Control method and device for realizing phase-shift full-bridge light-load soft switching, equipment and storage medium

Abstract

The application discloses a control method and device for realizing phase-shift full-bridge light-load soft switching, equipment and a storage medium, relates to the technical field of vehicle-mounted power supply, and the method comprises: the method comprises: obtaining current operation parameters of a DC-DC converter; determining the advance conduction time of a synchronous rectifier according to the current operation parameters; controlling the switch tube in the original side circuit to perform phase-shift control based on a phase-shift control signal; and controlling the synchronous rectifier to conduct in advance during the zero-crossing period of the secondary side current according to the advance conduction time in the control period of the phase-shift control signal, so as to increase the current of the original side resonant inductor, and enable the lagging bridge arm switch tube in the original side circuit to realize zero-voltage turn-on in the dead time. Compared with the prior art, the application realizes zero-voltage turn-on of the lagging bridge arm under light load without increasing hardware conditions, reduces switching loss, improves light load efficiency and EMI performance by controlling the secondary side synchronous rectifier to conduct in advance to increase the original side current.

Description

Technical Field

[0001] This application relates to the field of vehicle power supply technology, and in particular to a control method, device, equipment and storage medium for realizing phase-shifted full-bridge light-load soft switching. Background Technology

[0002] Phase-shifted full-bridge converters are widely used in automotive DC-DC converters because they can achieve zero-voltage turn-on of the switching transistors. In existing technologies, the converter achieves energy transfer through phase-shift control of the primary-side switching transistors and uses the resonant inductor current to charge and discharge the junction capacitance of the lagging bridge arm switching transistors during the dead time, thereby achieving soft switching.

[0003] However, under light load conditions, due to the small secondary current, the resonant inductor current coupled to the primary side lacks sufficient energy to discharge the junction capacitance voltage of the lagging bridge arm switch to zero within the dead time, preventing the switch from achieving zero-voltage turn-on. To address this issue, existing solutions have focused on increasing the resonant inductor or adding auxiliary circuitry to enhance the resonant current under light load conditions. However, these methods suffer from drawbacks such as significant duty cycle loss, circuit redundancy, and increased cost.

[0004] Therefore, how to achieve zero-voltage turn-on of the lagging bridge arm under light load without increasing hardware is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this application is to provide a control method, device, equipment, and storage medium for realizing phase-shifted full-bridge light-load soft switching, aiming to solve the technical problem of how to achieve zero-voltage turn-on of the lagging bridge arm under light load without increasing hardware.

[0006] To achieve the above objectives, this application proposes a control method for implementing phase-shifted full-bridge light-load soft switching, the method comprising: The method is applied to a DC-DC converter, which includes a primary-side circuit, a transformer, and a secondary-side circuit. The secondary-side circuit includes a synchronous rectifier diode. The method includes: Obtain the current operating parameters of the DC-DC converter; Based on the current operating parameters, determine the advance conduction time of the synchronous rectifier tube; Based on the phase-shift control signal, the switching transistors in the primary-side circuit are controlled to perform phase-shift control. During the control period of the phase-shift control signal, the synchronous rectifier is controlled to turn on in advance during the zero-crossing period of the secondary current according to the advance turn-on time, so as to increase the current of the primary resonant inductor and enable the lagging bridge arm switch in the primary circuit to achieve zero-voltage turn-on during the dead time.

[0007] In one embodiment, the step of determining the advance conduction time of the synchronous rectifier tube based on the current operating parameters includes: Obtain a preset advance conduction time mapping table, which is used to characterize the correspondence between operating parameters and advance conduction time; Using the current operating parameters as an index, the advance conduction time corresponding to the current operating parameters is queried from the advance conduction time mapping table and determined.

[0008] In one embodiment, the advance turn-on time mapping table is pre-established through a calibration process, which includes: The operating voltage of the DC-DC converter is set to multiple voltage values; For each voltage value, within the range of load current from zero to a preset current threshold, the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on is sequentially calibrated to generate the advance turn-on time mapping table.

[0009] In one embodiment, the step of sequentially determining the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on within a load current range from zero to a preset current threshold includes: At the voltage value, the load current is gradually increased from zero in preset steps; Under the current load current, adjust the advance turn-on time of the synchronous rectifier until the drain-source voltage of the lagging bridge arm switch is observed to drop to zero before its gate drive signal arrives. Record the current load current that enables the lagging bridge arm switch to turn on at zero voltage and its corresponding turn-on time.

[0010] In one embodiment, the step of determining the advance conduction time of the synchronous rectifier tube based on the current operating parameters further includes: Obtain the output current of the DC-DC converter; Determine whether the output current is greater than a preset current threshold; If the output current is greater than the preset current threshold, the early turn-on time is set to zero.

[0011] In one embodiment, before the step of obtaining the current operating parameters of the DC-DC converter, the method further includes: The soft-start procedure is executed to control the output voltage to rise smoothly by gradually increasing the phase shift angle. When the output voltage reaches the preset closed-loop control point, the soft-start program exits and switches to closed-loop control mode.

[0012] In one embodiment, the closed-loop control mode includes voltage outer loop control and current inner loop control, and the method further includes: By using voltage outer loop control, a current reference value is generated based on the difference between the output voltage reference value and the actual output voltage; The phase shift angle required for the phase shift control signal is generated based on the difference between the current reference value and the actual output current through the current inner loop control.

[0013] Furthermore, to achieve the above objectives, this application also proposes a control device for realizing phase-shifted full-bridge light-load soft switching, the device comprising: The parameter acquisition module is used to acquire the current operating parameters of the DC-DC converter; The time determination module is used to determine the advance conduction time of the synchronous rectifier tube based on the current operating parameters. The phase-shift control module is used to control the switching transistors in the primary circuit to perform phase-shift control based on the phase-shift control signal; The conduction control module is used to control the synchronous rectifier to conduct earlier during the zero-crossing period of the secondary current according to the advance conduction time within the control cycle of the phase shift control signal, so as to increase the current of the primary resonant inductor and enable the lagging bridge arm switch in the primary circuit to achieve zero-voltage turn-on within the dead time.

[0014] In addition, to achieve the above objectives, this application also proposes a control device for implementing phase-shifted full-bridge light-load soft switching, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the control method for implementing phase-shifted full-bridge light-load soft switching as described above.

[0015] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the control method for implementing phase-shifted full-bridge light-load soft switching as described above.

