A method and related apparatus for preventing reverse energy flow

Abstract

The application discloses a reverse energy backflow prevention method and a related device, which can be applied to the field of electronic circuits. In the method, firstly, a reference voltage and a real-time converter output voltage are acquired; then, an absolute value of a difference between the reference voltage and the converter output voltage is calculated; finally, based on a comparison result of the absolute value and a preset threshold, a turn-on / off state of an output freewheeling tube in the converter is controlled. Thus, by calculating the difference between the reference voltage and the converter output voltage, the turn-on / off state of the output freewheeling tube in the converter is dynamically adjusted, the required data for acquisition is less, the control logic is simple, and the robustness of the scheme is strong. In addition, in the scheme, a specific hardware anti-reverse energy backflow protection circuit does not need to be designed, the original hardware topology is used, the anti-reverse energy backflow protection can be realized through a software control strategy, and thus the hardware cost is saved and the implementation is easy.

Description

Technical Field

[0001] This application relates to the field of electronic circuit technology, and in particular to a method and device for preventing reverse energy backflow. Background Technology

[0002] With the increasing demand for high-power power supply and redundancy backup in fields such as industrial control, new energy vehicles and energy storage systems, parallel operation of multiple bidirectional DC / DC converters has become the mainstream solution.

[0003] Currently, in parallel systems, the output voltage of each converter is prone to deviation due to factors such as component tolerances, temperature drift, line impedance differences, and voltage fluctuations during startup. When the actual output voltage of a converter is lower than the system bus voltage, energy will flow in the reverse direction from the high-potential bus to the low-potential converter, a phenomenon known as reverse energy backflow. This backflow can not only lead to overheating and damage to power devices and a decrease in the quality of system output power, but may also cause serious faults such as short circuits, threatening the stable operation of the entire parallel system.

[0004] Therefore, how to prevent reverse energy backflow during the operation of bidirectional DC / DC converters has become a problem that needs to be solved. Summary of the Invention

[0005] In view of the above problems, this application provides a method and related device for preventing reverse energy backflow, which can prevent reverse energy backflow from occurring during the operation of a bidirectional DC / DC converter.

[0006] The embodiments of this application disclose the following technical solutions: In a first aspect, embodiments of this application provide a method for preventing reverse energy backflow, the method comprising: Obtain the reference voltage and the real-time converter output voltage; Calculate the absolute value of the difference between the reference voltage and the converter output voltage; Based on the comparison result between the absolute value of the difference and the preset threshold, the on / off state of the output freewheeling tube in the converter is controlled.

[0007] Optionally, controlling the on / off state of the output freewheeling diode in the converter based on the comparison result of the absolute value of the difference and a preset threshold includes: When the absolute value of the difference between the reference voltage and the converter output voltage is greater than a preset threshold, the output freewheeling diode in the converter is turned off. When the absolute value of the difference between the reference voltage and the converter output voltage is less than or equal to a preset threshold, the output freewheeling diode in the converter is turned on.

[0008] Optionally, the output freewheeling diode is a metal-oxide-semiconductor field-effect transistor; When the output freewheeling diode is turned off, the body diode of the output freewheeling diode blocks the reverse energy backflow from the bus to the converter and transmits the positive energy from the converter to the bus.

[0009] Optionally, before calculating the absolute value of the difference between the reference voltage and the converter output voltage, the method further includes: During the droop control adjustment process when multiple converters are operating in parallel, the output freewheeling tube is turned off.

[0010] Optionally, the converter is a bidirectional DC / DC converter.

[0011] Optionally, the reference voltage is set via RS485 communication.

[0012] Optionally, the preset threshold is 0.5 volts.

[0013] Secondly, embodiments of this application provide a reverse energy backflow prevention device, the device comprising: The acquisition module is used to acquire the reference voltage and the real-time converter output voltage; A calculation module is used to calculate the absolute value of the difference between the reference voltage and the converter output voltage; The control module is used to control the on / off state of the output freewheeling tube in the converter based on the comparison result of the absolute value of the difference and the preset threshold.

[0014] Thirdly, embodiments of this application provide a device for preventing reverse energy backflow, the device comprising: a memory and a processor; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute, according to the program code, the steps of the method for preventing reverse energy backflow as described in any embodiment of the first aspect.

[0015] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer instructions. When the computer instructions are executed on a reverse energy backflow prevention device, the reverse energy backflow prevention device performs the steps of the reverse energy backflow prevention method described in any embodiment of the first aspect.

