Circuit control method, dual active bridge inverter and power system
By cross-loading the internal phase shift angle in the DAB circuit, positive and negative bias current components are generated, which solves the bias saturation problem of the transformer under extreme working conditions and improves the stability and durability of the circuit.
Patent Information
- Application Number
- CN202411218500.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2024-03-15
- Filing Date
- 2024-08-30
- Publication Date
- 2025-09-16
AI Technical Summary
The DAB circuit is prone to transformer saturation damage under extreme operating conditions such as sudden load changes and input and output voltage changes.
By cross-loading the internal phase shift angle, the internal phase shift angle of the primary active bridge is adjusted respectively at the rising and falling edges of the secondary voltage of the transformer, generating bias current components in the positive and negative directions, thereby suppressing the accumulation of bias current components in a single direction.
The transformer magnetic saturation phenomenon is reduced, and the stability and durability of the circuit under extreme working conditions are improved.
Smart Images
Figure CN120658124A_ABST
Abstract
Description
[0001] CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This application is based on the Chinese patent application with application number: 2024103032614 and application date of March 15, 2024, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby introduced into this application as a reference. Technical Field
[0003] The present application belongs to the field of electronic power technology, and in particular relates to a circuit control method, a dual active bridge inverter, and a power system. Background Art
[0004] A dual active bridge (DAB) consists of two active bridges and a transformer connected between them. It features a small number of switching devices, a wide soft switching range, and bidirectional power transmission. A common DAB modulation method is extended phase-shift control, which has two degrees of freedom: the inner and outer phase-shift angles. By adjusting the inner and outer phase-shift angles in real time, the duty cycle of the primary voltage and the phase of the primary-secondary voltage can be controlled, thereby achieving a given power transmission and voltage gain control. However, DAB circuits are prone to damage when operating under extreme conditions such as sudden load changes and input and output voltage variations. Summary of the Invention
[0005] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a circuit control method, a dual-active bridge inverter, and a power system that generates positive and negative bias current components by cross-loading internal phase shift angles. This suppresses the accumulation of bias current components in a single direction, reduces transformer bias saturation, and is less susceptible to damage under extreme operating conditions.
[0006] In a first aspect, the present application provides a circuit control method, the circuit control method comprising:
[0007] determining a target internal phase shift angle of a primary active bridge of a dual active bridge circuit, the dual active bridge circuit further comprising a transformer electrically connected to the primary active bridge;
[0008] When the secondary voltage of the transformer is at a rising edge or a falling edge, the internal phase shift angle of the primary active bridge is adjusted to a target internal phase shift angle;
[0009] In the control process of the primary active bridge, the inner phase shift angle is adjusted at least once when the secondary voltage is at a rising edge, and the inner phase shift angle is adjusted at least once when the secondary voltage is at a falling edge.
[0010] According to the circuit control method of the present application, when adjusting the internal phase shift angle of the primary active bridge, the internal phase shift angle is loaded at the rising edge and falling edge of the secondary voltage of the transformer, respectively, so that the transformer generates a positive direction bias current component and a negative direction bias current component, suppressing the accumulation of bias current components in a single direction, improving the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation, and not easily damaged under extreme working conditions.
[0011] According to one embodiment of the present application, in two adjacent control cycles of the primary active bridge, the adjustment moment of the internal phase shift angle in one control cycle corresponds to the rising edge of the secondary voltage, and the adjustment moment of the internal phase shift angle in the other control cycle corresponds to the falling edge of the secondary voltage.
[0012] According to the control method of this embodiment, in adjacent control cycles, the bias current is not easily accumulated rapidly in one direction due to continuous loading through the cross-loading internal phase shift angle based on the rising edge or falling edge of the secondary voltage of the transformer, thereby reducing the bias saturation of the transformer.
[0013] According to one embodiment of the present application, when the secondary voltage of the transformer is at a rising edge or a falling edge, adjusting the internal phase shift angle of the primary active bridge to a target internal phase shift angle includes:
[0014] Obtaining a historical edge state of the secondary voltage of the transformer corresponding to the internal phase shift angle adjustment history of the primary active bridge;
[0015] Determine the current edge state based on the historical edge state;
[0016] When the secondary side voltage of the transformer is in a current edge state, the internal phase shift angle of the primary side active bridge is adjusted to a target internal phase shift angle.
[0017] According to one embodiment of the present application, determining a current edge state based on a historical edge state includes:
[0018] An edge state opposite to an edge state corresponding to a previous internal phase shift angle adjustment of the primary active bridge is determined as a current edge state, and the edge state is a rising edge or a falling edge.
[0019] According to one embodiment of the present application, determining the current edge state according to the historical edge state includes:
[0020] The edge state corresponding to the previous internal phase angle adjustment of the primary active bridge is used as the reference edge state, and the historical adjustment amount corresponding to the internal phase angle adjustment of the primary active bridge in the reference edge state is determined;
[0021] The current edge state is determined according to the current adjustment amount, the historical adjustment amount and the reference edge state corresponding to the target internal phase shift angle. The edge state includes a rising edge or a falling edge.
[0022] According to one embodiment of the present application, determining a current edge state according to a current adjustment amount, a historical adjustment amount, and a reference edge state corresponding to a target internal phase shift angle includes:
[0023] When the sum of the current adjustment amount and the historical adjustment amount corresponding to the target internal phase shift angle is greater than or equal to a threshold, determining the edge state opposite to the reference edge state as the current edge state;
[0024] When the sum of the current adjustment amount corresponding to the target internal phase shift angle and the historical adjustment amount is less than a threshold, the edge state that is the same as the reference edge state is determined as the current edge state.