[0016] This application provides a control method for implementing phase-shifted full-bridge light-load soft switching. The method is applied to a DC-DC converter, which includes a primary circuit, a transformer, and a secondary circuit. The secondary circuit includes a synchronous rectifier. The method includes: acquiring the current operating parameters of the DC-DC converter; determining the advance turn-on time of the synchronous rectifier based on the current operating parameters; controlling the switching transistor in the primary circuit to perform phase-shift control based on a phase-shift control signal; and controlling the synchronous rectifier to turn on earlier during the secondary current zero-crossing period within the control period of the phase-shift control signal, according to the advance turn-on time, to increase the current of the primary resonant inductor, thereby enabling the lagging bridge arm switching transistor in the primary circuit to achieve zero-voltage turn-on within the dead time.

[0017] This application first obtains the current operating parameters of the DC-DC converter. Then, based on the current operating parameters, it determines the advance turn-on time of the synchronous rectifier. Next, it controls the phase-shift control of the switching transistors in the primary circuit based on a phase-shift control signal. Finally, within the control cycle of the phase-shift control signal, based on the advance turn-on time, it controls the synchronous rectifier to turn on earlier during the zero-crossing period of the secondary current, thereby increasing the current of the primary resonant inductor. This allows the lagging bridge arm switching transistor in the primary circuit to achieve zero-voltage turn-on within the dead time. Compared to existing methods, this application achieves zero-voltage turn-on of the lagging bridge arm under light load conditions without adding hardware by controlling the secondary synchronous rectifier to turn on earlier to increase the primary current, reducing switching losses and improving light-load efficiency and EMI performance. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A flowchart is provided for Embodiment 1 of the control method for implementing phase-shifted full-bridge light-load soft switching in this application; Figure 2 A flowchart illustrating Embodiment 2 of the control method for implementing phase-shifted full-bridge light-load soft switching in this application; Figure 3 This is a flowchart illustrating Embodiment 3 of the control method for implementing phase-shifted full-bridge light-load soft switching in this application; Figure 4This is a schematic diagram of the module structure of the control device for implementing phase-shifted full-bridge light-load soft switching in an embodiment of this application; Figure 5 This is a schematic diagram of the equipment structure of the hardware operating environment involved in the control method for implementing phase-shifted full-bridge light-load soft switching in the embodiments of this application.

[0021] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0023] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0024] The main solution of this application embodiment is: the phase-shifted full-bridge converter is widely used in automotive DC-DC converters because it can achieve zero-voltage turn-on of the switching transistors. In the prior art, the converter achieves energy transfer through phase-shift control of the primary-side switching transistors, and completes the charging and discharging of the junction capacitance of the lagging bridge arm switching transistors by utilizing the resonant inductor current during the dead time, thereby achieving soft switching.

[0025] However, under light load conditions, due to the small secondary current, the resonant inductor current coupled to the primary side lacks sufficient energy to discharge the junction capacitance voltage of the lagging bridge arm switch to zero within the dead time, preventing the switch from achieving zero-voltage turn-on. To address this issue, existing solutions have focused on increasing the resonant inductor or adding auxiliary circuitry to enhance the resonant current under light load conditions. However, these methods suffer from drawbacks such as significant duty cycle loss, circuit redundancy, and increased cost.

[0026] This application first obtains the current operating parameters of the DC-DC converter. Then, based on the current operating parameters, it determines the advance turn-on time of the synchronous rectifier. Next, it controls the phase-shift control of the switching transistors in the primary circuit based on a phase-shift control signal. Finally, within the control cycle of the phase-shift control signal, based on the advance turn-on time, it controls the synchronous rectifier to turn on earlier during the zero-crossing period of the secondary current, thereby increasing the current of the primary resonant inductor. This allows the lagging bridge arm switching transistor in the primary circuit to achieve zero-voltage turn-on within the dead time. Compared to existing methods, this application achieves zero-voltage turn-on of the lagging bridge arm under light load conditions without adding hardware by controlling the secondary synchronous rectifier to turn on earlier to increase the primary current, reducing switching losses and improving light-load efficiency and EMI performance.

[0027] It should be noted that the execution subject of the following embodiments can be a control device for implementing phase-shifted full-bridge light-load soft switching, or a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or a control device capable of implementing the above functions for phase-shifted full-bridge light-load soft switching, etc. This embodiment does not specifically limit it in this way. The following uses the control device for implementing phase-shifted full-bridge light-load soft switching (hereinafter referred to as the device) as the execution subject as an example to describe this embodiment and the following embodiments.

[0028] Based on this, this application proposes a control method for implementing phase-shifted full-bridge light-load soft switching according to the first embodiment. Please refer to [link / reference]. Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the control method for implementing phase-shifted full-bridge light-load soft switching according to this application. The control method for implementing phase-shifted full-bridge light-load soft switching includes steps S10 to S40: The method is applied to a DC-DC converter, which includes a primary circuit, a transformer, and a secondary circuit, wherein the secondary circuit includes a synchronous rectifier diode.

[0029] Step S10: Obtain the current operating parameters of the DC-DC converter.

[0030] It should be noted that the aforementioned DC-DC converter can be a power electronic device that converts DC voltage into different levels of DC voltage.

[0031] The primary-side circuit mentioned above can be the side circuit of a DC-DC converter connected to the input power supply, and typically includes a switching transistor and a resonant inductor.

[0032] The aforementioned transformer can be an electromagnetic component that achieves voltage transformation and electrical isolation, comprising a primary winding and a secondary winding. The aforementioned secondary circuit can be the circuit connected to the load in a DC-DC converter, typically including rectifier components and filter components.

[0033] The aforementioned synchronous rectifier can be a component that uses a controllable switching device (such as a metal-oxide-semiconductor field-effect transistor) instead of a traditional diode for rectification, thereby reducing the conduction loss of the rectification stage by controlling the on and off of the switching device.

[0034] It is understandable that the above-mentioned current operating parameters can be a set of physical quantities that reflect the real-time operating status of the DC-DC converter, such as input voltage value, output voltage value, output current value, or load power value.

[0035] In its implementation, before performing any control adjustments, the device first identifies the applicable circuit topology. It confirms that its control method applies to a DC-DC converter, and that the DC-DC converter includes a primary circuit, a transformer, and a secondary circuit, with a synchronous rectifier diode included in the secondary circuit. Next, it begins executing the control flow to obtain the current operating parameters of the DC-DC converter. This can be achieved by acquiring the input and output voltages using internal voltage sensors and the output current using current sensors, thus obtaining a set of parameter values ​​representing the current operating state.

