Control method and device for dual active bridge dc-ac converter

Abstract

This application discloses a control method and apparatus for a dual active bridge DC-AC converter, belonging to the field of power technology. The DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm is either a full bridge or a half bridge. The control method includes: determining whether the current grid voltage is within a preset range of zero-crossing points; if the current grid voltage is within the preset range, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle is 0.5 when the grid voltage crosses zero. The control method and apparatus for the dual active bridge DC-AC converter disclosed in this application, by adjusting the duty cycle of the converter's outer phase shift angle to 0.5 when the grid voltage crosses zero, can reduce the fluctuation of output current or output voltage when the converter outputs reactive power and the grid voltage commutates at zero, while ensuring that the root mean square of the transformer current is minimized.

Description

Technical Field

[0001] This application belongs to the field of power technology, and in particular relates to a control method and device for a dual active bridge DC-AC converter. Background Technology

[0002] In related technologies, in scenarios such as photovoltaic energy storage or charging, the Dual Active Bridge (DAB) DC-AC converter can complete power conversion in a single stage when the DC side voltage is lower or higher than the AC side voltage. It also has advantages such as high conversion efficiency, small overall size, low hardware cost, primary and secondary side isolation, and the ability to realize bidirectional power transmission.

[0003] However, the control of a single-stage DAB-type DC / AC converter is relatively complex. When supplying reactive power to the grid (including both reactive and active power), traditional phase-shift control-based modulation methods such as dual phase-shift (DPS) or triple phase-shift (TPS) modulation (or control) have limitations near the grid voltage zero-crossing point. Near the grid voltage zero-crossing point, the AC side of the DAB-type DC / AC converter undergoes a positive-to-negative grid voltage reversal. Using traditional phase-shift control-based modulation methods, the secondary-side high-frequency excitation outputs a negative voltage on the AC side with a 180-degree phase shift compared to a positive voltage output. If reactive power is present at this point, the DAB-type DC / AC converter needs to continuously output or input current at the grid zero-crossing point. In traditional phase-shift control-based modulation methods, keeping the outer phase angle constant allows the output current of the DAB-type DC / AC converter to remain stable during positive and negative commutation of the grid voltage. However, the root mean square (RMS) of the transformer current in the DAB-type DC / AC converter is not equal in the positive and negative half-waves of the grid voltage, and a smaller RMS of the transformer current cannot be achieved for half a cycle, resulting in increased overall losses. Furthermore, if the traditional phase-shift control-based modulation method uses complementary modulation with an outer phase angle of 180 degrees, it will cause a 180-degree phase shift in the resonant current periodic conduction loop, leading to drastic changes in output or input current, degrading power quality, and increasing electromagnetic interference (EMI). In summary, traditional phase-shift control-based modulation methods cannot achieve the goal of minimizing the RMS of the transformer current in both the positive and negative half-waves of the grid voltage, ensuring that the pulse-width modulation (PWM) signal of the commutation point bridge arm of the grid voltage does not jump, and preventing drastic fluctuations in output current or voltage. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a control method and device for a dual active bridge DC-AC converter, which can reduce the jitter of the output current or output voltage of a single-stage dual active bridge DC-AC converter when the grid voltage crosses zero for commutation.

[0005] In a first aspect, this application provides a control method for a dual active bridge DC-AC converter, wherein the DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm of the dual active bridge DC-AC converter is either a full bridge or a half bridge; the method includes: Determine whether the current grid voltage is within the preset range of zero crossings; When the current grid voltage is within the preset range, the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter is adjusted so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

[0006] According to one embodiment of this application, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: The duty cycle of the outward phase shift is adjusted to 0.5 and maintained until the grid voltage crosses zero or exceeds the preset range.

[0007] According to the control method of the dual active bridge DC-AC converter of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0008] According to one embodiment of this application, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: Using the point where the duty cycle of the outward phase shift angle is 0.5 when the grid voltage crosses zero as a symmetrical point, determine the target value corresponding to the current value of the duty cycle of the outward phase shift angle; Based on the target adjustment strategy, the duty cycle of the outward phase angle is gradually adjusted from the current value to the target value.

[0009] According to one embodiment of this application, the target adjustment strategy includes at least one of a linear adjustment strategy and a nonlinear adjustment strategy.

[0010] According to one embodiment of this application, the method further includes: During the process of adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero, based on the deviation between the output current of the dual active bridge DC-AC converter and the output current reference, at least one of the following is adjusted: the inner phase shift angle of the DC side bridge arm, the inner phase shift angle of the AC side bridge arm, the frequency of the drive signal of the DC side bridge arm, and the frequency of the drive signal of the AC side bridge arm, so that the output current follows the output current reference.

[0011] According to one embodiment of this application, determining whether the current grid voltage is within a preset range of zero crossing points includes: Obtain the input voltage and output voltage of the dual active bridge DC-AC converter; If the absolute value of the ratio of the output voltage to the input voltage decreases to less than a first threshold, the current grid voltage is determined to be within the preset range.