[0025] In a second aspect, the present application provides a circuit control method, the circuit control method comprising:
[0026] determining a target internal phase shift angle of a primary active bridge of a dual active bridge circuit, the dual active bridge circuit further comprising a transformer electrically connected to the primary active bridge and a secondary active bridge;
[0027] When the driving signal of the upper bridge arm of the secondary active bridge is at a rising edge or a falling edge, the phase difference between the driving signals of the left and right bridge arms of the primary active bridge is adjusted to adjust the internal phase shift angle of the primary active bridge to a target internal phase shift angle;
[0028] In the control process of the primary active bridge, the inner phase shift angle is adjusted at least once when the driving signal is at a rising edge, and the inner phase shift angle is adjusted at least once when the driving signal is at a falling edge.
[0029] According to the control method of this embodiment, in adjacent control cycles, the bias current is not easily accumulated rapidly in one direction due to continuous loading based on the rising edge or falling edge of the driving signal that drives the upper bridge arm, and is not easily damaged under extreme working conditions.
[0030] According to one embodiment of the present application, the upper bridge arm includes a positive switch tube and a negative switch tube connected to each other, the positive switch tube conducts in a direction from the transformer to the grid, and the negative switch tube conducts in a direction from the grid to the transformer;
[0031] When the driving signal of the upper bridge arm is at the rising edge or falling edge, the internal phase shift angle of the primary active bridge is adjusted to the target internal phase shift angle, including:
[0032] When the voltage of the grid is in the positive half cycle, when it is detected that the forward switch tube switches from the open state to the closed state or from the closed state to the open state, the internal phase shift angle of the primary active bridge is adjusted to the target internal phase shift angle;
[0033] When the voltage of the grid is in the negative half cycle, when it is detected that the negative switch tube switches from the open state to the closed state or from the closed state to the open state, the internal phase shift angle of the primary active bridge is adjusted to the target internal phase shift angle.
[0034] In a third aspect, the present application provides a circuit control method, the circuit control method comprising:
[0035] When the bias current component of the inductor of the dual active bridge circuit is greater than or equal to a reference value, determining the accumulation direction of the bias current component, the dual active bridge circuit further comprising a primary active bridge connected to the inductor and a transformer, the transformer being electrically connected to the secondary active bridge;
[0036] Adjust the timing of the internal phase angle adjustment of the primary active bridge so that the bias current component of the inductor accumulates in the direction opposite to the accumulation direction;
[0037] Among them, the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the secondary voltage of the transformer is at the rising edge and the moment when it is at the falling edge; or the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the driving signal of the upper bridge arm of the secondary active bridge is at the rising edge and the moment when it is at the falling edge.
[0038] According to the control method of this embodiment, the internal phase shift angle is adjusted according to the bias current component of the inductor, which can reduce the accumulation of the bias current component in one direction, thereby reducing the bias saturation of the transformer.
[0039] According to one embodiment of the present application, the time when the primary active bridge performs internal phase shift angle adjustment includes the time when the secondary voltage of the transformer is at the rising edge and the falling edge, or the time when the driving signal of the upper bridge arm is at the rising edge or the falling edge.
[0040] In a fourth aspect, the present application provides a dual active bridge inverter, which includes a controller and a dual active bridge circuit. The controller is electrically connected to the dual active bridge circuit and is configured to execute the control method described above.
[0041] According to the dual active bridge inverter of the present application, the internal phase shift angle of the load generates a positive direction bias current component and a negative direction bias current component, which suppresses the accumulation of the bias current component in a single direction, improves the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation, and is not easily damaged under extreme working conditions.
[0042] According to one embodiment of the present application, a dual active bridge circuit includes a primary active bridge, a first inductor, a transformer and a secondary active bridge electrically connected in sequence, wherein the primary active bridge is a full bridge and the secondary active bridge is a half bridge.
[0043] In a fifth aspect, the present application provides a power system, which includes the dual active bridge inverter according to the aforementioned method.
[0044] According to the power system of the present application, the internal phase shift angle of the load generates a positive direction bias current component and a negative direction bias current component, which suppresses the accumulation of the bias current component in a single direction, improves the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation, and can operate stably under extreme working conditions.
[0045] According to one embodiment of the present application, the input side of the dual active bridge inverter is electrically connected to the power supply assembly, and the output side of the dual active bridge inverter is electrically connected to the AC power grid.
[0046] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0047] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0048] Figure 1 is a circuit block diagram of a dual active bridge circuit provided in an embodiment of the present application;
[0049] Figure 2 1 is a schematic structural diagram of a dual active bridge inverter provided in an embodiment of the present application;
[0050] Figure 3 : is a driving waveform diagram of the extended phase shift control provided in an embodiment of the present application;
[0051] Figure 4 This is one of the flow charts of the circuit control method provided in the embodiment of the present application;
[0052] Figure 5 This is a schematic diagram of the inner phase shift angle loading and bias current change provided by the embodiment of the present application;
[0053] Figure 6 This is the second flow chart of the circuit control method provided in the embodiment of the present application;
[0054] Figure 7 This is the third flow chart of the circuit control method provided in the embodiment of the present application;
[0055] Figure 8 This is the fourth flow chart of the circuit control method provided in the embodiment of the present application;
[0056] Figure 9 This is a circuit block diagram of a dual active bridge inverter provided in an embodiment of the present application.
[0057] Reference numerals:
[0058] The primary side active bridge 100, the secondary side active bridge 200, the controller 300, the first to eighth switching transistors S1-S8, the first to second inductors L1-L2, and the first to third capacitors C1-C3. DETAILED DESCRIPTION
[0059] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.
[0060] In the following description, a "circuit" refers to a conductive loop consisting of at least one element or subcircuit connected electrically or electromagnetically. When an element or circuit is said to be "coupled to" or "connected to" another element, or when an element / circuit is said to be "coupled to" or "connected between" two nodes, it can be directly coupled or connected to the other element or there can be intervening elements. The connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there are no intervening elements between the two elements.
[0061] In the description, the terms "first," "second," etc. are used to distinguish similar objects, not to describe a particular order or precedence. It should be understood that the numerical descriptors used in this manner are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than that illustrated or described herein, and that the objects distinguished by "first," "second," etc. are generally of a class and do not limit the number of objects; for example, the first object can be one or more. In addition, the term "and / or" in the specification and claims refers to at least one of the connected objects, and the character " / " generally indicates that the objects connected are in an "or" relationship.
