Dual active bridge dc-dc converter and control method and device thereof

Abstract

The application discloses a dual active bridge DC-DC converter and a control method and device thereof, and belongs to the technical field of power electronics. The converter comprises a controller, a full-bridge circuit and a half-bridge circuit. The controller is used for controlling the switching state of each switching device included in the converter, so that the first target voltage oscillates within the dead time of the first target bridge arm, and the number of oscillation cycles is greater than or equal to 1. The dual active bridge DC-DC converter and the control method and device thereof disclosed by the application can realize the intermittent conduction mode of the dual active bridge DC-DC converter by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, so that the first target voltage oscillates within the dead time of the first target bridge arm, and the number of oscillation cycles is greater than or equal to 1. In addition, the reactive circulating current generated by the dual active bridge DC-DC converter is reduced or not generated, and the energy conversion efficiency can be improved.

Description

Technical Field

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

[0002] In related technologies, dual active bridge (DAB) DC-DC converters, which have advantages such as low current stress, wide soft-switching range, and high power density, are widely used in new energy power generation, electric vehicles, and energy storage systems. Currently, when dual active bridge DC-DC converters operate under light load conditions, the common approach is to increase the operating frequency of the dual active bridge DC-DC converter. This allows the converter to enter a mode with large reactive circulating current and large turn-off current of the switching devices at the lowest possible resonant current, thus avoiding the typically high reactive circulating current and large turn-off current of the switching devices and improving the converter's efficiency. However, this approach leads to an increase in the switching losses of the switching devices in the dual active bridge DC-DC converter. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a dual active bridge DC-DC converter and its control method and device, which can reduce reactive circulating current or eliminate reactive circulating current.

[0004] In a first aspect, this application provides a dual active bridge DC-DC converter, comprising: a controller, a full-bridge circuit, a half-bridge circuit, and a power transmission branch connected between the full-bridge circuit and the half-bridge circuit; the half-bridge circuit includes a half-bridge arm composed of two switching devices and a series voltage divider capacitor branch connected in parallel with the DC bus; the power transmission branch includes at least one of a transformer leakage inductance, an external inductor, and a resonant network. The controller is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0005] According to the dual active bridge DC-DC converter of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0006] According to one embodiment of this application, the controller is further configured to control the switching state of each switching device included in the converter when the first target voltage oscillates to its lowest point, so that the first target voltage stops oscillating.

[0007] According to the dual active bridge DC-DC converter of this application, by controlling the switching state of each switching device included in the converter when the first target voltage oscillates to the valley, the valley opening of the main pipe in the first target bridge arm can be achieved. This can reduce the reactive circulating current when all switching devices are turned on at zero voltage or eliminate the reactive circulating current when all switching devices are turned on at zero voltage, thereby reducing the switching losses of the switching devices and improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0008] According to one embodiment of this application, the dead time is greater than 0 and less than or equal to the duration of one pulse width modulation period.

[0009] According to one embodiment of this application, the first target voltage includes the voltage between the midpoints of the two arms of the full-bridge circuit or the voltage between the midpoint of the arm of the half-bridge circuit and the midpoint of the series voltage divider capacitor branch.

[0010] According to one embodiment of this application, the controller is used to control the switching state of each switching device based on the input voltage, output voltage and preset power of the converter, or based on the input voltage, output voltage and output of the target control loop of the converter.

[0011] According to one embodiment of this application, the controller is configured to trigger at least one of the switching devices included in the first target bridge arm to switch to an on state when the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation has reached a target number.

[0012] According to one embodiment of this application, the controller is further configured to determine that the converter is in a light-load condition based on a preset power and a power threshold of the converter.

[0013] According to one embodiment of this application, the controller further controls the switching state of each switching device included in the converter when the first target voltage stops oscillating, so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

[0014] According to one embodiment of this application, the controller is used to determine that the first target voltage oscillates to the bottom based on the detection result of the first target voltage output by the valley detection circuit; or to determine that the first target voltage oscillates to the bottom when the current corresponding to the first target voltage crosses zero.

[0015] Secondly, this application provides a control method for a dual active bridge DC-DC converter, the method comprising: The switching states of each switching device included in the converter are controlled so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of cycles of the oscillation is greater than or equal to 1.

[0016] According to the control method of the dual active bridge DC-DC converter of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0017] According to one embodiment of this application, after controlling the switching states of each switching device included in the converter, the method further includes: When the first target voltage oscillates to its lowest point, the switching states of each switching device included in the converter are controlled so that the first target voltage stops oscillating.

[0018] According to the control method of the dual active bridge DC-DC converter of this application, by controlling the switching state of each switching device included in the converter when the first target voltage oscillates to the valley, the valley opening of the main pipe in the first target bridge arm can be realized. This can reduce the reactive circulating current when all switching devices are turned on at zero voltage or eliminate the reactive circulating current when all switching devices are turned on at zero voltage, thereby reducing the switching losses of the switching devices and improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0019] According to one embodiment of this application, controlling the switching states of each switching device included in the converter, such that the first target voltage oscillates during the dead time of the first target bridge arm, includes: The switching states of each switching device are controlled based on the input voltage, output voltage, and preset power of the converter, or based on the input voltage, output voltage, and output of the target control loop.

[0020] According to one embodiment of this application, controlling the switching states of each switching device included in the converter, such that the first target voltage oscillates during the dead time of the first target bridge arm, includes: When the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation has reached the target number, it triggers at least one of the switching devices included in the first target bridge arm to switch to the on state.

[0021] According to one embodiment of this application, before controlling the switching states of each switching device included in the converter to cause the first target voltage to oscillate during the dead time of the first target bridge arm, the method further includes: Based on the preset power and power threshold of the converter, it is determined that the converter is in a light load condition.

[0022] According to one embodiment of this application, after controlling the switching states of each switching device included in the converter, the method further includes: When the first target voltage stops oscillating, the switching state of each switching device included in the converter is controlled so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

[0023] According to one embodiment of this application, controlling the switching states of each switching device included in the converter so that the first target voltage stops oscillating when the first target voltage oscillates to its lowest point includes: Based on the detection result of the first target voltage output by the valley detection circuit, it is determined that the first target voltage has oscillated to the valley; or if the current corresponding to the first target voltage crosses zero, it is determined that the first target voltage has oscillated to the valley.

[0024] Thirdly, this application provides a control device for a dual active bridge DC-DC converter, the device comprising: The control module is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of cycles of the oscillation is greater than or equal to 1.

[0025] According to the control device of the dual active bridge DC-DC converter of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0026] According to one embodiment of this application, the control module is further configured to control the switching state of each switching device included in the converter when the first target voltage oscillates to its lowest point, so that the first target voltage stops oscillating.

[0027] Thirdly, this application provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the control method for a dual active bridge DC-DC converter as described in the first aspect above.

[0028] Fourthly, this application provides a non-volatile computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the control method for a dual active bridge DC-DC converter as described in the first aspect above.

[0029] Fifthly, this application provides a chip including a processor and a communication interface, the communication interface being coupled to the processor, the processor being used to run programs or instructions to implement the control method for the dual active bridge DC-DC converter as described in the first aspect.

