Power conversion device, control method, and energy storage device

Abstract

The application provides a power conversion device, a control method and an energy storage device. The DC input interface of the power conversion device is connected with the input side of the DC conversion circuit, and the DC input interface is used for receiving DC power output by an input source. The control method comprises the following steps: monitoring the actual input voltage of the DC input interface; when confirming that the input source is connected to the DC input interface, extracting the AC component of the actual input voltage; determining the target power supply type of the input source based on the AC component; and controlling the DC conversion circuit to work based on the control loop corresponding to the target power supply type. The control method provided by the application can identify the type of the connected input source at a lower cost, and improve the conversion efficiency of the power conversion device.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a power conversion device, a control method, and an energy storage device. Background Technology

[0002] In related technologies, the DC input interface of a power conversion device may be connected to different types of DC power sources. For example, the AC power output from a fuel generator can be rectified and then connected to the DC input interface of the power conversion device, and the DC power output from a photovoltaic module can also be connected to the DC input interface of the power conversion device.

[0003] Different types of DC power supplies correspond to different operating modes. If the power conversion equipment cannot determine whether the fuel generator or the photovoltaic module is connected, then the power conversion equipment cannot adopt the appropriate operating mode for the fuel generator and the photovoltaic module respectively, which will affect the working efficiency of the power conversion equipment. Summary of the Invention

[0004] In view of this, this application provides a power conversion device, a control method, and an energy storage device, which can identify the type of input source connected to the power conversion device at low cost and improve the conversion efficiency of the power conversion device.

[0005] The first aspect of this application provides a control method for a power conversion device, wherein the DC input interface of the power conversion device is connected to the input side of a DC conversion circuit, and the DC input interface is used to receive DC power output from an input source. The control method includes: monitoring the actual input voltage of the DC input interface; when it is confirmed that an input source is connected to the DC input interface, extracting the AC component of the actual input voltage; determining the target power source type based on the AC component; and controlling the DC conversion circuit to operate based on the control loop corresponding to the target power source type.

[0006] In one embodiment, extracting the AC component of the actual input voltage includes: extracting the fundamental component of the actual input voltage through a low-pass filter; and determining the AC component based on the actual input voltage and the fundamental component.

[0007] In one embodiment, when it is confirmed that an input source is connected to the DC input interface, extracting the AC component of the actual input voltage includes: when it is confirmed that an input source is connected to the DC input interface, controlling the DC-DC conversion circuit to operate based on a preset control loop; and when the DC-DC conversion circuit is operating under load, extracting the AC component of the actual input voltage.

[0008] In one embodiment, the preset control loop includes a bus voltage loop and an input current loop. The bus voltage loop is used to control the actual bus voltage on the output side of the DC-DC converter circuit, and the input current loop is used to control the actual input current on the input side of the DC-DC converter circuit. The reference input current of the input current loop is determined based on the output of the bus voltage loop. The control method further includes: confirming that the DC-DC converter circuit is operating under load when the reference input current reaches a preset current threshold.

[0009] In one embodiment, the control method further includes: confirming that an input source is connected to the DC input interface when the actual input voltage reaches the start-up voltage threshold.

[0010] In one embodiment, determining the target power source type based on the AC component includes: determining the target power source type as a fuel generator when the AC component is greater than a preset voltage threshold.

[0011] In one embodiment, determining the target power source type as a fuel cell generator when the AC component is greater than a preset voltage threshold includes: incrementing the count value and the number of detections by 1 when the AC component is greater than the preset voltage threshold; incrementing the number of detections by 1 when the AC component is less than or equal to the preset voltage threshold; returning to the step of extracting the AC component of the actual input voltage when the number of detections is less than a preset number of detections threshold; and determining the target power source type as a fuel cell generator if the count value matches the number of detections when the number of detections is greater than or equal to the preset number of detections threshold.

[0012] In one embodiment, controlling the DC-DC conversion circuit to operate based on the control loop corresponding to the target power type includes: when the target power type is a photovoltaic module, controlling the DC-DC conversion circuit to operate based on the maximum power point tracking control loop; and when the target power type is a fuel cell generator, controlling the DC-DC conversion circuit to operate based on the power factor correction control loop.

[0013] A second aspect of this application provides a power conversion device, wherein a DC input interface of the power conversion device is connected to the input side of a DC conversion circuit, and the DC input interface is used to receive DC power output from an input source. The power conversion device includes a controller for executing the control method of the power conversion device as described in any of the preceding claims.

[0014] A third aspect of this application provides an energy storage device, including an energy storage battery and a power conversion device as described above.

[0015] The control method for the power conversion device provided in this application monitors the actual input voltage of the DC input interface. When an input source is confirmed to be connected to the DC input interface, the AC component of the actual input voltage is extracted. Since the circuit topology and operating mode of input sources of different target power types differ, the fluctuation characteristics of the actual input voltage also differ when different target power types are connected to the DC input interface, resulting in different voltage fluctuation characteristics of the AC component of the actual input voltage. Thus, the target power type of the input source can be determined based on the voltage fluctuation characteristics of the AC component, and the DC conversion circuit can be controlled based on the control loop corresponding to the target power type. The control method for the power conversion device provided in this application does not require the addition of new hardware circuits, can confirm the target power type of the input source with low hardware cost, and control the DC conversion circuit according to the control loop corresponding to the target power type. This makes the power conversion device applicable to more power supply scenarios, improves the conversion efficiency of the power conversion device, and greatly enhances the intelligent control attributes of the power conversion device. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.

