Power converter and control method thereof

Abstract

The invention relates to the field of power equipment, in particular to a power converter and a control method thereof. The power converter comprises a primary side bridge arm, a secondary side bridge arm, a transformer connected between the primary side bridge arm and the secondary side bridge arm, and a control circuit connected with the primary side bridge arm and the secondary side bridge arm. The control circuit is used for detecting whether the output voltage of the power converter suddenly rises or not, and when the output voltage suddenly rises, the phase shift angle between the primary side bridge arm and the secondary side bridge arm is controlled to be smaller than 0 so as to reduce the output voltage. According to the invention, the dynamic performance and the load adaptability under the sudden rise of the output voltage are improved, the output voltage is rapidly recovered, and the safety of the load is ensured.

Description

Technical Field

[0001] The present application relates to the field of electric power equipment, and in particular to a power converter and a control method thereof. Background Art

[0002] Power converters generally include switching devices and magnetic components, and are used for power conversion, such as DC-DC converters and DC-AC converters. They are currently widely used in photovoltaic power generation systems, energy storage systems, etc.

[0003] The voltage stress of the switching device at the output end of the power converter is generally determined by its output voltage. When the output voltage of the power converter suddenly rises due to load shedding or other working conditions, the loop response speed is not fast enough to quickly restore the output voltage, resulting in an excessively high output voltage. This will not only cause the switching device to fail due to overvoltage, but also damage the connected load. Summary of the invention

[0004] Based on this, it is necessary to provide a power converter and a control method thereof to address the above technical issues.

[0005] In a first aspect, an embodiment of the present invention provides a power converter, comprising a primary bridge arm, a secondary bridge arm, a transformer connected between the primary bridge arm and the secondary bridge arm, and a control circuit connected to the primary bridge arm and the secondary bridge arm;

[0006] The control circuit is used to detect whether the output voltage of the power converter suddenly rises. When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage.

[0007] In some embodiments, when the output voltage suddenly increases, the control circuit controls the phase shift angle to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

[0008] In some embodiments, the second type of phase angle value is less than or equal to the opposite of the first type of phase angle value.

[0009] In some embodiments, the first type of phase angle value is determined based on an input voltage of the power converter, an output voltage of the power converter, and a turns ratio of a transformer.

[0010] In some embodiments, when the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the control circuit further controls the switching frequency of the power converter to decrease.

[0011] In some embodiments, when the output voltage suddenly rises, if the current flowing through the transformer is greater than the current threshold, the control circuit further controls the switching frequency of the power converter to increase.

[0012] In some embodiments, if the output voltage suddenly rises, the phase shift angle is greater than 0, and when the output voltage returns to normal, the control circuit controls the phase shift angle to switch to greater than 0.

[0013] In some embodiments, the control circuit generates a driving signal for the switch tube in the primary bridge arm and the secondary bridge arm to drive the power converter based on the second type of phase angle value of the phase shift angle and the switching frequency of the power converter, and the switching frequency of the power converter is determined based on the first type of phase angle value of the phase shift angle.

[0014] In some embodiments, the values ​​of the first phase angle value and the second phase angle value satisfy the soft switching of the switch tubes in the primary bridge arm and the secondary bridge arm.

[0015] In some embodiments, the control circuit determines whether the output voltage of the power converter suddenly increases or returns to normal based on a comparison result between the output voltage of the power converter and a preset reference voltage.

[0016] In some embodiments, the phase shift angle is the phase difference between the bridge arm output voltages of the primary bridge arm and the secondary bridge arm, and the bridge arm output voltage is the voltage of the ports where the primary bridge arm and the secondary bridge arm are connected to the transformer.

[0017] In some embodiments, the power converter further includes a resonant circuit connected between the transformer and the secondary bridge arm or between the transformer and the primary bridge arm.

[0018] In some embodiments, the power converter is a DC / AC converter or a DC / DC converter.

[0019] In a second aspect, an embodiment of the present invention provides a control method for a power converter, wherein the power converter includes a primary bridge arm, a secondary bridge arm, and a transformer connected between the primary bridge arm and the secondary bridge arm, and the method includes:

[0020] Detecting whether the output voltage of the power converter suddenly rises;

[0021] When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage.

