Safe power-off control method, matrix converter and device

Abstract

The invention discloses a safe power-off control method, a matrix converter and a device, and the method comprises the steps: determining a follow current path in the matrix converter when a shutdown instruction of the converter is received, determining a target switch tube in a matrix circuit from the matrix converter based on the follow current path, and controlling the target switch tube in the matrix circuit to be in an off state, and when the energy of the inductive device is completely released through the follow current path, the follow current path is controlled to be in a disconnected state, so that safe power-off of the matrix converter is realized. Based on the technical scheme, the follow current path is determined after the shutdown instruction is received, and the states of the follow current path and the target switch tube are reasonably managed, so that the energy of the inductive device is safely released, the problem of voltage spike caused by sudden interruption of current is avoided, and the service life of the device is prolonged. And the safety and stability of the matrix converter and related devices thereof are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of discharge control, and in particular to a safe power-off control method, a matrix converter and a device. Background Art

[0002] In the related technology, matrix converters are widely used in industrial control, renewable energy systems and power electronic equipment due to their compact structure and high energy conversion efficiency. Matrix converters use a unique matrix circuit structure, whose input end is directly connected to multiple switching devices, and the on and off control of the switches realizes the conversion of input and output signals. Its core feature is that it can directly convert AC input into the required AC output without the need for an intermediate DC energy storage link, thereby achieving high power density and high dynamic performance.

[0003] During use, when the matrix converter needs to stop output quickly, if all the switches are turned off at the same time, a series of problems will occur. Since the matrix converter contains a large number of inductive components (such as inductors and motor windings), the current of the inductive components cannot be interrupted instantaneously, otherwise it will cause a large voltage spike. This spike voltage will be generated at both ends of the switching device, which may exceed the withstand voltage of the device, causing damage to the circuit components or even failure of the entire circuit system.

[0004] Therefore, the prior art needs to be improved. Summary of the invention

[0005] The main purpose of the present invention is to propose a safe power-off control method, a matrix converter and a device, aiming to at least solve the technical problem in the related art that the circuit elements of the matrix converter are easily damaged when the output is quickly stopped.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] In a first aspect of the present invention, a safe power-off control method is provided, which is applied to a matrix converter, wherein the matrix converter comprises a filter, a matrix circuit and an inductive device connected in sequence, and the safe power-off control method comprises:

[0008] When receiving a converter shutdown instruction, determining a freewheeling path in the matrix converter; wherein the freewheeling path is used to release energy of the inductive device in the matrix converter during shutdown;

[0009] Determining a target switch tube in the matrix circuit from the matrix converter based on the freewheeling path; wherein the target switch tube is a switch tube in the matrix circuit that is not in the freewheeling path;

[0010] Controlling the target switch tube in the matrix circuit to be in an off state, and controlling the freewheeling path to be in an on state;

[0011] When the energy of the inductive device is completely released through the freewheeling path, the freewheeling path is controlled to be in an off state, so as to achieve safe power-off of the matrix converter.

[0012] A second aspect of the present invention provides a matrix converter, which includes a filter, a matrix circuit and an inductive device connected in sequence; the matrix converter is used to implement the safe power-off control method as described in the first aspect.

[0013] According to a third aspect of the present invention, an electronic device is provided, comprising a memory, a processor and a bus; the bus is used to realize connection and communication between the memory and the processor; the processor is used to execute a computer program stored in the memory; when the processor executes the computer program, the steps in the safe power-off control method of the bidirectional power supply circuit of the first aspect are realized.