[0016] Compared with the prior art, this application has the following beneficial effects: This application provides a method for preventing reverse energy backflow. In this method, firstly, a reference voltage and a real-time converter output voltage are obtained; then, the absolute value of the difference between the reference voltage and the converter output voltage is calculated; finally, based on the comparison result of the absolute value of the difference with a preset threshold, the on / off state of the output freewheeling diode in the converter is controlled.

[0017] Therefore, by calculating the difference between the reference voltage and the acquired output voltage of the converter, the on / off state of the freewheeling diode at the output end of the converter can be dynamically adjusted. This requires less data acquisition, has simple control logic, and strong robustness. In addition, this solution does not require the design of a specific hardware anti-reverse energy backflow protection circuit. The original hardware topology can be used, and the anti-reverse energy backflow protection can be achieved through software control strategies, saving hardware costs and being easy to implement. Attached Figure Description

[0018] 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, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating a method for preventing reverse energy backflow, as provided in an embodiment of this application; Figure 2 A power topology diagram of a bidirectional DC / DC converter provided in this application embodiment; Figure 3 A schematic diagram of a multi-channel bidirectional DC / DC converter parallel operation system provided in this application embodiment; Figure 4 A flowchart illustrating another method for preventing reverse energy backflow provided in this application embodiment; Figure 5 A schematic diagram of a reverse energy backflow prevention device provided for an embodiment of this application; Figure 6 This is a structural diagram of a device for preventing reverse energy backflow, provided as an embodiment of this application. Detailed Implementation

[0020] The reverse energy backflow prevention method and related device provided in this application can be used in the field of electronic circuits. The above is only an example and does not limit the application field of the reverse energy backflow prevention method and related device provided in this application.

[0021] The terms "first," "second," "third," and "fourth," etc., used in this application specification, claims, and drawings are used to distinguish different objects, not to limit a specific order.

[0022] In the embodiments of this application, the terms "as an example" or "for example" are used to indicate that they are examples, illustrations, or explanations. Any embodiment or design that is described as "as an example" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of terms such as "as an example" or "for example" is intended to present the relevant concepts in a specific manner.

[0023] The terminology used in the implementation section of this application is for the purpose of explaining specific embodiments of this application only, and is not intended to limit this application.

[0024] As mentioned earlier, in parallel systems, the output voltage of each converter is prone to deviation due to factors such as component tolerances, temperature drift, line impedance differences, and voltage fluctuations during startup. When the actual output voltage of a converter is lower than the system bus voltage, energy will flow in the reverse direction from the high-potential bus to the low-potential converter, a phenomenon known as reverse energy backflow. This backflow can not only lead to overheating and damage to power devices and a decrease in the quality of system output power, but may also cause serious faults such as short circuits, threatening the stable operation of the entire parallel system.

[0025] Current reverse energy backflow prevention technologies mainly rely on adding additional hardware circuitry, such as connecting diodes or metal-oxide-semiconductor field-effect transistors (MOSFETs) in series in the power path. While this method can block reverse current, diodes generate additional conduction losses, and MOSFETs require complex drive and coordinated control logic. Alternatively, a dual-determination scheme combining current direction detection and voltage signal analysis can be used. Although this method improves the accuracy of the determination, it increases hardware costs and control complexity, making it unsuitable for low-cost applications requiring high reliability. Furthermore, traditional reverse energy backflow prevention schemes struggle to quickly respond to backflow risks caused by voltage deviations during the droop control adjustment process in parallel operation startup, resulting in insufficient timeliness and flexibility in prevention and protection.

[0026] In view of this, embodiments of this application provide a method for preventing reverse energy backflow. In this method, firstly, a reference voltage and a real-time converter output voltage are obtained; then, the absolute value of the difference between the reference voltage and the converter output voltage is calculated; finally, based on the comparison result of the absolute value of the difference with a preset threshold, the on / off state of the output freewheeling tube in the converter is controlled.

[0027] Therefore, by calculating the difference between the reference voltage and the acquired output voltage of the converter, the on / off state of the freewheeling diode at the output end of the converter can be dynamically adjusted. This requires less data acquisition, has simple control logic, and strong robustness. In addition, this solution does not require the design of a specific hardware anti-reverse energy backflow protection circuit. The original hardware topology can be used, and the anti-reverse energy backflow protection can be achieved through software control strategies, saving hardware costs and being easy to implement.

[0028] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0029] See Figure 1 The figure is a flowchart of a method for preventing reverse energy backflow according to an embodiment of this application. The method includes: S101: Obtain the reference voltage and the real-time converter output voltage.