[0017] Figure 1 This is a schematic diagram of the application environment of a power conversion device according to an embodiment of this application.

[0018] Figure 2 This is a schematic flowchart illustrating a control method for a power conversion device provided in an embodiment of this application.

[0019] Figure 3 This is a waveform diagram of the actual input voltage when the fuel generator is connected to the DC input interface of the power conversion device in one embodiment of this application.

[0020] Figure 4 This is a schematic flowchart of the sub-step of step S202, which involves extracting the AC component of the actual input voltage, in one embodiment of this application.

[0021] Figure 5 This is a flowchart illustrating a sub-step of step S202 in one embodiment of this application.

[0022] Figure 6 The present application provides two specific control block diagrams for two preset control loops used to control the operation of the DC-DC conversion circuit when an input source is confirmed to be connected to the DC input interface.

[0023] Figure 7This is a flowchart illustrating the sub-steps for determining the target power source type as a fuel generator when the AC component is greater than a preset voltage threshold, as provided in an embodiment of this application.

[0024] Figure 8 This is a schematic diagram of the actual input voltage, the fundamental component of the actual input voltage, and the AC component curve of the actual input voltage when the target power source of the input source is a fuel generator, according to one embodiment of this application.

[0025] Figure 9 This is a schematic diagram of the actual input voltage, the fundamental component of the actual input voltage, and the AC component curve of the actual input voltage when the target power source of the input source is a photovoltaic module, according to one embodiment of this application.

[0026] Figure 10 A block diagram of an energy storage device provided in an embodiment of this application.

[0027] Figure 11 This is a functional block diagram of a control device provided in an embodiment of this application.

[0028] Figure 12 A functional block diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component.

[0031] It should also be noted that the methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0034] In related technologies, the DC input interface of a power conversion device may be connected to different types of DC power sources. For example, the AC power output from a fuel generator can be rectified and then connected to the DC input interface of the power conversion device, and the DC power output from a photovoltaic module can also be connected to the DC input interface of the power conversion device.

[0035] Different types of DC power supplies correspond to different operating modes. If the power conversion equipment cannot determine whether the fuel generator or the photovoltaic module is connected, then the power conversion equipment cannot adopt the appropriate operating mode for the fuel generator and the photovoltaic module respectively, which will affect the working efficiency of the power conversion equipment.

[0036] Therefore, this application provides a power conversion device, a control method, and an energy storage device, which can identify the target power type of the input source and control the power conversion device to work according to the control loop corresponding to the target power type, so as to improve the working efficiency of the power conversion device.

[0037] Please see Figure 1 , Figure 1 This is a schematic diagram illustrating the application environment of a power conversion device 10 according to an embodiment of this application. Figure 1 As shown, the power conversion device 10 may include a controller 11, a memory 12, a DC-DC conversion circuit 13, a DC input interface IN, and a DC bus 14. The DC input interface IN is used to receive DC power output from the input source 20, and is connected to the input side of the DC-DC conversion circuit 13. The output side of the DC-DC conversion circuit 13 is connected to the DC bus 14. In the power conversion device 10, the controller 11, the memory 12, and the DC-DC conversion circuit 13 can be connected via a bus, which can be any suitable bus such as an Inter-Integrated Circuit (I2C) bus.

[0038] The DC-DC converter 13 can operate in different modes depending on the type of input source 20 connected to the power conversion device 10. For example, the DC-DC converter 13 can operate in Maximum Power Point Tracking (MPPT) mode to perform maximum power tracking on the input source 20. The DC-DC converter 13 can also operate in Power Factor Correction (PFC) mode to improve the power quality of the DC power output from the input source 20 and reduce power loss. Understandably, by calling the corresponding program instructions in the memory 12, the controller 11 can control the DC-DC converter 13 to operate in the corresponding mode.

[0039] The DC-DC conversion circuit 13 may include, for example, at least one of a buck-boost circuit, a bridgeless PFC circuit, and other circuits for implementing DC-DC conversion. In some embodiments, the DC-DC conversion circuit may also include a filter circuit, a secondary DC-DC conversion circuit, etc., to improve the quality of the output DC power. This application does not limit the specific circuit structure of the DC-DC conversion circuit 13. Moreover, the DC-DC conversion circuit 13 may be a unidirectional or bidirectional conversion circuit, and this application does not limit it in this regard.

[0040] The memory 12 can store the operating system and computer programs. The controller 11 provides computing and control capabilities to support the operation of the entire power conversion device 10. The computer program stored in the memory 12 includes program instructions, which, when executed, cause the controller 11 to perform the control method of the power conversion device provided in this application.

[0041] Input source 20 can be any device for outputting direct current (DC). For example, in some embodiments, input source 20 can be a DC generator or a renewable DC power source, such as a photovoltaic module. In other embodiments, input source 20 can also be a power distribution device, and the input side of the power distribution device can be connected to a photovoltaic module or an AC generator. The power distribution device can be equipped with a rectifier circuit for rectifying the output of the AC generator, and the output side of the rectifier device can selectively output DC power from the photovoltaic module or DC power rectified by the AC generator.

[0042] In some embodiments, the DC bus 14 may be connected to the DC side of the inverter circuit. The inverter circuit may be a bidirectional inverter circuit, meaning it converts the DC power on the DC bus 14 into AC power to supply AC loads connected to the AC side of the inverter circuit. Alternatively, the inverter circuit may convert power received on the AC side (e.g., power received from the grid) into DC power to supply DC bus 14. For example, the AC load may include one or more of a refrigerator, air conditioner, washing machine, or other AC electrical equipment.