[0030] In a sixth aspect, this application provides a computer program product, including a computer program that, when executed by a processor, implements the control method for a dual active bridge DC-DC converter as described in the first aspect above.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the structure of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 2This is one of the timing diagrams of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 3 This is the second schematic diagram of the timing of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 4 This is the third schematic diagram of the timing of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 5 This is the fourth schematic diagram of the timing of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 6 This is one of the simplified circuit model diagrams of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 7 This is a second simplified circuit model diagram of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 8 This is the third simplified circuit model diagram of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 9 This is the fourth simplified circuit model diagram of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 10 This is the fifth schematic diagram of the timing of the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 11 This is a flowchart illustrating the control method for a dual active bridge DC-DC converter provided in an embodiment of this application. Figure 12 This is a schematic diagram of the control device for the dual active bridge DC-DC converter provided in the embodiments of this application; Figure 13 This is a schematic diagram of the structure of the electronic device provided in the embodiments of this application. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0034] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0035] The control method, dual active bridge DC-DC converter, control device, electronic device, and readable storage medium of the dual active bridge DC-DC converter provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0036] This application also provides a dual active bridge DC-DC converter. For example... Figure 1 As shown, the dual active bridge DC-DC converter may include: a controller 110, a full-bridge circuit 120, a half-bridge circuit 130, and a power transmission branch connected between the full-bridge circuit 120 and the half-bridge circuit 130; the half-bridge circuit includes a half-bridge arm composed of two switching devices and a series voltage divider capacitor branch 140 connected in parallel with the DC bus; the power transmission branch includes at least one of transformer leakage inductance, external inductance, and resonant network.

[0037] In actual implementation, a dual active bridge DC-DC converter may include a full-bridge circuit 120 and a half-bridge circuit 130, both of which are active bridges. The full-bridge circuit 120 is a full-bridge circuit including two bridge arms (which may be referred to as "full-bridge arms"), and the half-bridge circuit 130 is a half-bridge circuit including one bridge arm (which may be referred to as "half-bridge arm").

[0038] It is understood that both the full-bridge circuit 120 and the half-bridge circuit 130 may include at least one pair of switching devices. These switching devices may be field-effect transistors (FETs), bipolar junction transistors (BJTs), or insulated-gate bipolar transistors (IGBTs), such as metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0039] In some embodiments, the full-bridge circuit 120 and the half-bridge circuit 130 are respectively located on one side of the dual active bridge DC-DC converter. When the full-bridge circuit 120 is located on the input side of the dual active bridge DC-DC converter, the half-bridge circuit 130 is located on the output side of the dual active bridge DC-DC converter; when the half-bridge circuit 130 is located on the input side of the dual active bridge DC-DC converter, the full-bridge circuit 120 is located on the output side of the dual active bridge DC-DC converter.

[0040] In some embodiments, the half-bridge circuit 130 may include a half-bridge arm composed of two switching devices, and may also include a series voltage divider capacitor branch 140. The series voltage divider capacitor branch 140 is connected in parallel with the DC bus, that is, one end of the series voltage divider capacitor branch 140 is connected to the positive terminal (+) of the DC bus, and the other end is connected to the negative terminal (-) of the DC bus.

[0041] In some embodiments, the series voltage divider capacitor branch 140 may include a first voltage divider capacitor C1 and a second voltage divider capacitor C2 connected in series.

[0042] In some embodiments, the controller 110 can be used to control the full-bridge circuit 120 and the half-bridge circuit 130 to achieve power conversion.

[0043] In some embodiments, the dual active bridge DC-DC converter may further include a power transmission branch. The full-bridge circuit 120 and the half-bridge circuit 130 can be connected through this power transmission branch to achieve functions such as electrical isolation, voltage transformation, and energy transfer.

[0044] In some embodiments, the power transmission branch may include a transformer and / or a resonant network, etc.

[0045] In some embodiments, the resonant network can be used to implement soft switching of each switching device in the dual active bridge DC-DC converter, thereby reducing circuit losses.

[0046] In some embodiments, the resonant network can be configured in various ways, such as single L, LC, LLC, and CLLC. Here, L represents inductance, and C represents capacitance.

[0047] In some embodiments, the transformer can be used to step up or step down the voltage.

[0048] In some embodiments, where the power transmission branch includes a transformer, the power transmission branch may include transformer leakage inductance and / or external inductance.

[0049] In some embodiments, this dual active bridge DC-DC converter can operate bidirectionally, enabling bidirectional energy flow or transmission. Figure 2Taking the dual active bridge DC-DC converter topology as an example, if the energy transfer direction P>0, it means that energy is transferred from the left to the right, with the left side being the input side and the right side being the output side; if the energy transfer direction P<0, it means that energy is transferred from the right to the left, with the left side being the output side and the right side being the input side.

[0050] The controller 110 is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0051] In actual execution, the switching states of each switching device in the full-bridge circuit 120 and the half-bridge circuit 130 of the dual active bridge DC-DC converter can be controlled by the controller 110, so that the first target voltage oscillates in the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0052] In some embodiments, the first target bridge arm may include at least one bridge arm in the full-bridge circuit 120 and / or at least one bridge arm in the half-bridge circuit 130. It is understood that each bridge arm consists of a pair of switching devices.

[0053] In some embodiments, for each switching device included in the dual active bridge DC-DC converter, the controller 110 controls the switching state of the switching device by inputting a drive signal to the switching device. In some embodiments, the drive signal may be a pulse width modulation (PWM) signal or other modulation signal.

[0054] In some embodiments, the controller 110 can control the switching states of each switching device included in the converter to cause the first target bridge arm to enter the dead zone.

[0055] Bridge Arm Dead Time refers to a protection period in bridge circuits (such as H-bridge or half-bridge circuits) where both switching devices (such as MOSFETs or IGBTs) on the same bridge arm are turned off simultaneously due to switching delays (short circuit). This is a period of time artificially inserted between complementary drive signals to prevent both devices from being turned off. This avoids "shoot-through" between the two switching devices on the same bridge arm and prevents the power supply from directly short-circuiting through the two switching devices on the same bridge arm, which could cause the devices to burn out due to overcurrent.

[0056] The dead time of the first target bridge arm is the period during which the first target bridge arm is in a dead zone. During the dead time of the first target bridge arm, each pair of switching devices (i.e., the two switches mentioned above) included in the first target bridge arm are in an off state. Based on the control of the switching states of the switching devices other than the first target bridge arm in the full-bridge circuit 120 and half-bridge circuit 130 of the dual active bridge DC-DC converter, the direction of current flow between the other switching devices can be changed, thereby causing the first target voltage to oscillate between its peak (referring to the extreme value when the first target voltage is positive) and trough (or "valley", referring to the extreme value when the first target voltage is negative). Within one cycle of the first target voltage oscillation, the first target voltage undergoes a process of continuous change from peak to trough and from trough to peak.

[0057] In some embodiments, the waveform of the first target voltage oscillation can be a sine wave or other types of waveforms. This application does not limit this.

[0058] It should be noted that the first target voltage oscillates within the dead time of the first target bridge arm, and the first target voltage undergoes multiple commutations within the dead time of the first target bridge arm (including commutations from positive voltage to negative voltage and from negative voltage to positive voltage). The current that does not participate in active power transmission in the entire closed conversion loop of this dual active bridge DC-DC converter (which would form reactive circulating current if it flowed in one direction continuously) will not flow in one direction continuously, thus preventing the formation of a continuously circulating reactive circulating current. This reduces or even eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, achieving the purpose of suppressing reactive circulating current.

[0059] To prevent the formation of a continuous reactive power circulation, the dead time of the first target bridge arm needs to be long enough to ensure that the first target voltage undergoes at least two commutations within its dead time. Understandably, the first target voltage undergoes two commutations within one cycle of oscillation. Therefore, the dead time of the first target bridge arm can be controlled by adjusting the duration for which the pair of switching devices in each first target bridge arm remain off, ensuring that the number of oscillation cycles of the first target voltage within its dead time is greater than or equal to one.

[0060] In some embodiments, the first target voltage corresponds to the first target bridge arm, and both the first target voltage and the first target bridge arm can be determined based on the energy transfer direction P and voltage conversion ratio k of the dual active bridge DC-DC converter. Depending on the energy transfer direction P and voltage conversion ratio k of the dual active bridge DC-DC converter, the first target voltage can be the voltage output by the full-bridge circuit 120 or the voltage output by the half-bridge circuit 130.