[0030] As an example, each converter can be equipped with an independent microcontroller unit (MCU). The MCU starts the analog-to-digital converter (ADC) and collects the signal of the voltage sampling circuit at the output of the converter in real time according to the preset sampling frequency to obtain the actual output voltage Vout of the converter.

[0031] For example, the converter is a bidirectional DC / DC converter, also known as a bidirectional DC / DC power supply, which is a DC-DC power conversion device with bidirectional energy flow capability and can flexibly switch between two operating modes.

[0032] The bidirectional DC / DC converter supports both boost and buck modes, such as... Figure 2 As shown, its power topology includes four switching transistors, namely Q1, Q2, Q3, and Q4. In this embodiment, in boost mode, the output freewheeling transistor is the BOOST transistor Q4, which performs the freewheeling function in boost mode; in buck mode, the output freewheeling transistor is the BUCK transistor Q1, which performs the freewheeling function in buck mode.

[0033] Optionally, a unified reference voltage Vref can be set for each converter via RS485 communication. That is, at system startup, a unified reference voltage Vref is sent to each parallel converter via the RS485 communication bus. The MCU receives the reference voltage Vref, verifies it, and stores it at a designated memory address after confirmation, serving as a benchmark for subsequent voltage comparisons. RS485 communication is a differential serial communication technology conforming to the TIA / EIA-485 standard, which can be used to configure the operating parameters of bidirectional DC / DC converters.

[0034] S102: Calculate the absolute value of the difference between the reference voltage and the converter output voltage.

[0035] Specifically, the MCU can calculate the absolute value of the difference between the reference voltage and the converter output voltage in real time according to the following formula: the absolute value of the difference |ΔV|=|Vout-Vref|.

[0036] Here, ΔV reflects the degree of deviation between the converter output voltage Vout and the reference voltage Vref, and the magnitude of |ΔV| directly corresponds to the risk level of reverse energy backflow. When Vout < Vref, ΔV is negative, and the larger |ΔV| is, the greater the potential difference between the converter output voltage and the bus voltage, and the stronger the driving force of energy backflow.

[0037] S103: Based on the comparison result between the absolute value of the difference and the preset threshold, control the on / off state of the freewheeling tube at the output end of the converter.

[0038] For example, the preset threshold V0 can be 0.5V. This preset threshold can filter out small voltage fluctuations under normal operating conditions, such as fluctuations within ±0.3V caused by load changes or droop control adjustments, and can also trigger protection in time before the reverse potential difference reaches a level sufficient to cause significant backflow current.

[0039] Based on the comparison between the real-time calculated |ΔV| and the preset threshold, the MCU outputs a corresponding control signal to the drive circuit of the output freewheeling diode in the converter to control the on / off state of the output freewheeling diode. In the event of a risk of reverse energy backflow, the MCU can turn off the output freewheeling diode to avoid reverse energy backflow.

[0040] Specifically, when the absolute value of the difference between the reference voltage and the converter output voltage is greater than a preset threshold, i.e., |ΔV|>V0, it can be considered that there is a risk of reverse energy backflow, and the output freewheeling diode in the converter is turned off; when the absolute value of the difference between the reference voltage and the converter output voltage is less than or equal to the preset threshold, i.e., |ΔV|≤V0, it can be considered that there is no risk of reverse energy backflow, and the output freewheeling diode in the converter is turned on.

[0041] For example, the output freewheeling diode is a metal-oxide-semiconductor field-effect transistor (MOSFET). When Vout > Vref and |ΔV| > V0, energy flows from the converter to the bus in the forward direction. At this time, even if the output freewheeling diode is turned off, the forward energy can still be transferred to the bus by relying on the body diode of the output freewheeling diode, and the normal power supply will not be interrupted. When Vout < Vref and |ΔV| > V0, energy flows from the bus to the converter in the reverse direction. At this time, the logic for determining the risk of reverse energy backflow is effective. Relying on the unidirectional conduction characteristic of the body diode of the output freewheeling diode, the reverse energy backflow from the bus to the converter can be blocked.

[0042] Therefore, by calculating the difference between the reference voltage and the acquired output voltage of the converter, the on / off state of the freewheeling diode at the output end of the converter can be dynamically adjusted. This requires less data acquisition, has simple control logic, and strong robustness. In addition, this solution does not require the design of a specific hardware anti-reverse energy backflow protection circuit. The original hardware topology can be used, and the anti-reverse energy backflow protection can be achieved through software control strategies, saving hardware costs and being easy to implement.

[0043] join Figure 3 The embodiments of this application can be applied to a multi-way bidirectional DC / DC converter parallel operation system that adopts a droop control strategy. The system includes at least two bidirectional DC / DC converters connected in parallel, such as converter 1 and converter 2 in the figure. The output terminals of each converter are connected to the same system bus to jointly supply power to the load or to interact with energy storage units and the power grid.