[0012] According to one embodiment of this application, determining whether the current grid voltage is within a preset range of zero crossing points includes: Obtain the output voltage of the dual active bridge DC-AC converter; If the absolute value of the output voltage decreases to less than the second threshold, the current grid voltage is determined to be within the preset range.

[0013] According to one embodiment of this application, adjusting the duty cycle of the outward phase shift angle of the dual active bridge DC-AC converter includes: If the ratio is less than zero and the absolute value of the ratio decreases to less than the first threshold, reduce the duty cycle of the outward phase angle; If the ratio is greater than zero and the absolute value of the ratio decreases to less than the first threshold, the duty cycle of the outward phase angle is increased.

[0014] Secondly, this application provides a control device for a dual active bridge DC-AC converter, wherein the DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm of the dual active bridge DC-AC converter is either a full bridge or a half bridge; the device includes: The judgment module is used to determine whether the current grid voltage is within the preset range of zero crossing points; The control module is used to adjust the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter when the grid voltage is within the preset range, so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

[0015] According to the control device of the dual active bridge DC-AC converter of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is minimized in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference. Thirdly, this application provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the control method of the dual active bridge DC-AC converter as described in the first aspect above.

[0016] Fourthly, this application provides a non-volatile computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the control method for a dual active bridge DC-AC converter as described in the first aspect above.

[0017] Fifthly, this application provides a chip including a processor and a communication interface, the communication interface being coupled to the processor, the processor being used to run programs or instructions to implement the control method for the dual active bridge DC-AC converter as described in the first aspect.

[0018] In a sixth aspect, this application provides a computer program product, including a computer program that, when executed by a processor, implements the control method for a dual active bridge DC-AC converter as described in the first aspect above.

[0019] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart illustrating the control method for a dual active bridge DC-AC converter provided in an embodiment of this application. Figure 2 This is one of the structural schematic diagrams of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 3 This is the second schematic diagram of the structure of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 4 This is the third schematic diagram of the structure of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 5 This is a schematic diagram illustrating the definition of the duty cycle of the outer phase shift angle in the control method of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 6 This is a schematic diagram of the waveforms of the secondary modulation reference wave, secondary voltage, and high-frequency components of the secondary voltage of the transformer in the control method of the dual active bridge DC-AC converter provided in the embodiments of this application. Figure 7 This is a schematic diagram showing the flow direction of the secondary output current of the transformer in the control method of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 8 This is one of the schematic diagrams of the waveforms of transformer current and transformer secondary output current in the control method of traditional dual active bridge DC-AC converter; Figure 9 This is the second schematic diagram of the waveforms of transformer current and secondary output current in the control method of a traditional dual active bridge DC-AC converter. Figure 10 This is a schematic diagram of the waveforms of the transformer current and the secondary output current of the transformer in the control method of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 11 This is a schematic diagram of the control plane of the control method for the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 12 This is a schematic diagram illustrating the change process of the duty cycle of the outer phase shift angle in the control method of the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 13 This is a schematic diagram of the control device for the dual active bridge DC-AC converter provided in the embodiments of this application; Figure 14 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0022] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] The control method, control device, electronic equipment, and readable storage medium of the dual active bridge DC-AC converter provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0024] The control method for the dual active bridge DC-AC converter can be applied to the terminal, and can be executed by the hardware or software in the terminal.

[0025] The control method for a dual active bridge DC-AC converter provided in this application embodiment can be implemented by an electronic device or a functional module or entity within an electronic device that can implement the control method for the dual active bridge DC-AC converter. The electronic devices mentioned in this application embodiment include, but are not limited to, mobile phones, tablets, computers, cameras, and wearable devices. The control method for a dual active bridge DC-AC converter provided in this application embodiment will be described below using an electronic device as the implementation subject.

[0026] like Figure 1 As shown, the control method of the dual active bridge DC-AC converter includes steps 110 and 120.

[0027] In actual implementation, the dual active bridge DC-AC converter provided in this application embodiment is a single-stage dual active bridge DC-AC converter. The DC-side bridge arm of this dual active bridge DC-AC converter is a full bridge, and the AC-side bridge arm is either a full bridge or a half bridge.

[0028] Figures 2 to 4The structure of a typical single-stage dual-active bridge DC-AC converter is shown. A single-stage dual-active bridge DC-AC converter can mainly consist of: a full-bridge converter and a transformer on the DC side, and a half-bridge or full-bridge converter on the AC side.

[0029] Step 110: Determine whether the current grid voltage is within the preset range of zero crossing points.

[0030] In actual operation, the output of this single-stage dual active bridge DC-AC converter can be connected to the power grid via a filter and a relay.

[0031] In some embodiments, the grid voltage can be monitored or sampled, and the results of the monitoring or sampling can be used to determine whether the current grid voltage is within a preset range of zero crossings. It is understood that the grid voltage is an AC voltage, and the current grid voltage not being within the preset range of zero crossings can include two situations: either the grid voltage is greater than zero, or the grid voltage is less than zero.