[0062] In addition, descriptions with reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.
[0063] In extended phase-shift control (DAB), the increase (or decrease) in the internal phase-shift angle causes the transformer's excitation current to change on the positive (negative) half-axis compared to the previous switching cycle. Because the transformer's excitation current is asymmetrical and cannot be reset, magnetic bias is generated and accumulates. This can lead to transformer saturation under sudden load changes, input / output voltage fluctuations, and related extreme operating conditions, damaging the power circuit.
[0064] One embodiment of the present application provides a dual-active bridge inverter, comprising a controller and a dual-active bridge circuit, wherein the controller is electrically connected to the dual-active bridge circuit. The controller is configured to execute a control method to drive the dual-active bridge circuit using extended phase-shift control, and to apply an inner phase-shift angle at the rising and falling edges of the secondary voltage of the transformer, thereby causing the transformer to generate a positive bias current component and a negative bias current component, thereby suppressing the accumulation of bias current components in a single direction and improving the transformer bias saturation phenomenon caused by single-edge applied phase-shift angle modulation.
[0065] Reference Figure 1 , Figure 1 A circuit block diagram of a dual active bridge circuit is shown. The dual active bridge circuit includes a primary active bridge 100, a transformer T, and a secondary active bridge 200, which are electrically connected in sequence. The primary active bridge 100 can be connected to a DC power source, converting DC power to AC power and providing it to the primary side of the transformer T. The secondary active bridge 200 can convert AC power from the secondary side of the transformer T to DC power and provide it to the back-end circuit.
[0066] Reference Figure 2 , Figure 2 The circuit diagram of a dual-active-bridge micro-inverter is shown. As an example, the dual-active-bridge circuit includes a primary active bridge 100, a first inductor L1, a transformer T, and a secondary active bridge 200 electrically connected in sequence. The primary active bridge 100 is a full bridge, and the secondary active bridge 200 is a half bridge.
[0067] The primary active bridge 100 includes a first switch S1, a second switch S2, a third switch S3 and a fourth switch S4, and the secondary active bridge 200 includes a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first capacitor C1 and a second capacitor C2.
[0068] The first electrode of the first switching transistor S1 is electrically connected to the first electrode of the third switching transistor S3, and is also connected to a first power line. The second electrode of the first switching transistor S1 is electrically connected to the first electrode of the second switching transistor S2, and the connection point is electrically connected to the first end of the first inductor L1. The second end of the first inductor L1 is electrically connected to the first end of the primary winding of the transformer T. The second electrode of the third switching transistor S3 is electrically connected to the first electrode of the fourth switching transistor S4, and the connection point is electrically connected to the second end of the primary winding of the transformer T. The second electrode of the second switching transistor S2 is electrically connected to the second electrode of the fourth switching transistor S4, and is also connected to a second power line. The first and second power lines are used to input or output power.
[0069] The first electrode of the fifth switching transistor S5 is electrically connected to the first end of the first capacitor C1 and is also connected to the third power line. The second electrode of the fifth switching transistor S5 is electrically connected to the second electrode of the sixth switching transistor S6. The first electrode of the sixth switching transistor S6 and the first electrode of the seventh switching transistor S7 are both electrically connected to the first end of the secondary winding of the transformer T. The second electrode of the seventh switching transistor S7 is electrically connected to the second electrode of the eighth switching transistor S8. The first electrode of the eighth switching transistor S8 is electrically connected to the first end of the second capacitor and is also connected to the fourth power line. The second end of the first capacitor C1 is connected to the second end of the second capacitor C2, and the connection point is electrically connected to the second end of the secondary winding of the transformer T. The third and fourth power lines are used to receive or output power. If used for outputting power, a second inductor L2 can be provided on the third power line, and third capacitors C3 can be provided on the third and fourth power lines to maintain output stability.
[0070] Each switch tube can be a MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) tube or an IGBT (Insulated-Gate Bipolar Transistor) tube. When the switch tube is a MOS tube, the first and second electrodes are drain electrodes or source electrodes, and the gate electrode is electrically connected to the controller. When the switch tube is an IGBT, the first and second electrodes are collector electrodes or emitter electrodes, and the gate electrode is electrically connected to the controller.
[0071] Reference Figure 3 , Figure 3 The driving waveform of an extended phase shift control is shown in FIG. The driving signal of each switch tube when the grid voltage is in the positive half cycle is as follows: Figure 3As shown in Figure 1, the first and second switches S1 and S2 are alternately turned on, the third and fourth switches S3 and S4 are alternately turned on, the fifth and seventh switches S5 and S7 are alternately turned on, and the sixth and eighth switches S6 and S8 are continuously turned on. Up represents the primary voltage of transformer T. When the first and fourth switches S1 and S4 are turned on, the Up voltage is positive. When the second and fourth switches S2 and S4 are turned on, the Up voltage is negative. Both amplitudes are equal to the power supply voltage. Us represents the secondary voltage of transformer T. When the fifth switch S5 is turned on, the Us voltage is positive. When the seventh switch S7 is turned on, the Us voltage is negative. Its amplitude is equal to the product of Up and the transformer turns ratio. Is represents the current of the first inductor L1. During the conduction period of the first switch S1, Is shows an upward trend, and presents different slopes during the conduction periods of the third switch S3, the fourth switch S4, and the fifth switch S5. During the conduction period of the second switch S2, Is shows a downward trend, and presents different slopes during the conduction periods of the fourth switch S4, the third switch S3, and the seventh switch S7.
