A bidirectional synchronous rectification circuit and control method

Abstract

This invention discloses a bidirectional synchronous rectification circuit and control method. The circuit includes: a primary terminal, a primary power detection module, a primary full-bridge module, a primary current monitoring module, a resonant circuit, a secondary current detection module, a secondary full-bridge module, a secondary power detection module, a secondary terminal, and a controller. The primary power detection module is connected between the primary terminal and the primary full-bridge module; the primary current detection module is connected between the primary full-bridge module and the resonant circuit; the secondary current detection module is connected between the secondary full-bridge module and the resonant circuit; and the secondary power detection module is connected between the secondary terminal and the secondary full-bridge module. The controller controls the operation of the primary / secondary full-bridge circuit and, after determining the input direction of the bidirectional synchronous rectification circuit, determines whether to activate synchronous rectification through power detection and temperature detection. The bidirectional synchronous rectification circuit and control method proposed in this invention realize the function of synchronous rectification, improving the system's response speed and reliability.

Description

Technical Field

[0001] This invention relates to the field of bidirectional DC-DC converters, and more particularly to a bidirectional synchronous rectifier circuit and control method. Background Technology

[0002] In recent years, with the development of technology, the application scenarios of battery charging and discharging have become more and more diversified, and they are widely used in electric vehicles, photovoltaic cells and battery energy storage. Bidirectional DC-DC converters, as DC voltage supply devices, will be widely used.

[0003] With the increase in power levels and power density, the application of synchronous rectification technology can improve efficiency and reduce losses. However, existing synchronous rectification technology controls the conduction and shutdown of power devices by detecting the voltage across them, which places high demands on the design of the detection circuit and is not suitable for bidirectional converter topologies. Controlling power devices by sampling voltage and current also reduces the system's response speed.

[0004] Therefore, there is an urgent need for a bidirectional synchronous rectifier circuit and control method to improve the system's response speed and reliability. Summary of the Invention

[0005] This invention provides a bidirectional synchronous rectification circuit and control method to achieve synchronous rectification function and improve the system's response speed and reliability.

[0006] In a first aspect, embodiments of the present invention provide a bidirectional synchronous rectification circuit, comprising:

[0007] The system comprises a primary terminal, a primary power detection module, a primary full-bridge module, a primary current monitoring module, a resonant circuit, a secondary current detection module, a secondary full-bridge module, a secondary power detection module, a secondary terminal, and a controller. The primary power detection module is connected between the primary terminal and the primary full-bridge module; the primary current detection module is connected between the primary full-bridge module and the resonant circuit; the secondary current detection module is connected between the secondary full-bridge module and the resonant circuit; and the secondary power detection module is connected between the secondary terminal and the secondary full-bridge module.

[0008] The controller is configured to, when determining that the primary terminal is an input, acquire at least one of a first power detected by the secondary power detection module and a first temperature of the secondary full bridge; if at least one of the first power and the first temperature satisfies a first preset, then enable synchronous rectification; if neither the first power nor the first temperature satisfies the first preset, then determine whether to enable synchronous rectification based on the current detected by the secondary current detection module; or the controller is configured to, when determining that the secondary terminal is an input, acquire at least one of a second power detected by the primary power detection module and a second temperature of the primary full bridge; if at least one of the second power and the second temperature satisfies a second preset, then enable synchronous rectification; if neither the second power nor the second temperature satisfies the second preset, then determine whether to enable synchronous rectification based on the current detected by the primary current detection module.

[0009] Optionally, the bidirectional synchronous rectifier circuit further includes a primary drive module and a secondary drive module, wherein the primary drive module is connected between the primary full-bridge module and the controller, and the secondary drive module is connected between the secondary full-bridge module and the controller.

[0010] Optionally, the controller is specifically configured to disable synchronous rectification when the current detected by the primary current detection module is less than or equal to a first preset threshold; and to provide a drive signal to the primary drive module to control the primary full-bridge module and enable synchronous rectification when the current detected by the primary current detection module is greater than the first preset threshold. Optionally, the primary full-bridge module includes a first power transistor and a second power transistor connected in series, and a third power transistor and a fourth power transistor connected in series; the secondary full-bridge module includes a fifth power transistor and a sixth power transistor connected in series, and a seventh power transistor and an eighth power transistor connected in series.

[0011] Specifically, when the controller provides a drive signal to the secondary drive module to turn on the fifth and eighth power transistors in the secondary full-bridge module, it simultaneously provides a drive signal to the primary drive module to turn on the first and fourth power transistors in the primary full-bridge module.

[0012] Specifically, when the controller provides a drive signal to the secondary drive module to turn on the sixth and seventh power transistors in the secondary full-bridge module, it simultaneously provides a drive signal to the primary drive module to turn on the second and third power transistors in the primary full-bridge module.

[0013] Optionally, the controller is specifically configured to disable synchronous rectification when the current detected by the secondary current detection module is less than or equal to a second set threshold; and to provide a drive signal to the secondary drive module to control the secondary full-bridge module and enable synchronous rectification when the current detected by the secondary current detection module is greater than the second set threshold. Optionally, the primary full-bridge module includes a first power transistor and a second power transistor connected in series, and a third power transistor and a fourth power transistor connected in series; the secondary full-bridge module includes a fifth power transistor and a sixth power transistor connected in series, and a seventh power transistor and an eighth power transistor connected in series.

[0014] Specifically, when the controller provides a drive signal to the primary drive module to turn on the first power transistor and the fourth power transistor in the primary full-bridge module, it simultaneously provides a drive signal to the secondary drive module to turn on the fifth power transistor and the eighth power transistor in the secondary full-bridge module.

[0015] Specifically, when the controller provides a drive signal to the primary drive module to turn on the second and third power transistors in the primary full-bridge module, it simultaneously provides a drive signal to the secondary drive module to turn on the sixth and seventh power transistors in the secondary full-bridge module.

