In some embodiments, the bridge arm circuit includes: a DC power supply; a first switching transistor, with its control terminal connected to the control circuit and its first end connected to the positive terminal of the DC power supply; a second switching transistor, with its control terminal connected to the control circuit, its first end connected to the second end of the first switching transistor, and its second end connected to the negative terminal of the DC power supply; a third switching transistor, with its control terminal connected to the control circuit and its first end connected to the positive terminal of the DC power supply; a fourth switching transistor, with its control terminal connected to the control circuit, its first end connected to the second end of the third switching transistor, and its second end connected to the negative terminal of the DC power supply; an inverter inductor, with its first end connected to the second end of the first switching transistor; a resonant inductor, with its first end connected to the second end of the inverter inductor; and a resonant capacitor, with its first end connected to the second end of the inverter inductor and its second end connected to the second end of the third switching transistor; the second ends of the resonant inductor and the resonant capacitor serve as the output terminals of the bridge arm circuit.

[0020] The control method provided in this embodiment combines unipolar modulation and bipolar modulation to avoid current waveform distortion caused by excessively low switching frequency near the zero-crossing point, and effectively reduces switching losses. Furthermore, during bipolar modulation, compensation of the inductor current avoids current distortion due to inconsistent volt-second balance during switching between unipolar and bipolar modulation, reducing the total harmonic distortion rate and improving current quality. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the structure of the full-bridge inverter in an embodiment of this application is shown;

[0023] Figure 2 This paper shows a schematic diagram of the currents of the inverter under unipolar and bipolar hybrid modulation in an embodiment of this application.

[0024] Figure 3 The flowcharts corresponding to each step of the control method in the embodiments of this application are shown.

[0025] Figure 4This paper shows a schematic diagram of the currents of the inverter after peak compensation in an embodiment of this application.

[0026] Figure 5 The corresponding embodiments of this application are shown. Figure 4 A schematic diagram of a method for compensating for grid current;

[0027] Figure 6 This paper shows a schematic diagram of the current of each inverter after valley compensation in an embodiment of this application.

[0028] Figure 7 The corresponding embodiments of this application are shown. Figure 6 A schematic diagram of a method for compensating for grid current;

[0029] Figure 8 This invention illustrates the principle of error current compensation based on preset peak or preset valley values ​​in an embodiment of this application.

[0030] Figure 9 A schematic diagram of the structure of the full-bridge inverter in an embodiment of this application is shown. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] In the description of this application, the term "exemplary" is used to mean "serving as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0033] Full-bridge inverters are commonly used in electronic power systems to achieve voltage conversion. For example... Figure 1 As shown, the full-bridge inverter includes four switching transistors (Q1, Q2, Q3, and Q4), an inverter inductor (Ls), a resonant inductor (Lf), and a resonant capacitor (Cf). The full-bridge inverter converts the DC power supply U through the switching of the four transistors. DCConvert to AC power U AC .

[0034] Full-bridge inverters employ two control methods: unipolar TCM modulation and bipolar TCM modulation. In bipolar TCM modulation, both bridge arms (Q1 and Q2, Q3 and Q4) operate in high-frequency switching mode, resulting in significant switching losses. In unipolar TCM modulation, the voltage difference across the inductor Ls is almost zero near the zero-crossing point, leading to excessively low switching frequencies and potential current waveform distortion.

[0035] In some embodiments, a hybrid monopolar and bipolar modulation strategy combines the advantages of both modulation methods. Using bipolar TCM modulation near the zero-crossing point can effectively avoid the current waveform distortion problem caused by the low switching frequency near the zero-crossing point; using monopolar TCM modulation near the non-zero-crossing point can effectively reduce switching losses.

[0036] During the switching between monopolar and bipolar TCM modulation, the inconsistent volt-second balance may cause current distortion, which in turn increases the current distortion rate, raises the total harmonic current distortion (THDi), and reduces the current quality.