[0022] In some embodiments, when the output voltage suddenly rises, controlling the phase shift angle between the primary bridge arm and the secondary bridge arm to be less than 0 includes:

[0023] When the output voltage suddenly rises, the phase shift angle is controlled to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

[0024] In some embodiments, the method further comprises:

[0025] When the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the switching frequency of the power converter is controlled to decrease.

[0026] In some embodiments, the method further comprises:

[0027] When the output voltage suddenly rises, if the current flowing through the transformer is greater than a current threshold, the switching frequency of the power converter is also controlled to increase.

[0028] In some embodiments, the method further comprises:

[0029] If the output voltage suddenly rises, the value of the phase shift angle is greater than 0, and when the output voltage returns to normal, the phase shift angle is controlled to switch to be greater than 0.

[0030] In some embodiments, at the switching moment, the second type of phase angle value is less than or equal to the opposite number of the first type of phase angle value.

[0031] In some embodiments, a driving signal for the switch tubes in the primary bridge arm and the secondary bridge arm is generated based on the second type of phase angle value of the phase shift angle and the switching frequency of the power converter to drive the power converter, and the switching frequency of the power converter is determined based on the first type of phase angle value of the phase shift angle.

[0032] The present application detects whether the output voltage of the power converter suddenly rises. When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage, thereby improving the dynamic performance and load adaptability under the sudden rise of the output voltage, allowing the output voltage to recover quickly and ensuring the safety of the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural block diagram of a power converter in one embodiment of the present application;

[0034] Figure 2 is a schematic structural block diagram of a power converter in another embodiment of the present application;

[0035] Figure 3 A circuit schematic diagram of a power converter in an exemplary embodiment of the present application;

[0036] Figure 4 A control logic diagram of a control circuit in an exemplary embodiment of the present application;

[0037] Figure 5This is a waveform diagram of a DC / AC converter in an exemplary embodiment of the present application when it works in a rectification mode;

[0038] Figure 6 A waveform diagram of a DC / AC converter in an exemplary embodiment of the present application when operating in an inverter mode;

[0039] Figure 7 is the output voltage V of the DC / AC converter in an exemplary embodiment of the present application ac , the resonant cavity current amplitude envelope i rsmag , Phase shift angle Waveform diagram of ;

[0040] Figure 8 Schematic diagram of a flow chart of a method for controlling a power converter in an embodiment of the present application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the contents disclosed in the present application, some changes such as design, manufacturing or production based on the technical contents disclosed in the present application are only conventional technical means, and should not be understood as insufficient contents disclosed in the present application.

[0042] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0043] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to greater than or equal to two. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The terms "first", "second", "third" and the like involved in the present application are merely used to distinguish similar objects and do not represent a specific ordering of the objects.

[0044] As mentioned above, when the output voltage of the power converter suddenly rises, the loop response speed is not fast enough to quickly restore the output voltage, resulting in an over-high output voltage, which not only causes the switching device to fail due to overvoltage, but also damages the connected load.

[0045] According to an embodiment of the present application, a power converter is provided, which can control the phase shift angle between the primary bridge arm and the secondary bridge arm to be less than 0 to reduce the output voltage when the output voltage suddenly rises, so that the output voltage recovers quickly, thereby improving the dynamic performance and load adaptability under the sudden rise of the output voltage and ensuring the safety of electrical equipment.

[0046] In some possible implementations, the power converter according to the embodiment of the present application may include a DC / AC converter or a DC / DC converter. The following description is made by taking the power converter as a DC / AC converter as an example.

[0047] Figure 1 A structural schematic diagram of a power converter in one embodiment provided in the present application includes a primary bridge arm 101, a secondary bridge arm 102, a transformer 103 connected between the primary bridge arm 101 and the secondary bridge arm 102, and a control circuit (not shown in the figure) connected to the primary bridge arm 101 and the secondary bridge arm 102.

[0048] Among them, the input voltage of the power converter is V in , the output voltage of the power converter is Vac , the output current is I ac .

[0049] The primary bridge arm 101 is an inverter unit, including at least two switching tubes, for inverting direct current into alternating current, and may be a half-bridge circuit or a full-bridge circuit.

[0050] The secondary bridge arm 102 includes, for example, at least one cycloconverter, which may be a half-bridge cycloconverter or a full-bridge cycloconverter, and the secondary bridge arm 102 includes a plurality of switch tubes for AC-AC conversion, wherein each switch tube group includes at least two switch tubes connected in reverse, and the output end of the secondary bridge arm 102 provides an AC output, for example, to a load or a power grid.