[0014] The safe power-off control method, matrix converter and device of the present invention determine the freewheeling path in the matrix converter when receiving the converter shutdown command, determine the target switch tube in the matrix circuit from the matrix converter based on the freewheeling path, control the target switch tube in the matrix circuit to be in an off state, and control the freewheeling path to be in an on state. When the energy of the inductive device is completely released through the freewheeling path, the freewheeling path is controlled to be in an off state to achieve safe power-off of the matrix converter. Based on the above technical solution, by determining a freewheeling path after receiving the shutdown command, and rationally managing the freewheeling path and the state of the target switch tube, the safe release of the energy of the inductive device is achieved, the voltage spike problem caused by the sudden interruption of the current is avoided, and the safety and stability of the matrix converter and its related devices are guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A circuit connection diagram of a matrix converter mentioned in the related art;

[0017] Figure 2 A flowchart of a safe power-off control method provided in an embodiment of the present application;

[0018] Figure 3 A schematic diagram of determining the switch tube on the bridge arm of the target phase in the matrix circuit as the freewheeling path in the safe power-off control method provided in an embodiment of the present application;

[0019] Figure 4 A schematic diagram of determining a switch device connected in parallel with a matrix circuit as a freewheeling path in the safe power-off control method provided in an embodiment of the present application;

[0020] Figure 5 A schematic diagram of determining the switch tube on the half bridge arm of the target phase and the switch device connected in parallel with the matrix circuit as a freewheeling path in the safe power-off control method provided in an embodiment of the present application;

[0021] Figure 6 A schematic diagram of determining the switch tube on the half bridge arm of the target phase and the switch device connected in parallel with the matrix circuit as a freewheeling path in the safe power-off control method provided in an embodiment of the present application;

[0022] Figure 7 It is a circuit connection diagram of a matrix type dual active bridge converter;

[0023] Figure 8 A schematic diagram of waveforms of voltage across the inductor device and inductor current after the matrix type dual active bridge converter is powered off when the safe power-off control method is not executed;

[0024] Fig. 9 A schematic diagram of waveforms of voltage across the inductor device and inductor current after power-off when the matrix type dual active bridge converter executes a safe power-off control method;

[0025] Fig.10 A schematic diagram of module connections within an electronic device provided in an embodiment of the present application.

[0026] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0028] It should be noted that related terms such as "first", "second", etc. can be used to describe various components, but these terms do not limit the components. These terms are only used to distinguish one component from another component. For example, without departing from the scope of the present invention, a first component can be referred to as a second component, and the second component can also be referred to as a first component similarly. The term "and / or" refers to any one or more combinations of related items and description items.

[0029] For related technologies, see Figure 1The matrix converter shown in the figure refers to a converter containing a matrix circuit structure (the part selected by the dotted box). During use, when the matrix converter needs to stop output quickly, if all the switch tubes are turned off at the same time, a series of problems will occur. Since the matrix converter contains a large number of inductive components (such as inductors and motor windings), the current of the inductive devices cannot be interrupted instantaneously, otherwise it will cause a large voltage spike. This spike voltage formed by the sudden change of current to zero will be generated at both ends of the switching device, which may exceed the withstand voltage of the device, easily leading to damage to the circuit components, and even easily leading to failure of the entire circuit system.

[0030] To solve the above technical problems, please refer to Figure 2 and Figure 3 This embodiment provides a safe power-off control method, which is applied to a matrix converter including a filter 20, a matrix circuit 30 and an inductive device 40. The safe power-off control method includes the following steps:

[0031] Step S201, when a converter shutdown instruction is received, a freewheeling path in the matrix converter is determined.

[0032] In this embodiment, the electrical connection relationship between the filter 20, the matrix circuit 30 and the inductive device 40 in the matrix converter is as follows: the input end of the filter 20 is used to be electrically connected to the AC power source 10, the output end of the filter 20 is electrically connected to the input end of the matrix circuit 30, the output end of the matrix circuit is electrically connected to the input end of the inductive device 40, and the output end of the inductive device 40 is used to be electrically connected to the subsequent circuit 50. Among them, the matrix circuit 30 is generally composed of a plurality of bidirectional switches, each switch is connected between different input phases and output phases, so as to realize direct power conversion between the input power supply and the load. In general, the matrix circuit is used to provide comprehensive current path control between the three-phase input and the three-phase output.