[0061] In some embodiments, the dual active bridge DC-DC converter can operate bidirectionally, enabling bidirectional energy flow or transfer. The dual active bridge DC-DC converter includes two bridge circuits, each located on one side of the converter. Using one side (e.g., the primary side) of the dual active bridge DC-DC converter as a reference, energy flowing from the bridge circuit on that side to the bridge circuit on the other side can be denoted as the energy transfer direction P>0; conversely, energy flowing from the bridge circuit on the other side to the bridge circuit on that side can be denoted as the energy transfer direction P<0. Using one side (e.g., the primary side) of the dual active bridge DC-DC converter as a reference, if the voltage on that side is less than the voltage on the other side, the converter performs a boost operation, denoted as a voltage conversion ratio k>1; conversely, if the voltage on that side is greater than the voltage on the other side, the converter performs a buck operation, denoted as a voltage conversion ratio k<1.

[0062] In some embodiments, the number of cycles in which the first target voltage oscillates during the dead time of the first target arm can be an integer (e.g., 1, 2, or 3) or a non-integer (e.g., 1.5, 2.25, or 3.1).

[0063] It should be noted that, in this embodiment, the controller 110 controls the full-bridge circuit 120 and the half-bridge circuit 130 using a Discontinuous Conduction Mode (DCM) modulation method. In DCM, the current in the power transfer inductor of the dual active bridge DC-DC converter drops to zero in each switching cycle, forming an intermittent conduction state. DCM is commonly used in light-load or standby scenarios to reduce losses and achieve soft switching of the aforementioned switching devices. In some embodiments, the power transfer inductor may include the inductance in the resonant network and / or the leakage inductance of the transformer.

[0064] Under discontinuous conduction mode modulation, within one switching cycle, based on the different excitations applied to the power transfer inductor, it can be divided into a zero-voltage excitation segment, a positive-voltage excitation segment, and a negative-voltage excitation segment. This resets the current of the power transfer inductor, and energy can be transferred from the input side to the output side through high-frequency AC excitation. The zero-voltage excitation segment, positive-voltage excitation segment, and negative-voltage excitation segment represent the time periods when the excitation voltage of the power transfer inductor is 0, positive, and negative, respectively, with the zero-voltage excitation segment being a discontinuous excitation segment.

[0065] During the intermittent excitation phase of the first half of a switching cycle, both the upper and lower switching devices of each first target bridge arm are in the off state. Therefore, the intermittent excitation phase of the first half of a switching cycle constitutes the dead time of the first target bridge arm. Similarly, during the intermittent excitation phase of the second half of a switching cycle, both the upper and lower switching devices of each first target bridge arm are also in the off state. Therefore, the intermittent excitation phase of the second half of a switching cycle constitutes the dead time of the first target bridge arm.

[0066] In some embodiments, the controller 110 controls the switching states of each switching device included in the converter, such that the first target voltage oscillates during the dead time of the first target bridge arm. This may include controlling the switching devices included in the first target bridge arm to be in the off state during the aforementioned zero-voltage excitation segment.

[0067] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0068] In some embodiments of this application, the controller 110 is further configured to control the switching state of each switching device included in the converter when the first target voltage oscillates to a low point, so that the first target voltage stops oscillating.

[0069] In actual execution, after the number of cycles of the first target voltage oscillation reaches the target number, the controller 110 can trigger at least one of the pair of switching devices included in each first target bridge arm to switch from the off state to the on state, ending the dead zone of the first target bridge arm and causing the first target voltage to stop oscillating.

[0070] In some embodiments, the controller 110 may select the moment when the first target voltage oscillates to its lowest point to trigger at least one of a pair of switching devices included in each first target bridge arm to switch from an off state to an on state.

[0071] In some embodiments, when the first target voltage oscillates to its lowest point, the controller 110 controls the switching state of each switching device included in the converter so that the first target voltage stops oscillating. This may include controlling at least one of the switching devices included in the first target bridge arm to switch from the off state to the on state at the end of the aforementioned zero-voltage excitation segment.

[0072] It should be noted that at any moment during the oscillation of the first target voltage (provided the number of oscillation periods is greater than or equal to 1), controlling the switching state of each switching device in the converter can end the dead time of the first target bridge arm and stop the oscillation of the first target voltage. However, in this case, when at least one of the pair of switching devices in each first target bridge arm switches from the off state to the on state, the voltage across the switching device in the on state is not zero. During the turn-on process of the switching device in the on state, there is overlap between voltage and current, resulting in significant turn-on losses. When the first target voltage oscillates to its lowest point, switching at least one of the pair of switching devices in each first target bridge arm from the off state to the on state will result in zero voltage across the switching device in the on state. This eliminates the overlap between voltage and current during the turn-on process of the switching device in the on state, thereby reducing switching losses.

[0073] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the converter when the first target voltage oscillates to the valley, the valley opening of the main pipe in the first target bridge arm can be achieved. This can reduce the reactive circulating current when all switching devices are turned on at zero voltage or eliminate the reactive circulating current when all switching devices are turned on at zero voltage, thereby reducing the switching losses of the switching devices and improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0074] In some embodiments of this application, the dead time is greater than 0 and less than or equal to the duration of one pulse width modulation period.

[0075] In actual implementation, the dead time of the first target bridge arm can be variable, specifically greater than 0 and less than or equal to the duration of one pulse width modulation (PWM) cycle. The PWM cycle is the switching cycle or the excitation cycle of the power transfer inductor.

[0076] In some embodiments, unlike conventional DCM modulation, this embodiment dynamically controls the dead time of the first target bridge arm by controlling the switching states of each switching device in the full-bridge circuit 120 and the half-bridge circuit 130 of the dual active bridge DC-DC converter, thereby causing the first target voltage to oscillate within the dead time of the first target bridge arm. Dynamic control of the dead time of the first target bridge arm allows for flexibility in its duration, which can be greater than 0 and less than or equal to the duration of one switching cycle of the dual active converter.

[0077] In some embodiments, the controller 110 dynamically controls the dead time of the first target bridge arm, which may include turning on at least one of the pair of switching devices included in the first target bridge arm in advance, and / or turning off at least one of the pair of switching devices included in the first target bridge arm with a delay.

[0078] In some embodiments, when pulse width modulation is used, the drive signal for the switching device in the dual active converter is a pulse width modulation signal. Accordingly, one switching cycle of the dual active converter is one pulse width modulation cycle, and the duration of the switching cycle is the duration of the pulse width modulation cycle.

[0079] In some embodiments, in order to meet other requirements for the operation of the dual active converter, the dead time of the first target bridge arm can be greater than 0 and less than the duration of one switching cycle of the dual active converter.

[0080] It should be noted that the first target voltage oscillates within the dead time of the first target bridge arm, and undergoes multiple commutations within this dead time. Therefore, the current not involved in active power transmission in the entire closed-loop conversion of this dual active bridge DC-DC converter will not flow continuously in one direction, thus preventing the formation of a continuously circulating reactive current. Therefore, by flexibly controlling the duration of the dead time of the first target bridge arm, its maximum value can be less than or equal to the duration of one switching cycle of the dual active bridge converter. With the switching cycle duration unchanged, by flexibly controlling the duration of the dead time of the first target bridge arm, the duration of the dead time of the first target bridge arm can be increased within one switching cycle. Since the generation of reactive current can be suppressed within the dead time of the first target bridge arm, the duration of reactive current suppression within one switching cycle is longer when the switching cycle duration remains unchanged, further improving the suppression effect of reactive current and reducing or even eliminating the reactive current generated by the dual active bridge DC-DC converter.