[0036] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For instance, suppose an on-board DC-DC converter is operating with an input voltage of 400V and a light load connected to its output, resulting in an output current of 2A. The aforementioned device, acting as a controller, will first confirm that its control method is applied to this DC-DC converter. Next, the device will obtain the current input voltage of 400V through a voltage detection circuit and the current output current of 2A through a current detection circuit. These values ​​(400V input voltage, 2A output current) constitute the aforementioned current operating parameters.

[0037] Step S20: Determine the advance conduction time of the synchronous rectifier tube based on the current operating parameters.

[0038] It should be noted that the aforementioned early turn-on time can refer to the length of time during which the synchronous rectifier is controlled to turn on earlier than the moment when the secondary current naturally crosses zero within a switching cycle.

[0039] The aforementioned natural zero-crossing point of the secondary current can refer to the transition moment when the current in the secondary winding of the transformer changes from forward flow to reverse flow, or from reverse flow to forward flow, at which point the current value approaches zero.

[0040] In its implementation, after acquiring the current operating parameters, the device determines the advance turn-on time of the synchronous rectifier tube based on these parameters. Using the acquired current operating parameters as query conditions, it accesses the internally stored mapping relationship data. It searches for a record matching the current operating parameters in this mapping relationship data and extracts the corresponding advance turn-on time value from that record. If the current operating parameter corresponds exactly to a reference point in the mapping relationship data, the advance turn-on time corresponding to that reference point is directly read. If the current operating parameter lies between multiple reference points, the advance turn-on time corresponding to the current operating parameter can be estimated through interpolation.

[0041] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assume that the device has pre-stored an advance turn-on time mapping table, which records that when the input voltage is 400V and the output current is 2A, the corresponding advance turn-on time is 500 nanoseconds. In the previous step, the device obtained that the current input voltage is 400V and the current output current is 2A. Subsequently, the device uses the 400V input voltage and 2A output current as indexes to query the advance turn-on time mapping table, thereby determining that the advance turn-on time of the synchronous rectifier is 500 nanoseconds.

[0042] Step S30: Based on the phase-shift control signal, control the switching transistors in the primary circuit to perform phase-shift control.

[0043] It should be noted that the aforementioned phase-shift control signal can be a set of drive instructions used to control the turn-on timing of the switching transistors in the primary circuit.

[0044] The phase-shift control described above can be a control method that controls the output energy by adjusting the phase difference between the drive signals of the leading and lagging bridge arm switches in the primary-side circuit. The aforementioned switches can be power semiconductor devices whose on / off states are controlled by external signals, such as metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated-gate bipolar transistors (IGBTs).

[0045] In the specific implementation, after determining the advance turn-on time of the synchronous rectifier diodes, a phase-shift control signal is generated to control the primary circuit. Based on the phase-shift control signal, the switching transistors in the primary circuit are controlled to undergo phase shift control. The phase-shift control signal is sent to each switching transistor in the primary circuit. The phase-shift control signal specifies the start time and duration of conduction for each switching transistor within one switching cycle. Specifically, the two switching transistors of the leading arm are controlled to alternately conduct with a fixed 50% duty cycle, and the two switching transistors of the lagging arm are also controlled to alternately conduct with a fixed 50% duty cycle. Subsequently, by adjusting the phase difference between the leading arm drive signal and the lagging arm drive signal, alternating positive and negative voltage pulses are generated across the primary side of the transformer, thereby transferring the energy from the input to the secondary side.

[0046] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, suppose we need to control a phase-shifted full-bridge converter to operate under light load. A set of phase-shifting control signals is generated, where the upper and lower transistors of the leading arm conduct complementaryly with a 50% duty cycle, and a dead time is set between them. The upper and lower transistors of the lagging arm also conduct complementaryly with a 50% duty cycle, similarly with a dead time. The drive signal of the lagging arm is delayed by a phase shift angle relative to the drive signal of the leading arm. Assuming the phase shift angle is set to 30 degrees, the upper transistor of the lagging arm will only start conducting 30 degrees after the upper transistor of the leading arm has conducted, thereby achieving energy transfer and control.

[0047] Step S40: During the control period of the phase shift control signal, according to the advance turn-on time, the synchronous rectifier is controlled to turn on in advance during the zero-crossing period of the secondary current, so as to increase the current of the primary resonant inductor, so that the lagging bridge arm switch in the primary circuit can achieve zero-voltage turn-on during the dead time.

[0048] It should be noted that the control period mentioned above can refer to the time required for the switching transistor in the phase-shifted full-bridge converter to complete one full turn-on and turn-off process, and its reciprocal is the switching frequency.

[0049] The aforementioned period of zero-crossing secondary current can refer to the transition period during which the current in the secondary winding of the transformer decreases to zero in one direction and prepares to increase in the other direction.

[0050] The aforementioned primary resonant inductor can refer to an inductor element connected to the primary winding of a transformer or forming a resonant cavity together with the transformer leakage inductance, used to store energy and participate in the soft switching process of the switching transistor.

[0051] The aforementioned lagging bridge arm switches can refer to two switches in a phase-shifted full-bridge topology where the drive signal has a phase delay relative to the leading bridge arm switch.

[0052] The aforementioned dead time can refer to the interval between the upper and lower switches in the same bridge arm, which is set to avoid shoot-through short circuits, during which both switches are in the off state.

[0053] The aforementioned zero-voltage turn-on can refer to a working state in which the switching transistor is triggered to conduct when the voltage across its drain and source terminals drops to near zero volts, thereby significantly reducing switching losses.