[0016] Secondly, embodiments of the present invention also provide a control method for a bidirectional synchronous rectifier circuit, applicable to any bidirectional synchronous rectifier circuit provided in any embodiment of the present invention. The control method includes:

[0017] When the controller determines that the primary terminal is an input, it acquires at least one of the first power detected by the secondary power detection module and the first temperature of the secondary full bridge. If at least one of the first power and the first temperature meets a first preset, the synchronous rectification function is enabled. If neither the first power nor the first temperature meets the first preset, the controller determines whether to enable synchronous rectification based on the current detected by the secondary current detection module. Alternatively, when the controller determines that the secondary terminal is an input, it acquires at least one of the second power detected by the primary power detection module and the second temperature of the primary full bridge. If at least one of the second power and the second temperature meets a second preset, the synchronous rectification function is enabled. If neither the second power nor the second temperature meets the second preset, the controller determines whether to enable synchronous rectification based on the current detected by the primary current detection module.

[0018] Optionally, before determining the primary input or the secondary input as input, the method further includes:

[0019] After the power-on detection is normal, the controller checks whether the time difference between two consecutive startups meets the preset time; if it does, it starts working and detects the input / output direction of the bidirectional DC-DC converter.

[0020] Optionally, determining whether to enable synchronous rectification based on the current detected by the primary current detection module includes:

[0021] When the current detected by the primary current detection module is greater than the first set threshold, the controller provides a drive signal to the secondary drive module to turn on the fifth and eighth power transistors in the secondary full-bridge module, and simultaneously provides a drive signal to the primary drive module to turn on the first and fourth power transistors in the primary full-bridge module.

[0022] When the controller provides a drive signal to the secondary drive module to turn on the sixth and seventh power transistors in the secondary full-bridge module, it simultaneously provides a drive signal to the primary drive module to turn on the second and third power transistors in the primary full-bridge module.

[0023] Optionally, the secondary current detection module determines whether synchronous rectification should be enabled based on the detected current, including:

[0024] When the current detected by the secondary current detection module is greater than the second set threshold, the controller provides a drive signal to the primary drive module to turn on the first power transistor and the fourth power transistor in the primary full-bridge module. At the same time, the controller provides a drive signal to the secondary drive module to turn on the fifth power transistor and the eighth power transistor in the secondary full-bridge module.

[0025] When the controller provides a drive signal to the primary drive module to turn on the second and third power transistors in the primary full-bridge module, it simultaneously provides a drive signal to the secondary drive module to turn on the sixth and seventh power transistors in the secondary full-bridge module.

[0026] This invention provides a bidirectional synchronous rectifier circuit and control method, comprising a primary terminal, a primary power detection module, a primary full-bridge module, a primary current monitoring module, a resonant circuit, a secondary current detection module, a secondary full-bridge module, a secondary power detection module, a secondary terminal, and a controller. The primary power detection module is connected between the primary terminal and the primary full-bridge module; the primary current detection module is connected between the primary full-bridge module and the resonant circuit; the secondary current detection module is connected between the secondary full-bridge module and the resonant circuit; and the secondary power detection module is connected between the secondary terminal and the secondary full-bridge module. The controller, upon determining that the primary terminal is an input, acquires at least one of a first power detected by the secondary power detection module and a first temperature of the secondary full-bridge. If at least one of the first power and the first temperature meets a first preset value, synchronous rectification is initiated. If neither the first power nor the first temperature meets the first preset value, the controller determines whether to initiate synchronous rectification based on the current detected by the secondary current detection module. Alternatively, upon determining that the secondary terminal is an input, the controller acquires at least one of a second power detected by the primary power detection module and a second temperature of the primary full-bridge. If at least one of the second power and the second temperature meets a second preset value, synchronous rectification is initiated. If neither the second power nor the second temperature meets the second preset value, the controller determines whether to initiate synchronous rectification based on the current detected by the primary current detection module. The technical solution provided by this invention achieves the function of synchronous rectification through a threshold set by the hardware circuit combined with a corresponding software strategy, thereby improving the system's response speed and reliability. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a bidirectional synchronous rectifier circuit provided in Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of a bidirectional synchronous rectifier circuit provided in Embodiment 2 of the present invention;

[0029] Figure 3 This is a flowchart of a control method for a bidirectional synchronous rectifier circuit provided in Embodiment 3 of the present invention;

[0030] Figure 4 This is a flowchart of a control method for a bidirectional synchronous rectifier circuit provided in Embodiment 4 of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention and not the entire structure.

[0032] Example 1

[0033] Figure 1 This is a structural block diagram of a bidirectional synchronous rectifier circuit provided in Embodiment 1 of the present invention. See also... Figure 1 The bidirectional synchronous rectifier circuit includes:

[0034] The system comprises a primary terminal 11, a primary power detection module 12, a primary full-bridge module 13, a primary current detection module 14, a resonant circuit 1, a secondary current detection module 24, a secondary full-bridge module 23, a secondary power detection module 22, a secondary terminal 21, and a controller 2. The primary power detection module 12 is connected between the primary terminal 11 and the primary full-bridge module 13; the primary current detection module 14 is connected between the primary full-bridge module 13 and the resonant circuit 1; the secondary current detection module 24 is connected between the secondary full-bridge module 23 and the resonant circuit 1; and the secondary power detection module 22 is connected between the secondary terminal 21 and the secondary full-bridge module 23.

[0035] When the primary terminal 11 is determined to be an input, the controller 2 acquires at least one of the first power detected by the secondary power detection module 22 and the first temperature of the secondary full-bridge module 23. If at least one of the first power and the first temperature meets a first preset, the synchronous rectification function is enabled. If neither the first power nor the first temperature meets the first preset, the controller determines whether to enable synchronous rectification based on the current detected by the secondary current detection module 24. Alternatively, when the secondary terminal 21 is determined to be an input, the controller 2 acquires at least one of the second power detected by the primary power detection module 12 and the second temperature of the primary full-bridge module 13. If at least one of the second power and the second temperature meets a second preset, the controller enables synchronous rectification. If neither the second power nor the second temperature meets the second preset, the controller determines whether to enable synchronous rectification based on the current detected by the primary current detection module 14.