[0051] The primary winding of the transformer 103 is connected to the primary bridge arm 101 , and the secondary winding is connected to the secondary bridge arm 102 , for bucking and stepping up.

[0052] The control circuit is used to control the primary bridge arm 101 and the secondary bridge arm 102 to achieve power conversion.

[0053] In some embodiments, there may be multiple transformers, and the primary winding of each transformer is correspondingly connected to a primary bridge arm, and the secondary winding is correspondingly connected to the same secondary bridge arm.

[0054] In some embodiments, Figure 2 As shown, the power converter further includes a resonant circuit 104 connected between the transformer 103 and the secondary bridge arm 102. The resonant circuit 104 is used to implement soft switching of the switch tube in the power converter, thereby reducing circuit loss.

[0055] The resonant circuit 104 may be in various circuit forms such as single L, LC, and CLLC.

[0056] In some other embodiments, the resonant circuit 104 may also be connected between the transformer 103 and the primary bridge arm 101 .

[0057] In some embodiments, the power converter further includes a filter circuit 105 connected to the output end of the secondary bridge arm 102 for filtering.

[0058] In order to avoid the output voltage of the power converter from being too high when the output voltage suddenly rises, in some embodiments, the control circuit detects whether the output voltage of the power converter suddenly rises. When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage and restore the output voltage to normal, thereby improving the dynamic performance and load adaptability under the sudden rise of output voltage, allowing the output voltage to recover quickly and ensuring the safety of the load.

[0059] In some embodiments, the phase shift angle is the phase difference between the bridge arm output voltages of the primary bridge arm and the secondary bridge arm, and the bridge arm output voltage is the voltage of the ports where the primary bridge arm and the secondary bridge arm are connected to the transformer.

[0060] In some embodiments, when the output voltage suddenly increases, the control circuit controls the phase shift angle to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

[0061] If the output voltage suddenly rises, the value of the phase shift angle is greater than 0, and when the output voltage returns to normal, the control circuit controls the phase shift angle to be switched to be greater than 0.

[0062] The second type of phase angle value is less than or equal to the opposite number of the first type of phase angle value.

[0063] In some embodiments, when the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the control circuit further controls the switching frequency of the power converter to decrease.

[0064] Specifically, when it is detected that the current flowing through the transformer is not greater than the current threshold, the control circuit can control the switching frequency of the power converter to decrease by a preset step size to speed up the output voltage drop speed and improve the output voltage recovery speed.

[0065] In some embodiments, when the output voltage suddenly rises, if the current flowing through the transformer is greater than the current threshold, the control circuit further controls the switching frequency of the power converter to increase.

[0066] When it is detected that the current flowing through the transformer is greater than the current threshold, the control circuit may control the switching frequency of the power converter to increase with a preset step size to prevent the current flowing through the transformer from over-current.

[0067] This embodiment adjusts the switching frequency according to the current flowing through the transformer, which can further improve the recovery speed of the output voltage and the dynamic response of the power converter.

[0068] In some embodiments, the control circuit generates driving signals for the switches in the primary bridge arm and the secondary bridge arm based on the phase shift angle and the switching frequency of the power converter to drive the power converter.

[0069] Specifically, the control circuit can generate a driving signal for the switch tube in the primary bridge arm and the secondary bridge arm to drive the power converter based on the second type of phase angle value of the phase shift angle and the switching frequency of the power converter, and the switching frequency of the power converter can be determined based on the first type of phase angle value of the phase shift angle.

[0070] It should be noted that when the output voltage of the power converter in the above embodiments suddenly rises when it is in grid-connected mode or off-grid mode, the control circuit can adopt the above-mentioned technical solution to reduce the output voltage. When the power converter is used in a grid-connected scenario, high voltage crossing can be achieved.

[0071] It should be noted that the power converter may be a DC / DC converter in addition to a DC / AC converter, and the control circuit may adopt the same technical solution to reduce the output voltage, which will not be explained in examples here.