[0032] It should be noted that, in this embodiment, the concept of zero-crossing refers to a period of time during which the output voltage is equal to zero. The specific value of the preset range is not limited, as long as it can characterize that the grid voltage is currently near the zero-crossing point. In practical applications, it can be set according to the specific application environment. In some embodiments, the preset range can be a certain proportion of the maximum and minimum values ​​of the grid voltage, such as 5% or 3%. For example, the maximum and minimum values ​​of the grid voltage can generally be +220V and -220V, respectively, so the preset range can be -10V to +10V (220V * 5% = 11V).

[0033] It should be noted that the preset range of the zero-crossing point at least includes the zero-crossing point. Specifically, it can be a range of a small value fluctuating above and below the zero-crossing point. Of course, it can also be not centered on the zero-crossing point, as long as it includes the range in the relevant technology where frequent switching of working modes is likely to occur. The upper and lower limits can be determined according to the specific application scenario, and all of them are within the protection scope of this application.

[0034] In some embodiments, the phase angle of the grid voltage can be used to determine whether the grid voltage is within a preset range of zero crossings. In some embodiments, determining whether the current grid voltage is within a preset range of zero crossings may include: determining whether the phase angle of the current grid voltage is within a preset phase angle interval; if so, then determining that the current grid voltage is within the preset range of zero crossings.

[0035] In some embodiments, the grid voltage may be determined based on the instantaneous value of the grid voltage to determine whether the grid voltage is within a preset range of zero crossings. In some embodiments, determining whether the current grid voltage is within a preset range of zero crossings may include: determining whether the instantaneous value of the current grid voltage is within a preset value range; if so, then determining that the current grid voltage is within the preset range of zero crossings.

[0036] Since there are two types of zero crossings, one is the zero crossing of the grid voltage from positive to negative, and the other is the zero crossing of the grid voltage from negative to positive, the aforementioned preset phase angle interval and preset value interval may include: a first interval including the zero crossing of the grid voltage from positive to negative, and a second interval including the zero crossing of the grid voltage from negative to positive.

[0037] In some embodiments, for the aforementioned preset phase angle interval, the first interval can be [0.95π, 1.05π) and the second interval can be [1.95π, 0.03π); or, the first interval can be [0.95π, π] and the second interval can be [1.95π, 2π]. Here, π is the mathematical constant pi. The specific settings of the first and second intervals can correspond to the specific settings of the preset phase angle interval, and will not be elaborated further. Of course, the above are only two specific optional examples and are not limited to them. The specific ranges of the first and second intervals are determined according to the specific application scenario, and all are within the protection scope of this application.

[0038] Step 120: When the current grid voltage is within the preset range, adjust the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

[0039] In actual implementation, when the current grid voltage is within a preset range, the output current and output voltage during the commutation process can be stably and smoothly changed by controlling the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter during this period, through the method of this invention.

[0040] In some embodiments, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter can be maintained at or past 0.5 near the zero-crossing point of the grid voltage (i.e., within a preset range of the zero-crossing point), that is, the external phase shift angle of the dual active bridge DC-AC converter can be maintained at 90°. It should be noted that, based on the periodic relationship between the external phase shift angle and the output current of the dual active bridge DC-AC converter, maintaining the external phase shift angle at 90° can keep the periodic conduction loop of the resonant current continuously changing, thereby ensuring the stability of the output current or input current of the dual active bridge DC-AC converter, improving power quality, and ensuring that the duty cycle of the drive signals (usually PWM signals) of the two sides (including the DC side and the AC side) of the dual active bridge DC-AC converter does not change abruptly during the commutation process, and that the RMS of the transformer current in the positive and negative half-waves before and after the positive and negative commutation of the grid voltage (which can include both positive to negative and negative to positive cases) is as small as possible.

[0041] The external phase shift angle of a dual active bridge DC-AC converter is the phase difference between the drive signals of the DC-side bridge arm and the AC-side bridge arm. The duty cycle Dφ of the external phase shift angle of a dual active bridge DC-AC converter can be defined as follows: Figure 5 As shown. The external phase shift duty cycle Dφ of the active bridge DC-AC converter is the time difference T between the midpoint of the positive half-wave of the primary voltage Up and the midpoint of the positive half-wave of the secondary voltage Us. dφ Divide by the half-cycle duration T prd / 2 can be expressed as the formula Dφ=2T dφ / T prd .

[0042] In some embodiments, the external phase shift angle of the dual active bridge DC-AC converter can be adjusted by adjusting the phase of the drive signal of the DC side bridge arm and / or the phase of the drive signal of the AC side bridge arm, thereby adjusting the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter.