[0036] Specifically, the secondary power detection module 22 is used to detect the secondary side power and obtain the first power; the secondary current detection module 24 mainly consists of a current transformer and a comparator. The transformer is connected in series between the secondary full-bridge 23 and the resonant circuit 1, and the output terminal of the transformer is connected to the comparator. The output of the comparator is sent to the controller 2 by setting the threshold value of the comparator. The primary power detection module 12 is used to detect the primary side power value and obtain the second power; the primary current detection module 14 mainly consists of a current transformer and a comparator. The transformer is connected in series between the primary full-bridge 13 and the resonant circuit 1, and the output terminal of the transformer is connected to the comparator. The output of the comparator is sent to the controller 2 by setting the threshold value of the comparator.

[0037] Specifically, controller 2 controls the system to start working through the enable signal provided by signal control terminal 3. For example, if primary terminal 11 is determined to be an input, controller 2 determines whether to enable synchronous rectification function based on the first power of secondary power detection module 22 or the first temperature of secondary full-bridge module 23. If both the first power and the first temperature are less than or equal to the corresponding preset values ​​in controller 2, it indicates that the bidirectional synchronous rectification circuit does not meet the conditions for enabling synchronous rectification; if either the first power or the first temperature is greater than the preset value in controller 2, it indicates that the bidirectional synchronous rectification circuit meets the conditions for enabling synchronous rectification. If secondary terminal 21 is determined to be an input, controller 2 determines whether to enable synchronous rectification through the second power of primary power detection module 12 or the second temperature of primary full-bridge module 13. If both the second power and the second temperature are less than or equal to the preset threshold in controller 2, it indicates that the bidirectional synchronous rectification circuit does not meet the conditions for enabling synchronous rectification; if either the second power or the second temperature is greater than the preset value in controller 2, it indicates that the bidirectional synchronous rectification circuit meets the conditions for enabling synchronous rectification.

[0038] It should be noted that, since this embodiment of the invention is for a bidirectional DC-DC converter, if the primary terminal 11 is used as an input, the corresponding secondary terminal 21 is the output; if the secondary terminal 21 is used as an input, the corresponding primary terminal 11 is the output.

[0039] This invention provides a bidirectional synchronous rectification circuit, comprising a primary terminal 11, a primary power detection module 12, a primary full-bridge module 13, a primary current monitoring module 14, a resonant circuit 1, a secondary current detection module 24, a secondary full-bridge module 23, a secondary power detection module 22, a secondary terminal 21, and a controller 2. The controller 2 is configured to, when the primary terminal 11 is determined to be an input, acquire at least one of a first power detected by the secondary power detection module 22 and a first temperature of the secondary full-bridge module 23. If at least one of the first power and the first temperature satisfies a first preset condition, synchronous rectification is enabled. If neither the first power nor the first temperature satisfies the first preset condition, synchronous rectification is enabled based on the current detected by the secondary current detection module 24. Alternatively, when the secondary terminal 21 is determined to be an input, the controller 2 is configured to acquire at least one of a second power detected by the primary power detection module 12 and a second temperature of the primary full-bridge module 13. If at least one of the second power and the second temperature satisfies a second preset condition, synchronous rectification is enabled. If both the second power and the second temperature satisfy the second preset condition, synchronous rectification is enabled based on the current detected by the primary current detection module 14. Traditional synchronous rectification requires detecting the voltage across the power devices to control their on / off states. Furthermore, traditional synchronous rectification controls the power devices by sampling voltage and current. In this embodiment, however, the power of the primary and secondary power detection modules, as well as the temperatures of the primary and secondary full-bridge modules, are acquired and compared with preset thresholds to gradually initiate synchronous rectification. By combining the thresholds set by the hardware circuit with corresponding software strategies, the synchronous rectification function is achieved, improving the system's response speed and reliability, and meeting the application requirements of bidirectional synchronous rectification.

[0040] Example 2

[0041] Figure 2 This is a schematic diagram of a bidirectional synchronous rectifier circuit provided in Embodiment 2 of the present invention. Based on the above technical solution, the bidirectional synchronous rectifier circuit further includes a primary drive module 15 and a secondary drive module 25. The primary drive module 15 is connected between the primary full-bridge module 13 and the controller 2, and the secondary drive module 25 is connected between the secondary full-bridge module 23 and the controller 2.

[0042] Specifically, the primary drive module 15 is located on the primary side of the bidirectional synchronous rectifier circuit, and is used to control the primary full-bridge module 13 according to the control signal provided by the controller 2 when the controller 2 determines that the primary segment 11 is the input; the secondary drive module 25 is located on the secondary side of the bidirectional synchronous rectifier circuit, and is used to control the secondary full-bridge module 23 according to the control signal provided by the controller 2 when the controller 2 determines that the secondary segment 21 is the input.

[0043] Optionally, the bidirectional synchronous rectifier circuit also includes a primary temperature detection module 16 and a secondary temperature detection module 26.

[0044] Specifically, the primary temperature detection module 16 is located on the primary side of the bidirectional synchronous rectifier circuit and connected to the controller 2. It is used to detect the temperature of the primary full-bridge module 13 and obtain the second temperature. The secondary temperature detection module 26 is located on the secondary side of the bidirectional synchronous rectifier circuit and connected to the controller 2. It is used to detect the temperature of the secondary full-bridge 23 and obtain the first temperature.

[0045] Optionally, the controller 2 is specifically used to disable the synchronous rectification function when the current of the primary current detection module 14 is less than or equal to the first set threshold; and to provide a drive signal to the primary drive module 15 to control the primary full-bridge module 13 to enable synchronous rectification when the current of the primary current detection module 14 is greater than the first set threshold.