[0072] Figure 3 Schematic diagram of the topology of a power converter in an exemplary embodiment, the power converter is a resonant DC / AC converter. The primary bridge arm 101 of the DC / AC converter adopts an H-bridge structure (i.e., a full-bridge circuit), the input end is connected in parallel with a capacitor Cin, the primary bridge arm 101 includes a switch tube Q1H, a switch tube Q1L, a switch tube Q2H, and a switch tube Q2L. Specifically, the switch tube Q1H and the switch tube Q1L are connected in series at the input end to form a half bridge arm, the switch tube Q2H and the switch tube Q2L are connected in series at the input end to form the other half bridge arm, and the bridge arm output voltage v of the primary bridge arm 101 is x is the difference between the output voltages of the two half-bridge arms, that is, the voltage of the port connected to the transformer 103; the secondary bridge arm 102 is composed of two groups of switch elements connected in series in a common source connection mode. Specifically, the two groups of switch elements are connected in series between the two output terminals of the secondary bridge arm 102 to form a half bridge arm. The first group of switch elements of the secondary bridge arm 102 includes switch tubes Q3 and Q4 connected in common source, and the second group of switch elements includes switch tubes Q5 and Q6 connected in common source. The two groups of switch elements are connected together at the midpoint of the bridge arm. One end of the secondary winding of the transformer 103 is connected to the midpoint of the bridge arm through the resonant circuit 104, and the other end is connected to an output terminal of the secondary bridge arm 102. The bridge arm output voltage v o is the voltage between the middle point of the bridge arm and an output terminal of the secondary bridge arm 102, that is, the voltage of the port connected to the transformer 103. The two output terminals of the secondary bridge arm 102 are connected to the filter circuit 105, wherein the filter circuit 105 includes a capacitor C f and inductor L f The resonant circuit 104 includes an inductor Lr and a capacitor Cr connected in series. The current flowing through the transformer 103 is the resonant cavity current i rs , the turns ratio of the primary and secondary windings of the transformer 103 is 1:n.

[0073] The bridge arm output voltage v of the primary bridge arm 101 x The fundamental wave component zero crossing point and the bridge arm output voltage v of the secondary bridge arm 102 oThe phase difference between the zero crossing points of the fundamental wave component is the phase shift angle The output voltage between the two half-bridge arms of the primary bridge arm 101 (output voltage v 1 and the output voltage v 2 Specifically, the phase shift angle θ can be achieved by adjusting the phase difference between the driving signals of the switch tubes in the primary bridge arm 101 and the secondary bridge arm 102. By adjusting the phase difference between the driving signals of the switch tubes of the two half-bridge arms of the primary bridge arm 101, the phase shift angle θ is controlled. Therefore, in some other embodiments, the phase shift angle It may also refer to the phase difference between the driving signals of the corresponding switching tubes in the primary bridge arm 101 and the secondary bridge arm 102 .

[0074] It should be noted that when the primary bridge arm 101 is a half-bridge circuit, it can be understood that the phase shift angle θ is 0 or does not exist.

[0075] Figure 4 FIG. 1 is a control logic diagram of a control circuit in an exemplary embodiment. Figure 4 As shown, the control circuit includes a frequency determination unit, a phase shift angle determination unit, a phase shift angle selection unit, and a drive signal generation unit. Specifically, the phase shift angle determination unit is used to determine the phase shift angle based on the input voltage V in , output voltage V ac , the transformer turns ratio n determines the phase shift angle θ and the phase shift angle The first phase angle value A frequency determination unit is used to determine the frequency based on the phase shift angle. The first phase angle value Phase shift angle θ and instantaneous current command i ac * Determine the switching frequency f s ; Phase shift angle selection unit, used to select the phase shift angle according to whether the output voltage rises suddenly The driving signal generating unit is used to generate a signal according to the phase shift angle Phase shift angle θ and switching frequency f s Generate driving signals for each switch tube to realize the control of the power converter.

[0076] Specifically, the output voltage V ac During normal operation, the phase angle selection unit selects the first type of phase angle value. As the phase shift angle value, when the output voltage V ac When the phase angle rises suddenly, the phase angle selection unit selects the second type of phase angle value As the phase shift angle The value of the phase shift angle From the first phase angle value Switch to the second phase angle value When the output voltage V ac After recovery, the phase angle selection unit selects the first type of phase angle value As the phase shift angle The value of the phase shift angle From the second phase angle value Switch to the first phase angle value

[0077] The second type of phase angle value Less than 0, for example, it can be the first type phase angle value The opposite of

[0078] In some embodiments, the output voltage V ac During the sudden rise period, the phase shift angle determination unit is based on the real-time input voltage V in , output voltage V ac , the transformer turns ratio n determines the first type of phase angle value At this time, the second type of phase angle value can be directly set to Equal to the current first-order phase angle value The opposite of, or less than the first-order phase angle value The opposite of, the second kind of phase angle value With the first phase angle value changes in real time.