[0043] It should be noted that for a single-stage dual-active-bridge DC-AC converter, the output power can be controlled by controlling the external phase-shift angle duty cycle. The external phase-shift angle duty cycle Dφ and power have a periodic relationship, which can be expressed as: P(Dφ)=P(1-Dφ)=-P(-Dφ). Here, P(Dφ), P(1-Dφ), and P(-Dφ) respectively represent the output power of the dual-active-bridge DC-AC converter when the external phase-shift angle duty cycle is Dφ, (1-Dφ), and -Dφ. Although the powers at Dφ and (1-Dφ) are the same, for the case where both the primary and secondary sides of the transformer have positive voltages, the RMS of the transformer current is different, and Irms(Dφ) < Irms(1-Dφ). Here, Irms(Dφ) and Irms(1-Dφ) respectively represent the root mean square of the transformer current Itrans when the external phase-shift angle duty cycle is Dφ and (1-Dφ). To reduce losses, Dφ can be used as the basis for wave generation, Dφ∈[0,0.5], and the high-frequency excitation duty cycle DsecHF of the secondary side of the transformer can be expressed as DsecHF = Dφ.

[0044] Reference Figure 6 , PWM0 represents the modulation reference wave of the secondary side of the transformer; when the output voltage of the secondary side of the transformer is a positive voltage, PWM0 being 1 indicates that the secondary side voltage Us is a positive voltage, and PWM0 being 0 indicates that the secondary side voltage Us is zero or a negative voltage. And in the case where the secondary side output voltage is a negative voltage, it is the opposite, that is, PWM0 being 1 indicates that the secondary side voltage Us is a negative voltage, and PWM0 being 0 indicates that the secondary side voltage Us is zero or a positive voltage. But 0 both indicate that the transformer current Itrans does not flow to the secondary side output capacitor, and 1 both indicate that Itrans flows to the secondary side output capacitor. At this time, the secondary side output current Isec can be expressed as the secondary side modulation wave Pwm0 multiplied by the transformer current Itrans, as Figure 7 shown. It should be noted that Figure 6 in which Vg is the grid voltage, Vgpeak is the peak value of the grid voltage, Vsec is the secondary side voltage Us, IoCmd is the effective value command of the output current of the dual-active-bridge DC-AC converter, and VsecHF is the high-frequency component after Vsec subtracts its 50Hz fundamental wave component.

[0045] When the current grid voltage is within the preset range of zero crossing, and the primary voltage Up is positive while the secondary voltage Us is negative, the secondary high-frequency excitation and the secondary drive signal are reversed, resulting in a 180° phase shift. In this case, the secondary excitation duty cycle can be expressed as DsecHF = Dφ - 1. Using Dφ as the modulation basis, the output power of the dual active bridge DC-AC converter is P = P(DsecHF) = P(Dφ - 1) = -P(Dφ), but the RMS of the transformer current will become Irms(Dφ - 1). By changing the phase shift duty cycle to 1 - Dφ, the secondary high-frequency excitation duty cycle becomes DsecHF = 1 - Dφ - 1 = -Dφ. The output power of the dual active bridge DC-AC converter remains unchanged, P = P(DsecHF) = -P(Dφ), but the RMS of the transformer current becomes Irms(-Dφ) = Irms(Dφ), which is less than Irms(Dφ - 1). By adjusting the duty cycle of the external phase shift angle in the positive and negative half-wave converter of the power grid, the root mean square of the transformer current can be reduced while keeping the output power of the dual active bridge DC-AC converter constant, thereby reducing losses.

[0046] Even with reactive power output, a dual active bridge DC-AC converter still outputs current (Isec) near the zero-crossing point of the grid voltage. However, using traditional control methods to keep Dφ constant results in a significantly larger RMS value of the transformer current during the negative half-wave of the grid voltage compared to the positive half-wave, leading to greater losses. Figure 8 As shown. However, if the traditional control method is used to optimize Irms and generate a wave according to 1-Dφ, the secondary-side modulation wave Pwm0 will experience a phase shift, causing severe oscillations in the output current Isec at this point, such as... Figure 9 As shown.

[0047] In such Figure 10On the control plane, k is the ratio of the secondary voltage Vsec (i.e., Us, the secondary output voltage) to the primary voltage Vpri (i.e., Up, the primary input voltage). When the ratio k is close to zero, it indicates that the current grid voltage is within the preset range of zero crossing. When the ratio k is close to zero, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter is kept at 0.5 or beyond 0.5. This satisfies both DφA + DφB = 1, minimizing Irms while keeping the output power of the dual active bridge DC-AC converter constant, and DφA = DφB, ensuring that the secondary modulation wave Pwm0 will not shift or change abruptly. Therefore, by maintaining the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter at 0.5 or beyond 0.5, the transition from DφA to DφB modulation can be achieved. This ensures that the secondary modulation reference wave remains unchanged at the zero-crossing point, and the output current Isec remains constant, while minimizing the RMS of the transformer current within the positive and negative half-waves of the grid voltage. Figure 11 As shown, the output current and output voltage are stabilized when the single-stage dual active bridge DC-AC converter completes reactive commutation.

[0048] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0049] In some embodiments of this application, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: adjusting the duty cycle of the outer phase shift angle to 0.5 and maintaining it until the grid voltage crosses zero or the grid voltage exceeds a preset range.