[0037] refer to Figure 1 and Figure 2 , Figure 2 This is a schematic diagram of the inverter currents under unipolar and bipolar hybrid modulation. The green dashed line represents the boundary between unipolar and bipolar TCM modulation; the black line represents the current of the inverter inductor Ls, which is a triangular wave pattern; the dark blue line represents the peak current curve of the inverter inductor Ls; the light blue line represents the valley current curve of the inverter inductor Ls; and the red line represents the grid current output by the inverter.

[0038] It should be noted that in the description of this embodiment, the black line represents the actual current value of the inductor current, the dark blue line represents the envelope curve of the peak value of the inductor current, and the light blue line represents the envelope curve of the valley value of the inductor current. Furthermore, the "peak value" described in this embodiment refers to the maximum value of the inductor current during positive output (positive half-cycle) and the minimum value of the inductor current during negative output (negative half-cycle). The "valley value" described in this embodiment refers to the minimum value of the inductor current during positive output (positive half-cycle) and the maximum value of the inductor current during negative output (negative half-cycle).

[0039] Specifically, by controlling the conduction of switching transistors Q1, Q2, Q3, and Q4, the rise and fall of the inductor current are controlled, causing the inductor current to commutate between the peak curve and the valley range. At this time, the output current of the inverter is a sinusoidal current.

[0040] Inverters under a hybrid unipolar and bipolar modulation strategy can exist in two forms: unipolar modulation and bipolar modulation.

[0041] In unipolar modulation, the on-time and off-time of the high-frequency switching transistor can be calculated based on the current flow path, as follows:

[0042] On time t on1 :

[0043] On time t off1 :

[0044] In bipolar modulation, the on-time and off-time of the high-frequency switching transistor can be calculated based on the current flow path, as follows:

[0045] On time t on2 :

[0046] On time t off2 :

[0047] Among them, u g *sin(ωt) represents the AC power supply U AC The voltage value, i.e., the grid voltage, V DC DC power supply U DC The voltage value, L s For inductor L s The inductance value, I ref The desired peak grid current is given by I, where sin(ωt) is the grid phase angle. B This is the preset grid current valley value.

[0048] Based on the above formula, it can be seen that, regardless of whether it is unipolar or bipolar modulation, the inductor current Ls decreases much faster than it rises. Actual sampling circuits, filtering circuits, and signal processing all introduce delays, with the delay being greater at high frequencies than at low frequencies. Therefore, during the switching between unipolar and bipolar TCM modulation, the magnitude of the mains current will change due to the delay. Figure 2 As indicated by the red line.

[0049] This application provides a control method applied to a full-bridge inverter, characterized by comprising: switching control of the full-bridge inverter based on unipolar modulation and bipolar modulation; wherein the bipolar modulation covers the zero-crossing point of the full-bridge inverter's output; obtaining a compensation current value, the compensation current value being the negative current change value of the full-bridge inverter during the switching between unipolar modulation and bipolar modulation; and compensating the full-bridge inverter's inductor current to a preset maximum value based on the compensation current value during the bipolar modulation process.

[0050] The control method provided in this embodiment combines unipolar modulation and bipolar modulation to avoid current waveform distortion caused by excessively low switching frequency near the zero-crossing point, and effectively reduces switching losses. Furthermore, during bipolar modulation, compensation of the inductor current avoids current distortion due to inconsistent volt-second balance during switching between unipolar and bipolar modulation, reducing the total harmonic distortion rate and improving current quality.

[0051] The control method provided in this embodiment will be described in detail below with reference to the accompanying drawings. Figure 3 , Figure 3 This is a flowchart illustrating the steps of the control method provided in this embodiment. The control method is applied to a full-bridge inverter and includes steps 101 to 103.

[0052] The structure of the full-bridge inverter can be referenced. Figure 1 A full-bridge inverter includes a first switch Q1, a second switch Q2, a third switch Q3, a fourth switch Q4, an inverter inductor Ls, a resonant inductor Lf, and a resonant capacitor Cf. The full-bridge inverter is used to convert the input DC power U... DC Convert to AC power U AC Output.

[0053] It should be noted that the control object of the control method mentioned in this embodiment is the first switch Q1, the second switch Q2, the third switch Q3, or the fourth switch Q4 in the full-bridge inverter; by controlling the on and off of the first switch Q1, the second switch Q2, the third switch Q3, or the fourth switch Q4, the current waveform required by this embodiment can be achieved.