[0033] When a converter shutdown command is received, the freewheeling path can be determined according to the real-time circuit conditions of the matrix converter. The freewheeling path is used to release the energy of the inductive device 40 in the matrix converter during the shutdown process. That is, the freewheeling path refers to a path that needs to be in a conductive state during the shutdown process and is electrically connected to the inductive device 40. The path can be a partial circuit in the matrix circuit connected to the inductive device 40 or an external circuit connected to the inductive device 40.

[0034] It should be noted that the inductive device 40 (such as motor windings, inductors, etc.) will store electromagnetic energy when powered on, and this energy is associated with the current. When the current passes through the inductive device, the energy is stored in the inductive device in the form of a magnetic field. When the converter shutdown command is issued and the main power circuit is cut off, the electromagnetic energy in the inductive device 40 will not disappear immediately, and this electromagnetic energy will try to maintain the flow of current. If the current is interrupted directly, the inductive device 40 will try to maintain the flow of current, which may generate high voltage spikes and endanger the components of the converter. Therefore, by determining the freewheeling path, a path can be provided so that the current in the inductive device 40 can continue to flow. Through this freewheeling path, the current can be gradually attenuated, and the electromagnetic energy in the inductive device will also be gradually released and converted into heat energy or other forms of energy. Therefore, the freewheeling path is actually managing and guiding the current flow in the inductive device 40, so that the current gradually decreases to achieve the purpose of safely releasing energy.

[0035] In addition, the converter shutdown instruction is different from the converter shutdown instruction. The converter shutdown instruction generally refers to temporarily suspending the power output of the converter, but keeping the converter in standby mode, while the converter shutdown instruction generally refers to completely shutting down all functions of the converter, including the main circuit and the control circuit.

[0036] Step S202, determining a target switch tube in a matrix circuit from a matrix converter based on a freewheeling path.

[0037] Specifically, in a matrix converter, after the freewheeling path is determined, the remaining electronic components in the entire matrix converter can be identified based on the freewheeling path, that is, the switch tubes in the matrix circuit that are not in the freewheeling path are identified, and the switch tubes in the matrix circuit that are not in the freewheeling path are determined as target switch tubes. Among them, the target switch tube is the target component that needs to be in the disconnected state during the shutdown process. These target components do not undertake the current conduction task under the current freewheeling path, so their state can be optimized through appropriate control strategies, or they can be set to the off state in special circumstances to reduce losses or perform other control functions.

[0038] Step S203, controlling the target switch tube in the matrix circuit to be in an off state, and controlling the freewheeling path to be in an on state.

[0039] Specifically, after the freewheeling path and the target switch tube are determined, corresponding control operations can be performed on the target switch tube and the freewheeling path according to the preset shutdown control strategy, that is, the target switch tube in the control matrix circuit is in the off state, and the freewheeling path is controlled to be in the on state.

[0040] Among them, the purpose of controlling the target switch tube in the matrix circuit to be in the disconnected state is: 1. In the matrix converter, multiple bidirectional switch tubes are interconnected to form a complex current path. If some switch tubes are turned on during the shutdown process, it may cause a short circuit, generate excessive short-circuit current, and damage the power device. 2. Keeping the target switch tube in the disconnected state can avoid the formation of these unexpected current paths, thereby protecting the components in the converter and ensuring system safety. 3. The target switch tube refers to the electronic components in the matrix circuit that are not involved in the freewheeling path. In order to reduce power consumption and protect the device, these switch tubes should be controlled to be in the disconnected state. 4. The matrix circuit itself needs to perform the shutdown operation based on the converter shutdown instruction.

[0041] In addition, the purpose of controlling the freewheeling path to be in the on state is that inductive devices (such as motor windings, transformers or other inductive components) generally store electromagnetic energy when shut down. If the load current is directly interrupted, it will cause high voltage spikes, which may damage the power semiconductor devices. Therefore, ensuring that the freewheeling path is turned on can provide a smooth release path for the load current, allowing the stored energy (energy) in the inductive device to be gradually released through the freewheeling path, thereby avoiding voltage and current shocks and protecting the converter and its related devices. At the same time, when the system is shut down or the load current changes suddenly, providing a suitable freewheeling path, the energy is gradually released in a controlled environment, and the electrical stability of the system can be maintained. In this way, unnecessary current oscillations or voltage spikes in the circuit can be avoided, and the safe operation state of the system can be maintained.