[0050] In actual implementation, refer to Figure 12 The broken line in the graph shows that the ratio k of the secondary-side output voltage Vsec to the primary-side voltage Vpri is less than the positive limit k. thp or greater than the negative limit k thnUnder these conditions, when the grid voltage is within the preset range of the zero-crossing point, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter can be adjusted towards 0.5 and maintained at 0.5 near k=0. That is, for a period of time before and after the grid voltage zero-crossing point, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter remains at 0.5. It can be understood that when k=0, the grid voltage is at its zero-crossing point.

[0051] In some embodiments, the external phase shift angle of the dual active bridge DC-AC converter can be adjusted to 90° by adjusting the phase of the drive signal of the DC side bridge arm and / or the phase of the drive signal of the AC side bridge arm, thereby achieving the adjustment of the external phase shift angle duty cycle Dφ of the dual active bridge DC-AC converter to 0.5.

[0052] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0053] In some embodiments of this application, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: taking the duty cycle of the outer phase shift angle of 0.5 when the grid voltage crosses zero as the symmetrical point, determining the target value corresponding to the current value of the duty cycle of the outer phase shift angle.

[0054] In actual implementation, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter can be adjusted so that when the current grid voltage is within the preset range of zero crossing, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter increases or decreases monotonically, and at the time of the grid voltage zero crossing, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter is 0.5, that is, when the grid voltage crosses zero, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter passes through 0.5.

[0055] In some embodiments, the target value corresponding to the current value of the external phase shift duty cycle can be determined with the point where the external phase shift duty cycle is 0.5 when the grid voltage crosses zero as the symmetrical point. For example, if the current value of the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter is 0.75, then the target value of the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter is 0.25; or, if the current value of the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter is 0.3, then the target value of the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter is 0.7.

[0056] Based on the target adjustment strategy, the duty cycle of the outward phase angle is gradually adjusted from the current value to the target value.

[0057] In practical implementation, after determining the target value of the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter, the external phase shift duty cycle Dφ can be adjusted from its current value to the target value based on the target adjustment strategy. The adjustment process can be referenced... Figure 12 The diagonal lines and curves in the text.

[0058] In some embodiments, the phase of the drive signal of the DC-side arm and / or the phase of the drive signal of the AC-side arm of the dual active bridge DC-AC converter can be adjusted to adjust the external phase shift angle of the dual active bridge DC-AC converter from its current value to a target value, and the external phase shift angle is 90° when the grid voltage crosses zero. This achieves the adjustment of the external phase shift angle duty cycle Dφ of the dual active bridge DC-AC converter from its current value to a target value, and the external phase shift angle duty cycle Dφ being 0.5 when the grid voltage crosses zero.

[0059] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0060] In some embodiments of this application, the target adjustment strategy includes at least one of a linear adjustment strategy and a nonlinear adjustment strategy.

[0061] In practical implementation, the target adjustment strategy can employ either a linear or nonlinear adjustment strategy. The process of adjusting the external phase shift duty cycle Dφ of a dual active bridge DC-AC converter using a linear adjustment strategy can be found in [reference needed]. Figure 12 The slash in the text; the process of adjusting the outer phase shift duty cycle Dφ of the dual active bridge DC-AC converter using a nonlinear adjustment strategy can be found in [reference]. Figure 12 The curve in the middle.

[0062] In some embodiments, the linear adjustment strategy may employ an adjustment strategy in which the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter changes from its current value to a target value as the aforementioned ratio k changes, satisfying a linear equation with a non-zero slope.

[0063] In some embodiments, the nonlinear adjustment strategy may employ an adjustment strategy in which the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter changes from its current value to a target value as the aforementioned ratio k changes, satisfying a non-first-order equation (e.g., a second-order or higher-order equation, an exponential equation, or a logarithmic equation, etc.).

[0064] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adopting a linear adjustment strategy or a nonlinear adjustment strategy, the duty cycle of the outer phase shift angle is gradually adjusted from the current value to the target value, so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero. Under the condition that the root mean square of the transformer current is minimized in the positive and negative half-waves of the grid voltage, the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power, etc.) and the grid voltage crosses zero for commutation, reducing the jitter of the output current or output voltage, improving the power quality of the output of the dual active bridge DC-AC converter, and reducing electromagnetic interference.

[0065] In some embodiments of this application, the control method further includes: during the process of adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero, adjusting at least one of the inner phase shift angle of the DC side bridge arm, the inner phase shift angle of the AC side bridge arm, the frequency of the drive signal of the DC side bridge arm, and the frequency of the drive signal of the AC side bridge arm of the dual active bridge DC-AC converter based on the deviation between the output current of the dual active bridge DC-AC converter and the output current reference, so that the output current follows the output current reference.

[0066] In actual operation, if the output current of the dual active bridge DC-AC converter fluctuates during the adjustment of the external phase shift duty cycle Dφ, the output current of the dual active bridge DC-AC converter can be controlled by adjusting at least one of the drive signals of the two bridge arms of the dual active bridge DC-AC converter, so that the output current of the dual active bridge DC-AC converter can follow the output current reference.

[0067] Understandably, the output current reference can be calculated based on the desired active power output of the dual active bridge DC-AC converter, the desired reactive power output of the dual active bridge DC-AC converter, and the frequency and phase of the grid voltage.