[0054] In practical implementation, after controlling the phase-shifting transistor in the primary circuit with the phase-shifting control signal, the synchronous rectifier in the secondary circuit is further controlled. Within a control cycle defined by the phase-shifting control signal, the synchronous rectifier is controlled to turn on early during the zero-crossing period of the secondary current, according to the previously determined advance turn-on time. The zero-crossing point of the secondary current is monitored, and before the secondary current completely drops to zero, a turn-on drive signal is output to the synchronous rectifier according to the duration specified by the advance turn-on time. After the synchronous rectifier turns on early, the output filter capacitor or low-voltage battery forms a loop through the synchronous rectifier and the output filter inductor, causing the secondary current to rise. This rise in secondary current is coupled to the primary side through the transformer, thereby increasing the current of the primary resonant inductor. When the current of the primary resonant inductor increases to meet the energy condition, within the aforementioned dead time, the increased current can complete the charging and discharging of the junction capacitance of the lagging bridge arm switch, causing the voltage across the lagging bridge arm switch to drop to near zero volts. Subsequently, at the end of the aforementioned dead time, the lagging bridge arm switch is triggered to conduct under conditions where the voltage across its terminals is close to zero volts, thereby achieving zero-voltage turn-on.

[0055] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assuming the switching frequency of a phase-shifted full-bridge converter is 100 kHz, then one control cycle is 10 microseconds. The aforementioned device previously determined the advance turn-on time to be 500 nanoseconds. The device monitors the secondary current waveform and outputs a turn-on drive signal to the synchronous rectifier 500 nanoseconds before detecting that the secondary current is about to cross zero. After the synchronous rectifier turns on early, the secondary current rises from near zero amperes to 5 amperes. This 5-ampere secondary current is coupled through the transformer, causing the current in the primary resonant inductor to increase from 1 ampere to 8 amperes. During the dead time of the lagging bridge arm switch, the aforementioned 8-ampere resonant inductor current charges and discharges the junction capacitance of the lagging bridge arm switch, pulling the voltage across the switch down from 400 volts to near 0 volts. Subsequently, the gate drive signal of the lagging bridge arm switch arrives, and the switch turns on under the condition that the drain-source voltage is about 0 volts, realizing zero-voltage turn-on.

[0056] This embodiment first obtains the current operating parameters of the DC-DC converter. Then, based on the current operating parameters, it determines the advance turn-on time of the synchronous rectifier. Next, it controls the phase-shift control of the switching transistors in the primary circuit based on the phase-shift control signal. Finally, within the control period of the phase-shift control signal, based on the advance turn-on time, it controls the synchronous rectifier to turn on earlier during the zero-crossing period of the secondary current, thereby increasing the current of the primary resonant inductor. This allows the lagging bridge arm switching transistor in the primary circuit to achieve zero-voltage turn-on within the dead time. Compared to existing methods, this embodiment achieves zero-voltage turn-on of the lagging bridge arm under light load conditions without adding hardware by controlling the secondary synchronous rectifier to turn on earlier to increase the primary current, reducing switching losses and improving light-load efficiency and EMI performance.

[0057] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description and will not be repeated hereafter. On this basis, a second embodiment of the control method for implementing phase-shifted full-bridge light-load soft switching of this application is proposed. Please refer to... Figure 2 , Figure 3 This is a flowchart illustrating Embodiment 2 of the control method for implementing phase-shifted full-bridge light-load soft switching in this application. To determine the advance conduction time of the synchronous rectifier diodes, such as... Figure 2 As shown, in this embodiment, the step of determining the advance conduction time of the synchronous rectifier tube based on the current operating parameters includes: Step S201: Obtain a preset advance conduction time mapping table, which is used to characterize the correspondence between operating parameters and advance conduction time.

[0058] It should be noted that the aforementioned early turn-on time mapping table can be a data structure used to store the correspondence between operating parameters and early turn-on times.

[0059] The above operating parameters can be a combination of input voltage and output current.

[0060] The above correspondence can mean that each specific combination of operating parameters uniquely corresponds to a pre-conduction time value.

[0061] In the specific implementation, when determining the advance turn-on time of the synchronous rectifier, a pre-established and stored advance turn-on time mapping table is first obtained. This mapping table is then read from internal memory. The mapping table records multiple operating parameter nodes and the corresponding advance turn-on time for each node. Using the previously obtained current operating parameters as a query index, the mapping table is searched for a matching relationship. Through this matching relationship, the appropriate advance turn-on time for the current operating state can be determined.

[0062] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assume that an advance turn-on time mapping table is stored internally. The first column of this mapping table records the input voltage value, the second column records the output current value, and the third column records the advance turn-on time. The mapping table records a data point: an input voltage of 400V and an output current of 2A correspond to an advance turn-on time of 500 nanoseconds. After obtaining the current input voltage of 400V and the current output current of 2A, the mapping table is read from memory. Then, using the input voltage of 400V and the output current of 2A as indices, the corresponding advance turn-on time of 500 nanoseconds is found in the mapping table.

[0063] Step S202: Using the current operating parameters as an index, query and determine the advance conduction time corresponding to the current operating parameters from the advance conduction time mapping table.

[0064] It should be noted that the above index can be an identifier used to quickly locate the target data position in a data table.

[0065] In this step, the aforementioned current operating parameters serve as an index, meaning that the device uses the specific values ​​of the current operating parameters as search keywords to match records in the advance conduction time mapping table.

[0066] In the specific implementation, after obtaining the preset advance conduction time mapping table, the previously obtained current operating parameters are used as indexes. The specific values ​​of these current operating parameters are then used to perform a query operation in the advance conduction time mapping table. Each record in the mapping table is compared to find an entry that matches the value of the current operating parameter. When a matching entry is found, the advance conduction time corresponding to the current operating parameter is extracted from that entry. If the current operating parameter is exactly equal to the value of a preset node in the mapping table, the advance conduction time corresponding to that node is directly read. If the current operating parameter lies between two adjacent nodes in the mapping table, an advance conduction time value between the corresponding times of the two nodes can be calculated using linear interpolation or other interpolation methods.

[0067] To facilitate understanding, the following example is used for explanation, but it does not impose specific limitations on this embodiment. For example, assume that the above early turn-on time mapping table records an early turn-on time of 500 nanoseconds corresponding to an input voltage of 400V and an output current of 2A, and also records an early turn-on time of 200 nanoseconds corresponding to an input voltage of 400V and an output current of 5A. The obtained current operating parameters are an input voltage of 400V and an output current of 3A. Using the 400V input voltage and 3A output current as indexes, a lookup is performed in the above mapping table. Since there is no record in the mapping table that corresponds exactly to 3A, the 500 nanoseconds corresponding to 2A and the 200 nanoseconds corresponding to 5A are obtained. Through linear interpolation, the following calculation is performed: 200 nanoseconds plus (500 nanoseconds minus 200 nanoseconds) multiplied by (5A minus 3A) divided by (5A minus 2A), i.e., 200 + 300 × 2 / 3 = 400 nanoseconds. The final early turn-on time is determined to be 400 nanoseconds.