[0046] Optionally, the primary full-bridge module 13 includes a first power transistor Q1 and a second power transistor Q2 connected in series, and a third power transistor Q3 and a fourth power transistor Q4 connected in series; the secondary full-bridge module 23 includes a fifth power transistor Q5 and a sixth power transistor Q6 connected in series, and a seventh power transistor Q7 and an eighth power transistor Q8 connected in series. Specifically, when the controller 2 provides a drive signal to the secondary drive module 25 to turn on the fifth power transistor Q5 and the eighth power transistor Q8 in the secondary full-bridge module 23, it simultaneously provides a drive signal to the primary drive module 15 to turn on the first power transistor Q1 and the fourth power transistor Q4 in the primary full-bridge module 13; specifically, when the controller 2 provides a drive signal to the secondary drive module 25 to turn on the sixth power transistor Q6 and the seventh power transistor Q7 in the secondary full-bridge module 23, it simultaneously provides a drive signal to the primary drive module 15 to turn on the second power transistor Q2 and the third power transistor Q3 in the primary full-bridge module 13.

[0047] Specifically, the primary full-bridge module 13 includes a first bridge arm and a second bridge arm connected in parallel. The first bridge arm includes a first power transistor Q1 and a second power transistor Q2 connected in series, and the second bridge arm includes a third power transistor Q3 and a fourth power transistor Q4 connected in series. A first node is formed between the first power transistor Q1 and the second power transistor Q2, and a second node is formed between the third power transistor Q3 and the fourth power transistor Q4. The first node and the second node are connected to the primary side of the resonant circuit 1. The primary current detection module 14 is electrically connected between the primary full-bridge module 13 and the resonant circuit 1. The secondary full-bridge module 23 includes a third bridge arm and a fourth bridge arm connected in parallel. The third bridge arm includes a fifth power transistor Q5 and a sixth power transistor Q6 connected in series. The fourth bridge arm includes a seventh power transistor Q7 and an eighth power transistor Q8 connected in series. There is a third node between the fifth power transistor Q5 and the sixth power transistor Q6, and a fourth node between the seventh power transistor Q7 and the eighth power transistor Q8. The third node and the fourth node are connected to the secondary side of the resonant circuit 1. The secondary current detection module 24 is electrically connected between the secondary full-bridge module 23 and the resonant circuit 1.

[0048] Specifically, when the secondary terminal 21 is determined to be an input terminal, the second power and the second temperature of the primary full-bridge module 13 are obtained through the primary power detection module 12 and the primary temperature detection module 16, respectively. If both the measured second power and the second temperature are less than or equal to a preset threshold in the controller 2, the synchronous rectification function is turned off; if either the measured second power or the second temperature is greater than the preset threshold in the controller 2, the synchronous rectification function is turned on. Further, when the current of the primary current detection module 14 is less than or equal to a first set threshold, the synchronous rectification function is turned off; when the current of the primary current detection module 14 is greater than the first set threshold, a drive signal is provided to the primary drive module 15 to control the primary full-bridge module 13, thereby enabling synchronous rectification, including:

[0049] 1. When controller 2 provides a drive signal to secondary drive module 25 to enable Q5 and Q8 in secondary full-bridge module 23 to conduct, controller 2 simultaneously provides a drive signal to primary drive module 15 to enable Q1 and Q4 in primary full-bridge module 13 to conduct;

[0050] 2. When the controller 2 provides a drive signal to the secondary drive module 25 to enable Q6 and Q7 in the secondary full-bridge module 23 to conduct, the microcontroller 2 simultaneously provides a drive signal to the primary drive module 15 to enable Q2 and Q3 in the primary full-bridge module 13 to conduct.

[0051] Optionally, the controller 2 is specifically configured to not enable synchronous rectification when the current detected by the secondary current detection module 24 is less than or equal to the second set threshold; and to provide a drive signal to the secondary drive module 25 to control the secondary full-bridge module 22 to enable synchronous rectification when the current detected by the secondary current detection module 24 is greater than the second set threshold.

[0052] Optionally, the controller 2 is specifically configured to simultaneously provide a drive signal to the secondary drive module 25 to enable the fifth power transistor Q5 and the eighth power transistor Q8 in the secondary full-bridge module 23 when the primary drive module 15 provides a drive signal to enable the first power transistor Q1 and the fourth power transistor Q4 in the primary full-bridge module 13 to conduct; and the controller 2 is specifically configured to simultaneously provide a drive signal to the secondary drive module 25 to enable the sixth power transistor Q6 and the seventh power transistor Q7 in the secondary full-bridge module 23 when the primary drive module 15 provides a drive signal to enable the second power transistor Q2 and the third power transistor Q4 in the primary full-bridge module 13 to conduct.

[0053] Specifically, when the primary terminal 11 is determined to be an input terminal, the first power and the first temperature of the secondary full-bridge module 23 are obtained through the secondary power detection module 22 and the secondary temperature detection module 26, respectively. If both the measured first power and the first temperature are less than or equal to a preset threshold in the controller 2, the synchronous rectification function is turned off; if either the measured first power or the first temperature is greater than the preset threshold in the controller 2, the synchronous rectification function is turned on. Further, when the current of the secondary current detection module 24 is less than or equal to a second set threshold, the synchronous rectification function is turned off; when the current of the secondary current detection module 24 is greater than the second set threshold, a drive signal is provided to the secondary drive module 25 to control the secondary full-bridge module 23, thereby enabling synchronous rectification, including:

[0054] 1. When the controller 2 provides a drive signal to the primary drive module 15 to enable Q1 and Q4 in the primary full-bridge module 13 to conduct, the controller 2 simultaneously provides a drive signal to the secondary drive module 25 to enable Q5 and Q8 in the secondary full-bridge module 23 to conduct.