[0079] In some embodiments, to achieve optimal efficiency of the power converter, the phase shift angle can be set The values ​​of the phase shift angle θ satisfy the soft switching of the switch tubes in the primary bridge arm 101 and the secondary bridge arm 102. Specifically, the soft switching condition can be:

[0080]

[0081] in, is the boost ratio of the power converter, |V ac | is the output voltage V ac The absolute value of the instantaneous value.

[0082] At this time, the second phase angle value Less than or equal to the first type phase angle value The opposite of

[0083] In some embodiments, the instantaneous current command i ac * It can be generated by the output voltage loop of the power converter, the switching frequency f s With instantaneous current command i ac *Phase shift angle The relationship of θ is:

[0084]

[0085] Among them, L r Indicates the value of inductance Lr, C r Indicates the value of capacitance Cr.

[0086] It should be understood that the above is only an example, and those skilled in the art may obtain a specific representation of the switching frequency according to the actual topology of the power converter, and the present application does not impose any limitation on this.

[0087] Furthermore, whether the output voltage of the power converter suddenly rises or returns to normal can be determined based on a comparison result between the output voltage of the power converter and a preset reference voltage.

[0088] Specifically, when the preset reference voltage is greater than zero, if the difference between the output voltage of the power converter and the reference voltage is greater than a voltage threshold, or when the preset reference voltage is less than zero, if the difference between the reference voltage and the output voltage of the power converter is greater than a voltage threshold, it is determined that the output voltage of the power converter has suddenly risen.

[0089] That is, when the output voltage V ac When the following formula is satisfied, the output voltage V of the power converter is determined ac Sudden rise:

[0090]

[0091] Among them, V ac * It is expressed as the instantaneous command of output voltage, that is, the preset reference voltage of output voltage, V ac Expressed as the instantaneous output voltage of the power converter, V th Expressed as a voltage threshold.

[0092] Correspondingly, when the preset reference voltage is greater than zero, if the difference between the output voltage of the power converter and the reference voltage is less than a voltage threshold, or when the preset reference voltage is less than zero, if the difference between the reference voltage and the output voltage of the power converter is less than a voltage threshold, it is determined that the output voltage of the power converter has returned to normal.

[0093] It should be noted that other methods can also be used to determine whether the output voltage rises suddenly, such as through hysteresis: when the output voltage Determined as output voltage V ac Sudden rise; when satisfied Determined as output voltage V ac recovery, where the voltage threshold V th+ >Vth- .

[0094] In other embodiments, the sudden rise of the output voltage may also be determined by other methods, such as based on power, etc., but the present application is not limited thereto.

[0095] It should be understood that those skilled in the art may set the specific value of the electrical reference voltage and the specific method of determining the voltage surge condition and the voltage recovery condition according to actual conditions, and this application does not impose any restrictions on this.

[0096] By using the output voltage judgment method, voltage surge and voltage recovery can be judged. The judgment method is relatively simple and can improve the judgment speed, thereby improving the subsequent response speed.

[0097] Specifically, in some embodiments, Figure 3 When the DC / AC converter is working normally (output voltage V ac Normal, no abnormal rise), phase shift angle At this time, the DC / AC converter works in the inverter mode. The key waveforms of the DC / AC converter are as follows: Figure 6 As shown, when the output voltage V ac When the sudden rise occurs, control the phase shift angle The second phase angle value Can be the first kind of phase angle value The opposite number of, at this time, the key waveform of the DC / AC converter is as follows Figure 5 As shown, the DC / AC converter works in rectification mode, and the output voltage V ac Down to normal value.

[0098] In some embodiments, the second phase angle value It can also be set to a phase angle value greater than the first type The opposite number is smaller, which can further improve the dynamic response speed of the circuit and increase the voltage recovery speed.

[0099] In some other embodiments, under some working conditions, such as when the output end of the DC / AC converter is connected to a capacitive or inductive load, when the DC / AC converter is working normally (output voltage V ac Normal, no abnormal rise), phase shift angle At this time, the DC / AC converter works in rectification mode. The key waveforms of the DC / AC converter are as follows: Figure 5 As shown, when the output voltage V ac When the sudden rise occurs, control the phase shift angle At this time, the second phase angle value It can be directly equal to the first-order phase angle value No need to invert, at this time, the switching frequency f sThe output voltage V ac Recovery can be achieved by reducing the switching frequency f s Make the output voltage V ac Back to normal.