[0072] The commonly used modulation method of the dual active bridge inverter is extended phase shift control, which has two control degrees of freedom, namely the inner phase shift angle D1 and the outer phase shift angle D2. Among them, the inner phase shift angle D1 is usually defined as the angle between the negative rising edge of the primary square wave voltage and the positive rising edge of the primary square wave voltage; Figure 3 The signal phase difference between the turn-off time of the third switch S3 and the turn-off time of the first switch S1 (t1 ~ Ts / 2). The external phase shift angle D2 is usually defined as the angle between the primary voltage of the transformer and the secondary voltage of the transformer; Figure 3 The signal phase difference between the turn-off time of the third switch S3 and the turn-off time of the seventh switch S7 (t1-t2). By adjusting D1 and D2 in real time, the duty cycle of the primary voltage Up and the phase of the primary-secondary voltage Up and Us can be controlled, thereby achieving a given power transmission and voltage gain control.
[0073] In order to more clearly illustrate the circuit control method proposed in this application, the above-mentioned dual active bridge inverter is taken as an example for explanation below.
[0074] Reference Figure 4 , Figure 4 A schematic flow chart of a circuit control method is shown. An embodiment of the present application provides a circuit control method.
[0075] In this embodiment, the circuit control method includes step 10 and step 20 .
[0076] Step 10: determining a target internal phase shift angle of the primary active bridge 100 of the dual active bridge circuit;
[0077] Step 20: When the secondary voltage of the transformer is on a rising edge or a falling edge, adjust the internal phase shift angle of the primary active bridge 100 to a target internal phase shift angle; wherein, during the control process of the primary active bridge 100, the internal phase shift angle is adjusted at least once when the secondary voltage is on a rising edge, and the internal phase shift angle is adjusted at least once when the secondary voltage is on a falling edge.
[0078] The circuit control method proposed in this embodiment is executed by the controller in the dual active bridge inverter described above. Of course, it can also be other devices with similar functions, which will not be described in detail in this embodiment.
[0079] It should be noted that during the control process of the dual active bridge circuit, the internal phase shift angle of the primary active bridge 100 needs to be adjusted multiple times based on the actual operation of the dual active bridge circuit. Of course, the external phase shift angle between the primary active bridge 100 and the secondary active bridge 200 can also be adjusted. Each internal phase shift angle adjustment is considered as a control cycle, and the control process of the dual active bridge circuit will go through multiple control cycles.
[0080] The target internal phase shift angle refers to the internal phase shift angle value that the primary active bridge 100 needs to achieve in each control cycle. If the target internal phase shift angle is different from the internal phase shift angle in the previous control cycle, the internal phase shift angle value of the primary active bridge 100 needs to be adjusted. Among them, the internal phase shift angle value that the primary active bridge 100 needs to achieve in each control cycle can be determined by calculating the actual operating parameters of the dual active bridge circuit according to the set control strategy. For example, based on the actual power of the dual active bridge circuit, the power is kept above the target value by adjusting the internal phase shift angle; or, based on the minimum stress current of the dual active bridge circuit, the power is kept below the target value by adjusting the internal phase shift angle.
[0081] It should be noted that adjusting the internal phase shift angle of the primary active bridge 100 to the target internal phase shift angle when the secondary voltage of the transformer T is at a rising or falling edge specifically refers to adjusting the duty cycle of the drive signal of the primary active bridge 100 corresponding to the rising or falling edge when the secondary voltage of the transformer T is at a rising or falling edge to adjust the internal phase shift angle. In the related art, the state of the secondary voltage corresponding to the internal phase shift angle is fixed (e.g., fixed at the rising edge of the secondary voltage).
[0082] Continue to refer to Figure 3, the inner phase shift angle can be expressed as the phase difference between the falling edge of the turn-on signal of the first switch tube S1 and the falling edge of the turn-on signal of the third switch tube S3. The inner phase shift angle is adjusted by extending or shortening the duty cycle of the turn-on signal of the first switch tube S1. Taking the rising edge as an example, the corresponding drive signal is the turn-on signal of the first switch tube S1; taking the falling edge as an example, the corresponding drive signal is the turn-on signal of the third switch tube S3. The adjustment range of the inner phase shift angle is usually 0~0.5 (0~90°). The specific adjustment value of each inner phase shift angle adjustment can be set according to needs. Optionally, a smaller step size can be used to adjust the inner phase shift angle, thereby reducing the sudden change of current and voltage in the dual active bridge circuit, and further weakening the abnormal operation of the inverter caused by the sudden change.
[0083] It can be understood that the increase (or decrease) in the internal phase shift angle will cause the transformer T to generate a change in the excitation current on the positive (negative) half-axis compared to the previous switching cycle. By adjusting the internal phase shift angle in different directions, the excitation current changes in different directions can be generated. The excitation current changes in different directions offset each other, thereby reducing the accumulation of bias magnetism.
[0084] Reference Figure 5 , Figure 5 A schematic diagram of internal phase shift angle loading and bias current change is shown. Up represents the primary voltage of transformer T, Us represents the primary voltage of transformer T, i Lm Indicates the bias current of the first inductor L1. In the second control cycle, the rising edge of the secondary voltage of the transformer T is loaded with an internal phase shift angle. At this time, the bias current i Lm The amplitude of the positive half axis is larger than that of the previous cycle, that is, the bias current accumulates. In the third control cycle, the falling edge of the secondary voltage of the transformer T is loaded with the internal phase shift angle. At this time, the bias current i Lm The amplitude of the negative half-axis is larger than that of the previous cycle, indicating a bias current accumulation, but the amplitude of the positive half-axis remains unchanged, reducing the accumulation of bias current in one direction. Inner phase angle loading refers to performing an inner phase angle adjustment.
[0085] According to the circuit control method of the present application, extended phase shift control is adopted for driving, and the internal phase shift angle is loaded at the rising edge and falling edge of the secondary voltage of the transformer T, respectively, so that the transformer T generates a positive direction bias current component and a negative direction bias current component, suppressing the accumulation of the bias current component in a single direction, improving the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation, and is not easily damaged under extreme working conditions.
[0086] In some embodiments, at least one second control cycle is included between two adjacent first control cycles, or at least one first control cycle is included between two adjacent second control cycles.