[0054] Step 101: Based on unipolar modulation and bipolar modulation, switch the control of the full-bridge inverter.

[0055] refer to Figure 1 For a full-bridge inverter, there are two bridge arms (first bridge arm and second bridge arm). The first bridge arm includes a first switch Q1 and a second switch Q2, and the second bridge arm includes a third switch Q3 and a fourth switch Q4. In unipolar modulation, the control object is one of the first bridge arm and the second bridge arm, while the other operates at the power frequency. In bipolar modulation, the control object is both the first bridge arm and the second bridge arm.

[0056] Switching transistors are functionally categorized into magnetizing transistors and freewheeling transistors. For example, during the forward output phase, when the magnetizing transistor is on, the freewheeling transistor is off, and the inductor current rises. When the inductor current reaches the expected peak value, the controller turns off the magnetizing transistor and turns on the freewheeling transistor. After the freewheeling transistor is on, the inductor current decreases. When the inductor current drops to the expected valley value, the controller turns off the freewheeling transistor and turns on the magnetizing transistor.

[0057] Specifically, the full-bridge inverter is switched based on unipolar modulation and bipolar modulation; among them, bipolar modulation covers the zero-crossing point of the full-bridge inverter output. Using bipolar TCM modulation near the zero-crossing point can effectively avoid the current waveform distortion problem caused by the low frequency of the switching transistor near the zero-crossing point; using unipolar TCM modulation near the non-zero-crossing point can effectively reduce switching losses.

[0058] Step 102: Obtain the compensation current value.

[0059] Specifically, the compensation current value is obtained, which is the change in negative current of the full-bridge inverter during the switching between unipolar modulation and bipolar modulation.

[0060] Step 103: Compensate the preset maximum value of the inductor current of the full-bridge inverter based on the compensation current value.

[0061] Specifically, during bipolar modulation, the preset maximum value of the inductor current of the full-bridge inverter is compensated based on the compensation current value.

[0062] As discussed above, during the switching between single- and bipolar TCM modulation, the magnitude of the grid current will change abruptly due to the delay, such as... Figure 2 As shown by the red line, the reason for the grid current jump is the change in negative current during the switching process between unipolar and bipolar modulation. By obtaining the negative current change value as feedback, the inductor current of the bipolar modulation device is adjusted to make the grid current reach the preset waveform. The control method provided in this embodiment avoids the problem of current distortion caused by the inconsistency of volt-second balance during the switching between unipolar and bipolar modulation by compensating for the inductor current during bipolar modulation, thereby reducing the total harmonic distortion rate of the current and improving the current quality.

[0063] For step 102, in some embodiments, the method for obtaining the compensation current value includes: obtaining the negative current change value during the switching process of unipolar modulation and bipolar modulation based on the volt-second balance principle.

[0064] At this point, step 103 compensates the negative current change value to the preset maximum value of the inductor current, thereby offsetting the impact of the negative current change and maintaining the positive limit of the AC current output by the inverter.

[0065] In some embodiments, the method for obtaining the negative current change value includes:

[0066]

[0067] Where ΔI is the increase in negative current, V DC DC power supply U input to the full-bridge inverter DC The voltage value, V AC The full-bridge inverter outputs AC power U AC The voltage value, L s Δt is the inductance value of the inverter in the full-bridge inverter, and Δt is the delay time during the switching process between unipolar modulation and bipolar modulation.

[0068] In some embodiments, V DC and V AC The instantaneous value obtained by real-time sampling of the full-bridge inverter is calculated by adding the hardware delay and the DSP software delay. The hardware delay includes the sampling chip delay and filter delay, while the software delay includes the analog-to-digital conversion delay and the calculation delay.

[0069] For step 103, in some embodiments, the preset maximum value of the inductor current of the full-bridge inverter is compensated based on the compensation current, including: during the positive phase output stage and the negative phase output stage of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current.

[0070] refer to Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the currents (it) of the inverter after peak compensation provided in this embodiment. Figure 5 The corresponding embodiment provided in this example Figure 4 A schematic diagram of the power grid current compensation method.