[0043] In some embodiments, the DC bus 14 may also be connected to a DC load, and the DC bus 14 supplies power to the DC load. For example, the DC load may include one or more of an energy storage battery, a mobile phone, a laptop, or other DC-powered devices.

[0044] Understandably, the power conversion device 10 may be configured with more functional circuits or interfaces as needed, and this application does not further limit the specific device type or working scenario of the power conversion device 10.

[0045] Please refer to the following: Figure 2 , Figure 2 This is a schematic flowchart illustrating a control method for a power conversion device according to an embodiment of this application. It is understood that the control method for the power conversion device provided in this application can be executed by controller 11, or by a controller independent of the power conversion device 10. It is also understood that the control method for the power conversion device provided in this application can be applied to... Figure 1 The power conversion device 10 shown can also be applied to other application environments that require differentiation of input source types. Figure 1 The application environment shown does not limit the power conversion device and its control method, or the energy storage device provided in this application. The control method for the power conversion device provided in this application includes steps S201-S204.

[0046] Step S201: Monitor the actual input voltage of the DC input interface.

[0047] In some embodiments, the voltage of the DC input interface IN can be obtained through a voltage sampling circuit to determine the actual input voltage. For example, the voltage sampled from the DC input interface IN can be filtered to use the filtered voltage as the actual input voltage. For example, a moving average filtering algorithm or an arithmetic average filtering algorithm can be used; this application does not limit the specific filtering algorithm employed. In other embodiments, the voltage sampled from the DC input interface IN can also be directly used as the actual input voltage.

[0048] Step S202: When it is confirmed that an input source is connected to the DC input interface, extract the AC component of the actual input voltage.

[0049] When the actual input voltage output from input source 20 to DC input interface IN is periodic, the actual input voltage can be considered as being obtained by superimposing a specific frequency AC component onto the corresponding fundamental frequency. Here, the fundamental frequency refers to the DC component output from input source 20 and / or the AC component of the specified frequency band, rather than specifically referring to the 50Hz fundamental frequency of the power grid. Therefore, in step S202, the fundamental frequency component in the actual input voltage can be separated, and then the AC component can be extracted based on the actual input voltage and the fundamental frequency component.

[0050] Step S203: Determine the target power type of the input source based on the AC component.

[0051] Because the circuit topologies and operating modes of input sources 20 of different target power types are different, the fluctuation characteristics of the actual input voltage will also be different when the input sources 20 of different target power types are connected to the DC input interface IN, resulting in different voltage fluctuation characteristics of the AC component of the actual input voltage. These voltage fluctuation characteristics can be reflected by the degree of fluctuation in voltage amplitude or the magnitude of voltage frequency. Therefore, in step S203, the target power type of the input source 20 can be determined based on the fluctuation characteristics of the AC component.

[0052] For example, the target power source type may include fuel cell generators, photovoltaic modules, etc. When the target power source type of input source 20 is a fuel cell generator, the waveform of the actual input voltage can be approximately as follows: Figure 3 The diagram illustrates a "bun wave". When the target power source of input source 20 is a photovoltaic module, the actual input voltage is the DC photovoltaic voltage output by the photovoltaic module, which is a relatively stable DC waveform. Clearly, under steady-state conditions, the bun wave obtained after rectifying the AC power output from the fuel generator fluctuates more than the photovoltaic voltage, indicating that the peak value of the harmonics in the bun wave within a specific frequency band is larger than the peak value of the harmonics in the photovoltaic voltage within the same frequency band. Therefore, by extracting the harmonics of the actual input voltage at a specific frequency (i.e., extracting the AC component within a specific frequency band of the actual input voltage) and obtaining at least one of the voltage fluctuation parameters such as the voltage peak value, voltage RMS value, voltage peak-to-peak value, and voltage frequency, the target power source type of input source 20 corresponding to the actual input voltage can be determined based on the magnitude of the voltage fluctuation parameters.

[0053] Understandably, this application does not limit the number of target power sources. In other embodiments, other target power sources besides photovoltaic modules and fuel generators can be determined based on the AC component characteristics of other input sources 20 in a specific frequency band.

[0054] Step S204: Control the DC-DC conversion circuit to work based on the control loop corresponding to the target power type.

[0055] In other words, by executing step S204, the power conversion device 10 can switch to the corresponding operating mode according to different target power types, so as to control the DC conversion circuit 13 to operate based on the corresponding control loop.

[0056] Each control loop represents an abstract logic chain of an algorithm that implements the corresponding operating mode of the DC-DC converter 13. Understandably, since different target power source types of input sources 20 result in different characteristics of the actual input voltage, different control loops can be configured for different target power source types of input sources 20 to control the DC-DC converter in different operating modes. This allows the power conversion device 10 to be applicable to more power supply scenarios and improves the conversion efficiency of the power conversion device 10.

[0057] Understandably, each corresponding control loop can output corresponding control parameters to the DC-DC conversion circuit 13 based on the sampled electrical parameters of the DC input interface IN and / or the DC bus 14 (i.e., the input side and / or output side of the DC-DC conversion circuit 13), such as voltage parameters, current parameters, power parameters, and at least one of other electrical parameters, to control the operation of the DC-DC conversion circuit 13. These control parameters include, but are not limited to, at least one of pulse width modulation (PWM) signals, modulation parameters, and other parameters.