[0055] 2. When the controller 2 provides a drive signal to the primary drive module 15 to enable Q2 and Q3 in the primary full-bridge module 13 to conduct, the controller 2 simultaneously provides a drive signal to the secondary drive module 25 to enable Q6 and Q7 in the secondary full-bridge module 23 to conduct.

[0056] This embodiment provides a bidirectional synchronous rectification circuit, including a primary terminal 11, a primary power detection module 12, a primary full-bridge module 13, a primary current monitoring module 14, a primary drive module 15, a primary temperature detection module 16, a resonant circuit 1, a secondary temperature detection module 26, a secondary drive module 25, a secondary current detection module 24, a secondary full-bridge module 23, a secondary power detection module 22, a secondary terminal 21, and a controller 2. The controller 2 is used to, when determining that the primary terminal 11 is an input, acquire at least one of the first power detected by the secondary power detection module 22 and the first temperature of the secondary full-bridge module 23. If at least one of the first power and the first temperature meets a first preset, synchronous rectification is enabled; if neither the first power nor the first temperature meets the first preset, synchronous rectification is enabled based on the current detected by the secondary current detection module 24. Alternatively, the controller 2 is used to, when determining that the secondary terminal 21 is an input, acquire the second power detected by the primary power detection module 12 and the primary temperature detection module 25. At least one of the second temperatures of the full-bridge module 13 is selected. If the second power and the second temperature meet the second preset, the synchronous rectification function is enabled. If neither the second power nor the second temperature meets the second preset, the synchronous rectification function is enabled based on the current detected by the primary current detection module 14. The primary drive module 15 is connected between the primary full-bridge module 13 and the controller 2. The primary drive module 15 is used to control the primary full-bridge module 13 according to the control signal provided by the controller 2. The secondary drive module 25 is connected between the secondary full-bridge module 23 and the controller 2. The secondary drive module 25 is used to control the secondary full-bridge module 23 according to the control signal provided by the controller 2. The primary temperature detection module 16 is located on the primary side of the bidirectional synchronous rectification circuit and connected to the controller 2. It is used to detect the temperature of the primary full-bridge module 13. The secondary temperature detection module 26 is located on the secondary side of the bidirectional synchronous rectification circuit and connected to the controller 2. It is used to detect the temperature of the secondary full-bridge module 23. Traditional synchronous rectification requires detecting the voltage across the power devices to control their on / off states. Furthermore, traditional synchronous rectification controls the power devices by sampling voltage and current. In this embodiment, however, the power of the primary and secondary power detection modules, as well as the temperatures of the primary and secondary full-bridge modules, are acquired and compared with preset thresholds to gradually initiate synchronous rectification. By combining the thresholds set by the hardware circuit with corresponding software strategies, the synchronous rectification function is achieved, improving the system's response speed and reliability, and meeting the application requirements of bidirectional synchronous rectification.

[0057] Example 3

[0058] Embodiment 3 of the present invention provides a control method for a bidirectional synchronous rectifier circuit, which can be applied to any bidirectional synchronous rectifier circuit provided in any embodiment of the present invention. Figure 3 This is a flowchart of a control method for a bidirectional synchronous rectifier circuit provided in Embodiment 3 of the present invention. The following is in conjunction with… Figure 2 The illustrated bidirectional synchronous rectifier circuit illustrates the control method for the bidirectional synchronous rectifier circuit provided in this embodiment of the invention. See also... Figure 2 and Figure 3 The control method for this bidirectional synchronous rectifier circuit includes the following steps:

[0059] S301. After the power-on detection is normal, determine whether the time difference between two adjacent startups detected by the controller meets the preset time.

[0060] Specifically, the power-on detection is used to check whether the drive, temperature and control signals of each stage are normal after the bidirectional synchronous rectifier circuit is powered on. If the time difference between the two startups is greater than the preset value T1, the bidirectional DC-DC converter starts to work; otherwise, the drive, temperature and control signals of each stage of the circuit need to be re-detected until the time difference between the two startups is greater than T1.

[0061] Specifically, T1 can be understood as the minimum time for continuous power-on and power-off.

[0062] S302. If the conditions are met, start operation and detect the input / output direction of the bidirectional DC-DC converter.

[0063] S303. When the controller determines that the primary terminal is an input, it acquires at least one of the first power detected by the secondary power detection module and the first temperature of the secondary full bridge. If at least one of the first power and the first temperature meets the first preset, the synchronous rectification function is enabled. If neither the first power nor the first temperature meets the first preset, the controller determines whether to enable synchronous rectification based on the current detected by the secondary current detection module.

[0064] Specifically, if the primary terminal is determined to be an input, the controller determines whether to enable synchronous rectification by measuring the first power of the secondary power detection module or the first temperature of the secondary full-bridge module 23. If the measured first power and first temperature are both less than or equal to the preset threshold in the controller, it indicates that the bidirectional synchronous rectification circuit does not meet the conditions for enabling synchronous rectification; if either the first power or the first temperature is greater than the preset threshold in the controller, it indicates that the bidirectional synchronous rectification circuit meets the conditions for enabling synchronous rectification.

[0065] Furthermore, when the current of the secondary current detection module is less than or equal to the second set threshold, the synchronous rectification function is disabled; when the current of the secondary current detection module is greater than the second set threshold, a drive signal is provided to the secondary drive module to control the secondary full-bridge module and enable synchronous rectification, including:

[0066] (1) When the controller provides a drive signal to the primary drive module to enable Q1 and Q4 in the primary full-bridge module to conduct, it simultaneously provides a drive signal to the secondary drive module to enable Q5 and Q8 in the secondary full-bridge module to conduct.

[0067] Specifically, the controller provides complementary PWM signals to the primary drive module to control the primary full-bridge module.

[0068] (2) When the controller provides a drive signal to the primary drive module to enable Q2 and Q3 in the primary full-bridge module to conduct, it simultaneously provides a drive signal to the secondary drive module to enable Q6 and Q7 in the secondary full-bridge module to conduct.