[0044] The output voltage of converter 1 is Vout1, and the output voltage of converter 2 is Vout2.

[0045] When Vout1 equals Vout2, the energy flow is as shown by arrows 1 and 3, with both parallel DC / DC converters outputting power to the load RL.

[0046] When Vout1 is less than Vout2, the energy flow is as shown by arrows 3 and 2. While converter 2 outputs power to load RL, some energy will flow back to converter 1 through arrow 2. At this time, if Q3 or Q2 in converter 1 is turned on, it will cause a short circuit on the bus and damage the power devices.

[0047] When Vout1 is greater than Vout2, the energy flow is as shown by arrows 4 and 1. While converter 1 outputs power to the load RL, some energy will flow back to converter 2 through arrow 4. At this time, if Q3 or Q2 in converter 2 is turned on, it will cause a short circuit on the bus and damage the power devices.

[0048] Therefore, in a multi-channel bidirectional DC / DC converter parallel operation system, a droop control strategy, namely load sharing control, can be adopted. This is a distributed, interconnection-free control strategy based on local measurements. By simulating the droop characteristics of synchronous generator frequency-active power and voltage-reactive power, the load can be autonomously distributed among multiple converters.

[0049] like Figure 4 As shown, in a system with multiple converters operating in parallel, after the output is turned on, the first stage of droop control adjustment is entered. At this time, there may be a large deviation between the converter output voltage Vout and the reference voltage Vref. The output freewheeling diode can be directly controlled to turn off, and only the body diode of the output freewheeling diode is used for freewheeling to ensure that reverse energy cannot flow back to the converter through the output freewheeling diode.

[0050] During the droop control adjustment phase, the MCU can continuously acquire the converter output voltage Vout and calculate the absolute value of the difference between the output voltage Vout and the reference voltage Vref, |ΔV|. When the absolute value of the difference is less than or equal to a preset threshold, i.e., |ΔV|≤V0, it is determined that the risk of reverse energy backflow is eliminated, the droop control adjustment is in place, the MCU outputs the conduction control signal of the output terminal freewheeling tube, restores the normal switching operation of the output terminal freewheeling tube, and the converter enters steady-state operation.

[0051] During the steady-state operation phase of the system, the MCU can start a real-time monitoring task and continuously execute steps S101 to S103 in a loop.

[0052] Specifically, when |ΔV|≤V0 is detected, it is determined that there is no risk of reverse backflow in the system. The output freewheeling diode conducts in accordance with the preset logic of the current mode, i.e., boost mode or buck mode, complementing the conduction of other switching transistors to ensure normal bidirectional energy transmission. When |ΔV|>V0 is detected, it is determined that there is reverse backflow in the system. The MCU immediately outputs a shutdown signal to control the output freewheeling diode to turn off quickly. At this time, the body diode of the output freewheeling diode is in a reverse bias state, blocking the reverse flow path of energy from the bus to the inside of the converter, thereby avoiding damage to the power devices by the backflow current.

[0053] After the output freewheeling diode is turned off, the MCU continues to monitor the change of |ΔV|. When |ΔV| recovers to |ΔV|≤V0, it immediately outputs a turn-on signal to restore the normal working state of the output freewheeling diode.

[0054] Compared to a MOSFET connected in series in a bidirectional power path, a hardware protection circuit that uses an MCU to monitor the direction of voltage or current and drives the MOSFET to turn off to cut off the reverse path when reverse energy is detected: Hardware protection circuits are costly and rely on high-precision real-time monitoring. The control logic is complex, and the series-connected MOSFETs need to work in coordination with other switches in the topology. The dead time must be set precisely. If the dead time is not properly controlled, the MOSFETs and other switches may conduct simultaneously, causing a short circuit on the bus, burning out the power devices, and posing a significant risk of runaway.

[0055] The reverse energy backflow prevention method provided in this application dynamically adjusts the on / off state of the output freewheeling diode in the converter by calculating the difference between the reference voltage and the acquired output voltage of the converter. This requires less data acquisition, has simple control logic, and does not need to consider the bus short circuit caused by the on / off state of the output freewheeling diode. The solution is robust and has a low risk of power device burnout. In addition, this solution does not require the design of a specific hardware reverse energy backflow protection circuit. It can use the original hardware topology and achieve reverse energy backflow protection through software control strategy, saving hardware costs and being easy to implement.