[0068] Furthermore, in order to generate a complete advance turn-on time mapping table, in this embodiment, the advance turn-on time mapping table is pre-established through a calibration process, which includes: Step S2011: Set the operating voltage of the DC-DC converter to multiple voltage values.

[0069] Step S2012: For each voltage value, within the range of load current from zero to a preset current threshold, the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on is sequentially calibrated to generate the advance turn-on time mapping table.

[0070] It should be noted that the above operating voltage can refer to the DC voltage value input to the primary circuit of the DC-DC converter.

[0071] The aforementioned preset current threshold can be a pre-set current limit value. When the load current exceeds this limit value, the converter can achieve zero-voltage turn-on of the lagging bridge arm switch using its own energy, without the need to pre-turn on the synchronous rectifier.

[0072] The aforementioned minimum turn-on time can refer to the shortest turn-on time value required for the lagging bridge arm switch to achieve zero-voltage turn-on, which is less than or equal to any other turn-on time value that can achieve zero-voltage turn-on.

[0073] In the specific implementation, during the generation of the early turn-on time mapping table, the operating voltage of the aforementioned DC-DC converter is first set to multiple different voltage values. Starting from the highest operating voltage, the voltage is gradually decreased according to a preset voltage step size, and multiple voltage test points are selected. Next, for each selected voltage value, within the range where the load current gradually increases from zero amperes to a preset current threshold, the minimum early turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on is calibrated sequentially. For each fixed voltage value and fixed load current value, the early turn-on time of the synchronous rectifier is gradually increased from zero, while the drain-source voltage waveform of the lagging bridge arm switch is observed. When the drain-source voltage of the lagging bridge arm switch is observed to have dropped to near zero volts before the gate drive signal arrives, the currently set early turn-on time is recorded as the minimum early turn-on time at that operating point. The above calibration process is repeated for each load current test point at each voltage value, and the minimum early turn-on time data corresponding to all test points are collected. Finally, all the calibrated data are organized into a table to generate a complete early turn-on time mapping table.

[0074] To facilitate understanding, the following examples are provided for illustration, but they do not impose specific limitations on this embodiment. For instance, assume that the operating voltage range of the aforementioned DC-DC converter is 200V to 400V, and set the operating voltage to five values: 400V, 350V, 300V, 250V, and 200V. Set the preset current threshold to 10A. With an input voltage of 400V, set the electronic load to 0A, and gradually increase the synchronous rectifier's turn-on advance time. It is found that when the turn-on advance time is 800 nanoseconds, the lagging bridge arm switch achieves zero-voltage turn-on, so the minimum turn-on advance time is recorded as 800 nanoseconds. Next, increase the load current to 2A, and find that zero-voltage turn-on is achieved when the turn-on advance time is 500 nanoseconds, so 500 nanoseconds is recorded. Continue to increase the load current to 4A, 6A, 8A, and 10A, and record the corresponding minimum turn-on advance time for each. Subsequently, the input voltage was reduced to 350V, and the load current calibration process from 0A to 10A was repeated, recording the minimum turn-on time corresponding to each current point. Finally, the minimum turn-on times recorded at all voltage and current points were summarized to generate a mapping table with the input voltage as the x-axis, the load current as the y-axis, and the table content as the minimum turn-on time.

[0075] Further, in this embodiment, the step of sequentially determining the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on within the range of load current from zero to a preset current threshold includes: Step S20121: Under the voltage value, the load current is gradually increased from zero with a preset step size.

[0076] Step S20122: Under the current load current, adjust the advance turn-on time of the synchronous rectifier until the drain-source voltage of the lagging bridge arm switch is observed to have dropped to zero before its gate drive signal arrives.

[0077] It should be noted that the preset step size mentioned above can refer to a fixed increment value for each increase in load current.

[0078] The aforementioned drain-source voltage can refer to the voltage difference between the drain and source terminals of a metal-oxide-semiconductor field-effect transistor when it is used as a switching transistor.

[0079] The aforementioned gate drive signal can refer to a control voltage pulse used to control the switching transistor to turn on and off. When this signal is applied to the gate of the switching transistor, the switching transistor enters the on state.

[0080] In the specific implementation, when calibrating for a fixed voltage value, the load current is gradually increased from zero amperes in preset steps. First, the electronic load is set to zero amperes. After completing the calibration at the current current point, the load current is increased by a preset step, and the calibration continues for the next current point until the load current reaches a preset current threshold. Under the current load current, the advance turn-on time of the synchronous rectifier is adjusted, while continuously observing the drain-source voltage waveform and gate drive signal waveform of the lagging bridge arm switch. The advance turn-on time is gradually increased from zero, with each increment being a small time increment. After each adjustment, it is determined whether the drain-source voltage of the lagging bridge arm switch has dropped to near zero volts before the arrival of its gate drive signal. When it is observed that the drain-source voltage has dropped to near zero volts before the rising edge of the gate drive signal arrives, the adjustment of the advance turn-on time is stopped, and the current advance turn-on time is recorded as the calibration result at that operating point.

[0081] To facilitate understanding, the following example is used for explanation, but it does not impose specific limitations on this embodiment. For example, suppose we are calibrating an operating point with an input voltage of 400V, setting a preset step size of 2A and a preset current threshold of 10A. First, the electronic load is set to 0A, and the turn-on time of the synchronous rectifier is gradually increased. It is found that the turn-on time needs to reach 800 nanoseconds for the drain-source voltage of the lagging bridge arm switch to drop to zero before the gate drive signal arrives. After completing the 0A calibration, the load current is increased from 2A to 2A. At a 2A load current, the turn-on time is gradually increased from zero. When the turn-on time increases to 500 nanoseconds, the drain-source voltage waveform of the lagging bridge arm switch is observed on an oscilloscope to have dropped to near 0 volts before the rising edge of the gate drive signal arrives. At this point, the adjustment is stopped and 500 nanoseconds is recorded. Then, the load current is increased to 4A, and the above adjustment and observation process is repeated.

[0082] Step S20213: Record the current load current that enables the lagging bridge arm switch to turn on at zero voltage and its corresponding early turn-on time.

[0083] It should be noted that the aforementioned current load current may refer to the instantaneous current value set by the electronic load during calibration, which reflects the output current of the DC-DC converter at the current operating point.