[0087] It is understandable that transformer bias saturation is likely to occur when the same-direction bias current component accumulates more. Therefore, by interleaving the first control cycle and the second control cycle, the accumulation of bias current in one direction can be reduced to prevent transformer bias saturation.
[0088] As an example, in five consecutive control cycles, the first, second, fourth, and fifth control cycles may be the first control cycle, and the third control cycle may be the second control cycle. Alternatively, in five consecutive control cycles, the first, second, fourth, and fifth control cycles may be the second control cycle, and the third control cycle may be the first control cycle.
[0089] In some embodiments, in two adjacent control cycles of the primary active bridge 100, the adjustment moment of the internal phase shift angle in one control cycle corresponds to the rising edge of the secondary voltage, and the adjustment moment of the internal phase shift angle in the other control cycle corresponds to the falling edge of the secondary voltage.
[0090] In this embodiment, if the internal phase-shift angle is applied at the rising edge of the transformer's secondary voltage in one control cycle, then the internal phase-shift angle is applied at the falling edge of the transformer's secondary voltage in the next control cycle. Alternatively, if the internal phase-shift angle is applied at the falling edge of the transformer's secondary voltage in one control cycle, then the internal phase-shift angle is applied at the rising edge of the transformer's secondary voltage in the next control cycle. Thus, by cross-applying the internal phase-shift angle based on the rising or falling edges of the transformer's secondary voltage in adjacent control cycles, the bias current is less likely to accumulate rapidly in one direction due to continuous application, thereby reducing transformer bias saturation.
[0091] Reference Figure 6 In some embodiments, the specific process of step 20 may include step 210, step 220 and step 230.
[0092] Step 210: Obtain the historical edge state of the secondary voltage of the transformer corresponding to the internal phase shift angle adjustment history of the primary active bridge 100;
[0093] Step 220: Determine the current edge state based on the historical edge state;
[0094] Step 230 : When the secondary voltage of the transformer is in the current edge state, adjust the internal phase shift angle of the primary active bridge 100 to the target internal phase shift angle.
[0095] In this embodiment, when the controller loads the internal phase shift angle in each control cycle, it can determine the accumulated bias current of the transformer based on the internal phase shift angle adjustment information in the historical control cycle, thereby determining the loading position of the internal phase shift angle in the current control cycle, and better reducing the bias saturation of the transformer.
[0096] In some embodiments, determining the current edge state based on the historical edge state may include: determining the edge state opposite to the edge state corresponding to the last internal phase angle adjustment of the primary active bridge 100 as the current edge state, where the edge state is a rising edge or a falling edge.
[0097] As an example, in the previous control cycle, if the inner phase angle adjustment corresponds to the rising edge of the secondary voltage, then in the current control cycle, the current edge state is the falling edge; if the inner phase angle adjustment corresponds to the falling edge of the secondary voltage, then in the current control cycle, the current edge state is the rising edge.
[0098] In other embodiments, the controller may further determine the loading position of the inner phase angle in the current controller cycle based on the adjustment amount of the inner phase angle in the historical control cycle and the adjustment amount of the inner phase angle in the current controller cycle, where the adjustment amount refers to the change in the inner phase angle.
[0099] The greater the adjustment of the inner phase angle, the greater the accumulation of the inductor's bias current component. Therefore, based on the historical adjustment of the inner phase angle within previous control cycles and the current adjustment of the inner phase angle within the current controller cycle, the degree of accumulation of the bias current component after the current inner phase angle adjustment can be estimated, and the corresponding edge state can be determined based on the degree of accumulation. Therefore, different edge states can be used to adjust the inner phase angle, causing the generated bias current components to accumulate in different directions, thereby reducing the accumulation of bias current components.
[0100] When determining the historical adjustment amount, the edge state corresponding to the previous internal phase angle adjustment of the primary active bridge is used as a reference edge state, and the historical adjustment amount corresponding to the internal phase angle adjustment performed by the primary active bridge in the reference edge state is determined. For example, if the edge state corresponding to the previous internal phase angle adjustment of the primary active bridge was a rising edge, the sum of the adjustment amounts of a target number of control cycles in which the internal phase angle adjustment was performed on the rising edge in the historical control cycles is used as the historical adjustment amount. The target number can be set as required.
[0101] As an example, if the sum of the historical adjustment values of the internal phase-shift angle within the historical control cycles and the current adjustment value of the internal phase-shift angle within the current controller cycle is greater than or equal to a threshold value, the edge state corresponding to the internal phase-shift angle within the current control cycle is controlled to be opposite to the edge state corresponding to the internal phase-shift angle within the previous control cycle. Alternatively, if the sum of the historical adjustment values of the internal phase-shift angle within the historical control cycles and the current adjustment value of the internal phase-shift angle within the current controller cycle is less than a threshold value, the edge state corresponding to the internal phase-shift angle within the current control cycle is controlled to be the same as the edge state corresponding to the internal phase-shift angle within the previous control cycle.
[0102] Reference Figure 7 , Figure 7 A flow chart of a circuit control method is shown. One embodiment of the present application also provides a circuit control method applied to a dual-active bridge circuit. The structure of the dual-active bridge circuit can refer to the aforementioned embodiments. In this embodiment, the secondary active bridge 200 is connected to the power grid. The secondary active bridge 200 includes an upper bridge arm and a lower bridge arm. The circuit control method includes steps 30 and 40.
[0103] Step 30: determining a target internal phase shift angle of the primary active bridge 100 of the dual active bridge circuit;
[0104] Step 40: When the driving signal of the upper bridge arm of the secondary active bridge 200 is at a rising edge or a falling edge, adjust the phase difference between the driving signals of the left and right bridge arms of the primary active bridge 100 to adjust the internal phase shift angle of the primary active bridge 100 to a target internal phase shift angle;
[0105] In the control process of the primary active bridge, the inner phase shift angle is adjusted at least once when the driving signal is at a rising edge, and the inner phase shift angle is adjusted at least once when the driving signal is at a falling edge.