[0042] Step S204: When the energy of the inductive device is completely released through the freewheeling path, the freewheeling path is controlled to be in an off state, so as to achieve safe power-off of the matrix converter.

[0043] Specifically, during the shutdown process, since the freewheeling path is in the on state, the freewheeling path has been guiding the current flow in the inductive device 40, causing the current to decay and gradually decrease naturally, thereby smoothly releasing the electromagnetic energy of the inductive device 40 to avoid generating transient voltages that damage the system. Among them, since the energy stored in the inductive device 40 is directly related to the current. When the current gradually decreases and approaches zero, it indicates that the energy in the inductive device 40 has been basically released, and the state of the remaining devices in the on state in the entire matrix converter is controlled to be in the off state, that is, the freewheeling path is controlled to be in the off state, so as to achieve safe power-off of the matrix converter.

[0044] Based on the above steps S201 to S204, this embodiment determines a freewheeling path after receiving the converter shutdown command, reasonably manages the state of the freewheeling path and the target switch tube, and reduces the current based on gradual guidance, thereby achieving the safe release of energy of the inductive device, avoiding the voltage spike problem caused by sudden current interruption, and ensuring the safety and stability of the matrix converter and its related devices.

[0045] In an optional implementation of the present embodiment, determining the freewheeling path in the matrix converter includes: selecting a freewheeling device in the matrix converter, configuring the freewheeling device to be turned on during the shutdown process, and determining it as the freewheeling path in the matrix converter. Wherein, the freewheeling device includes at least one of the following: a switch tube on a bridge arm of a target phase in a matrix circuit, a switch device connected in parallel with the matrix circuit, a switch tube on half a bridge arm of a target phase, and a switch device connected in parallel with the matrix circuit, i.e., three different freewheeling device options. That is, the first option is: a switch tube on a bridge arm of a target phase in a matrix circuit, the second option is: a switch device connected in parallel with the matrix circuit, and the third option is: a switch tube on half a bridge arm of a target phase and a switch device connected in parallel with the matrix circuit.

[0046] The following describes the application scenarios of various devices as freewheeling paths:

[0047] Please continue reading Figure 3 In an optional embodiment, the selected freewheeling device is a switch tube on the bridge arm of the target phase in the matrix circuit. For example, when the selected freewheeling device is the switch tube 30E and the switch tube 30F on the bridge arm of the third phase in the matrix circuit, the corresponding switch tubes 30A, 30B, 30C and 30D are used as target switch tubes, and the switch tubes 30E and 30F are configured to be turned on in the preset shutdown process, and the switch tubes 30A, 30B, 30C and 30D are used as target switch tubes to be disconnected in the preset shutdown process, so as to determine the switch tubes 30E and 30F as the freewheeling path in the matrix converter, so that the switch tubes 30E and 30F are controlled to be in the on state during the shutdown process, so as to gradually guide the reduction of the current of the inductive device 40, and realize the safe release of the energy of the inductive device 40.

[0048] See also Figure 4In an optional embodiment, the selected freewheeling device is a switch device 60 connected in parallel with the matrix circuit, and all the switch tubes (30A, 30B, 30C, 30D, 30E and 30F) in the corresponding matrix circuit are used as target switch tubes. That is, by adding a switch device 60 to the matrix converter, and performing a preset on-configuration for the switch device 60 during the shutdown process, all the switch tubes (30A, 30B, 30C, 30D, 30E and 30F) in the corresponding matrix circuit are configured to be off during the shutdown process, so that the switch device 60 is controlled to be in a conducting state during the shutdown process, and all the switch tubes (30A, 30B, 30C, 30D, 30E and 30F) in the matrix circuit are in a disconnected state during the shutdown process, so as to gradually guide and reduce the current of the inductive device 40, thereby realizing the safe release of the energy of the inductive device 40. Among them, the switching device 60 is used to turn off the positive and negative polarity voltages, so it cannot be a single MOSFET (insulated gate bipolar field effect transistor) or a single IGBT (insulated gate bipolar transistor), but can be two MOSFETs connected in reverse series, two IGBTs connected in reverse series, or a relay, etc.