[0058] In some embodiments, the control loop may include at least one of a voltage loop, a current loop, a power loop, a combined loop, and other control loops. This application does not limit the specific loop. The control loop may include one or more control elements / controllers, such as adders, subtractors, derivative controllers (D), proportional-integral (PI) controllers, proportional-integral-derivative (PI-D) controllers, limiters, etc., and this application does not limit such control loops / controllers.

[0059] In summary, the control method for the power conversion device provided in this application monitors the actual input voltage of the DC input interface IN to extract the AC component of the actual input voltage when an input source 20 is confirmed to be connected to the DC input interface IN. Since the circuit topology and operating mode of input sources 20 of different target power types are different, the fluctuation characteristics of the corresponding actual input voltage are also different when different target power types of input sources 20 are connected to the DC input interface IN, resulting in different voltage fluctuation characteristics of the AC component of the actual input voltage. Thus, the target power type of the input source 20 can be determined based on the voltage fluctuation characteristics of the AC component, and the DC conversion circuit 13 can be controlled based on the control loop corresponding to the target power type. Compared to related technologies that attempt to identify the target power type of the input source 20 by trying to lower the actual input voltage using hardware circuits, the control method for the power conversion device provided in this application can confirm the target power type of the input source 20 at a lower hardware cost and control the DC conversion circuit 13 based on the control loop corresponding to the target power type. This makes the power conversion device 10 applicable to more power supply scenarios, improves the conversion efficiency of the power conversion device 10, and greatly enhances the intelligent control attributes of the power conversion device 10.

[0060] Please see Figure 4 In some embodiments, the extraction of the AC component of the actual input voltage in step S202 includes the following steps S401-S402.

[0061] Step S401: Extract the fundamental component of the actual input voltage using a low-pass filter.

[0062] The cutoff frequency of the low-pass filter can be set according to the fundamental component to be extracted. This application does not limit the cutoff frequency of the low-pass filter.

[0063] For example, when identifying the target power source as the input source 20 of a fuel cell generator, since the frequency of the fuel cell generator's output voltage is generally 50Hz or 60Hz, considering error factors, the frequency range of the fuel cell generator's output voltage can be considered to be between 40Hz and 70Hz. Since rectifying the output voltage of the fuel cell generator essentially flips the negative half-cycle of the output voltage to the positive half-cycle, the frequency range of the rectified output voltage's peak value can be considered to be between 80Hz and 140Hz. Therefore, the cutoff frequency of the low-pass filter in step S401 can be set to 80Hz to extract the DC component and harmonic components below 80Hz from the actual input voltage as the fundamental frequency component.

[0064] In some embodiments, a first duration can be delayed to allow the low-pass filter to reach its adjustment time and maintain a stable output before the fundamental component of the actual input voltage within a second duration is extracted using the low-pass filter. The second duration is longer than the first duration, thus reducing sampling error by sampling the fundamental component over a longer period. For example, the first duration could be 10 milliseconds, and the second duration could be 100 milliseconds. This application does not limit the specific values ​​of the first and second durations.

[0065] Step S402: Determine the AC component based on the actual input voltage and fundamental component.

[0066] Understandably, since the actual input voltage can be considered as being obtained by superimposing the fundamental component with the AC component, in step S502, the actual input voltage can be subtracted from the fundamental component to obtain the AC component.

[0067] Understandably, in other embodiments, after performing step S401, other filters, such as second-order low-pass filters, multi-order low-pass filters, band-pass filters, etc., can be set to filter the fundamental component output by the low-pass filter, and the AC component can be determined based on the actual input voltage and the filtered fundamental component, thereby improving the accuracy of the obtained AC component.

[0068] In summary, by executing steps S401-S402, the AC component of the actual input voltage can be extracted quickly and effectively, thereby determining the target power supply type of the input source 20 based on the extracted AC component.

[0069] Please see Figure 5 In some embodiments, step S202 may include the following steps S501-S502.

[0070] Step S501: When it is confirmed that an input source is connected to the DC input interface, the DC conversion circuit is controlled to work based on the preset control loop.

[0071] The preset control loop controls the DC-DC converter circuit 13 to operate within the identification time, thereby limiting the actual input voltage of the DC input interface IN to below a first voltage threshold. The first voltage threshold is less than or equal to the overvoltage protection threshold of the DC input interface IN. The identification time is defined as the period from the moment the input source 20 is connected to the DC input interface IN of the power conversion device 10 until the moment the power conversion device 10 identifies the target power type of the input source 20 and controls the DC-DC converter circuit 13 to operate according to the target power type. Thus, by executing step S501 to limit the actual input voltage to below the first voltage threshold within the identification time, the probability of the DC input interface IN triggering overvoltage protection and the probability of the power conversion device 10 pulling down or under-voltage the output voltage of the input source 20 are effectively reduced before the power conversion device 10 switches to the corresponding operating mode according to the target power type of the input source 20. This improves the safety of the power conversion device 10 and reduces the number of times the power conversion device 10 repeatedly starts and stops due to the input source 20 being pulled down.

[0072] Understandably, each preset control loop can output corresponding control parameters to the DC-DC conversion circuit 13 based on the sampled electrical parameters of the DC input interface IN and / or the DC bus 14 (i.e., the input side and / or output side of the DC-DC conversion circuit 13), such as voltage parameters, current parameters, power parameters, and at least one of other electrical parameters, to control the operation of the DC-DC conversion circuit 13. These control parameters include, but are not limited to, at least one of pulse width modulation (PWM) signals, modulation parameters, and other parameters.