[0100] In the above exemplary embodiment, when the output voltage V of the DC / AC converter ac When the voltage rises suddenly, the converter shows typical external characteristics, the output voltage V ac , Phase shift angle Resonant cavity current i rs The envelope of the amplitude i rsmag like Figure 7 As shown, the resonant cavity current i rs The upper limit value is i rsmax , the lower limit is i rsmin .

[0101] In the range of 0<ωt<2π, when the output voltage is normal, the output voltage V ac , resonant cavity current i rs The envelope of the amplitude i rsmag , Phase shift angle Changes such as Figure 7 As shown. At ωt=ωt 0 When the load is removed, the output voltage V ac The sudden rise determines the output voltage V ac After the sudden rise, the phase angle selection unit will shift the phase angle From the first phase angle value Switch to the second phase angle value Phase shift angle The DC / AC converter works in rectification mode, and the output voltage V ac Rapid decline. At ωt=ωt 1 When the amplitude envelope i rsmag Reach steady state. At ωt=ωt 2 When the output voltage V ac Return to normal, the phase angle selection unit will shift the phase angle From the second phase angle value Switch to the first phase angle value Phase shift angle The DC / AC converter starts to operate normally in inverter mode.

[0102] In some embodiments, the dynamic response speed of the circuit can be further improved by adjusting the switching frequency.

[0103] This application proposes a control method for a power converter, such as Figure 8 As shown, the method includes:

[0104] S802: Detect whether the output voltage of the power converter suddenly rises;

[0105] S404: When the output voltage suddenly rises, control the phase shift angle between the primary bridge arm and the secondary bridge arm to be less than 0 to reduce the output voltage.

[0106] In some embodiments, when the output voltage suddenly rises, controlling the phase shift angle between the primary bridge arm and the secondary bridge arm to be less than 0 includes:

[0107] When the output voltage suddenly rises, the control circuit controls the phase shift angle to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

[0108] In some embodiments, the method further comprises:

[0109] When the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the switching frequency of the power converter is controlled to decrease.

[0110] In some embodiments, the method further comprises:

[0111] When the output voltage suddenly rises, if the current flowing through the transformer is greater than the current threshold, the control circuit further controls the switching frequency of the power converter to increase.

[0112] In some embodiments, the method further comprises:

[0113] If the output voltage suddenly rises, the value of the phase shift angle is greater than 0, and when the output voltage returns to normal, the phase shift angle is controlled to switch to be greater than 0.

[0114] In some embodiments, the second type of phase angle value is less than or equal to the opposite of the first type of phase angle value.

[0115] In some embodiments, the first type of phase angle value is determined based on an input voltage of the power converter, an output voltage of the power converter, and a turns ratio of a transformer.

[0116] In some embodiments, driving signals for the switches in the primary bridge arm and the secondary bridge arm are generated based on the phase shift angle and the switching frequency of the power converter to drive the power converter.

[0117] Specifically, based on the second type of phase angle value of the phase shift angle and the switching frequency of the power converter, a driving signal for the switch tube in the primary bridge arm and the secondary bridge arm is generated to drive the power converter, and the switching frequency of the power converter is determined based on the first type of phase angle value of the phase shift angle.

[0118] In some embodiments, the values ​​of the first phase angle value and the second phase angle value satisfy the soft switching of the switch tubes in the primary bridge arm and the secondary bridge arm.

[0119] In some embodiments, the method further comprises:

[0120] The control circuit determines whether the output voltage of the power converter suddenly increases or returns to normal based on a comparison result between the output voltage of the power converter and a preset reference voltage.

[0121] In some embodiments, the phase shift angle is the phase difference between the bridge arm output voltages of the primary bridge arm and the secondary bridge arm, and the bridge arm output voltage is the voltage of the ports where the primary bridge arm and the secondary bridge arm are connected to the transformer.

[0122] Since the control method of the power converter of this embodiment corresponds to the embodiments, principles and examples of the power converter described above, for details not fully described in this embodiment, please refer to the relevant descriptions in the above embodiments and will not be repeated here.