[0081] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by ensuring that the dead time is greater than 0 and less than or equal to the duration of one pulse width modulation period, the dual active bridge DC-DC converter can operate in intermittent conduction mode, and the intermittent conduction is more flexible. The control of the dead time of the first target bridge arm is more flexible. While ensuring the normal operation of the dual active bridge DC-DC converter, the reactive circulating current generated by the dual active bridge DC-DC converter can be further reduced or eliminated, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0082] In some embodiments of this application, the first target voltage includes the voltage between the midpoints of the two arms of a full-bridge circuit or the voltage between the midpoint of the arm of a half-bridge circuit and the midpoint of the series voltage divider capacitor branch 140.

[0083] In actual implementation, depending on the direction P of energy transmission and the voltage conversion ratio k of the dual active bridge DC-DC converter, the first target voltage can be the voltage output by the full-bridge circuit 120 or the voltage output by the half-bridge circuit 130.

[0084] In some embodiments, the voltage output by the full-bridge circuit 120 is the voltage between the midpoints of the two bridge arms of the full-bridge circuit 120.

[0085] In some embodiments, the voltage output by the half-bridge circuit 130 is the voltage between the midpoint of the half-bridge arm of the half-bridge circuit 130 and the two voltage-dividing capacitors (e.g., Figure 1 The voltage between the midpoints of the first voltage divider capacitor C1 and the second voltage divider capacitor C2 in the dual active bridge DC-DC converter topology shown. It can be understood that the midpoint of the two voltage divider capacitors is the connection point between them.

[0086] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching states of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter. In some embodiments of this application, the controller 110 is used to trigger at least one switching device included in the first target bridge arm to switch to the on state when the oscillation detection circuit detects that the number of oscillation periods of the first target voltage reaches the target number.

[0087] In some embodiments of this application, the controller 110 is used to control the switching state of each switching device based on the input voltage, output voltage and preset power of the converter, or based on the input voltage, output voltage and output of the target control loop of the converter.

[0088] In actual operation, the controller 110 can control the switching states of each switching device included in the dual active bridge DC-DC converter based on the input voltage, output voltage, and preset power, so as to achieve oscillation of the first target voltage within the dead time of the first target bridge arm. The preset power can be the output power of the dual active bridge DC-DC converter.

[0089] In some embodiments, the controller 110 can also control the switching states of each switching device included in the dual active bridge DC-DC converter based on the input voltage, output voltage, and output of the target control loop of the dual active bridge DC-DC converter, so as to achieve the oscillation of the first target voltage in the dead time of the first target bridge arm.

[0090] It should be noted that the target control loop is the control loop used to control the target physical quantity of the dual active bridge DC-DC converter. The control loop can be a control loop based on the proportional-integral-derivative control (PID) algorithm, used to determine the target value of the target physical quantity.

[0091] It is understood that the above proportional-integral-derivative control algorithm includes control algorithms that employ at least one of proportional control, integral control, and derivative control, such as proportional-integral (PI control) algorithms that employ both proportional and integral control.

[0092] It should be noted that the target physical quantity can be flexibly selected according to the method of controlling the dual active bridge DC-DC converter. For example, the target physical quantity may include at least one of input voltage, input current, output voltage, output current, and output power. The embodiments of this application do not limit the specific target physical quantity used.

[0093] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0094] In some embodiments of this application, the controller 110 is used to trigger at least one switching device included in the first target bridge arm to switch to the on state when the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation has reached a target number.

[0095] In actual execution, when the first target voltage begins to oscillate, the number of cycles of the first target voltage oscillation can be detected.

[0096] In some embodiments, the number of cycles of the first target voltage oscillation can be detected by software and / or hardware methods. In some embodiments, the software method involves the controller 110 executing a program to detect the number of cycles of the first target voltage oscillation. In some embodiments, the hardware method involves a hardware circuit detecting the cycle of the first target voltage oscillation, sending a signal to the controller 110 each time a complete cycle or other duration (e.g., 1 / 4 cycle or half a cycle) of the first target voltage oscillation is detected. The controller 110 can count the number of received signals to obtain the number of cycles of the first target voltage oscillation.

[0097] In some embodiments, the number of cycles of the first target voltage oscillation can be detected in hardware by using an oscillation detection circuit to detect the first target voltage in real time.

[0098] In some embodiments, the number of cycles of the first target voltage oscillation can be detected by software, which may include: obtaining the duration of the first target voltage oscillation cycle in advance based on the input voltage and output voltage of the dual active bridge DC-DC converter; starting timing from when the first target voltage begins to oscillate, and determining the number of cycles of the first target voltage oscillation based on the timing duration and the duration of the first target voltage oscillation cycle.

[0099] In some embodiments, when the number of cycles of the first target voltage oscillation is detected to reach a target number, at least one of the pair of switching devices included in each first target bridge arm can be triggered to switch from the off state to the on state, ending the dead zone of the first target bridge arm, and correspondingly, the first target voltage stops oscillating.

[0100] It should be noted that the target number is a number greater than 1 (e.g., 1.5, 2, or 3.25). The target number can be determined based on the actual situation of the dual active bridge DC-DC converter. This application does not limit the specific value of the target number in its embodiments.

[0101] According to the dual active bridge DC-DC converter provided in the embodiments of this application, the number of cycles of the first target voltage oscillation is detected by the hardware detection circuit, which does not depend on the accuracy of the software modeling and can further improve the accuracy of the control of the dead time of the first target bridge arm.

[0102] In some embodiments of this application, the controller 110 is also configured to determine that the converter is in a light-load condition based on the converter's preset power and power threshold.

[0103] In actual operation, before controlling the switching states of the various switching devices included in the converter to cause the first target voltage to oscillate within the dead time of the first target bridge arm, the controller 110 can acquire the preset power of the dual active bridge DC-DC converter. After acquiring the preset power of the dual active bridge DC-DC converter, the controller 110 can determine whether the preset power of the dual active bridge DC-DC converter is less than a power threshold. If the preset power of the dual active bridge DC-DC converter is less than the power threshold, the controller 110 can determine that the dual active bridge DC-DC converter is under light load operation. Under the light load operation condition, the controller 110 can control the switching states of the various switching devices included in the converter to cause the first target voltage to oscillate within the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0104] It should be noted that when the preset power of the dual active bridge DC-DC converter is greater than or equal to the power threshold, it can be determined that the dual active bridge DC-DC converter is not under light load conditions. Therefore, the first target voltage can oscillate within the dead time of the first target bridge arm without controlling the switching state of each switching device included in the converter.

[0105] It should be noted that the power threshold can be determined based on the actual conditions such as the model of the switching devices, input voltage, and output voltage of the dual active bridge DC-DC converter. This application does not limit the specific value of the power threshold in its embodiments.

[0106] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter under light load conditions, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0107] In some embodiments of this application, the controller 110, upon the termination of the oscillation of the first target voltage, controls the switching state of each switching device included in the converter, such that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

[0108] In actual execution, after the first target voltage ends its oscillation, the controller 110 can also control the switching states of each switching device in the full-bridge circuit 120 and the half-bridge circuit 130 of the dual active bridge DC-DC converter, so that the second target voltage oscillates in the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0109] It should be noted that the second target voltage corresponds to the first target voltage. When the first target voltage is the output voltage of the full-bridge circuit 120, the second target voltage is the output voltage of the half-bridge circuit 130; when the first target voltage is the output voltage of the half-bridge circuit 130, the second target voltage is the output voltage of the full-bridge circuit 120.