[0073] For example, in some embodiments, the preset control loop may include a bus voltage loop. The bus voltage loop is used to control the actual bus voltage on the output side of the DC-DC converter circuit 13, and in the preset control loop, the output value of the bus voltage loop is limited to below a preset threshold to clamp the actual bus voltage below a preset voltage value, thereby forcing the actual input voltage of the DC input interface IN to be limited to below a first voltage threshold.

[0074] It is understood that in other embodiments, the preset control loop may also include at least one of voltage loop, current loop, power loop, combined loop, or other control loops. This application does not limit the specific loop. The preset control loop may include one or more control elements / controllers, such as adders, subtractors, derivative controllers (D), proportional-integral (PI) controllers, proportional-integral-derivative (PI-DE) controllers, limiters, etc., and this application does not limit this.

[0075] Step S502: When the DC-DC converter circuit is operating under load, extract the AC component of the actual input voltage.

[0076] Since step S501 has confirmed that an input source 20 is connected to the DC input interface IN, when step S502 confirms that the DC conversion circuit 13 is working under load, it means that the power conversion device 10 needs to perform power conversion processing on the DC power output by the input source 20. At this time, extracting the AC component of the actual input voltage can reduce the number of times the power conversion device 10 extracts the AC component of the actual input voltage, thereby reducing the computational power occupied by the controller 11. Moreover, compared with extracting the AC component of the actual input voltage when it is confirmed that an input source 20 is connected to the DC input interface IN, the sampling error can be effectively reduced.

[0077] It is understandable that when the DC-DC converter circuit 13 is not detected to be operating under load, the AC component of the actual input voltage is not extracted.

[0078] In summary, by executing steps S501-S502, the safety of the power conversion device 10 can be improved and the number of times the power conversion device 10 is repeatedly started and stopped can be reduced before the power conversion device 10 switches to the working mode corresponding to the target power type, and the error in extracting the AC component of the actual input voltage can be reduced.

[0079] In some embodiments, the preset control loop includes a bus voltage loop and an input current loop. The bus voltage loop controls the actual bus voltage on the output side of the DC-DC converter 13, and the input current loop controls the actual input current on the input side of the DC-DC converter 13. The reference input current of the input current loop is determined based on the output of the bus voltage loop.

[0080] For example, please see Figure 6 A in Figure 6 In the diagram, A represents a specific control block diagram of a preset control loop provided in an embodiment of this application for controlling the operation of the DC-DC conversion circuit 13 when it is confirmed that an input source 20 is connected to the DC input interface IN. Figure 6The preset control loop shown in Figure A includes a bus voltage loop and an input current loop. The bus voltage loop controls the actual bus voltage on the output side of the DC-DC converter 13, and the input current loop controls the actual input current on the input side of the DC-DC converter 13. The reference input current of the input current loop is determined based on the output of the bus voltage loop.

[0081] In the bus voltage loop, the first subtractor 61 calculates the bus voltage based on the actual bus voltage v. bus and bus voltage setpoint v busref Determine the voltage deviation value v dev Next, the first PI controller 62 measures the voltage deviation value v. dev Deviation adjustment is performed to obtain the first input current reference amplitude I. amp1 Then, the first limiter 63 limits the first input current reference amplitude I. amp1 Amplitude limiting is performed to obtain the second input current reference amplitude I. amp2 Multiplier 66 operates based on the second input current reference amplitude I. amp2 The reference input current I is obtained by calculating the second phase sine value sinθ. ref Among them, divider 64 calculates the actual input voltage v. fdb_in Divide by the peak input voltage v p A first phase sine value sinθ' is obtained, and then a second limiter 65 limits the first phase sine value sinθ' to output a second phase sine value sinθ. In some embodiments, the first limiter 62 is used to limit the second input current reference amplitude I. amp2 Limiting the current to a range greater than 0 and less than a preset current threshold helps to limit the actual input voltage of the DC input interface IN, reducing the probability of triggering overvoltage protection or causing the input source 20 to fail. In some embodiments, the second limiter 65 is used to limit the second phase sine value sinθ to a range of 0 to 1.05, so as to clip the phase sine value and reduce the probability of overcurrent or backflow.

[0082] In the input current loop, the second subtractor 67 is based on the reference input current I. ref and actual input current I fdb_in The current deviation value I was calculated. dev Then, the second PI controller 68 adjusts the current deviation value I. dev Deviation adjustment is performed to output the reference bus voltage v. ref Next, the third limiter 69 pairs the reference bus voltage v. ref Amplification is applied to output the target bus voltage v. aim Finally, the PWM controller 70 determines the target bus voltage v based on the target bus voltage v. aimA corresponding PWM signal is generated and output to the DC-DC converter circuit 13. In some embodiments, the reference bus voltage v is limited by the third limiter 69. ref Perform amplitude limiting and output the target bus voltage v aim This allows the PWM controller 70 to adjust the voltage based on the target bus voltage v. aim When generating the corresponding PWM signal, the actual input current can be limited to below the rated input current, thereby effectively reducing the probability of actual input current overcurrent.

[0083] For example, please see Figure 6 B in Figure 6 B in this application is a specific control block diagram of a preset control loop for controlling the operation of the DC-DC conversion circuit 13 when it is confirmed that an input source 20 is connected to the DC input interface IN. Figure 6 The preset control loop shown in Figure B may include an input voltage loop, a bus voltage loop, and an input current loop. The input voltage loop controls the actual input voltage on the input side of the DC-DC converter 13. The bus voltage loop controls the actual bus voltage on the output side of the DC-DC converter 13, and the input current loop controls the actual input current on the input side of the DC-DC converter 13. The reference input current of the input current loop is determined by the smaller of the output values ​​from the input voltage loop and the bus voltage loop.