[0123] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A power converter, characterized in that: It includes a primary bridge arm, a secondary bridge arm, a transformer connected between the primary bridge arm and the secondary bridge arm, and a control circuit connected to the primary bridge arm and the secondary bridge arm; The control circuit is used to detect whether the output voltage of the power converter suddenly rises. When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage.

2. The power converter according to claim 1, characterized in that: When the output voltage suddenly rises, the control circuit controls the phase shift angle to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

3. The power converter according to claim 2, characterized in that: The second type of phase angle value is less than or equal to the opposite number of the first type of phase angle value.

4. The power converter according to claim 2, characterized in that: The first type of phase angle value is determined based on an input voltage of the power converter, an output voltage of the power converter, and a turns ratio of a transformer.

5. The power converter according to claim 1, characterized in that: When the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the control circuit further controls the switching frequency of the power converter to decrease.

6. The power converter according to claim 1, characterized in that: When the output voltage suddenly rises, if the current flowing through the transformer is greater than a current threshold, the control circuit further controls the switching frequency of the power converter to increase.

7. The power converter according to claim 1, characterized in that: If the output voltage suddenly rises, the phase shift angle is greater than 0, and when the output voltage returns to normal, the control circuit controls the phase shift angle to be greater than 0.

8. The power converter according to claim 2, characterized in that: The control circuit generates a driving signal for the switch tubes in the primary bridge arm and the secondary bridge arm to drive the power converter based on the second type phase angle value of the phase shift angle and the switching frequency of the power converter, and the switching frequency of the power converter is determined based on the first type phase angle value of the phase shift angle.

9. The power converter according to claim 2, characterized in that: The values ​​of the first phase angle value and the second phase angle value satisfy the soft switching of the switch tubes in the primary bridge arm and the secondary bridge arm.

10. The power converter according to claim 1, characterized in that: The control circuit determines whether the output voltage of the power converter suddenly increases or returns to normal based on a comparison result between the output voltage of the power converter and a preset reference voltage.

11. The power converter according to claim 1, characterized in that: The phase shift angle is the phase difference between the bridge arm output voltages of the primary bridge arm and the secondary bridge arm, and the bridge arm output voltage is the voltage of the ports where the primary bridge arm and the secondary bridge arm are connected to the transformer.

12. The power converter according to claim 1, characterized in that: The power converter further includes a resonant circuit, which is connected between the transformer and the secondary bridge arm or between the transformer and the primary bridge arm.

13. The power converter according to claim 1, characterized in that: The power converter is a DC / AC converter or a DC / DC converter.

14. A control method for a power converter, the power converter comprising a primary bridge arm, a secondary bridge arm, and a transformer connected between the primary bridge arm and the secondary bridge arm, characterized in that: The method comprises: Detecting whether the output voltage of the power converter suddenly rises; When the output voltage suddenly rises, the phase shift angle between the primary bridge arm and the secondary bridge arm is controlled to be less than 0 to reduce the output voltage.

15. The method according to claim 14, characterized in that When the output voltage suddenly rises, controlling the phase shift angle between the primary bridge arm and the secondary bridge arm to be less than 0 comprises: When the output voltage suddenly rises, the phase shift angle is controlled to switch from a first phase angle value to a second phase angle value, and the second phase angle value is less than 0.

16. The method according to claim 14, characterized in that The method further comprises: When the output voltage suddenly rises, if the current flowing through the transformer is not greater than a current threshold, the switching frequency of the power converter is controlled to decrease.

17. The method according to claim 14, characterized in that The method further comprises: When the output voltage suddenly rises, if the current flowing through the transformer is greater than a current threshold, the switching frequency of the power converter is also controlled to increase.

18. The method according to claim 14, characterized in that The method further comprises: If the output voltage suddenly rises, the value of the phase shift angle is greater than 0, and when the output voltage returns to normal, the phase shift angle is controlled to switch to be greater than 0.

19. The method according to claim 15, characterized in that The second type of phase angle value is less than or equal to the opposite number of the first type of phase angle value.

20. The method according to claim 15, characterized in that Based on the second type of phase angle value of the phase shift angle and the switching frequency of the power converter, driving signals for the switching tubes in the primary bridge arm and the secondary bridge arm are generated to drive the power converter, and the switching frequency of the power converter is determined based on the first type of phase angle value of the phase shift angle.

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