[0110] In some embodiments, the second target bridge arm is a bridge arm different from the first target bridge arm. The second target bridge arm may include at least one bridge arm in the full-bridge circuit 120 and / or one bridge arm in the half-bridge circuit 130. It is understood that each bridge arm consists of a pair of switching devices.

[0111] In some embodiments, the second target voltage corresponds to the second target bridge arm, and both the second target voltage and the second target bridge arm can be determined based on the energy transfer direction P and voltage conversion ratio k of the dual active bridge DC-DC converter. Depending on the energy transfer direction P and voltage conversion ratio k of the dual active bridge DC-DC converter, the second target voltage can be the voltage output by the full-bridge circuit 120 or the voltage output by the half-bridge circuit 130.

[0112] It is understandable that the time during which the second target bridge arm is in dead zone is called the dead time of the second target bridge arm. Similar to how the oscillation of the first target voltage during the dead time of the first target bridge arm can suppress reactive circulating current, during the dead time of the second target bridge arm, each pair of switching devices in each second target bridge arm is in an off state. Based on the control of the switching states of the switching devices other than those in the second target bridge arm among the switching devices in the full-bridge circuit 120 and half-bridge circuit 130 of the dual active bridge DC-DC converter, the direction of current flow between these other switching devices can be changed, thereby causing the second target voltage to oscillate between its peak (referring to the extreme value when the second target voltage is positive) and trough (or "valley," referring to the extreme value when the second target voltage is negative). Within one cycle of the second target voltage oscillation, the second target voltage undergoes a process of continuous change from peak to trough and from trough to peak.

[0113] In some embodiments, the waveform of the second target voltage oscillation can be a sine wave or other types of waveforms. This application does not limit this.

[0114] It should be noted that the second target voltage oscillates during the dead time of the second target bridge arm. During the dead time of the second target bridge arm, the second target voltage undergoes multiple commutations (including commutations from positive voltage to negative voltage and from negative voltage to positive voltage). The current that does not participate in active power transmission in the entire closed conversion loop of this dual active bridge DC-DC converter (which would form reactive circulating current if it flowed in one direction) will not flow in one direction in one direction, thus preventing the formation of a continuously circulating reactive circulating current. This reduces or even eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, achieving the purpose of suppressing reactive circulating current.

[0115] It should be noted that after the first target voltage oscillates within the dead time of the first target bridge arm, the controller 110 further controls the switching state of each switching device included in the dual active bridge DC-DC converter, so that the second target voltage oscillates within the dead time of the second target bridge arm. During the dead time of the second target bridge arm, the generation of reactive circulating current can also be suppressed. With the duration of the switching cycle remaining unchanged, the duration of reactive circulating current suppression in one switching cycle is longer, which can further improve the effect of suppressing reactive circulating current and reduce or even eliminate the reactive circulating current generated by the dual active bridge DC-DC converter.

[0116] In some embodiments, to ensure that a continuous reactive current circulation does not occur, the dead time of the second target bridge arm needs to be long enough to ensure that the second target voltage undergoes at least two commutations within the dead time of the second target bridge arm. It is understood that the second target voltage undergoes two commutations within one cycle of oscillation. Therefore, the dead time of the second target bridge arm can be controlled by controlling the duration for which the pair of switching devices included in each second target bridge arm remain off, so that the number of cycles of oscillation of the second target voltage within the dead time of the second target bridge arm is greater than or equal to 1.

[0117] In some embodiments, the number of cycles during which the second target voltage oscillates in the dead time of the second target bridge arm can be an integer (e.g., 1, 2, or 3) or a non-integer (e.g., 1.5, 2.25, or 3.1).

[0118] According to the dual active bridge DC-DC converter provided in this application embodiment, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter when the first target voltage stops oscillating, the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0119] In some embodiments of this application, the controller 110 is used to determine that the first target voltage oscillates to the bottom based on the detection result of the first target voltage output by the valley detection circuit; or to determine that the first target voltage oscillates to the bottom when the current corresponding to the first target voltage crosses zero.

[0120] In actual execution, it can be determined from the perspective of voltage and / or current whether the first target voltage has oscillated to the bottom.

[0121] In some embodiments, a valley detection circuit can be used to detect whether the first target voltage has oscillated to a valley. The valley detection circuit can output the detection result of the first target voltage to the controller 110. If the value of the first target voltage is the valley value, the controller 110 can determine that the first target voltage has oscillated to a valley.

[0122] In some embodiments, the controller 110 can determine whether the first target voltage has oscillated to a trough by detecting whether the current corresponding to the first target voltage crosses zero. When the current corresponding to the first target voltage crosses zero, the controller 110 can determine that the first target voltage has oscillated to a trough.

[0123] In some embodiments, when the first target voltage is the primary voltage Vp, the current corresponding to the first target voltage is the primary current Ip; when the first target voltage is the secondary voltage Vs, the current corresponding to the first target voltage is the secondary current Is.

[0124] According to the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the converter when the first target voltage oscillates to the valley, the valley opening of the main pipe in the first target bridge arm can be achieved. This can reduce the reactive circulating current when all switching devices are turned on at zero voltage or eliminate the reactive circulating current when all switching devices are turned on at zero voltage, thereby reducing the switching losses of the switching devices and improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0125] To facilitate understanding of the above embodiments of this application, the control timing of the dual active bridge DC-DC converter provided in the above embodiments of this application is described below, so as to reduce reactive circulating current or even completely eliminate reactive circulating current.

[0126] It is understood that the dual active bridge DC-DC converter may also include a transformer and / or a resonant network. The full-bridge circuit and the half-bridge circuit can be connected through the transformer and / or resonant network to achieve functions such as electrical isolation, voltage transformation and energy transfer.

[0127] Figures 2 to 5 As shown Figure 1The timing diagram of the dual active bridge DC-DC converter topology shown is presented under different operating conditions. Among them, Figures 2 to 5 The following diagrams illustrate the boost positive power operation (energy transfer direction P>0 and voltage conversion ratio k>1, with the input side being...). Figure 1 The left side of the middle, the output side is Figure 1 (Right side of the image), boost negative power operation (energy transfer direction P<0 and voltage conversion ratio k>1, input side is...) Figure 1 The right side of the output side is Figure 1 (Left side of the image), buck positive power mode (energy transfer direction P>0 and voltage conversion ratio k<1, input side is...) Figure 1 The left side of the middle, the output side is Figure 1 (right side of the image), and buck negative power operation (energy transfer direction P<0 and voltage conversion ratio k<1, input side is...) Figure 1 The right side of the output side is Figure 1 (Left side of the middle) below, such as Figure 1 The timing diagram shows the topology of the dual active bridge DC-DC converter. It illustrates the boost positive power mode, boost negative power mode, buck positive power mode, and buck negative power mode. Figure 1 The simplified circuit model of the dual active bridge DC-DC converter topology shown can be represented as follows: Figures 6 to 9 As shown.

[0128] Figures 2 to 5 In the timing sequence shown, t2~t3 and t5~t0 are the intermittent excitation segments or the target arm turn-off intervals. Figure 2 and Figure 4 Under the positive power condition shown, the positive pressure excitation ranges are t0~t1 and t4~t5, and the negative pressure excitation ranges are t1~t2 and t3~t4; Figure 3 and Figure 5 Under the negative power condition shown, the negative pressure excitation range is t0~t1 and t4~t5, and the positive pressure excitation range is t1~t2 and t3~t4.