[0068] In some embodiments, at least one of the drive signals of the two bridge arms of the dual active bridge DC-AC converter is adjusted, that is, at least one of the inner phase shift angle of the DC side bridge arm, the inner phase shift angle of the AC side bridge arm, the frequency of the drive signal of the DC side bridge arm, and the frequency of the drive signal of the AC side bridge arm of the dual active bridge DC-AC converter is adjusted.

[0069] The inner phase shift angle is the phase difference between the drive signals of the switching transistors of different arms on the same side. Therefore, a dual active bridge DC-AC converter has two inner phase shift angles: the inner phase shift angle of the DC side arm and the inner phase shift angle of the AC side arm.

[0070] In some embodiments, the deviation between the output current of the dual active bridge DC-AC converter and the output current reference can be continuously observed, and a proportional-integral (PI) control algorithm is used to adjust at least one of the following in real time based on the deviation: the inner phase shift angle of the DC-side bridge arm, the inner phase shift angle of the AC-side bridge arm, the frequency of the drive signal of the DC-side bridge arm, and the frequency of the drive signal of the AC-side bridge arm, in order to reduce the deviation and enable the output current of the dual active bridge DC-AC converter to follow the output current reference.

[0071] In some embodiments, if the deviation between the output current of the dual active bridge DC-AC converter and the output current reference is too large (e.g., the deviation is greater than a certain preset threshold), a corresponding control algorithm can be used to adjust at least one of the following in real time based on the deviation: the inner phase shift angle of the DC-side bridge arm, the inner phase shift angle of the AC-side bridge arm, the frequency of the drive signal of the DC-side bridge arm, and the frequency of the drive signal of the AC-side bridge arm of the dual active bridge DC-AC converter. This reduces the deviation and allows the output current of the dual active bridge DC-AC converter to follow the output current reference.

[0072] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting at least one of the following based on the deviation between the output current of the dual active bridge DC-AC converter and the output current reference: the inner phase shift angle of the DC side bridge arm, the inner phase shift angle of the AC side bridge arm, the frequency of the drive signal of the DC side bridge arm, and the frequency of the drive signal of the AC side bridge arm, so that the output current follows the output current reference, the fluctuation of the output current of the dual active bridge DC-AC converter can be reduced, the power quality of the output of the dual active bridge DC-AC converter can be improved, and electromagnetic interference can be reduced.

[0073] In some embodiments of this application, determining whether the current grid voltage is within a preset range of zero crossing points includes: acquiring the input voltage and output voltage of the dual active bridge DC-AC converter; and determining that the current grid voltage is within the preset range when the absolute value of the ratio of the output voltage to the input voltage decreases to less than a first threshold.

[0074] In actual implementation, the preset range of the zero-crossing point can be a range that fluctuates slightly above and below the zero-crossing point. Correspondingly, the absolute value of the ratio k of the input voltage and output voltage of the dual active bridge DC-AC converter ranges from 0 to a first threshold (e.g., the aforementioned...). Figure 12 k in thp As the first threshold, k thp With k thn (These are opposites). Therefore, when the absolute value of the ratio k of the input voltage and output voltage of the dual active bridge DC-AC converter decreases from greater than the first threshold to less than the first threshold, it can be determined that the current grid voltage is within the preset range.

[0075] It is understandable that the ratio of the input voltage to the output voltage of a dual active bridge DC-AC converter is equal to the ratio of the secondary output voltage Vsec to the primary voltage Vpri.

[0076] The first threshold can be set according to the actual situation. The specific value of the first threshold is not limited in the embodiments of this application.

[0077] In some embodiments, the input voltage of the dual active bridge DC-AC converter can be obtained by a voltage sensor disposed at the input terminal of the dual active bridge DC-AC converter.

[0078] In some embodiments, the output voltage of the dual active bridge DC-AC converter can be obtained by a voltage sensor disposed at the output terminal of the dual active bridge DC-AC converter.

[0079] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0080] In some embodiments of this application, determining whether the current grid voltage is within a preset range of zero crossing points includes: acquiring the output voltage of the dual active bridge DC-AC converter; and determining that the current grid voltage is within the preset range when the absolute value of the output voltage decreases to less than a second threshold.

[0081] In actual operation, the output voltage of the dual active bridge DC-AC converter can be obtained by using a voltage sensor installed at the output terminal of the converter. After obtaining the output voltage, it can be determined whether the absolute value of the output voltage has decreased from greater than a second threshold to less than a second threshold. If so, it can be determined that the current grid voltage is within a preset range.

[0082] The second threshold can be set according to the actual situation, such as the aforementioned 5% or 3%, but is not limited thereto. The specific value of the second threshold is not limited in the embodiments of this application.

[0083] It is understandable that the output of a single-stage dual active bridge DC-AC converter can be connected to the power grid through a filter and a relay. It can be assumed that the output voltage of the dual active bridge DC-AC converter is approximately equal to the grid voltage. Therefore, by judging whether the absolute value of the output voltage of the dual active bridge DC-AC converter decreases from greater than the second threshold to less than the second threshold, it can be determined that the current grid voltage is within the preset range of the zero-crossing point.