[0084] In the specific implementation, after observing that the drain-source voltage of the lagging bridge arm switch has dropped to zero before its gate drive signal arrives, a recording operation is performed. The load current value set by the electronic load at this time is recorded as the current load current that enables the lagging bridge arm switch to achieve zero-voltage turn-on. Simultaneously, the adjusted and determined advance turn-on time value of the synchronous rectifier is recorded as the advance turn-on time corresponding to the aforementioned current load current. A one-to-one correspondence is established between the recorded current load current and the advance turn-on time, and this correspondence is stored as a record in the advance turn-on time mapping table. The load current is gradually increased according to a preset step size, and the above adjustment and recording process is repeated at each load current point, thereby collecting correspondence data at multiple different load current points.

[0085] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assume calibration is performed under an input voltage of 400V. When the electronic load is set to 2A, after adjustment, it is found that the bridge arm switch achieves zero-voltage turn-on when the turn-on advance time is 500 nanoseconds. Record the current load current as 2A and the corresponding turn-on advance time as 500 nanoseconds. Subsequently, the electronic load is increased to 4A, and after adjustment, it is found that zero-voltage turn-on is achieved when the turn-on advance time is 300 nanoseconds. Therefore, record the turn-on advance time of 300 nanoseconds corresponding to a load current of 4A. Continue to increase the load current to 6A, and record that 6A corresponds to 200 nanoseconds. Finally, store these three sets of correspondences (2A corresponds to 500 nanoseconds, 4A corresponds to 300 nanoseconds, and 6A corresponds to 200 nanoseconds) in the turn-on advance time mapping table as calibration data under an input voltage of 400V.

[0086] Furthermore, in order to set the early turn-on time to zero, in this embodiment, the step of determining the early turn-on time of the synchronous rectifier tube based on the current operating parameters further includes: Step S203: Obtain the output current of the DC-DC converter.

[0087] Step S204: Determine whether the output current is greater than a preset current threshold.

[0088] Step S205: If the output current is greater than the preset current threshold, set the early turn-on time to zero.

[0089] It should be noted that the above output current may refer to the DC current value provided by the DC-DC converter to the load, which can be obtained in real time by a current sensor.

[0090] The aforementioned preset current threshold can be a pre-set current limit value. When the output current exceeds this limit value, the energy stored in the primary resonant inductor itself is large enough to independently complete the charging and discharging of the junction capacitance of the lagging bridge arm switch within the dead time, thus eliminating the need to increase the current by turning on the synchronous rectifier in advance.

[0091] In the specific implementation, the process of determining the early turn-on time of the synchronous rectifier is first performed by acquiring the output current of the aforementioned DC-DC converter. The output current value is acquired in real time through a current detection circuit connected to the output circuit. Next, it is determined whether the acquired output current is greater than a preset current threshold. The acquired output current value is compared with the internally stored preset current threshold. If the comparison result shows that the output current is greater than the preset current threshold, it indicates that the current load is heavy, and the converter is already in the operating region where it can naturally achieve zero-voltage turn-on. In this case, the early turn-on time of the synchronous rectifier is set to zero. Setting the early turn-on time to zero means that the synchronous rectifier turns on in the normal manner when the secondary current naturally crosses zero, and early turn-on control is no longer performed.

[0092] To facilitate understanding, the following examples are provided for illustration, but they do not impose specific limitations on this embodiment. For instance, suppose the preset current threshold stored in the example is 10A. The output current is collected in real time by a current sensor, and the current output current is found to be 15A. 15A is compared with 10A, and it is determined that 15A is greater than 10A. Based on this determination, the advance turn-on time of the synchronous rectifier is set to zero, that is, no advance turn-on operation is performed, and the synchronous rectifier is controlled to turn on according to the standard synchronous rectification timing. As another example, if the obtained output current is 5A, and it is determined that 5A is not greater than 10A, the advance turn-on time will not be set to zero, but a non-zero advance turn-on time will be determined by looking up a table or other methods.

[0093] Based on the first and / or second embodiments of this application, in the third embodiment of this application, the content that is the same as or similar to that in embodiments one and two above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 3 , Figure 3 This is a flowchart illustrating Embodiment 3 of the control method for implementing phase-shifted full-bridge light-load soft switching in this application. Figure 3As shown, in this embodiment, before the step of obtaining the current operating parameters of the DC-DC converter, the method further includes: Step S11: Execute the soft start procedure, gradually increasing the phase shift angle to control the output voltage to rise smoothly.

[0094] Step S12: When the output voltage reaches the preset closed-loop control point, exit the soft-start program and switch to closed-loop control mode.

[0095] It should be noted that the aforementioned soft-start procedure can be a control process that avoids input current surges and output voltage overshoots by gradually increasing the output energy during the startup of a DC-DC converter. The aforementioned phase shift angle refers to the phase delay angle between the lagging bridge arm drive signal and the leading bridge arm drive signal in a phase-shifted full-bridge converter; the magnitude of the phase shift angle directly determines the amount of energy transmitted to the output. The aforementioned closed-loop control point can be a pre-set output voltage threshold. When the output voltage reaches this threshold, it indicates that the converter has established a sufficiently stable output voltage and can switch to normal closed-loop regulation.

[0096] The closed-loop control mode described above can be a control method that compares the actual output voltage with the target voltage and automatically adjusts the control parameters based on the difference between the two, so as to stabilize the output voltage at the target value.

[0097] In the specific implementation, a soft-start procedure is executed before acquiring the current operating parameters. The phase shift angle is gradually increased from zero degrees, with a small increment in each control cycle. As the phase shift angle gradually increases, the voltage applied across the primary side of the transformer is extended, resulting in more energy transferred to the secondary side and a smooth increase in the output voltage. The output voltage is continuously monitored during the soft-start process. The real-time detected output voltage is compared with a preset closed-loop control point. When it is determined that the output voltage has reached the aforementioned closed-loop control point, the soft-start procedure is exited, and the gradual increase of the phase shift angle is stopped. Then, the system switches to closed-loop control mode, where the closed-loop control circuit automatically adjusts the phase shift angle based on the difference between the output voltage reference value and the actual output voltage, stabilizing the output voltage at the target value.