[0129] Under boost positive power operation, the waveforms of the drive signals for switching devices S1 to S6 are as follows: Figure 2As shown. For switching devices S1 to S6, the switching device is turned on when its drive signal is high, and turned off when its drive signal is low. In this embodiment, switching devices S1 to S6 can all be turned on using a critical soft-switching method, switching from the off state to the on state.During one switching cycle, from time t0 to t1, switching devices S1, S4, and S6 are turned on, while switching devices S2, S3, and S5 are turned off, and the current IL of the power transfer inductor increases. At time t1, the current IL of the power transfer inductor reaches its peak value. The switching states of switching devices S1, S2, S3, and S4 remain unchanged, while switching device S5 can switch to the on state, and switching device S6 switches to the off state. From time t1 to t2, the current IL of the power transfer inductor decreases. At time t2, the current IL of the power transfer inductor decreases to zero. The switching states of switching devices S1 and S2 remain unchanged, while switching device S3 switches to the on state, switching device S4 switches to the off state, and switching device S5 can switch to the off state. In the off state, switch S6 remains off, entering the dead time of the bridge arm composed of switches S5 and S6 (the first target bridge arm in this embodiment), and the secondary voltage Vs oscillates; after the dead time (t2~t3) of the bridge arm composed of switches S5 and S6, at time t3, switch S1 switches to the off state, switch S2 switches to the on state, switch S3 remains on state, switch S4 remains off state, switch S5 switches to the on state, switch S6 remains off state, and the dead time of the bridge arm composed of switches S5 and S6 ends; at times t3~t4, the current IL of the power transmission inductor rises in the reverse direction (the direction of the current IL of the power transmission inductor is relative to...). (Regarding times t0~t2); at time t4, the current IL of the power transfer inductor reaches its reverse peak (the direction of the current IL of the power transfer inductor is relative to times t0~t2). The switching states of switching devices S1, S2, S3, and S4 remain unchanged, switching device S5 switches to the off state, and switching device S6 can switch to the on state. From time t4~t5, the current IL of the power transfer inductor decreases in the reverse direction (the direction of the current IL of the power transfer inductor is relative to times t0~t2); at time t5, the current IL of the power transfer inductor decreases to zero in the reverse direction (the direction of the current IL of the power transfer inductor is relative to times t0~t2), and the switching states of switching devices S1 and S2 remain unchanged. Switching device S3 switches to the off state, switching device S4 switches to the on state, switching device S5 remains off, and switching device S6 can switch to the off state. The dead time of the bridge arm composed of switching devices S5 and S6 is entered, and the secondary voltage Vs oscillates. After the dead time of the bridge arm composed of switching devices S5 and S6 (t5 to the next t0), at the next t0 time, switching device S1 switches to the on state, switching device S2 switches to the off state, switching device S3 remains off, switching device S4 remains on, switching device S5 remains off, and switching device S6 switches to the on state. The dead time of the bridge arm composed of switching devices S5 and S6 ends, and one switching cycle ends.

[0130] In some embodiments, unlike conventional DCM modulation, the dead time of the first target bridge arm is dynamically controlled by controlling the switching states of each switching device in the full-bridge circuit and each switching device in the half-bridge circuit of the dual active bridge converter, and the first target voltage oscillates within the dead time of the first target bridge arm.

[0131] In some embodiments, for times t1 to t2, the switching device S5 can remain in the off state, or it can switch to the on state at any time between t1 and t2 after switching to the on state at t1. That is, the switching device S5 does not need to wait until time t2 to switch from the on state to the off state, so that the bridge arm composed of switching devices S5 and S6 enters the dead time. Instead, it can switch to the off state at any time between t1 and t2 (including t1) (for t1, it remains in the off state). The bridge arm composed of switching devices S5 and S6 can enter the dead time before time t2, suppressing the generation of reactive circulating current. Similarly, for times t4 to t5, switching device S6 can remain in the off state, or it can switch to the on state at time t4 and then switch to the off state at any time between t4 and t5. That is, switching device S6 does not need to wait until time t5 to switch from the on state to the off state, causing the bridge arm composed of switching devices S5 and S6 to enter the dead time. Instead, it can switch to the off state at any time between t4 and t5 (including t4) (while remaining in the off state at t4). The bridge arm composed of switching devices S5 and S6 can enter the dead time before time t5, suppressing the generation of reactive circulating current. Therefore, in this embodiment, on the one hand, the generation of reactive circulating current is suppressed by causing the first target voltage to oscillate within the dead time of the first target bridge arm and by the multiple commutations of the first target voltage within the dead time of the first target bridge arm; on the other hand, the duration of the dead time of the first target bridge arm can be increased within a switching cycle. With the duration of the switching cycle remaining unchanged, the duration for suppressing reactive circulating current within a switching cycle is longer. By taking the above two measures, the effect of suppressing reactive circulating current can be improved, thereby reducing or eliminating the reactive circulating current generated by the dual active bridge converter.

[0132] For example Figure 1 Other operating conditions of the dual active bridge DC-DC converter topology shown can be referred to as follows: Figures 3 to 5 The timing understanding of the process and principle of suppressing reactive circulating current in dual active bridge DC-DC converters will not be elaborated here to avoid repetition.

[0133] It should be noted that for the dual active bridge DC-DC converter, under both boost positive power and boost negative power conditions, the voltage conversion ratio k > 1, and the switching devices (referring to switching devices S5 to S6) included in the half-bridge circuit 130 operate twice in one switching cycle.

[0134] In some embodiments, for Figure 1 In the topology shown, the first target bridge arm may include a bridge arm composed of switching devices S5 and S6.

[0135] In some embodiments, within a switching cycle, the duration of the intermittent excitation segment in the first half of the cycle may be unequal to or equal to the duration of the intermittent excitation segment in the second half of the cycle; the duration of the positive voltage excitation segment in the first half of the cycle may be unequal to or equal to the duration of the positive voltage excitation segment in the second half of the cycle; the duration of the negative voltage excitation segment in the first half of the cycle may be unequal to or equal to the duration of the negative voltage excitation segment in the second half of the cycle. Figures 2 to 4 Taking the timing sequence shown as an example, the duration of the intermittent excitation segment in the first half of the cycle can be unequal to the duration of the intermittent excitation segment in the second half of the cycle, meaning that the duration of t2~t3 can be unequal to the duration of t5~t0; the duration of the positive pressure excitation segment in the first half of the cycle can be unequal to the duration of the positive pressure excitation segment in the second half of the cycle, meaning that the duration of t0~t1 can be unequal to the duration of t3~t4; the duration of the negative pressure excitation segment in the first half of the cycle can be unequal to the duration of the negative pressure excitation segment in the second half of the cycle, meaning that the duration of t1~t2 can be unequal to the duration of t4~t5.

[0136] by Figure 2 and Figure 4 Taking the timing sequence shown as an example, when the first target voltage is the secondary voltage Vs, the second target voltage is the primary voltage Vp; Figure 3 and Figure 5 Taking the timing sequence shown as an example, when the first target voltage is the primary voltage Vp, the second target voltage is the secondary voltage Vs.

[0137] In some embodiments, Figure 10 It shows that for such Figure 1 The topology shown illustrates the timing of the second target voltage oscillation after the first target voltage ends its oscillation. Figure 10 The first target voltage is the secondary voltage Vs, and the second target voltage is the primary voltage Vp. The oscillation time of the secondary voltage Vs is t3~t4, and the oscillation time of the primary voltage Vp is t5~t6.