[0069] S304. When the controller determines that the secondary terminal is an input, it acquires at least one of the second power detected by the primary power detection module and the second temperature of the primary full bridge. If at least one of the second power and the second temperature meets the second preset, the synchronous rectification function is enabled. If neither the second power nor the second temperature meets the second preset, the synchronous rectification function is enabled based on the current detected by the primary current detection module.

[0070] Specifically, if the secondary terminal is determined to be an input, the controller determines whether to enable synchronous rectification by measuring the second power of the primary power detection module or the second temperature of the primary full-bridge module. If the measured second power and second temperature are both less than or equal to the preset threshold in the controller, it indicates that the bidirectional synchronous rectification circuit does not meet the conditions for enabling synchronous rectification; if either the second power or the second temperature is greater than the preset threshold in the controller, it indicates that the bidirectional synchronous rectification circuit meets the conditions for enabling synchronous rectification.

[0071] Furthermore, when the current of the primary current detection module is less than or equal to the first set threshold, the synchronous rectification function is disabled; when the current of the primary current detection module is greater than the first set threshold, a drive signal is provided to the primary drive module to control the primary full-bridge module and enable synchronous rectification, including:

[0072] (1) When the controller provides a drive signal to the secondary drive module to enable Q5 and Q8 in the secondary full-bridge module to conduct, it simultaneously provides a drive signal to the primary drive module to enable Q1 and Q4 in the primary full-bridge module to conduct.

[0073] Specifically, the controller provides complementary PWM signals to the secondary drive module to control the secondary full-bridge module.

[0074] (2) When the controller provides a drive signal to the secondary drive module to enable Q6 and Q7 in the secondary full-bridge module to conduct, it simultaneously provides a drive signal to the primary drive module to enable Q2 and Q3 in the primary full-bridge module to conduct.

[0075] This invention provides a control method for a bidirectional synchronous rectifier circuit. When the controller determines that the primary terminal is an input, it acquires at least one of a first power detected by the secondary power detection module and a first temperature of the secondary full-bridge. If at least one of the first power and the first temperature meets a first preset, synchronous rectification is activated. If neither the first power nor the first temperature meets the first preset, synchronous rectification is activated, and the activation of synchronous rectification is determined based on the current detected by the secondary current detection module. Alternatively, when the controller determines that the secondary terminal is an input, it acquires at least one of a second power detected by the primary power detection module and a second temperature of the primary full-bridge. If at least one of the second power and the second temperature meets a second preset, synchronous rectification is activated. If neither the second power nor the second temperature meets the second preset, the activation of synchronous rectification is determined based on the current detected by the primary current detection module. This control method for the bidirectional synchronous rectifier circuit achieves the synchronous rectification function, improving the system's response speed and reliability.

[0076] Example 4

[0077] Embodiment 4 of the present invention provides a control method for a bidirectional synchronous rectifier circuit, which can be applied to the bidirectional synchronous rectifier circuit provided in any embodiment of the present invention. Figure 4 This is a flowchart of a control method for a bidirectional synchronous rectifier circuit provided in Embodiment 4 of the present invention. The technical solution of this embodiment is further refined based on the above technical solution. See also Figure 2 and Figure 4 The control method for this bidirectional synchronous rectifier circuit includes the following steps:

[0078] S401, System powered on.

[0079] S402. Power on and check whether the drive, temperature and control signals at each level are normal.

[0080] S403. Determine if the time difference between the two startups is greater than T1. If yes, execute S404; otherwise, execute S402.

[0081] In this embodiment of the invention, T1 can be specifically understood as the minimum time for continuous power on and off.

[0082] S404, the bidirectional DC-DC converter starts working.

[0083] S405, Detect the input / output direction of the bidirectional DC-DC converter.

[0084] S406. Determine whether the primary terminal is an input terminal. If yes, execute S407; otherwise, execute S408.

[0085] S407, the controller provides drive signals to the primary drive module to control the primary full bridge.

[0086] In this embodiment of the invention, the controller provides complementary PWM signals to the primary drive module to control the primary full-bridge module.

[0087] Specifically, when the PWM is high: Q1 and Q4 are both on, Q2 and Q3 are both off. Current flows from the positive terminal of the power supply through Q1, from left to right, and then through Q4 into the negative terminal of the power supply. When the PWM is low: Q2 and Q3 are both on, Q1 and Q4 are off. According to Lenz's law, there is a self-induced electromotive force, and the current still flows from left to right, forming a current loop through Q2 and Q3.

[0088] S4071. Determine whether both secondary power and temperature are less than or equal to a threshold. If yes, proceed to S409; otherwise, proceed to S4072. In this embodiment of the invention, secondary power and temperature can be understood as the first power detected by the secondary power detection module and the first temperature of the secondary full-bridge detected by the secondary temperature detection module, respectively. If both the measured first power and the first temperature are less than or equal to a preset threshold in the controller, the synchronous rectification function is turned off; if either the measured first power or the first temperature is greater than the preset threshold in the controller, the synchronous rectification function is turned on.

[0089] S4072, Enable synchronous rectification function.

[0090] S4073. Determine if there is a trigger signal in the secondary current detection circuit. If yes, execute S4074; otherwise, execute S4071.

[0091] In this embodiment of the invention, whether the secondary current detection circuit has a trigger signal can be determined by comparing the current of the secondary current detection module with a second set threshold. If the current detected by the secondary current detection module is less than or equal to the second set threshold, it is determined that there is no trigger signal; when the current of the secondary current detection module is greater than the second set threshold, it is determined that there is a trigger signal.

[0092] S4074. Determine whether the controller drives Q1 and Q4 in the primary full-bridge module to conduct. If yes, execute S4075; otherwise, execute S4076.

[0093] S4075: The controller provides a drive signal to the secondary drive module to enable Q5 and Q8 in the secondary full-bridge module to conduct, and then executes S4071.