[0084] Specifically, in Figure 6 In the input voltage loop shown by B, the first subtractor 802 calculates the input voltage based on the actual input voltage v. fdb_in and input voltage setpoint v ref_in Determine the first voltage deviation value v dev1 Among them, the input voltage setpoint v ref_in The first limiter 801 limits the input voltage peak value v p_in The amplitude is obtained by performing a limiting process. For example, the first limiter 801 can calculate a preset limiting coefficient (e.g., 0.6) and the input voltage peak value v. p_in The product of the two voltage limits is used, and the product is limited according to the preset upper and lower voltage limits. The limited output is then used as the input voltage setpoint v. ref_in The preset limiting factor is much smaller than the FFU factor of a normal photovoltaic curve, that is, much smaller than the ratio of the maximum power point voltage to the open-circuit voltage of the photovoltaic module. For example, the preset limiting factor can be 0.6. The preset upper and lower voltage limits can be set to pre-configured MPPT upper and lower voltage limits, respectively, or they can be set to other voltages. In this way, it can be ensured that the input voltage setpoint is much smaller than the actual input voltage, so that the input voltage loop saturates, thereby reducing the probability of the input source 20 being pulled down due to the actual input voltage being too large. Then, the first PI controller 803 adjusts the first voltage deviation value v. dev1Perform deviation adjustment to output the first current reference value I. amp1 Then, the second limiter 804 limits the first current reference value I. amp1 Amplification is performed to output the second current reference value I. amp2 The loop output is taken from the smaller current collector 808. Understandably, the actual input current is limited below the rated current by the limiting process of the second limiter 804.

[0085] exist Figure 6 In the bus voltage loop shown in Figure B, the second subtractor 805 calculates the bus voltage based on the actual bus voltage v. bus and bus voltage setpoint v busref Determine the second voltage deviation value v dev2 Next, the second PI controller 806 measures the second voltage deviation value v. dev2 Deviation adjustment is performed to obtain the third current reference value I. amp3 Then, the third limiter 807 limits the third current reference value I. amp3 Amplification is performed to obtain the fourth current reference value I. amp4 And output to the loop output parser 808. Similarly, the limiting processing of the third limiter 807 can avoid the fourth current reference value I. amp4 An excessively large input source 20 will be overwhelmed.

[0086] exist Figure 6 In the input current loop shown by B, the loop output taker 808 sets the second current reference value I. amp2 With the fourth current reference value I amp4 The minimum value in is used as the reference input current I. ref The output is sent to the third subtractor 809. The third subtractor 809 outputs based on the reference input current I. ref and actual input current I fdb_in The current deviation value I was calculated. dev Then, the third PI controller 810 measures the current deviation value I. dev Deviation adjustment is performed to output the reference bus voltage v. ref Next, the fourth limiter 811 limits the reference bus voltage v. ref Amplification is applied to output the target bus voltage v. aim Finally, the PWM controller 812 determines the target bus voltage based on the voltage v. aim A corresponding PWM signal is generated and output to the DC-DC converter circuit 13. In some embodiments, the reference bus voltage v is limited by the fourth limiter 812. ref Perform amplitude limiting and output the target bus voltage v aim This allows the PWM controller 812 to adjust the voltage based on the target bus voltage v. aimWhen generating the corresponding PWM signal, the actual input current can be limited to below the rated input current, thereby effectively reducing the probability of actual input current overcurrent.

[0087] Accordingly, the control methods for power conversion equipment also include: When the reference input current reaches the preset current threshold, confirm that the DC-DC conversion circuit is operating under load.

[0088] It is understandable that when the DC-DC converter circuit 13 is operating under load, the load 30 will pull down the DC bus voltage on the output side of the DC-DC converter circuit 13, thereby increasing the voltage deviation between the DC bus voltage and the given bus voltage. Since the reference input current output by the bus voltage loop is positively correlated with the voltage deviation, the reference input current will also increase. Therefore, when the reference input current reaches the preset current threshold, it is possible to confirm that the DC-DC converter circuit 13 is operating under load without the need for additional hardware circuitry.

[0089] In some embodiments, a corresponding preset current range can also be determined based on a preset current threshold. For example, the maximum value of the preset current range is the sum of the preset current threshold and the current tolerance, and the minimum value of the preset current range is the difference between the preset current threshold and the current tolerance. Thus, when the reference input current is greater than or equal to the minimum value of the preset current range and less than or equal to the maximum value of the preset current range, it can be confirmed that the DC-DC converter circuit 13 is operating under load. The current tolerance can be, for example, 0.5A.

[0090] In other embodiments, other methods can be used to confirm that the DC-DC converter circuit 13 is operating under load. For example, it is understood that the moment the load 30 is connected to the power conversion device 10, the actual bus voltage and / or actual bus current at the DC bus 14 will fluctuate. Therefore, in some embodiments, the DC-DC converter circuit 13 can be determined to be operating under load when a spike fluctuation in the actual bus voltage and / or actual bus current of the DC bus 14 is detected. In other embodiments, the DC-DC converter circuit 13 can also be determined to be operating under load when a preset signal is received at a preset pin of the output interface of the power conversion device 10. In other embodiments, the connection of the load 30 to the power conversion device 10 can also be determined through a communication handshake between the load 30 and the power conversion device 10. This application does not limit the specific method for confirming that the DC-DC converter circuit 13 is operating under load.