[0056] See Figure 5 The figure is a schematic diagram of a reverse energy backflow prevention device provided in an embodiment of this application. The device includes: The acquisition module 501 is used to acquire the reference voltage and the real-time converter output voltage; Calculation module 502 is used to calculate the absolute value of the difference between the reference voltage and the converter output voltage; The control module 503 is used to control the on / off state of the output freewheeling tube in the converter based on the comparison result of the absolute value of the difference and the preset threshold.

[0057] Therefore, by calculating the difference between the reference voltage and the acquired output voltage of the converter, the on / off state of the freewheeling diode at the output end of the converter can be dynamically adjusted. This requires less data acquisition, has simple control logic, and strong robustness. In addition, this solution does not require the design of a specific hardware anti-reverse energy backflow protection circuit. The original hardware topology can be used, and the anti-reverse energy backflow protection can be achieved through software control strategies, saving hardware costs and being easy to implement.

[0058] Optionally, the control module 503 is specifically used to control the output freewheeling diode in the converter to turn off when the absolute value of the difference between the reference voltage and the converter output voltage is greater than a preset threshold; and to control the output freewheeling diode in the converter to turn on when the absolute value of the difference between the reference voltage and the converter output voltage is less than or equal to the preset threshold.

[0059] Optionally, the control module 503 is also configured to: shut off the output freewheeling diode during the droop control adjustment process when multiple converters are operating in parallel, before calculating the absolute value of the difference between the reference voltage and the converter output voltage.

[0060] See Figure 6 The figure is a structural diagram of a reverse energy backflow prevention device provided in an embodiment of this application. The device includes a memory 601 and a processor 602.

[0061] Memory 601: Used to store program code and transfer program code to the processor.

[0062] Processor 602: Used to execute the steps of the above-described method for preventing reverse energy backflow according to instructions in the program code.

[0063] This application also provides a computer-readable storage medium storing computer instructions that, when executed on a reverse energy backflow prevention device, perform the steps of the aforementioned reverse energy backflow prevention method.

[0064] In addition, this application also provides a bidirectional DC / DC converter parallel operation system, characterized in that the system includes at least two converters connected in parallel; each converter is configured with a uniform reference voltage; Each converter independently executes the steps of the above-mentioned method for preventing reverse energy backflow.

[0065] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for the device and storage medium embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments. The device and storage medium embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components indicated as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0066] The above description is merely one 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 technical scope 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.

Claims

1. A method for preventing reverse energy backflow, characterized in that, The method includes: Obtain the reference voltage and the real-time converter output voltage; Calculate the absolute value of the difference between the reference voltage and the converter output voltage; Based on the comparison result between the absolute value of the difference and the preset threshold, the on / off state of the output freewheeling tube in the converter is controlled.

2. The method according to claim 1, characterized in that, The step of controlling the on / off state of the output freewheeling diode in the converter based on the comparison result of the absolute value of the difference and a preset threshold includes: When the absolute value of the difference between the reference voltage and the converter output voltage is greater than a preset threshold, the output freewheeling diode in the converter is turned off. When the absolute value of the difference between the reference voltage and the converter output voltage is less than or equal to a preset threshold, the output freewheeling diode in the converter is turned on.

3. The method according to claim 1, characterized in that, The output freewheeling diode is a metal-oxide-semiconductor field-effect transistor; When the output freewheeling diode is turned off, the body diode of the output freewheeling diode blocks the reverse energy backflow from the bus to the converter and transmits the positive energy from the converter to the bus.

4. The method according to claim 1, characterized in that, Before calculating the absolute value of the difference between the reference voltage and the converter output voltage, the method further includes: During the droop control adjustment process when multiple converters are operating in parallel, the output freewheeling tube is turned off.

5. The method according to claim 1, characterized in that, The converter is a bidirectional DC / DC converter.

6. The method according to claim 1, characterized in that, The reference voltage is set via RS485 communication.

7. The method according to claim 1, characterized in that, The preset threshold is 0.5 volts.

8. A device for preventing reverse energy backflow, characterized in that, The device includes: The acquisition module is used to acquire the reference voltage and the real-time converter output voltage; A calculation module is used to calculate the absolute value of the difference between the reference voltage and the converter output voltage; The control module is used to control the on / off state of the output freewheeling tube in the converter based on the comparison result of the absolute value of the difference and the preset threshold.

9. A device for preventing reverse energy backflow, characterized in that, The device includes: a memory and a processor; The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the steps of the method for preventing reverse energy backflow according to any one of claims 1-7, based on the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed on a reverse energy backflow prevention device, perform the steps of the reverse energy backflow prevention method according to any one of claims 1-7.

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