[0071] Specifically, refer to Figure 4 In the positive and negative phases of bipolar modulation, the preset peak value of the inductor current is compensated based on the compensation current.

[0072] refer to Figure 5 The positive and negative phase output stages of bipolar modulation are obtained based on the grid phase angle. When the grid phase angle represents a phase of 0° to 180°, the bipolar modulation is in the positive phase output stage; when the grid phase angle represents a phase of 180° to 360°, the bipolar modulation is in the negative phase output stage.

[0073] During the positive output phase, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)+2*|I B|, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of -I. B I B This is a fixed value, selected based on hardware parameters and engineering debugging results to find a relatively suitable value. During the negative phase output stage, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)-2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of I. B .

[0074] refer to Figure 4 and Figure 5 When the bipolar modulation is in the positive phase output stage, the preset peak value is compensated based on the compensation current, the magnitude of which is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)+2*|I B |+ΔI, the valley current of the inductor is -I B By compensating for the preset peak value of the inductor current in bipolar modulation, the positive output current of the inverter is increased, thus allowing the inverter's output current to rise; Reference Figure 2 and Figure 4 In the positive phase output stage of bipolar modulation, after the inverter's output current rises, the output waveform of the inverter's output current is a sinusoidal current.

[0075] Similarly, when bipolar modulation is in the negative phase output stage, the preset peak value is compensated based on the compensation current, and the magnitude of the compensation current is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)-2*|I B |-ΔI, the valley current value of the inductor is I B By compensating for the preset peak value of the inductor current in bipolar modulation, the negative phase output current of the inverter is increased, thereby reducing the inverter's output current; Reference Figure 2 and Figure 4 In the negative phase output stage of bipolar modulation, after the inverter's output current decreases, the output waveform of the inverter's output current becomes a sinusoidal current.

[0076] In some embodiments, since the preset peak current of the inductor current in the compensated bipolar modulation increases, or the absolute value of the preset valley current increases, the switching frequency can be reduced accordingly to prevent the frequency of the switching transistor from becoming too high.

[0077] For step 103, in some embodiments, the preset maximum and minimum values ​​of the inductor current of the full-bridge inverter are compensated based on the compensation current, including: during the positive phase output stage and the negative phase output stage of the full-bridge inverter, the preset valley values ​​of the inductor current are compensated based on the compensation current.

[0078] refer to Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the currents (it) of the inverter after valley compensation provided in this embodiment. Figure 7 The corresponding embodiment provided in this example Figure 6 A schematic diagram of the power grid current compensation method.

[0079] Specifically, refer to Figure 6 In the positive and negative phases of bipolar modulation, the preset valley value of the inductor current is compensated based on the compensation current.

[0080] refer to Figure 7 The positive and negative phase output stages of bipolar modulation are obtained based on the grid phase angle. When the grid phase angle represents a phase of 0° to 180°, the bipolar modulation is in the positive phase output stage; when the grid phase angle represents a phase of 180° to 360°, the bipolar modulation is in the negative phase output stage.

[0081] During the positive output phase, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)+2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of -I. B I B This is a fixed value, selected based on hardware parameters and engineering debugging results to find a relatively suitable value. During the negative phase output stage, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)-2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of I. B .

[0082] refer to Figure 6 and Figure 7 When the bipolar modulation is in the positive phase output stage, the compensation current is based on the preset valley value, and the magnitude of the compensation current is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)+2*|I B The valley current value of the inductor current is -I. B+ΔI; By compensating for the preset valley value of the inductor current in bipolar modulation, the negative phase output current of the inverter is reduced, allowing the inverter's output current to increase; Reference Figure 2 and Figure 6 In the positive phase output stage of bipolar modulation, after the inverter's output current rises, the output waveform of the inverter's output current is a sinusoidal current.