[0091] In some embodiments, the control method for the power conversion device further includes: When the actual input voltage reaches the start-up voltage threshold, confirm that an input source is connected to the DC input interface.

[0092] Among them, the start-up voltage threshold is greater than or equal to the minimum sustaining voltage of the DC input interface IN, and the start-up voltage threshold is less than or equal to the overvoltage protection threshold of the DC input interface IN.

[0093] It is understood that the instant input source 20 is connected to the DC input interface IN, the actual input voltage and / or actual input current at the DC input interface IN will fluctuate. Therefore, in some embodiments, the connection of input source 20 to the DC input interface IN can be determined when the actual input voltage of the DC input interface IN reaches the start-up voltage threshold. In other embodiments, the connection of input source 20 to the DC input interface IN can also be determined when the actual input current of the DC input interface IN reaches the start-up current threshold, or when a preset signal is received by a preset pin of the DC input interface IN. In other embodiments, the connection of input source 20 to the DC input interface IN can also be determined through a communication handshake between input source 20 and power conversion device 10. This application does not limit the specific method of determining the connection of input source 20 to the DC input interface IN.

[0094] In some embodiments, step S203 includes: When the AC component is greater than the preset voltage threshold, the target power source type is determined to be a fuel generator.

[0095] The preset voltage threshold can be, for example, 30V, 40V or other values. This application does not limit the specific value of the preset voltage threshold.

[0096] In other embodiments, when the AC component is less than or equal to a preset voltage value, the target power source type can be determined to be a photovoltaic module. The preset voltage value is less than or equal to a preset voltage threshold.

[0097] Thus, it can be determined whether the input source 20 is a fuel generator based on the AC component.

[0098] Please see Figure 7 In some embodiments, when the AC component is greater than a preset voltage threshold, the target power source type is determined to be a fuel generator, including the following steps S701-S704.

[0099] Step S701: When the AC component is greater than the preset voltage threshold, increment the count value by 1 and increment the detection count by 1.

[0100] Step S702: When the AC component is less than or equal to the preset voltage threshold, increment the detection count by 1.

[0101] Step S703: When the number of detections is less than the preset threshold, return to the step of extracting the AC component of the actual input voltage.

[0102] Step S704: When the number of detections is greater than or equal to the preset threshold, if the count value is consistent with the number of detections, then the target power source type is determined to be a fuel generator.

[0103] The preset number of times threshold can be, for example, 2 or any value greater than 2. This application does not limit the specific value of the preset number of times threshold.

[0104] Thus, by executing steps S701-S704, the target power type of the input source 20 can be confirmed as a fuel generator only when the AC component of the actual input voltage is extracted multiple times in succession and each AC component is greater than the preset voltage threshold, thereby reducing the probability of misjudgment when determining the target power type.

[0105] In some embodiments, the control method for the power conversion device further includes: When the target power source is a photovoltaic module, the DC-DC conversion circuit is controlled based on the maximum power point tracking (MPPT) control loop. When the target power source is a fuel generator, the DC-DC converter is controlled by a power factor correction (PFC) control loop.

[0106] In some embodiments, the MPPT control loop includes a bus voltage loop, an input voltage loop, and an input current loop. The bus voltage loop controls the actual bus voltage at the output side of the DC-DC converter 13. The input voltage loop controls the actual input voltage at the input side of the DC-DC converter 13. The input current loop controls the actual input current at the input side of the DC-DC converter 13. The outputs of the bus voltage loop and the input voltage loop compete to determine the smaller value, generating an input current reference value. The input current loop generates a PWM control signal for the DC-DC converter 13 based on the input current reference value and the input voltage feedforward control, thereby controlling the operation of the DC-DC converter 13 and putting the power conversion device 10 in MPPT operating mode to perform maximum power point tracking (MPPT) on the input source 20.

[0107] In some embodiments, the PFC control loop includes a bus voltage loop and an input current loop. The bus voltage loop outputs an input current reference value to the input current loop. The input current loop generates a PWM control signal based on the input current reference value and input voltage feedforward control, which is sent to the DC-DC converter circuit 13 to control the operation of the DC-DC converter circuit 13. This enables the power conversion device 10 to operate in PFC mode, thereby improving the power quality of the DC power output from the input source 20 and reducing power loss.

[0108] It is understood that in other embodiments, when the target power type includes other types, the DC-DC conversion circuit 13 can also be controlled to operate according to other control loops so that the power conversion device 10 is in the corresponding operating mode.

[0109] Please continue reading. Figure 8 and Figure 9 , Figure 8 This illustration shows a schematic diagram of the actual input voltage, the fundamental component of the actual input voltage, and the AC component curves of the actual input voltage when the target power source type of the input source 20 is a fuel generator, according to an embodiment of this application. Figure 8 Curve L801 is a schematic diagram of the actual input voltage, curve L802 is a schematic diagram of the fundamental component of the actual input voltage, and curve L803 is a schematic diagram of the AC component of the actual input voltage.