[0049] See also Figure 5 and Figure 6 In some optional embodiments, the selected freewheeling device is the switch tube on the half bridge arm of the target phase and the switch device connected in parallel with the matrix circuit. That is, a switch device 60 connected in parallel with the matrix circuit is added to the matrix converter, and the switch device 60 and the switch tube of the half bridge arm of any phase are configured to be turned on in a preset shutdown process, so that the switch tube of the half bridge arm of any phase and the switch device 60 are controlled to be in a conductive state during the shutdown process, so as to gradually guide and reduce the current of the inductive device 40, thereby realizing the safe release of the energy of the inductive device 40. For example, in Figure 5 The freewheeling path determined in the embodiment includes the switch tube 30E and the switch device 60. Figure 6 The freewheeling path determined in includes the switch tube 30F and the switch device 60 .

[0050] In an optional implementation of this embodiment, after determining the target switch tube in the matrix circuit from the matrix converter based on the freewheeling path, it also includes: detecting the real-time residual energy of the inductive device, and when the real-time residual energy is greater than the permitted residual energy, controlling the working parameters of the matrix converter in the shutdown process based on the shutdown mode, shutdown delay time, shutdown current and shutdown voltage; and, when the real-time residual energy is equal to or less than the permitted residual energy, controlling all the switches in the matrix circuit to be in a disconnected state to achieve safe power-off of the matrix converter. That is, in the matrix converter, after determining the freewheeling path and the target switch tube, it is also necessary to compare the real-time residual energy of the inductive device with the permitted residual energy, execute different shutdown control logics based on different comparison results, and dynamically adjust the working parameters of the matrix converter accordingly to ensure the safety and stability of the entire system during the shutdown process.

[0051] The allowable residual energy can be calculated through the safe power-off current. The specific calculation formula is allowable residual energy=L*ix*ix / 2, where L represents the inductance value of the inductive device and ix represents the safe power-off current.

[0052] In an optional implementation manner of the present embodiment, after the target switch tube in the control matrix circuit is in the off state, it also includes: determining the corresponding on-state control time according to the inductance value, effective resistance, initial current and preset safety power-off current of the inductor device, and controlling the freewheeling path to be in the on state includes: controlling the duration of the freewheeling path in the on state according to the on-state control time.

[0053] Specifically, it can be calculated by the following formula t represents the conduction control time, τ represents the attenuation coefficient, which is equal to the ratio of the inductance value L of the inductive device 40 to the effective resistance R (a larger attenuation coefficient indicates that the current decays more slowly, and a smaller attenuation coefficient indicates that the current decays more quickly), ix represents the safe power-off current (which indicates the safe level to which the current in the inductive device 40 drops, usually close to zero, and is used to determine whether the inductive energy release process is completed), I0 represents the initial current (indicates the current size in the inductive device at the beginning of the conduction state), and ln represents the natural logarithmic function operation. That is, the conduction control time of the freewheeling path during the shutdown process can be calculated by the inductance value, effective resistance, initial current and preset safe power-off current of the inductive device, so as to accurately ensure that the freewheeling path is turned on within the appropriate time to smoothly release the inductive energy storage. Generally, when the inductance value is in the normal range, the conduction control time is greater than 0 and less than 1. When the inductance value is greater than the normal range, the conduction control time can also be greater than 1.