[0098] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assume a DC-DC converter has a target output voltage of 12V and a preset closed-loop control point of 11.5V. After startup, a soft-start program is executed, increasing the phase shift angle from 0 degrees to 0.5 degrees every millisecond. As the phase shift angle increases, the output voltage gradually rises from 0V, successively reaching 2V, 5V, 8V, and 10V. When the output voltage reaches 11.5V, it is detected that the output voltage has reached the closed-loop control point. At this point, the soft-start program exits, and the phase shift angle is no longer forcibly increased. Subsequently, the system switches to closed-loop control mode, where the closed-loop control circuit, consisting of an outer voltage loop and an inner current loop, takes over, automatically adjusting the phase shift angle according to the target voltage of 12V to stabilize the output voltage at 12V.

[0099] Furthermore, to achieve precise and stable regulation of the output voltage through dual closed-loop control after the converter completes soft start and enters normal operation, while providing the required phase shift angle for phase shift control, in this embodiment, the closed-loop control mode includes voltage outer loop control and current inner loop control. The method further includes: Step S50: Through voltage outer loop control, a current reference value is generated based on the difference between the output voltage reference value and the actual output voltage.

[0100] Step S60: Through current inner loop control, generate the phase shift angle required for the phase shift control signal based on the difference between the current reference value and the actual output current.

[0101] It should be noted that the above-mentioned voltage outer loop control can be a closed-loop control circuit that uses the output voltage as the controlled variable and indirectly controls the output voltage by adjusting the current reference value.

[0102] The aforementioned current inner loop control can be a closed-loop control circuit that uses the output current as the controlled variable and directly controls the output current by adjusting the phase shift angle.

[0103] The aforementioned output voltage reference value can be a pre-set target output voltage value, representing the voltage value that the DC-DC converter is expected to output stably.

[0104] The aforementioned actual output voltage can refer to the voltage value detected in real time at the output terminal of the DC-DC converter. The aforementioned current reference value can be the target output current value calculated by the outer voltage loop control, used as the given input for the inner current loop.

[0105] The actual output current mentioned above can refer to the current value detected in real time at the output terminal of the DC-DC converter.

[0106] In the specific implementation, after switching to closed-loop control mode, the adopted closed-loop control mode includes voltage outer loop control and current inner loop control. Voltage outer loop control is executed to obtain a preset output voltage reference value, while simultaneously acquiring the actual output voltage through a voltage detection circuit. The difference between the output voltage reference value and the actual output voltage is calculated and used as the input to the voltage regulator. The voltage regulator performs proportional-integral calculations on the difference to generate a current reference value. This current reference value represents the target output current required to stabilize the output voltage at the reference value. Next, current inner loop control is executed to obtain the current reference value generated by the voltage outer loop, while simultaneously acquiring the actual output current through a current detection circuit. The difference between the current reference value and the actual output current is calculated and used as the input to the current regulator. The current regulator performs proportional-integral calculations on the difference to generate a phase shift angle. This phase shift angle is output to the waveform generation module to generate the phase shift control signal for the primary circuit switching transistor.

[0107] To facilitate understanding, the following explanation uses examples, but does not impose specific limitations on this embodiment. For example, assume that the output voltage reference value of the above DC-DC converter is set to 12V, and the actual output voltage is currently 11V. The outer loop voltage control is executed, calculating the difference between the output voltage reference value of 12V and the actual output voltage of 11V as 1V. The voltage regulator performs proportional-integral calculations on this 1V difference to generate a current reference value, for example, 50A. Next, the inner loop current control is executed, acquiring the current reference value of 50A, while simultaneously acquiring the actual output current of 40A, calculating a difference of 10A. The current regulator performs proportional-integral calculations on this 10A difference to generate a phase shift angle, for example, 30 degrees. This 30-degree phase shift angle is sent to the waveform generation module, which generates a phase shift control signal accordingly, delaying the lagging bridge arm drive signal by 30 degrees relative to the leading bridge arm drive signal, thereby increasing the energy transmitted to the secondary side and boosting the output voltage from 11V to 12V.

[0108] This application also provides a control device for realizing phase-shifted full-bridge light-load soft switching; please refer to... Figure 4 The device includes: Parameter acquisition module 10 is used to acquire the current operating parameters of the DC-DC converter; The time determination module 20 is used to determine the advance conduction time of the synchronous rectifier tube based on the current operating parameters. Phase-shift control module 30 is used to control the switching transistors in the primary circuit to perform phase-shift control based on the phase-shift control signal; The conduction control module 40 is used to control the synchronous rectifier to conduct earlier during the zero-crossing period of the secondary current according to the advance conduction time within the control period of the phase shift control signal, so as to increase the current of the primary resonant inductor and enable the lagging bridge arm switch in the primary circuit to achieve zero-voltage turn-on within the dead time.

[0109] The control device for implementing phase-shifted full-bridge light-load soft switching provided in this application adopts the control method for implementing phase-shifted full-bridge light-load soft switching in the above embodiments, which can solve the technical problem of how to achieve zero-voltage switching of the lagging bridge arm under light load without increasing hardware. Compared with the prior art, the beneficial effects of the control device for implementing phase-shifted full-bridge light-load soft switching provided in this application are the same as the beneficial effects of the control method for implementing phase-shifted full-bridge light-load soft switching provided in the above embodiments, and other technical features in the control device for implementing phase-shifted full-bridge light-load soft switching are the same as the features disclosed in the methods of the above embodiments, and will not be repeated here.

[0110] This application provides a control device for implementing phase-shifted full-bridge light-load soft switching. The control device for implementing phase-shifted full-bridge light-load soft switching includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the control method for implementing phase-shifted full-bridge light-load soft switching in the above embodiment 1.

[0111] The following is for reference. Figure 5 This document illustrates a schematic diagram of a control device suitable for implementing a phase-shifted full-bridge light-load soft switch in the embodiments of this application. The control device for implementing a phase-shifted full-bridge light-load soft switch in the embodiments of this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 5 The control device shown for implementing phase-shifted full-bridge light-load soft switching is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0112] like Figure 5As shown, the control device for implementing phase-shifted full-bridge light-load soft switching may include a processing unit 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1002 or a program loaded from storage device 1003 into random access memory (RAM) 1004. RAM 1004 also stores various programs and data required for the operation of the control device for implementing phase-shifted full-bridge light-load soft switching. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via bus 1005. Input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the control device implementing phase-shifted full-bridge light-load soft switching to exchange data wirelessly or via wired communication with other devices. Although the figure shows a control device implementing phase-shifted full-bridge light-load soft switching with various systems, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented alternatively.