[0094] S4076: The controller provides a drive signal to the secondary drive module to enable Q6 and Q7 in the secondary full-bridge module to conduct, and then executes S4071.

[0095] S408, the controller provides drive signals to the secondary drive module to control the secondary full bridge.

[0096] In this embodiment of the invention, the controller provides complementary PWM signals to the secondary drive module to control the secondary full-bridge module.

[0097] Specifically, when the PWM is high: Q5 and Q8 are both on, while Q6 and Q7 are both off. Current flows from the positive terminal of the power supply through Q5, from right to left, and then through Q8 into the negative terminal of the power supply. When the PWM is low: Q6 and Q7 are both on, while Q5 and Q8 are both off. According to Lenz's law, there is a self-induced electromotive force, and the current still flows from left to right, forming a current loop through Q6 and Q7.

[0098] S4081. Determine whether the primary power and temperature are both less than or equal to the threshold. If yes, execute S409; otherwise, execute S4082.

[0099] In this embodiment of the invention, primary power and temperature can be understood as the second power detected by the primary power detection module and the second temperature of the primary full-bridge detected by the primary temperature detection module, respectively. If both the measured second power and the second temperature are less than or equal to a preset threshold in the controller, the synchronous rectification function is turned off; if either the measured second power or the second temperature is greater than the preset threshold in the controller, the synchronous rectification function is turned on.

[0100] S4082, Enable synchronous rectification function.

[0101] S4083. Determine if there is a trigger signal in the primary current detection circuit. If yes, execute S4084; otherwise, execute S4081.

[0102] In this embodiment of the invention, whether the primary current detection circuit has a trigger signal can be determined by comparing the current of the primary current detection module with a first set threshold. If the current detected by the primary current detection module is less than or equal to the first set threshold, it is determined that there is no trigger signal; when the current of the secondary current detection module is greater than the first set threshold, it is determined that there is a trigger signal.

[0103] S4084. Determine whether the controller drives Q5 and Q8 in the secondary full-bridge module to conduct. If yes, execute S4085; otherwise, execute S4086.

[0104] S4085: The controller provides a drive signal to the primary drive module to enable Q1 and Q4 in the primary full-bridge module to conduct, and then executes S4071.

[0105] S4076: The controller provides a drive signal to the secondary drive module to enable Q6 and Q7 in the secondary full-bridge module to conduct, and then executes S4081.

[0106] This invention provides a control method for a bidirectional synchronous rectifier circuit. When the system powers on normally and the time interval between two startups is greater than a preset value T1, the bidirectional synchronous rectifier circuit starts working. The controller determines the input terminal. When the controller determines the primary terminal as the input, it acquires at least one of the first power detected by the secondary power detection module and the first temperature of the secondary full-bridge. If at least one of the first power and the first temperature meets a first preset, the synchronous rectification function is activated. If neither the first power nor the first temperature meets the first preset, the activation of synchronous rectification is determined based on the current detected by the secondary current detection module. Alternatively, when the controller determines the secondary terminal as the input, it acquires at least one of the second power detected by the primary power detection module and the second temperature of the primary full-bridge. If at least one of the second power and the second temperature meets a second preset, the synchronous rectification function is activated. If neither the second power nor the second temperature meets the second preset, the activation of synchronous rectification is determined based on the current detected by the primary current detection module. This control method for the bidirectional synchronous rectifier circuit achieves the synchronous rectification function, improving the system's response speed and reliability.

[0107] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A bidirectional synchronous rectification circuit, characterized by, The bidirectional synchronous rectification circuit comprises a primary terminal, a primary power detection module, a primary full-bridge module, a primary current detection module, a resonant circuit, a secondary current detection module, a secondary full-bridge module, a secondary power detection module, a secondary terminal and a controller; the primary power detection module is connected between the primary terminal and the primary full-bridge module, the primary current detection module is connected between the primary full-bridge module and the resonant circuit, the secondary current detection module is connected between the secondary full-bridge module and the resonant circuit, and the secondary power detection module is connected between the secondary terminal and the secondary full-bridge module. The bidirectional synchronous rectification circuit further comprises a primary temperature detection module and a secondary temperature detection module; the primary temperature detection module is arranged on the primary side of the bidirectional synchronous rectification circuit, is connected with the controller, and is used for detecting the temperature of the primary full-bridge module; and the secondary temperature detection module is arranged on the secondary side of the bidirectional synchronous rectification circuit, is connected with the controller, and is used for detecting the temperature of the secondary full-bridge. The controller is configured to, when determining that the primary terminal is input, acquire at least one of a first power detected by the secondary power detection module and a first temperature of the secondary full-bridge, and start the synchronous rectification function if at least one of the first power and the first temperature meets a first preset, or determine whether to start the synchronous rectification according to a current detected by the secondary current detection module if neither of the first power and the first temperature meets the first preset; or the controller is configured to, when determining that the secondary terminal is input, acquire at least one of a second power detected by the primary power detection module and a second temperature of the primary full-bridge, and start the synchronous rectification if at least one of the second power and the second temperature meets a second preset, or determine whether to start the synchronous rectification according to a current detected by the primary current detection module if neither of the second power and the second temperature meets the second preset.

2. The bidirectional synchronous rectification circuit of claim 1, wherein, The bidirectional synchronous rectification circuit further comprises a primary drive module and a secondary drive module; the primary drive module is connected between the primary full-bridge module and the controller, and the secondary drive module is connected between the secondary full-bridge module and the controller.

3. The bidirectional synchronous rectification circuit of claim 1, wherein, The controller is specifically configured to, when the current detected by the primary current detection module is less than or equal to a first set threshold, not start the synchronous rectification function; and when the current detected by the primary current detection module is greater than the first set threshold, provide a drive signal to the primary drive module to realize the control of the primary full-bridge module and to start the synchronous rectification.