[0138] In some embodiments, with Figure 10 Taking the timing sequence shown as an example (energy transfer direction P>0 and voltage conversion ratio k<1, primary side on the input side, secondary side on the output side). At time t0, the primary voltage Vp reaches its peak value, and switching device S1 turns on with zero voltage; during the t0~t1 period, switching devices S1, S4, and S5 are all in the on state, the primary voltage Vp is equal to the input voltage u1, the secondary voltage Vs is equal to half of the output voltage (2 times u2) u2, and u1>u2. At this time, the voltage V of the power transfer inductor is V L >0, the current I of the power transfer inductor LThe current I in the power transfer inductor rises; at time t1, the current I... L Upon reaching the peak value, switch S4 is turned off. After the dead time (t1~t2) of the bridge arm composed of switches S3 and S4, at time t2, switch S3 is turned on. During the t2~t3 period, switches S1, S3, and S5 are all in the on state, the primary voltage Vp is equal to 0, and the secondary voltage Vs is equal to the output voltage u2. At this time, the voltage V of the power transfer inductor is... L <0, the current i of the power transfer inductor L The current I in the power transfer inductor decreases at time t3. L When the voltage drops to 0, switching device S5 is turned off. During the t3~t4 period, this is the dead time of the bridge arm composed of switching devices S5 and S6 (this bridge arm is the first target bridge arm), and the secondary voltage Vs (the secondary voltage Vs is the first target voltage) oscillates. At time t4, the secondary voltage Vs oscillates to its lowest point, allowing zero-voltage switching device S6 to be turned on and switching device S1 to be turned off, ending the dead time of the first target bridge arm. During the t4~t6 period, the primary voltage Vp (the primary voltage Vp is the second target voltage, and the bridge arm composed of switching devices S1 and S2 is the second target bridge arm) decreases and then oscillates (starting from time t5). At time t6, the primary voltage Vp decreases to its lowest point, allowing zero-voltage switching device S2 to be turned on, ending the dead time of the second target bridge arm. The above describes the timing of the first half of a switching cycle. The timing of the second half of this switching cycle (t6~the next t0) is dual to the timing of the first half of the cycle described above; to avoid repetition, it will not be repeated here.

[0139] In some embodiments, Figure 10 In the timing sequence shown, the switching device S5 can be turned off earlier than time t3, and its turn-on duration can be determined based on software calculation or the output of a hardware comparator.

[0140] In some embodiments, the conduction time of the main controller can be controlled by software to achieve peak-level activation. For example... Figure 10 In the timing sequence shown, the conduction time of the main conductor includes the t0~t1 segment and the t6~t7 segment.

[0141] Understandable Figure 10 In the timing sequence shown, within one switching cycle, the oscillation time periods of the first target voltage are t3~t4 and t9~t10, and the oscillation time periods of the second target voltage are t5~t6 and t11~the next t0.

[0142] This application also provides a control method for a dual active bridge DC-DC converter. This control method for the dual active bridge DC-DC converter can be applied to a terminal, and can be executed by hardware or software within the terminal.

[0143] The control method for a dual active bridge DC-DC converter provided in this application embodiment can be executed by an electronic device or a functional module or entity in an electronic device that can implement the control method for the dual active bridge DC-DC converter. The electronic devices mentioned in this application embodiment include, but are not limited to, mobile phones, tablets, computers, cameras, and wearable devices. The control method for a dual active bridge DC-DC converter provided in this application embodiment will be described below using an electronic device as the execution subject.

[0144] like Figure 11 As shown, the control method of the dual active bridge DC-DC converter includes: controlling the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0145] In actual implementation, the dual active bridge DC-DC converter, which is the control object of this control method, may include a controller, a full-bridge circuit, a half-bridge circuit, and a power transmission branch connected between the full-bridge circuit and the half-bridge circuit. The half-bridge circuit includes a half-bridge arm composed of two switching devices and a series voltage divider capacitor branch connected in parallel with the DC bus. The power transmission branch includes at least one of transformer leakage inductance, external inductance, and resonant network.

[0146] In some embodiments of this application, controlling the switching state of each switching device included in the converter so that the first target voltage oscillates during the dead time of the first target bridge arm includes: controlling the switching state of each switching device based on the input voltage, output voltage and preset power of the converter, or based on the input voltage, output voltage and output of the target control loop of the converter.

[0147] In some embodiments of this application, controlling the switching state of each switching device included in the converter so that the first target voltage oscillates during the dead time of the first target bridge arm includes: triggering at least one switching device included in the first target bridge arm to switch to the on state when the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation reaches a target number.

[0148] In some embodiments of this application, before controlling the switching states of each switching device included in the converter so that the first target voltage oscillates within the dead time of the first target bridge arm, the method further includes: determining that the converter is under light load conditions based on the preset power and power threshold of the converter.

[0149] In some embodiments of this application, after controlling the switching states of each switching device included in the converter, the method further includes: when the first target voltage stops oscillating, controlling the switching states of each switching device included in the converter so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

[0150] According to the control method of the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0151] In some embodiments of this application, after controlling the switching states of each switching device included in the converter, the method further includes: when the first target voltage oscillates to a trough, controlling the switching states of each switching device included in the converter so that the first target voltage stops oscillating.

[0152] In some embodiments of this application, when the first target voltage oscillates to a valley, controlling the switching state of each switching device included in the converter so that the first target voltage stops oscillating includes: determining that the first target voltage oscillates to a valley based on the detection result of the first target voltage output by the valley detection circuit; or determining that the first target voltage oscillates to a valley when the current corresponding to the first target voltage crosses zero.

[0153] According to the control method of the dual active bridge DC-DC converter provided in the embodiments of this application, when the first target voltage oscillates to the valley, the switching state of each switching device included in the converter is controlled to realize the valley opening of the main pipe in the first target bridge arm. This can reduce the reactive circulating current when all switching devices are turned on at zero voltage or eliminate the reactive circulating current when all switching devices are turned on at zero voltage, reduce the switching losses of the switching devices, and improve the energy conversion efficiency of the dual active bridge DC-DC converter.

[0154] It should be noted that the implementation process of the control method of the dual active bridge DC-DC converter provided in the various embodiments of this application can be referred to the aforementioned embodiments of the dual active bridge DC-DC converter. To avoid repetition, it will not be repeated here.

[0155] The control method for a dual active bridge DC-DC converter provided in this application can be executed by a control device for the dual active bridge DC-DC converter. This application uses the example of a control device for the dual active bridge DC-DC converter executing the control method to illustrate the control device for the dual active bridge DC-DC converter provided in this application.

[0156] This application also provides a control device for a dual active bridge DC-DC converter. For example... Figure 12 As shown, the control device 1200 of the dual active bridge DC-DC converter includes a control module 1210.

[0157] The control module 1210 is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

[0158] In actual implementation, the dual active bridge DC-DC converter, which is the controlled object of the control device, may include a controller, a full-bridge circuit, a half-bridge circuit, and a power transmission branch connected between the full-bridge circuit and the half-bridge circuit. The half-bridge circuit includes a half-bridge arm composed of two switching devices and a series voltage divider capacitor branch connected in parallel with the DC bus. The power transmission branch includes at least one of transformer leakage inductance, external inductance, and resonant network.

[0159] According to the control device of the dual active bridge DC-DC converter provided in the embodiments of this application, by controlling the switching state of each switching device included in the dual active bridge DC-DC converter, the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1. This enables the dual active bridge DC-DC converter to operate in discontinuous conduction mode, and reduces or eliminates the reactive circulating current generated by the dual active bridge DC-DC converter, thereby improving the energy conversion efficiency of the dual active bridge DC-DC converter.

[0160] In some embodiments, the control module 1210 is further configured to control the switching state of each switching device included in the converter when the first target voltage oscillates to a low point, so that the first target voltage stops oscillating.

[0161] In some embodiments, the dead time is greater than 0 and less than or equal to the duration of one pulse width modulation period.

[0162] In some embodiments, the first target voltage includes the voltage between the midpoints of the two arms of a full-bridge circuit or the voltage between the midpoint of the arm of a half-bridge circuit and the midpoint of the series voltage divider capacitor branch.

[0163] In some embodiments, the control module 1210 may be specifically used to control the switching state of each switching device based on the input voltage, output voltage and preset power of the converter, or based on the input voltage, output voltage and output of the target control loop of the converter.