[0084] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0085] In some embodiments of this application, adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter includes: decreasing the duty cycle of the outer phase shift angle when the ratio is less than zero and the absolute value of the ratio decreases to less than a first threshold; and increasing the duty cycle of the outer phase shift angle when the ratio is greater than zero and the absolute value of the ratio decreases to less than the first threshold.

[0086] In actual implementation, in order to minimize the RMS of the transformer current in the dual active bridge DC-AC converter during both the positive and negative half-waves of the grid voltage, the external phase shift duty cycle Dφ of the dual active bridge DC-AC converter must be greater than 0.5 when the ratio k of the input voltage to the output voltage of the dual active bridge DC-AC converter is less than zero (i.e., the output voltage and the grid voltage are negative).

[0087] In some embodiments, when the ratio k of the input voltage to the output voltage of the dual active bridge DC-AC converter is less than zero and its absolute value decreases from greater than a first threshold to less than a first threshold, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter can be reduced to achieve a duty cycle Dφ of 0.5 when the grid voltage crosses zero.

[0088] In some embodiments, when the ratio k of the input voltage to the output voltage of the dual active bridge DC-AC converter is greater than zero and its absolute value decreases from greater than a first threshold to less than a first threshold, the duty cycle Dφ of the external phase shift angle of the dual active bridge DC-AC converter can be increased to achieve a duty cycle Dφ of 0.5 when the grid voltage crosses zero.

[0089] According to the control method of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0090] The control method for a dual active bridge DC-AC converter provided in this application embodiment can be executed by a control device for the dual active bridge DC-AC converter. This application embodiment uses the control device of the dual active bridge DC-AC converter executing the control method as an example to illustrate the control device for the dual active bridge DC-AC converter provided in this application embodiment.

[0091] This application also provides a control device for a dual active bridge DC-AC converter. The DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm of the dual active bridge DC-AC converter is either a full bridge or a half bridge. For example... Figure 13 As shown, the control device of the dual active bridge DC-AC converter includes: a judgment module 1310 and a control module 1320.

[0092] The judgment module 1310 is used to determine whether the current grid voltage is within the preset range of zero crossing points; The control module 1320 is used to adjust the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter when the grid voltage is within a preset range, so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

[0093] According to the control device of the dual active bridge DC-AC converter provided in the embodiments of this application, by adjusting the duty cycle of the outer phase angle of the single-stage dual active bridge DC-AC converter when the current grid voltage is within a preset range of zero crossing, so that the duty cycle of the outer phase angle is 0.5 when the grid voltage crosses zero, it can reduce the jitter of output current or output voltage when the dual active bridge DC-AC converter outputs reactive power (including outputting reactive power alone or reactive power mixed with active power) and the grid voltage crosses zero for commutation, while ensuring that the root mean square of the transformer current is as small as possible in both the positive and negative half-waves of the grid voltage. This can improve the power quality of the output of the dual active bridge DC-AC converter and reduce electromagnetic interference.

[0094] In some embodiments, the control module 1320 may be specifically used to adjust the duty cycle of the outward phase shift to 0.5 and maintain it until the grid voltage crosses zero or the grid voltage exceeds a preset range.

[0095] In some embodiments, the control module 1320 may include: The first determining unit is used to determine the target value corresponding to the current value of the external phase shift duty cycle, with the point of symmetry when the grid voltage crosses zero and the external phase shift duty cycle is 0.5. The control unit is used to gradually adjust the duty cycle of the outward phase angle from the current value to the target value based on the target adjustment strategy.

[0096] In some embodiments, the target adjustment strategy includes at least one of a linear adjustment strategy and a nonlinear adjustment strategy.

[0097] In some embodiments, the control module 1320 can also be used to adjust at least one of the following during the process of adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero: based on the deviation between the output current of the dual active bridge DC-AC converter and the output current reference, so that the output current follows the output current reference.

[0098] In some embodiments, the determining module 1310 may include: The first acquisition unit is used to acquire the input voltage and output voltage of the dual active bridge DC-AC converter; The second determining unit is used to determine that the current grid voltage is within a preset range when the absolute value of the ratio of the output voltage to the input voltage decreases to less than a first threshold.

[0099] In some embodiments, the determining module 1310 may include: The second acquisition unit is used to acquire the output voltage of the dual active bridge DC-AC converter; The third determining unit is used to determine that the current grid voltage is within a preset range when the absolute value of the output voltage decreases to less than the second threshold.

[0100] In some embodiments, the control module 1320 may be specifically used for: When the ratio is less than zero and the absolute value of the ratio decreases to less than the first threshold, reduce the duty cycle of the outward phase angle. If the ratio is greater than zero and the absolute value of the ratio decreases to less than the first threshold, increase the duty cycle of the outward phase angle.