[0054] In an optional implementation of this embodiment, after controlling the freewheeling path to be in the on state, it also includes: detecting the real-time current in the freewheeling path, comparing the real-time current with the preset safety power-off current, and determining the energy release state of the inductive device according to the comparison result. Among them, the safety power-off current can be determined by the physical characteristics of the inductive device, electromagnetic compatibility requirements, system withstand voltage level, power device protection and load characteristics. Therefore, after controlling the freewheeling path to be in the on state, by detecting the real-time current and comparing it with the preset safety power-off current, the energy release state of the inductive device can be accurately determined.

[0055] Among them, under normal conditions, the safe power-off current and the peak current satisfy the following relationship: the safe power-off current <1% of the peak current, and its specific value is generally less than 3A.

[0056] In an optional implementation manner of the present embodiment, before controlling the freewheeling circuit to be in an off state, it also includes: detecting the output voltage in the freewheeling circuit, comparing the output voltage with a preset shutdown voltage, and if the comparison result is that the output voltage is less than the shutdown voltage, executing the step of controlling the freewheeling circuit to be in an off state.

[0057] Specifically, by detecting the output voltage in the freewheeling circuit and comparing the output voltage in the freewheeling circuit with the preset shutdown voltage, the energy release state of the inductive device can be accurately determined. When the output voltage is less than the shutdown voltage (generally set to 1% of the rated output voltage), indicating that the energy of the inductive device has been completely released, the freewheeling circuit is controlled to be in the disconnected state, that is, the freewheeling circuit can be shut down.

[0058] An embodiment of the present application also provides a matrix converter, which includes a filter, a matrix circuit and an inductive device connected in sequence; the matrix converter applies a safe power-off control method as in any of the above embodiments.

[0059] Please refer to Figure 7 , Figure 8 and Fig. 9, the matrix converter is a matrix dual active bridge converter, and the waveform comparison of the voltage across the inductor and the inductor current before and after the safe power-off control method of the above embodiment is given. It can be seen that before the safe power-off control method of the above embodiment is used, due to the absence of a freewheeling path, the inductor current is instantly forced to drop to zero, and a voltage spike of several thousand volts is induced at both ends; after the safe power-off control method of the above embodiment is used, the inductor current is linearly dropped to zero through the determined freewheeling path, and there is no voltage spike at both ends of the inductor. Through the above comparison, this embodiment determines a freewheeling path after receiving the converter shutdown command, reasonably manages the freewheeling path and the state of the target switch tube, and based on step-by-step guidance to reduce the current, realizes the safe release of the energy of the inductive device, avoids the voltage spike problem caused by the sudden interruption of the current, ensures the safety and stability of the matrix converter and its related devices, and correspondingly proves the feasibility of the technical solution.

[0060] Fig.10 An electronic device provided by an embodiment of the present invention is shown, and the electronic device can be used to implement the safe power-off control method in any of the above embodiments. The electronic device includes:

[0061] The memory 1001, the processor 1002, the bus 1003, and the computer program stored in the memory 1001 and executable on the processor 1002, the memory 1001 and the processor 1002 are connected via the bus 1003. When the processor 1002 executes the computer program, the safe power-off control method in the aforementioned embodiment is implemented. The number of processors may be one or more.

[0062] The memory 1001 may be a high-speed random access memory (RAM) memory, or a non-volatile memory, such as a disk memory. The memory 1001 is used to store executable program codes, and the processor 1002 is coupled to the memory 1001 .

[0063] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of modules is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0064] The modules described as separate components may or may not be physically separated, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed on multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0065] In addition, each functional module in each embodiment of the present application can be integrated into a processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The above integrated modules can be implemented in the form of hardware or software functional modules.

[0066] If the integrated module is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a readable storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned readable storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks, or optical disks.

[0067] It should be noted that, for the above-mentioned method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present application.