4. The bidirectional synchronous rectification circuit of claim 3, wherein, The primary full-bridge module comprises a first power tube and a second power tube connected in series and a third power tube and a fourth power tube connected in series; and the secondary full-bridge module comprises a fifth power tube and a sixth power tube connected in series and a seventh power tube and an eighth power tube connected in series. The controller is specifically configured to, when a drive signal is provided to the secondary drive module to realize the conduction of the fifth power tube and the eighth power tube in the secondary full-bridge module, synchronously provide a drive signal to the primary drive module to realize the conduction of the first power tube and the fourth power tube in the primary full-bridge module. The controller is specifically configured to provide a driving signal to the primary driving module to realize conduction of the second power tube and the third power tube in the primary full-bridge module when a driving signal is provided to the secondary driving module to realize conduction of the sixth power tube and the seventh power tube in the secondary full-bridge module.

5. The bidirectional synchronous rectification circuit of claim 2, wherein, The controller is specifically configured to not start the synchronous rectification function when the current detected by the secondary current detection module is less than or equal to a second set threshold, and to provide a driving signal to the secondary driving module to realize control of the secondary full-bridge module to start the synchronous rectification when the current detected by the secondary current detection module is greater than the second set threshold.

6. The bidirectional synchronous rectification circuit of claim 5, wherein, The primary full-bridge module comprises the first power tube and the second power tube connected in series and the third power tube and the fourth power tube connected in series, and the secondary full-bridge module comprises the fifth power tube and the sixth power tube connected in series and the seventh power tube and the eighth power tube connected in series. The controller is specifically configured to provide a driving signal to the primary driving module to realize conduction of the first power tube and the fourth power tube in the primary full-bridge module, and to simultaneously provide a driving signal to the secondary driving module to realize conduction of the fifth power tube and the eighth power tube in the secondary full-bridge module. The controller is specifically configured to provide a driving signal to the primary driving module to realize conduction of the second power tube and the third power tube in the primary full-bridge module, and to simultaneously provide a driving signal to the secondary driving module to realize conduction of the sixth power tube and the seventh power tube in the secondary full-bridge module.

7. A control method of a bidirectional synchronous rectification circuit, characterized by, The bidirectional synchronous rectification circuit comprises a primary terminal, a primary power detection module, a primary full-bridge module, a primary current detection module, a resonant circuit, a secondary current detection module, a secondary full-bridge module, a secondary power detection module, a secondary terminal and a controller; the primary power detection module is connected between the primary terminal and the primary full-bridge module, the primary current detection module is connected between the primary full-bridge module and the resonant circuit, the secondary current detection module is connected between the secondary full-bridge module and the resonant circuit, and the secondary power detection module is connected between the secondary terminal and the secondary full-bridge module. The bidirectional synchronous rectification circuit further comprises a primary temperature detection module and a secondary temperature detection module; the primary temperature detection module is arranged on the primary side of the bidirectional synchronous rectification circuit, is connected with the controller, and is used to detect the temperature of the primary full-bridge module; and the secondary temperature detection module is arranged on the secondary side of the bidirectional synchronous rectification circuit, is connected with the controller, and is used to detect the temperature of the secondary full-bridge module. The control method comprises: The controller, when determining that the primary terminal is input, acquires at least one of a first power detected by the secondary power detection module and a first temperature of the secondary full-bridge, and turns on a synchronous rectification function if at least one of the first power and the first temperature meets a first preset, and determines whether to turn on the synchronous rectification according to a current detected by the secondary current detection module if neither of the first power and the first temperature meets the first preset; or the controller, when determining that the secondary terminal is input, acquires at least one of a second power detected by the primary power detection module and a second temperature of the primary full-bridge, and turns on the synchronous rectification function if at least one of the second power and the second temperature meets a second preset, and determines whether to turn on the synchronous rectification according to a current detected by the primary current detection module if neither of the second power and the second temperature meets the second preset.

8. The method of claim 7, wherein, Before determining that the primary input or the secondary input is input, the method further comprises: After normal power-on detection, the controller detects whether a time difference between two adjacent startings meets a preset time; If yes, the controller turns on the operation and detects an input / output direction of the bidirectional direct-current converter.

9. The method of claim 7, wherein, The bidirectional synchronous rectification circuit further comprises a primary drive module and a secondary drive module, the primary drive module is connected between the primary full-bridge module and the controller, and the secondary drive module is connected between the secondary full-bridge module and the controller; the primary full-bridge module comprises a first power tube and a second power tube connected in series and a third power tube and a fourth power tube connected in series; the secondary full-bridge module comprises a fifth power tube and a sixth power tube connected in series and a seventh power tube and an eighth power tube connected in series; The determination of whether to turn on the synchronous rectification according to the current detected by the primary current detection module comprises: When the current detected by the primary current detection module is greater than a first set threshold, the controller provides a drive signal to the secondary drive module to realize that the fifth power tube and the eighth power tube in the secondary full-bridge module are turned on, and simultaneously provides a drive signal to the primary drive module to realize that the first power tube and the fourth power tube in the primary full-bridge module are turned on; When the controller provides a drive signal to the secondary drive module to realize that the sixth power tube and the seventh power tube in the secondary full-bridge module are turned on, the controller simultaneously provides a drive signal to the primary drive module to realize that the second power tube and the third power tube in the primary full-bridge module are turned on.

10. The method of claim 9, wherein, The determination of whether to turn on the synchronous rectification according to the current detected by the secondary current detection module comprises: When the current detected by the secondary current detection module is greater than a second set threshold, the controller provides a drive signal to the primary drive module to realize that the first power tube and the fourth power tube in the primary full-bridge module are turned on, and simultaneously provides a drive signal to the secondary drive module to realize that the fifth power tube and the eighth power tube in the secondary full-bridge module are turned on; The controller provides a driving signal to the primary driving module to realize that the second power tube and the third power tube in the primary full-bridge module are turned on, and simultaneously provides a driving signal to the secondary driving module to realize that the sixth power tube and the seventh power tube in the secondary full-bridge module are turned on.

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