[0101] The control device for the dual active bridge DC-AC converter in this application embodiment can be an electronic device or a component within an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal or other devices besides a terminal. For example, the electronic device can be a mobile phone, tablet computer, laptop computer, PDA, in-vehicle electronic device, mobile internet device (MID), augmented reality (AR) / virtual reality (VR) device, robot, wearable device, ultra-mobile personal computer (UMPC), netbook, or personal digital assistant (PDA), etc. It can also be a server, network attached storage (NAS), personal computer (PC), television (TV), ATM, or self-service machine, etc. This application embodiment does not specifically limit the specific implementation.

[0102] The control device for the dual active bridge DC-AC converter in this embodiment can be a device with an operating system. This operating system can be Microsoft Windows, Android, iOS, or other possible operating systems; this embodiment does not specifically limit the specific operating system used.

[0103] The control device for the dual active bridge DC-AC converter provided in this application embodiment can achieve... Figures 1 to 12 The various processes implemented in the method implementation examples will not be described again here to avoid repetition.

[0104] In some embodiments, such as Figure 14 As shown, this application embodiment also provides an electronic device 1400, including a processor 1401, a memory 1402, and a computer program stored in the memory 1402 and executable on the processor 1401. When the computer program is executed by the processor 1401, it implements the various processes of the control method embodiment of the dual active bridge DC-AC converter described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0105] It should be noted that the electronic devices in the embodiments of this application include the mobile electronic devices and non-mobile electronic devices described above.

[0106] This application also provides a non-volatile computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the control method embodiment of the dual active bridge DC-AC converter described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0107] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0108] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the control method for the dual active bridge DC-AC converter described above.

[0109] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0110] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the control method embodiment of the dual active bridge DC-AC converter described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0111] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0112] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0113] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0114] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0115] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "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 this application. 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.

[0116] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A control method for a dual active bridge DC-AC converter, characterized in that, The DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm of the dual active bridge DC-AC converter is either a full bridge or a half bridge; the control method includes: Determine whether the current grid voltage is within the preset range of zero crossings; When the current grid voltage is within the preset range, the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter is adjusted so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

2. The control method for the dual active bridge DC-AC converter according to claim 1, characterized in that, Adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: The duty cycle of the outward phase shift is adjusted to 0.5 and maintained until the grid voltage crosses zero or exceeds the preset range.

3. The control method for the dual active bridge DC-AC converter according to claim 1, characterized in that, Adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero includes: Using the point where the duty cycle of the outward phase shift angle is 0.5 when the grid voltage crosses zero as a symmetrical point, determine the target value corresponding to the current value of the duty cycle of the outward phase shift angle; Based on the target adjustment strategy, the duty cycle of the outward phase angle is gradually adjusted from the current value to the target value.

4. The control method for the dual active bridge DC-AC converter according to claim 3, characterized in that, The target adjustment strategy includes at least one of a linear adjustment strategy and a nonlinear adjustment strategy.

5. The control method for the dual active bridge DC-AC converter according to claim 1, characterized in that, The method further includes: During the process of adjusting the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero, based on the deviation between the output current of the dual active bridge DC-AC converter and the output current reference, at least one of the following is adjusted: the inner phase shift angle of the DC side bridge arm, the inner phase shift angle of the AC side bridge arm, the frequency of the drive signal of the DC side bridge arm, and the frequency of the drive signal of the AC side bridge arm, so that the output current follows the output current reference.

6. The control method for a dual active bridge DC-AC converter according to any one of claims 1 to 5, characterized in that, The determination of whether the current grid voltage is within the preset range of zero crossing points includes: Obtain the input voltage and output voltage of the dual active bridge DC-AC converter; If the absolute value of the ratio of the output voltage to the input voltage decreases to less than a first threshold, the current grid voltage is determined to be within the preset range.

7. The control method for a dual active bridge DC-AC converter according to any one of claims 1 to 5, characterized in that, The determination of whether the current grid voltage is within the preset range of zero crossing points includes: Obtain the output voltage of the dual active bridge DC-AC converter; If the absolute value of the output voltage decreases to less than the second threshold, the current grid voltage is determined to be within the preset range.

8. The control method for the dual active bridge DC-AC converter according to claim 6, characterized in that, The adjustment of the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter includes: If the ratio is less than zero and the absolute value of the ratio decreases to less than the first threshold, reduce the duty cycle of the outward phase angle; If the ratio is greater than zero and the absolute value of the ratio decreases to less than the first threshold, the duty cycle of the outward phase angle is increased.

9. A control device for a dual active bridge DC-AC converter, characterized in that, The DC-side bridge arm of the dual active bridge DC-AC converter is a full bridge; the AC-side bridge arm of the dual active bridge DC-AC converter is either a full bridge or a half bridge; the control device includes: The judgment module is used to determine whether the current grid voltage is within the preset range of zero crossing points; The control module is used to adjust the duty cycle of the outer phase shift angle of the dual active bridge DC-AC converter when the grid voltage is within the preset range, so that the duty cycle of the outer phase shift angle is 0.5 when the grid voltage crosses zero.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the control method for the dual active bridge DC-AC converter as described in any one of claims 1-8.

Images