[0083] Similarly, when bipolar modulation is in the negative phase output stage, the compensation current is based on the preset valley value, and the magnitude of the compensation current is the negative current change value ΔI; after compensation, the peak inductor current value is 2*Iref*sin(wt)-2*|I B The valley current value of the inductor current is I. B -ΔI; By compensating for the preset valley value of the inductor current in bipolar modulation, the positive phase output current of the inverter is reduced, thus lowering the inverter's output current. (Reference) Figure 2 and Figure 6 In the negative phase output stage of bipolar modulation, after the inverter's output current decreases, the output waveform is approximately a sinusoidal current.

[0084] For step 103, in some embodiments, the preset maximum and minimum values ​​of the inductor current of the full-bridge inverter are compensated based on the compensation current value, including: during the positive phase output stage of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current; during the negative phase output stage of the full-bridge inverter, the preset valley value of the inductor current is compensated based on the compensation current.

[0085] Specifically, refer to Figure 4 and Figure 6 In the positive phase output stage of bipolar modulation, the preset peak value of the inductor current is compensated based on the compensation current; in the negative phase output stage of bipolar modulation, the preset valley value of the inductor current is compensated based on the compensation current.

[0086] During the positive output phase, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)+2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of -I. B I B This is a fixed value, selected based on hardware parameters and engineering debugging results to find a relatively suitable value. During the negative phase output stage, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)-2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of I. B.

[0087] refer to Figure 4 and Figure 5 When the bipolar modulation is in the positive phase output stage, the preset peak value is compensated based on the compensation current, the magnitude of which is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)+2*|I B |+ΔI, the valley current of the inductor is -I B By compensating for the preset peak value of the inductor current in bipolar modulation, the positive output current of the inverter is increased, thus allowing the inverter's output current to rise; Reference Figure 2 and Figure 4 In the positive phase output stage of bipolar modulation, after the inverter's output current rises, the output waveform of the inverter's output current is a sinusoidal current.

[0088] refer to Figure 6 and Figure 7 When bipolar modulation is in the negative phase output stage, the compensation current is based on the preset valley value, and the magnitude of the compensation current is the negative current change value ΔI; after compensation, the peak inductor current value is 2*Iref*sin(wt)-2*|I B The valley current value of the inductor current is I. B -ΔI; By compensating for the preset valley value of the inductor current in bipolar modulation, the positive phase output current of the inverter is reduced, thus lowering the inverter's output current. (Reference) Figure 2 and Figure 6 In the negative phase output stage of bipolar modulation, after the inverter's output current decreases, the output waveform is approximately a sinusoidal current.

[0089] For step 103, in some embodiments, the preset maximum and minimum values ​​of the inductor current of the full-bridge inverter are compensated based on the compensation current value, including: during the positive phase output stage of the full-bridge inverter, the preset valley value of the inductor current is compensated based on the compensation current; during the negative phase output stage of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current.

[0090] Specifically, refer to Figure 4 and Figure 6 In the positive phase output stage of bipolar modulation, the preset valley value of the inductor current is compensated based on the compensation current; in the negative phase output stage of bipolar modulation, the preset peak value of the inductor current is compensated based on the compensation current.

[0091] During the positive output phase, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)+2*|I B|, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of -I. B I B This is a fixed value, selected based on hardware parameters and engineering debugging results to find a relatively suitable value. During the negative phase output stage, the preset peak value is obtained based on the DC amplitude and the grid phase angle. The DC amplitude is the current amplitude Iref generated by the bus voltage loop. In one example, the preset peak value is 2*Iref*sin(wt)-2*|I B |, sin(wt) is the phase angle of the sinusoidal signal on the grid side, with a preset valley value of I. B .

[0092] refer to Figure 6 and Figure 7 When the bipolar modulation is in the positive phase output stage, the compensation current is based on the preset valley value, and the magnitude of the compensation current is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)+2*|I B The valley current value of the inductor current is -I. B +ΔI; By compensating for the preset valley value of the inductor current in bipolar modulation, the negative phase output current of the inverter is reduced, allowing the inverter's output current to increase; Reference Figure 2 and Figure 6 In the positive phase output stage of bipolar modulation, after the inverter's output current rises, the output waveform of the inverter's output current is a sinusoidal current.