[0113] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0114] The control device for implementing phase-shifted full-bridge light-load soft switching provided in this application adopts the control method for implementing phase-shifted full-bridge light-load soft switching in the above embodiments, which can solve the technical problem of how to achieve zero-voltage switching of the lagging bridge arm under light load without increasing hardware. Compared with the prior art, the beneficial effects of the control device for implementing phase-shifted full-bridge light-load soft switching provided in this application are the same as the beneficial effects of the control method for implementing phase-shifted full-bridge light-load soft switching provided in the above embodiments, and other technical features in the control device for implementing phase-shifted full-bridge light-load soft switching are the same as the features disclosed in the method of the previous embodiment, and will not be repeated here.

[0115] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0116] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0117] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, which are used to execute the control method for implementing phase-shifted full-bridge light-load soft switching in the above embodiments.

[0118] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0119] The aforementioned computer-readable storage medium may be included in the control device for implementing phase-shifted full-bridge light-load soft switching; or it may exist independently and not be assembled into the control device for implementing phase-shifted full-bridge light-load soft switching.

[0120] The aforementioned computer-readable storage medium carries one or more programs that, when executed by a control device implementing phase-shifted full-bridge light-load soft switching, cause the control device to: acquire the current operating parameters of the DC-DC converter; determine the advance turn-on time of the synchronous rectifier based on the current operating parameters; control the switching transistor in the primary circuit to perform phase-shift control based on a phase-shift control signal; and, within the control period of the phase-shift control signal, control the synchronous rectifier to turn on early during the zero-crossing period of the secondary current, thereby increasing the current of the primary resonant inductor and enabling the lagging bridge arm switching transistor in the primary circuit to achieve zero-voltage turn-on within the dead time.

[0121] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0122] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0123] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0124] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the control method for implementing the phase-shifted full-bridge light-load soft switching described above. This solves the technical problem of how to achieve zero-voltage switching of the lagging bridge arm under light load without increasing hardware. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the control method for implementing the phase-shifted full-bridge light-load soft switching provided in the above embodiments, and will not be repeated here.

[0125] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A control method for realizing phase-shifted full-bridge light-load soft switching, characterized in that, The method is applied to a DC-DC converter, which includes a primary-side circuit, a transformer, and a secondary-side circuit. The secondary-side circuit includes a synchronous rectifier diode. The method includes: Obtain the current operating parameters of the DC-DC converter; Based on the current operating parameters, determine the advance conduction time of the synchronous rectifier tube; Based on the phase-shift control signal, the switching transistors in the primary-side circuit are controlled to perform phase-shift control. During the control period of the phase-shift control signal, the synchronous rectifier is controlled to turn on in advance during the zero-crossing period of the secondary current according to the advance turn-on time, so as to increase the current of the primary resonant inductor and enable the lagging bridge arm switch in the primary circuit to achieve zero-voltage turn-on during the dead time.

2. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 1, characterized in that, The step of determining the advance conduction time of the synchronous rectifier tube based on the current operating parameters includes: Obtain a preset advance conduction time mapping table, which is used to characterize the correspondence between operating parameters and advance conduction time; Using the current operating parameters as an index, the advance conduction time corresponding to the current operating parameters is queried from the advance conduction time mapping table and determined.

3. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 2, characterized in that, The advance conduction time mapping table is pre-established through a calibration process, which includes: The operating voltage of the DC-DC converter is set to multiple voltage values; For each voltage value, within the range of load current from zero to a preset current threshold, the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on is sequentially calibrated to generate the advance turn-on time mapping table.

4. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 3, characterized in that, The step of sequentially calibrating the minimum advance turn-on time required for the lagging bridge arm switch to achieve zero-voltage turn-on within the range of load current from zero to a preset current threshold includes: At the voltage value, the load current is gradually increased from zero in preset steps; Under the current load current, adjust the advance turn-on time of the synchronous rectifier until the drain-source voltage of the lagging bridge arm switch is observed to drop to zero before its gate drive signal arrives. Record the current load current that enables the lagging bridge arm switch to turn on at zero voltage and its corresponding turn-on time.

5. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 1, characterized in that, The step of determining the advance conduction time of the synchronous rectifier tube based on the current operating parameters further includes: Obtain the output current of the DC-DC converter; Determine whether the output current is greater than a preset current threshold; If the output current is greater than the preset current threshold, the early turn-on time is set to zero.

6. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 1, characterized in that, Before the step of obtaining the current operating parameters of the DC-DC converter, the method further includes: The soft-start procedure is executed to control the output voltage to rise smoothly by gradually increasing the phase shift angle. When the output voltage reaches the preset closed-loop control point, the soft-start program exits and switches to closed-loop control mode.

7. The control method for realizing phase-shifted full-bridge light-load soft switching as described in claim 6, characterized in that, The closed-loop control mode includes voltage outer loop control and current inner loop control, and the method further includes: By using voltage outer loop control, a current reference value is generated based on the difference between the output voltage reference value and the actual output voltage; The phase shift angle required for the phase shift control signal is generated based on the difference between the current reference value and the actual output current through the current inner loop control.

8. A control device for realizing phase-shifted full-bridge light-load soft switching, characterized in that, Applied to a DC-DC converter, the DC-DC converter including a primary-side circuit, a transformer, and a secondary-side circuit, the secondary-side circuit including a synchronous rectifier diode, the device includes: The parameter acquisition module is used to acquire the current operating parameters of the DC-DC converter; The time determination module is used to determine the advance conduction time of the synchronous rectifier tube based on the current operating parameters. The phase-shift control module is used to control the switching transistors in the primary circuit to perform phase-shift control based on the phase-shift control signal; The conduction control module is used to control the synchronous rectifier to conduct earlier during the zero-crossing period of the secondary current according to the advance conduction time within the control cycle of the phase shift control signal, so as to increase the current of the primary resonant inductor and enable the lagging bridge arm switch in the primary circuit to achieve zero-voltage turn-on within the dead time.

9. A control device for realizing phase-shifted full-bridge light-load soft switching, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the control method for implementing a phase-shifted full-bridge light-load soft switching as claimed in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the control method for implementing phase-shifted full-bridge light-load soft switching as described in any one of claims 1 to 7.

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