[0068] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0069] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A safe power-off control method, characterized in that: Applied to a matrix converter, the matrix converter includes a filter, a matrix circuit and an inductive device connected in sequence, and the safe power-off control method includes: When receiving a converter shutdown instruction, determining a freewheeling path in the matrix converter; wherein the freewheeling path is used to release energy of the inductive device in the matrix converter during shutdown; Determining a target switch tube in the matrix circuit from the matrix converter based on the freewheeling path; wherein the target switch tube is a switch tube in the matrix circuit that is not in the freewheeling path; Controlling the target switch tube in the matrix circuit to be in an off state, and controlling the freewheeling path to be in an on state; When the energy of the inductive device is completely released through the freewheeling path, the freewheeling path is controlled to be in an off state, so as to achieve safe power-off of the matrix converter.

2. The safe power-off control method according to claim 1, characterized in that: Determining a freewheeling path in the matrix converter comprises: Selecting a freewheeling device in the matrix converter; wherein the freewheeling device includes at least one of the following: a switch tube on a bridge arm of a target phase in the matrix circuit, a switch device connected in parallel with the matrix circuit, a switch tube on a half bridge arm of the target phase, and a switch device connected in parallel with the matrix circuit; The selected freewheeling device is configured to be turned on during the shutdown process and is determined as a freewheeling path in the matrix converter.

3. The safe power-off control method according to claim 2, characterized in that: Before selecting the freewheeling device, the method further includes: Acquiring a shutdown mode, a shutdown delay time, a shutdown current, a shutdown voltage, and an allowable remaining energy of the inductive device according to the converter shutdown instruction; A freewheeling device is determined in the matrix converter according to the shutdown mode, the shutdown delay time, the shutdown current, the shutdown voltage and the allowable residual energy of the inductive device.

4. The safe power-off control method according to claim 3, characterized in that: After determining the target switch tube in the matrix circuit from the matrix converter based on the freewheeling path, the method further includes: Detecting the real-time residual energy of the inductive device; When the real-time residual energy is greater than the permitted residual energy, the operating parameters of the matrix converter in the shutdown process are controlled based on the shutdown mode, shutdown delay time, shutdown current and shutdown voltage; wherein the permitted residual energy is calculated by the safe power-off current.

5. The safe power-off control method according to claim 4, characterized in that: After detecting the real-time residual energy of the inductive device, the method further includes: When the real-time residual energy is equal to or less than the permitted residual energy, all the switch tubes in the matrix circuit are controlled to be in an off state to achieve safe power-off of the matrix converter.

6. The safe power-off control method according to claim 1, characterized in that: After controlling the target switch tube in the matrix circuit to be in an off state, the method further includes: Determine the corresponding on-state control time according to the inductance value, effective resistance, initial current and preset safety power-off current of the inductor; wherein the on-state control time is greater than 0 and less than 1; The controlling the freewheeling path to be in a conducting state comprises: The duration of the freewheeling path being in the on state is controlled according to the on control time.

7. The safe power-off control method according to claim 1, characterized in that: After controlling the freewheeling path to be in the on state, the method further includes: Detecting the real-time current in the freewheeling path, and comparing the real-time current with a preset safety power-off current; wherein the safety power-off current and the peak current satisfy the following relationship: the safety power-off current < 1% of the peak current; The energy release state of the inductive device is determined according to the comparison result.

8. The safe power-off control method according to claim 1, characterized in that: Before controlling the freewheeling path to be in an off state, the method further includes: Detecting the output voltage in the freewheeling path, and comparing the output voltage with a preset shutdown voltage; wherein the shutdown voltage is 1% of the rated output voltage; If the comparison result is that the output voltage is less than the shutdown voltage, the step of controlling the freewheeling path to be in an off state is performed.

9. A matrix converter, characterized in that: The matrix converter comprises a filter, a matrix circuit and an inductive device connected in sequence; the matrix converter is used to implement the safe power-off control method as described in any one of claims 1 to 7.

10. An electronic device, characterized in that: Includes memory, processor and bus; The bus is used to realize the connection and communication between the memory and the processor; The processor is used to execute the computer program stored in the memory; When the processor executes the computer program, the steps of the safe power-off control method described in any one of claims 1 to 7 are implemented.

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