[0093] refer to Figure 4 and Figure 5 When the bipolar modulation is in the negative phase output stage, the preset peak value is compensated based on the compensation current, the magnitude of which is the negative current change value ΔI; after compensation, the peak current value of the inductor is 2*Iref*sin(wt)-2*|I B |-ΔI, the valley current value of the inductor is I B By compensating for the preset peak value of the inductor current in bipolar modulation, the negative phase output current of the inverter is increased, thereby reducing the inverter's output current; Reference Figure 2 and Figure 4 In the negative phase output stage of bipolar modulation, after the inverter's output current decreases, the output waveform of the inverter's output current becomes a sinusoidal current.

[0094] In some embodiments, after performing step 103, the control method further includes: obtaining the output current of the full-bridge inverter; obtaining the error current between the output current and the desired output current of the full-bridge inverter; and adjusting the preset peak value or preset valley value of the inductor current based on the error current.

[0095] In some embodiments, the error current is the difference between the output current and the desired output current.

[0096] refer to Figure 8 , Figure 8 This is a schematic diagram illustrating the principle of error current compensation based on preset peak or preset valley values ​​provided in this embodiment. Specifically, the output current is obtained by sampling the output current of the full-bridge inverter to obtain a sampled current; the desired output current of the full-bridge inverter is obtained, and in some embodiments, the desired output current of the full-bridge inverter is a sinusoidal current; the difference between the sampled current and the desired sinusoidal current is calculated to obtain the error current; the preset peak or preset valley value of the full-bridge inverter is adjusted based on the error current to make the output current of the full-bridge inverter closer to the desired sinusoidal current, further reducing the total harmonic distortion rate of the current and improving the current quality.

[0097] The control method provided in this embodiment combines unipolar modulation and bipolar modulation to avoid current waveform distortion caused by excessively low switching frequency near the zero-crossing point, and effectively reduces switching losses. Furthermore, during bipolar modulation, compensation of the inductor current avoids current distortion due to inconsistent volt-second balance during switching between unipolar and bipolar modulation, reducing the total harmonic distortion rate and improving current quality.

[0098] This application also provides a storage medium, which may include: read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk, etc. Multiple instructions are stored thereon, which are adapted for loading by a processor to execute the control method provided in the above embodiments.

[0099] This application also provides a full-bridge inverter, which includes bridge arm circuits and control circuits for suppressing current distortion, reducing the total harmonic distortion rate of the current, and improving current quality.

[0100] refer to Figure 9 , Figure 9 The diagram below shows the structure of the full-bridge inverter provided in this embodiment. The full-bridge inverter 200 includes a bridge arm circuit 201 and a control circuit 202. The bridge arm circuit 201 is connected to the control circuit 202, and the control circuit 202 is used to control the bridge arm circuit 201 to execute the control method provided in the above embodiment.

[0101] In some embodiments, reference Figure 1 The bridge arm circuit 201 includes: a DC power supply U DC The first switching transistor Q1 has its control terminal connected to the control circuit 202 and its first terminal connected to the DC power supply U. DCThe positive terminal; the second switch Q2, the control terminal is connected to the control circuit 202, the first terminal is connected to the second terminal of the first switch Q1, and the second terminal is connected to the DC power supply U. DC The negative terminal; the third switching transistor Q3, the control terminal is connected to the control circuit 202, and the first terminal is connected to the DC power supply U. DC The positive terminal; the fourth switch Q4, the control terminal is connected to the control circuit 202, the first terminal is connected to the second terminal of the third switch Q3, and the second terminal is connected to the DC power supply U. DC The negative terminal of the inverter inductor Ls is connected to the second terminal of the first switch Q1; the resonant inductor Lf is connected to the second terminal of the inverter inductor Ls; the resonant capacitor Cf is connected to the second terminal of the inverter inductor Ls and to the second terminal of the third switch Q3; the second terminals of the resonant inductor Lf and the resonant capacitor Cf serve as the output terminals of the bridge arm circuit 201 to output AC power U. AC .

[0102] This application also provides an electronic device, including the storage medium provided in the above embodiments, or including the full-bridge inverter provided in the above embodiments.