[0110] Figure 9 This illustration shows a schematic diagram of the actual input voltage, the fundamental component of the actual input voltage, and the AC component curves of the actual input voltage when the target power source type of the input source 20 is a photovoltaic module, according to an embodiment of this application. Figure 9 Curve L901 in the diagram represents the actual input voltage, curve L902 represents the fundamental component of the actual input voltage, and curve L903 represents the AC component of the actual input voltage. From... Figure 8 and Figure 9 It can be seen that when the target power source type of input source 20 is a fuel cell generator, the AC component of the actual input voltage is relatively large, while when the target power source type of input source 20 is a photovoltaic module, the AC component of the actual input voltage is almost zero. Therefore, the control method for the power conversion device provided in this application can quickly determine the target power source type of input source 20 based on the AC component of the actual input voltage when it is confirmed that input source 20 is connected to the DC input interface IN.

[0111] Please refer to it again. Figure 1 One embodiment of this application also provides a power conversion device 10, whose DC input interface IN is connected to the input side of a DC conversion circuit 13. The DC input interface IN is used to receive DC power output from an input source 20. A controller 11 is used to execute the control method of the power conversion device provided in any of the above embodiments.

[0112] Please refer to the following: Figure 1 and Figure 10 This application also provides an energy storage device 100, including an energy storage battery 101 and a power conversion device 10. The energy storage battery 101 is connected to the DC bus 14 of the power conversion device 10. Understandably, the energy storage device 100 can be a simple energy storage and release device, or it can be any electronic device including the energy storage battery 101, such as a self-moving device, air conditioner, refrigerator, etc. This application does not limit the specific type of the energy storage device 100.

[0113] Please see Figure 11An embodiment of this application also provides a control device 200, including a memory 12 and a processor 201. The memory 12 stores a computer program, causing the processor 201 to execute the computer program to implement the control method of the power conversion device as described in any of the above embodiments. It is understood that the control device 200 can be integrated into the power conversion device 10, or the control device 200 can be separately disposed from the power conversion device 10.

[0114] Please see Figure 12 This application also provides a computer-readable storage medium 300, including a computer program 301. When executed by a processor, the computer program 301 implements the control method for the power conversion device as described in the above technical solutions. The computer-readable storage medium may be a portable compact disc read-only memory (CD-ROM) and include program code, and may run on a terminal device, such as a personal computer. However, the program product of this invention is not limited thereto. In this document, the readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, apparatus, or device.

[0115] It is understood that the controller 11 and processor 201 mentioned in this application may include at least one of a microcontroller unit (MCU), a central processing unit (CPU), other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices.

[0116] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0117] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0118] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0119] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0120] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0121] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered 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 control method for a power conversion device, wherein the DC input interface of the power conversion device is connected to the input side of a DC conversion circuit, and the DC input interface is used to receive DC power output from an input source, characterized in that, The control method includes: Monitor the actual input voltage of the DC input interface; When it is confirmed that the input source is connected to the DC input interface, the AC component of the actual input voltage is extracted; The target power type of the input source is determined based on the AC component; The DC-DC conversion circuit is controlled to operate based on the control loop corresponding to the target power type.

2. The method as described in claim 1, characterized in that, The extraction of the AC component of the actual input voltage includes: The fundamental component of the actual input voltage is extracted using a low-pass filter. The AC component is determined based on the actual input voltage and the fundamental component.

3. The method as described in claim 1, characterized in that, When it is confirmed that the input source is connected to the DC input interface, extracting the AC component of the actual input voltage includes: When it is confirmed that the input source is connected to the DC input interface, the DC conversion circuit is controlled to work based on a preset control loop. When the DC-DC conversion circuit is operating under load, the AC component of the actual input voltage is extracted.

4. The method as described in claim 3, characterized in that, The preset control loop includes a bus voltage loop and an input current loop. The bus voltage loop is used to control the actual bus voltage on the output side of the DC-DC converter circuit, and the input current loop is used to control the actual input current on the input side of the DC-DC converter circuit. The reference input current of the input current loop is determined based on the output of the bus voltage loop. The control method further includes: When the reference input current reaches the preset current threshold, the DC-DC conversion circuit is confirmed to be operating under load.

5. The method as described in claim 1, characterized in that, The control method further includes: When the actual input voltage reaches the start-up voltage threshold, it is confirmed that the input source is connected to the DC input interface.

6. The method as described in claim 1, characterized in that, Determining the target power type of the input source based on the AC component includes: When the AC component is greater than a preset voltage threshold, the target power source type is determined to be a fuel generator.

7. The method as described in claim 6, characterized in that, The step of determining the target power source type as a fuel generator when the AC component is greater than a preset voltage threshold includes: When the AC component is greater than a preset voltage threshold, the count value is incremented by 1, and the number of detections is incremented by 1. When the AC component is less than or equal to a preset voltage threshold, the detection count is incremented by 1; If the number of detections is less than a preset threshold, return to the step of extracting the AC component of the actual input voltage. If the count value matches the number of detections when the number of detections is greater than or equal to a preset threshold, then the target power source type is determined to be a fuel generator.

8. The method as described in claim 1, characterized in that, The control loop based on the target power type controls the operation of the DC-DC conversion circuit, including: When the target power source type is a photovoltaic module, the DC-DC conversion circuit is controlled to operate based on the maximum power point tracking control loop. When the target power source is a fuel generator, the DC-DC conversion circuit is controlled based on the power factor correction control loop.

9. A power conversion device, wherein the DC input interface of the power conversion device is connected to the input side of a DC conversion circuit, the DC input interface being used to receive DC power output from an input source, characterized in that, The power conversion device includes a controller for performing the control method of the power conversion device as described in any one of claims 1 to 8.

10. An energy storage device, characterized in that, The energy storage device includes an energy storage battery and a power conversion device as described in claim 9.

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