[0164] In some embodiments, the control module 1210 can also be used to trigger at least one switching device included in the first target bridge arm to switch to the on state when the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation reaches the target number.

[0165] In some embodiments, the control module 1210 can also be used to determine that the converter is in a light-load condition based on the converter's preset power and power threshold.

[0166] In some embodiments, the control module 1210 can also be used to control the switching state of each switching device included in the converter when the first target voltage stops oscillating, so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

[0167] In some embodiments, the control module 1210 can also be used to determine that the first target voltage oscillates to the bottom based on the detection result of the first target voltage output by the valley detection circuit; or to determine that the first target voltage oscillates to the bottom when the current corresponding to the first target voltage crosses zero.

[0168] The control device for the dual active bridge DC-DC converter in this application embodiment can be an electronic device or a component within an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal or other devices besides a terminal. For example, the electronic device can be a mobile phone, tablet computer, laptop computer, PDA, in-vehicle electronic device, mobile internet device (MID), augmented reality (AR) / virtual reality (VR) device, robot, wearable device, ultra-mobile personal computer (UMPC), netbook, or personal digital assistant (PDA), etc. It can also be a server, network attached storage (NAS), personal computer (PC), television (TV), ATM, or self-service machine, etc. This application embodiment does not specifically limit the specific implementation.

[0169] The control device for the dual active bridge DC-DC converter in this embodiment can be a device with an operating system. This operating system can be Microsoft Windows, Android, iOS, or other possible operating systems; this embodiment does not specifically limit the specific operating system used.

[0170] The control device for the dual active bridge DC-DC converter provided in this application embodiment can achieve... Figure 11 The various processes implemented in the method implementation examples will not be described again here to avoid repetition.

[0171] In some embodiments, such as Figure 13 As shown, this application embodiment also provides an electronic device 1300, including a processor 1301, a memory 1302, and a computer program stored in the memory 1302 and executable on the processor 1301. When the computer program is executed by the processor 1301, it implements the various processes of the above-described control method embodiment for the dual active bridge DC-DC converter and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0172] It should be noted that the electronic devices in the embodiments of this application include the mobile electronic devices and non-mobile electronic devices described above.

[0173] This application also provides a non-volatile computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the control method embodiment of the dual active bridge DC-DC converter described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0174] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0175] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the control method for the dual active bridge DC-DC converter described above.

[0176] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0177] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the control method embodiment of the dual active bridge DC-DC converter described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0178] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0179] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0180] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0181] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0182] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0183] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A dual active bridge DC-DC converter, characterized in that, include: The controller, the full-bridge circuit, the half-bridge circuit, and the power transmission branch connected between the full-bridge circuit and the half-bridge circuit; the half-bridge circuit includes a half-bridge arm composed of two switching devices and a series voltage divider capacitor branch connected in parallel with the DC bus; the power transmission branch includes at least one of transformer leakage inductance, external inductance, and resonant network. The controller is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of oscillation periods is greater than or equal to 1.

2. The dual active bridge DC-DC converter according to claim 1, characterized in that, The controller is further configured to control the switching state of each switching device included in the converter when the first target voltage oscillates to its lowest point, so that the first target voltage stops oscillating.

3. The dual active bridge DC-DC converter according to claim 1, characterized in that, The dead time is greater than 0 and less than or equal to the duration of one pulse width modulation period.

4. The dual active bridge DC-DC converter according to claim 1, characterized in that, The first target voltage includes the voltage between the midpoints of the two arms of the full-bridge circuit or the voltage between the midpoint of the arm of the half-bridge circuit and the midpoint of the series voltage divider capacitor branch.

5. The dual active bridge DC-DC converter according to claim 1, characterized in that, The controller is used to control the switching state of each switching device based on the input voltage, output voltage and preset power of the converter, or based on the input voltage, output voltage and output of the target control loop of the converter.

6. The dual active bridge DC-DC converter according to claim 1, characterized in that, The controller is configured to trigger at least one of the switching devices included in the first target bridge arm to switch to the on state when the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation has reached a target number.

7. The dual active bridge DC-DC converter according to claim 1, characterized in that, The controller is also used to determine that the converter is in a light-load condition based on the preset power and power threshold of the converter.

8. The dual active bridge DC-DC converter according to claim 1, characterized in that, The controller also controls the switching state of each switching device included in the converter when the first target voltage stops oscillating, so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

9. The dual active bridge DC-DC converter according to claim 2, characterized in that, The controller is used to determine, based on the detection result of the first target voltage output by the valley detection circuit, that the first target voltage oscillates to the valley. Alternatively, if the current corresponding to the first target voltage crosses zero, it is determined that the first target voltage has oscillated to its lowest point.

10. A control method for a dual active bridge DC-DC converter, characterized in that, The method includes: The switching states of each switching device included in the converter are controlled so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of cycles of the oscillation is greater than or equal to 1.

11. The control method for the dual active bridge DC-DC converter according to claim 10, characterized in that, After controlling the switching states of each switching device included in the converter, the method further includes: When the first target voltage oscillates to its lowest point, the switching states of each switching device included in the converter are controlled so that the first target voltage stops oscillating.

12. The control method for the dual active bridge DC-DC converter according to claim 10, characterized in that, Controlling the switching states of each switching device in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, includes: The switching states of each switching device are controlled based on the input voltage, output voltage, and preset power of the converter, or based on the input voltage, output voltage, and output of the target control loop.

13. The control method for the dual active bridge DC-DC converter according to claim 10, characterized in that, Controlling the switching states of each switching device in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, includes: When the oscillation detection circuit detects that the number of cycles of the first target voltage oscillation has reached the target number, it triggers at least one of the switching devices included in the first target bridge arm to switch to the on state.

14. The control method for the dual active bridge DC-DC converter according to any one of claims 10 to 13, characterized in that, Before controlling the switching states of the switching devices included in the converter to cause the first target voltage to oscillate during the dead time of the first target bridge arm, the method further includes: Based on the preset power and power threshold of the converter, it is determined that the converter is in a light load condition.

15. The control method for the dual active bridge DC-DC converter according to claim 10, characterized in that, After controlling the switching states of each switching device included in the converter, the method further includes: When the first target voltage stops oscillating, the switching state of each switching device included in the converter is controlled so that the second target voltage oscillates during the dead time of the second target bridge arm, and the number of oscillation periods is greater than or equal to 1; the second target voltage corresponds to the first target voltage.

16. The control method for a dual active bridge DC-DC converter according to claim 11, characterized in that, When the first target voltage oscillates to its lowest point, controlling the switching states of each switching device in the converter to stop the oscillation of the first target voltage includes: Based on the detection result of the first target voltage output by the valley detection circuit, it is determined that the first target voltage has oscillated to the valley; or if the current corresponding to the first target voltage crosses zero, it is determined that the first target voltage has oscillated to the valley.

17. A control device for a dual active bridge DC-DC converter, characterized in that, include: The control module is used to control the switching state of each switching device included in the converter, so that the first target voltage oscillates during the dead time of the first target bridge arm, and the number of cycles of the oscillation is greater than or equal to 1.

18. The control device for the dual active bridge DC-DC converter according to claim 17, characterized in that, The control module is also used to control the switching state of each switching device included in the converter when the first target voltage oscillates to its lowest point, so that the first target voltage stops oscillating.

19. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the control method for the dual active bridge DC-DC converter as described in any one of claims 10 to 16.

20. A non-volatile computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the control method for a dual active bridge DC-DC converter as described in any one of claims 10 to 16.

21. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the control method for the dual active bridge DC-DC converter as described in any one of claims 10 to 16.

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