[0106] by Figure 2 Taking the dual active bridge inverter shown in the figure as an example, the upper bridge arm refers to the fifth switch S5 and the sixth switch S6, and the lower bridge arm refers to the seventh switch S7 and the eighth switch S8. During a control cycle, one of the fifth switch S5 and the sixth switch S6 remains normally open, while the other performs high-frequency switching. Similarly, during a control cycle, one of the seventh switch S7 and the eighth switch S8 remains normally open, while the other performs high-frequency switching.
[0107] The drive signal for driving the upper bridge arm refers to a signal that drives the fifth switch tube S5 or the sixth switch tube S6 to perform a switching action. The signal can be a PWM (Pulse Width Modulation) signal or other form of switch control signal, which is not specifically limited in the embodiments of the present application. During the process of the fifth switch tube S5 or the sixth switch tube S6 performing a switching action, the rising edge of the drive signal means that the switch tube switches from the off state to the on state, and the secondary voltage of the transformer begins to rise. The falling edge of the drive signal means that the switch tube switches from the on state to the off state, and the secondary voltage of the transformer begins to decrease.
[0108] Continue to refer to Figure 2 and Figure 3 The left arm of the primary active bridge 100 includes the first and second switching transistors S1 and S2, and the right arm of the primary active bridge 100 includes the third and fourth switching transistors S3 and S4. The drive signals for the left and right arms of the primary active bridge 100 can be the phase difference between the drive signal for the first and fourth switching transistors S1 and S4, or the phase difference between the drive signal for the second and third switching transistors S2 and S3.
[0109] According to the control method of this embodiment, in adjacent control cycles, the bias current is not easily accumulated rapidly in one direction due to continuous loading through the cross-loading internal phase shift angle based on the rising edge or falling edge of the driving signal that drives the upper bridge arm, thereby reducing the bias saturation of the transformer.
[0110] In some embodiments, the upper bridge arm includes a positive switching tube and a negative switching tube connected to each other. The positive switching tube conducts in a direction from the transformer to the grid, and the negative switching tube conducts in a direction from the grid to the transformer. The step of loading the internal phase shift angle at the rising edge or falling edge of the driving signal driving the upper bridge arm includes: when the voltage of the grid is in a positive half cycle, upon detecting that the positive switching tube switches from an open state to a closed state or from a closed state to an open state, adjusting the internal phase shift angle of the primary active bridge 100 to a target internal phase shift angle; when the voltage of the grid is in a negative half cycle, upon detecting that the forward switching tube switches from an open state to a closed state or from a closed state to an open state, adjusting the internal phase shift angle of the primary active bridge 100 to the target internal phase shift angle.
[0111] Among them, taking the case where the switch tube is turned on under the control of a high-level driving signal as an example, when the switch tube switches from the open state to the closed state, the driving signal of the switch tube is at the rising edge; when the switch tube switches from the closed state to the open state, the driving signal of the switch tube is at the falling edge.
[0112] by Figure 2Taking the dual active bridge inverter shown as an example, the positive switch tube refers to the fifth switch tube S5, and the negative switch tube refers to the sixth switch tube S6.
[0113] As an example, during the positive half-cycle of the grid voltage, the sixth and eighth switches S6 and S8 remain normally on, while the fifth and seventh switches S5 and S7 are complementary and conduct at high frequency. After the system starts and stabilizes, during the kth control cycle, the controller sets the internal phase shift angle D1 based on the rising (falling) edge of the drive signal for the fifth switch S5. During the k+1th control cycle, the controller sets the internal phase shift angle D1 based on the falling (rising) edge of the drive signal for the fifth switch S5, and so on.
[0114] During the negative half-cycle of the grid voltage, the fifth and seventh switches S5 and S7 remain normally on, while the sixth and eighth switches S6 and S8 conduct complementary high-frequency conduction. After the system stabilizes after startup, during the kth control cycle, the controller sets the internal phase shift angle D1 based on the rising (falling) edge of the drive signal for the sixth switch S6. During the k+1th control cycle, the controller sets the internal phase shift angle D1 based on the falling (rising) edge of the drive signal for the sixth switch S6, and so on.
[0115] Reference Figure 8 , Figure 8 1 shows a flow chart of a circuit control method. One embodiment of the present application further provides a circuit control method applied to a dual active bridge circuit. The structure of the dual active bridge circuit can refer to the aforementioned embodiments. In this embodiment, the circuit control method includes steps 50 and 60.
[0116] Step 50: When the bias current component of the inductor of the dual active bridge circuit is greater than or equal to a reference value, determining the accumulation direction of the bias current component;
[0117] Step 60: Adjust the timing of the primary active bridge performing internal phase angle adjustment so that the bias current component of the inductor accumulates in a direction opposite to the accumulation direction.
[0118] Among them, the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the secondary voltage of the transformer is at the rising edge and the moment when it is at the falling edge; or the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the driving signal of the upper bridge arm of the secondary active bridge is at the rising edge and the moment when it is at the falling edge.
[0119] There are many ways to measure the bias current component of the inductor of the dual active bridge circuit. For example, in one example, a current detection device can be provided in the primary active bridge 100. The current detection device is electrically connected to the first inductor L1 to detect the current of the first inductor L1. The controller is connected to the current detection device, receives its detection signal to obtain the current information of the first inductor L1, and determines the magnitude of the bias current component of the first inductor L1, that is, the accumulation direction, by analysis. For details, please refer to Figure 5 Of course, the bias current component measurement can also be achieved through other methods, which are not specifically limited in the embodiments of the present application.
[0120] In this embodiment, the bias current component of the inductor may refer to the bias current component of the first inductor L1. The accumulation direction of the bias current component includes a positive direction and a negative direction. If the accumulation direction is positive, the inner phase shift angle is adjusted at the falling edge of the secondary voltage of the transformer during the previous control cycle. If the accumulation direction is negative, the inner phase shift angle is adjusted at the rising edge of the secondary voltage of the transformer during the previous control cycle.