[0103] In some embodiments, the full-bridge inverter can be used in solar power systems, home and office backup power supplies, vehicle power systems, uninterruptible power supply (UPS) systems, or mobile communication stations.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0105] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0106] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0107] The control method, storage medium, and full-bridge inverter provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A control method applied to a full-bridge inverter, characterized in that, include: The full-bridge inverter is switched based on unipolar modulation and bipolar modulation; wherein the bipolar modulation covers the zero-crossing point of the full-bridge inverter's output. Obtain the compensation current value, which is the negative current change value of the full-bridge inverter during the switching process of unipolar modulation and bipolar modulation; During the bipolar modulation process, the preset maximum value of the inductor current of the full-bridge inverter is compensated based on the compensation current value.

2. The control method according to claim 1, characterized in that, The preset maximum value of compensating the inductor current of the full-bridge inverter based on the compensation current value includes: During the positive and negative output phases of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current value.

3. The control method according to claim 1, characterized in that, The preset maximum value of compensating the inductor current of the full-bridge inverter based on the compensation current value includes: During the positive and negative output phases of the full-bridge inverter, the preset valley value of the inductor current is compensated based on the compensation current value.

4. The control method according to claim 1, characterized in that, The preset maximum value of compensating the inductor current of the full-bridge inverter based on the compensation current value includes: During the positive output phase of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current; During the negative phase output phase of the full-bridge inverter, the inductor current is compensated for a preset valley value based on the compensation current.

5. The control method according to claim 1, characterized in that, The preset maximum value of compensating the inductor current of the full-bridge inverter based on the compensation current value includes: During the positive output phase of the full-bridge inverter, the inductor current is compensated for a preset valley value based on the compensation current; During the negative phase output phase of the full-bridge inverter, the preset peak value of the inductor current is compensated based on the compensation current.

6. The control method according to any one of claims 1 to 5, characterized in that, The process of obtaining the compensation current value includes: Based on the volt-second balance principle, the negative current change value during the switching process of the unipolar modulation and the bipolar modulation is obtained.

7. The control method according to claim 6, characterized in that, Obtaining the negative current change value includes: Where ΔI is the change in the negative current, V DC V is the input voltage value of the full-bridge inverter. AC L represents the output voltage value of the full-bridge inverter. s Δt is the inductance value of the full-bridge inverter, and Δt is the delay time during the switching process between unipolar modulation and bipolar modulation.

8. The control method according to any one of claims 2 to 5, characterized in that, After compensating the inductor current of the full-bridge inverter based on the compensation current value, the control method further includes: Obtain the output current of the full-bridge inverter; Obtain the error current between the output current and the expected output current of the full-bridge inverter; Based on the error current, the preset maximum value of the inductor current is adjusted.

9. The control method according to claim 8, characterized in that, The error current is the difference between the output current and the expected output current.

10. A storage medium, characterized in that, The storage medium stores a plurality of instructions adapted for loading by a processor to execute the control method according to any one of claims 1 to 9.

11. A full-bridge inverter, characterized in that, include: Bridge arm circuit, and control circuit connected to the bridge arm circuit; The control circuit is used to control the bridge arm circuit to perform the control method according to any one of claims 1 to 9.

12. The full-bridge inverter according to claim 11, characterized in that, The bridge arm circuit includes: DC power supply; The first switching transistor has its control terminal connected to the control circuit and its first terminal connected to the positive terminal of the DC power supply. The second switching transistor has its control terminal connected to the control circuit, its first terminal connected to the second terminal of the first switching transistor, and its second terminal connected to the negative terminal of the DC power supply. The third switching transistor has its control terminal connected to the control circuit and its first terminal connected to the positive terminal of the DC power supply. The fourth switching transistor has its control terminal connected to the control circuit, its first terminal connected to the second terminal of the third switching transistor, and its second terminal connected to the negative terminal of the DC power supply. The inverter inductor has its first terminal connected to the second terminal of the first switching transistor. A resonant inductor, with its first end connected to the second end of the inverter inductor; The resonant capacitor has its first end connected to the second end of the inverter inductor, and its second end connected to the second end of the third switching transistor. The second end of the resonant inductor and the second end of the resonant capacitor serve as the output terminals of the bridge arm circuit.

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