[0121] It is understood that when the bias current component of the first inductor L1 is greater than or equal to the reference value, continuing to accumulate the bias current component in the original accumulation direction may easily lead to bias saturation, thereby damaging the power circuit. Therefore, by adjusting the accumulation direction of the bias current component, the occurrence of bias saturation can be reduced.
[0122] Referring to the aforementioned embodiment, the direction of accumulation of the bias current component is affected by the loading time during the internal phase angle adjustment. This loading time refers to the time when the internal phase angle adjustment is performed. This is typically the time when the drive signal in the current control cycle changes from the drive signal in the previous control cycle.
[0123] In some embodiments, the time when the primary active bridge performs internal phase angle adjustment includes the time when the secondary voltage of the transformer is on the rising edge and the time when it is on the falling edge. When the internal phase angle is adjusted at the time when the secondary voltage of the transformer is on the rising edge, the bias current component accumulates in the positive direction; when the internal phase angle is adjusted at the time when the secondary voltage of the transformer is on the falling edge, the bias current component accumulates in the negative direction. If it is detected that the accumulation direction of the bias current component of the inductor of the dual active bridge circuit is in the positive direction, the time when the primary active bridge performs internal phase angle adjustment is adjusted from the time when the secondary voltage of the transformer is on the rising edge to the time when it is on the falling edge. Therefore, by setting the internal phase angle at the time when the secondary voltage of the transformer is on the falling edge, the bias current component of the inductor accumulates in the negative direction, thereby reducing the bias saturation of the transformer.
[0124] In other embodiments, the time when the primary active bridge performs internal phase angle adjustment includes the time when the drive signal of the upper bridge arm of the secondary active bridge is at a rising edge and the time when the drive signal of the upper bridge arm of the secondary active bridge is at a falling edge. When the drive signal of the upper bridge arm of the secondary active bridge is at a rising edge, the internal phase angle is adjusted, and the bias current component accumulates in a positive direction; when the drive signal of the upper bridge arm of the secondary active bridge is at a falling edge, the internal phase angle is adjusted, and the bias current component accumulates in a negative direction. If it is detected that the accumulation direction of the bias current component of the inductor of the dual active bridge circuit is in a positive direction, the time when the primary active bridge performs internal phase angle adjustment is adjusted from the time when the drive signal of the upper bridge arm of the secondary active bridge is at a rising edge to the time when the drive signal of the upper bridge arm of the secondary active bridge is at a falling edge. Thus, by setting the internal phase angle when the drive signal of the upper bridge arm of the secondary active bridge is at a falling edge, the bias current component of the inductor accumulates in a negative direction, thereby reducing transformer bias saturation.
[0125] According to the control method of this embodiment, the internal phase angle is adjusted according to the bias current component of the inductor, which can reduce the accumulation of the bias current component in one direction, thereby reducing the bias saturation of the transformer and making it less likely to be damaged under extreme working conditions.
[0126] In some embodiments, the time when the primary active bridge 100 performs internal phase shift angle adjustment includes when the secondary voltage of the transformer is at the rising edge and falling edge, or when the driving signal of the upper bridge arm is at the rising edge or falling edge.
[0127] The timing of adjusting the internal phase angle can be the upper and lower edges of the secondary voltage of the transformer or the upper and lower edges of the driving signal of the upper bridge arm. The specific description of each edge can refer to the above embodiments, and this embodiment will not be repeated here.
[0128] As an example, when the bias current component of the inductor is greater than or equal to the reference value, if the cumulative direction of the bias current component is positive, and in the previous control cycle, the moment of internal phase angle adjustment is the falling edge of the secondary voltage of the transformer, then in the current control cycle, the internal phase angle is adjusted at the rising edge of the secondary voltage of the transformer.
[0129] As another example, when the bias current component of the inductor is greater than or equal to the reference value, if the cumulative direction of the bias current component is negative, and in the previous control cycle, the moment of internal phase angle adjustment is when the drive signal of the upper bridge arm is on the rising edge, then in the current control cycle, the internal phase angle is adjusted when the drive signal of the upper bridge arm is on the falling edge.
[0130] Reference Figure 9 , Figure 9A dual active bridge inverter is shown. An embodiment of the present application also provides a dual active bridge inverter, which includes a controller 300 and a dual active bridge circuit. The controller 300 is electrically connected to the dual active bridge circuit and is configured to execute the control method described above.
[0131] The controller 300 can be connected to the switch tubes in the primary active bridge 100 and the secondary active bridge 200 respectively to control the on or off of each switch tube. Figure 3 The working principle of the controller can be referred to above, and this embodiment will not be described in detail here.
[0132] In some embodiments, the dual active bridge circuit includes a primary active bridge 100 , a first inductor L1 , a transformer T, and a secondary active bridge 200 electrically connected in sequence. The primary active bridge 100 is a full bridge, and the secondary active bridge 200 is a half bridge.
[0133] According to the dual active bridge inverter of the present application, the internal phase shift angle of the load generates a positive direction bias current component and a negative direction bias current component, which suppresses the accumulation of the bias current component in a single direction and improves the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation.
[0134] An embodiment of the present application further provides a power system, the power system including the aforementioned dual active bridge inverter. The structure and principle of the dual active bridge inverter can refer to the aforementioned embodiment, and this embodiment will not be described in detail here.
[0135] According to the power system of the present application, the internal phase shift angle of the load generates a positive direction bias current component and a negative direction bias current component, which suppresses the accumulation of the bias current component in a single direction, improves the transformer bias saturation phenomenon caused by single-edge loading phase shift angle modulation, and is not easily damaged under extreme working conditions.
[0136] In some embodiments, an input side of the dual active bridge inverter is electrically connected to a power supply assembly, and an output side of the dual active bridge inverter is electrically connected to an AC power grid.
[0137] Understandably, because the instantaneous output voltage of the AC grid can vary significantly over time, the dual-active-bridge inverter must maintain a very wide voltage gain range. By employing the aforementioned control method, the dual-active-bridge inverter is less susceptible to transformer saturation, even under complex AC grid conditions.
[0138] In this document, the terms "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.
[0139] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present application is defined by the claims and their equivalents.
Claims
1. A circuit control method, characterized in that: The circuit control method comprises: determining a target internal phase shift angle of a primary active bridge of a dual active bridge circuit, the dual active bridge circuit further comprising a transformer electrically connected to the primary active bridge; When the secondary voltage of the transformer is at a rising edge or a falling edge, adjusting the internal phase shift angle of the primary active bridge to the target internal phase shift angle; In the control process of the primary active bridge, the inner phase shift angle is adjusted at least once when the secondary voltage is at a rising edge, and the inner phase shift angle is adjusted at least once when the secondary voltage is at a falling edge.
2. The circuit control method according to claim 1, wherein: In two adjacent control cycles of the primary active bridge, the adjustment moment of the inner phase shift angle in one of the control cycles corresponds to the rising edge of the secondary voltage, and the adjustment moment of the inner phase shift angle in the other control cycle corresponds to the falling edge of the secondary voltage.
3. The circuit control method according to claim 1 or 2, characterized in that: When the secondary voltage of the transformer is at a rising edge or a falling edge, adjusting the internal phase shift angle of the primary active bridge to the target internal phase shift angle includes: Acquire a historical edge state of the secondary voltage of the transformer corresponding to the internal phase shift angle adjustment history of the primary active bridge; determining a current edge state according to the historical edge state; When the secondary voltage of the transformer is in the current edge state, the internal phase shift angle of the primary active bridge is adjusted to the target internal phase shift angle.
4. The circuit control method according to claim 3, wherein: The determining the current edge state according to the historical edge state includes: An edge state opposite to an edge state corresponding to a previous internal phase shift angle adjustment of the primary active bridge is determined as a current edge state, where the edge state is a rising edge or a falling edge.
5. The circuit control method according to claim 3, wherein: The determining the current edge state according to the historical edge state includes: Taking the edge state corresponding to the previous internal phase angle adjustment of the primary active bridge as a reference edge state, and determining a historical adjustment amount corresponding to the internal phase angle adjustment of the primary active bridge in the reference edge state; The current edge state is determined according to the current adjustment amount corresponding to the target internal phase shift angle, the historical adjustment amount and the reference edge state, where the edge state includes a rising edge or a falling edge.
6. The circuit control method according to claim 5, characterized in that: The determining of the current edge state according to the current adjustment amount corresponding to the target internal phase shift angle, the historical adjustment amount, and the reference edge state includes: When the sum of the current adjustment amount corresponding to the target internal phase shift angle and the historical adjustment amount is greater than or equal to a threshold, determining an edge state opposite to the reference edge state as the current edge state; When the sum of the current adjustment amount corresponding to the target internal phase shift angle and the historical adjustment amount is less than a threshold, the edge state that is the same as the reference edge state is determined as the current edge state.
7. A circuit control method, characterized in that: The circuit control method comprises: determining a target internal phase shift angle of a primary active bridge of a dual active bridge circuit, the dual active bridge circuit further comprising a transformer electrically connected to the primary active bridge and a secondary active bridge; When the driving signal of the upper bridge arm of the secondary active bridge is at a rising edge or a falling edge, adjusting the phase difference between the driving signals of the left and right bridge arms of the primary active bridge to adjust the inner phase shift angle of the primary active bridge to the target inner phase shift angle; In the control process of the primary active bridge, the inner phase shift angle is adjusted at least once when the drive signal is at a rising edge, and the inner phase shift angle is adjusted at least once when the drive signal is at a falling edge.
8. The circuit control method according to claim 7, wherein: The upper bridge arm includes a positive switch tube and a negative switch tube connected to each other, wherein the positive switch tube is conducted from the transformer to the grid, and the negative switch tube is conducted from the grid to the transformer; When the driving signal of the upper bridge arm is at a rising edge or a falling edge, adjusting the internal phase shift angle of the primary active bridge to the target internal phase shift angle includes: When the voltage of the grid is in a positive half cycle and it is detected that the forward switch tube switches from an open state to a closed state or from a closed state to an open state, adjusting the internal phase shift angle of the primary active bridge to the target internal phase shift angle; When the voltage of the grid is in a negative half cycle and it is detected that the negative switch tube switches from an open state to a closed state or from a closed state to an open state, the internal phase shift angle of the primary active bridge is adjusted to the target internal phase shift angle.
9. A circuit control method, characterized in that: The circuit control method comprises: When a bias current component of an inductor of a dual active bridge circuit is greater than or equal to a reference value, determining an accumulation direction of the bias current component, the dual active bridge circuit further comprising a primary active bridge connected to the inductor and a transformer, the transformer being electrically connected to the secondary active bridge; Adjusting the timing of performing internal phase shift angle adjustment on the primary active bridge so that the bias current component of the inductor accumulates in a direction opposite to the accumulation direction; Among them, the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the secondary voltage of the transformer is at the rising edge and the moment when it is at the falling edge; or the moment when the primary active bridge performs internal phase shift angle adjustment includes the moment when the driving signal of the upper bridge arm of the secondary active bridge is at the rising edge and the moment when it is at the falling edge.
10. The circuit control method according to claim 9, wherein: The time when the primary active bridge performs internal phase shift angle adjustment includes when the secondary voltage of the transformer is at a rising edge or a falling edge, or when the driving signal of the upper bridge arm is at a rising edge or a falling edge.
11. A dual active bridge inverter, characterized in that: The dual active bridge inverter includes a controller and a dual active bridge circuit. The controller is electrically connected to the dual active bridge circuit and is configured to execute the circuit control method according to any one of claims 1 to 10.
12. A power system, characterized in that: The power system includes the dual active bridge inverter according to claim 11.
13. The power system according to claim 12, characterized in that The input side of the dual active bridge inverter is electrically connected to a power supply assembly, and the output side of the dual active bridge inverter is electrically connected to an AC power grid.