DC-DC converter, control method and apparatus therefor, and storage medium

Abstract

The present application relates to the field of voltage conversion control, and in particular to a DC-DC converter, a control method and apparatus therefor, and a storage medium. The method comprises: acquiring a first side parameter and a second side parameter of a DC-DC converter; searching for a target duty ratio of the DC-DC converter on the basis of a correspondence between the first side parameter, the second side parameter and a duty ratio; and determining a feedforward control signal of the DC-DC converter on the basis of the target duty ratio, and controlling the DC-DC converter on the basis of the feedforward control signal and a feedback control signal. By means of the method, the feedforward control signal can be quickly determined on the basis of the correspondence, thereby facilitating increasement of the response speed of a system and facilitating reduction of a PI parameter, thus reducing oscillation and improving the system stability.

Description

DC-DC converter, control method, device and storage medium thereof

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 11, 2024, with application number 202410039252.9 and invention name “DC-DC converter and its control method, device and storage medium”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of voltage conversion control, and in particular to a DC-DC converter and a control method, device and storage medium thereof. Background Art

[0003] With the rapid development of new energy grid integration, distributed energy systems, energy storage systems, and electric vehicles, the demand for bidirectional DC-DC converters (DC-DC converters) is increasing. For example, in energy storage systems, DC-DC converters can step down the high-voltage power from the grid to charge the energy storage battery, or step up the low-voltage power from the energy storage battery to provide power to the grid load.

[0004] When a DC-DC converter is used in an energy storage system and is in the charging state, the charging voltage or current of the energy storage battery may experience sudden changes during the charging process due to voltage fluctuations in the power grid and the time-varying and nonlinear nature of renewable energy generation. When the DC-DC converter is in the discharging state, the on / off switching or state switching of the DC load can cause sudden changes in the discharge power. Sudden changes in the charging or discharging power parameters can affect the stability of the system. Although increasing the PI parameter can suppress power fluctuations on both sides of the DC-DC converter to a certain extent, this method slows the system's response speed and is prone to oscillation, affecting system stability.

[0005] Application Contents

[0006] In view of this, the embodiments of the present application provide a DC-DC converter and its control method, device and storage medium to solve the problem in the prior art that when suppressing power fluctuations on both sides of the DC-DC converter, the system has a slow response speed, is prone to oscillation, and affects the stability of the system.

[0007] A first aspect of an embodiment of the present application provides a control method for a DC-DC converter, the method comprising: obtaining a first-side parameter and a second-side parameter of the DC-DC converter; searching for a target duty cycle of the DC-DC converter based on a correspondence between the first-side parameter, the second-side parameter, and the duty cycle, wherein the correspondence between the first-side parameter, the second-side parameter, and the duty cycle is a calibrated correspondence when the DC-DC converter is in a predetermined stable operating state; determining a feedforward control signal of the DC-DC converter based on the target duty cycle, and controlling the DC-DC converter based on the feedforward control signal and the feedback control signal.

[0008] Based on the calibrated correspondence, a target duty cycle corresponding to the first and second parameters of the DC-DC converter is determined. A feedforward control signal for the DC-DC converter is determined based on the target duty cycle. Conversion control is performed based on the determined feedforward control signal in combination with the feedback control signal of the DC-DC converter. Because this method can quickly determine the feedforward control signal based on the correspondence, it is beneficial for improving the system's response speed and reducing PI parameters, thereby reducing oscillations and improving system stability.

[0009] In combination with the first aspect, in a first possible implementation of the first aspect, determining the feedforward control signal of the DC-DC converter according to the target duty cycle includes: allocating the target duty cycle according to a set duty cycle allocation strategy, and determining a first duty cycle of the feedforward control signal.

[0010] When determining the feedforward control signal based on the target duty cycle, the target duty cycle can be allocated based on various duty cycle allocation strategies, such that a portion of the target duty cycle is allocated to the feedforward control signal. Because the feedforward control signal is allocated a portion of the duty cycle, the increase in the feedback control signal can be reduced, thereby improving system response speed. The feedback control signal does not require large PI control parameters, which helps reduce system oscillations and improves system stability.

[0011] In combination with the first possible implementation method of the first aspect, in the second possible implementation method of the first aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal, including: determining the first duty cycle of the feedforward control signal based on the product of the target duty cycle and the set duty cycle allocation coefficient.

[0012] When allocating the target duty cycle, the allocation can be performed according to a set duty cycle allocation coefficient. That is, the value of the first duty cycle of the feedforward control signal is determined based on the product of the target duty cycle and the duty cycle allocation coefficient. The duty cycle allocation coefficient has a value range of [0, 1]. The smaller the duty cycle allocation coefficient, the smaller the duty cycle allocated to the feedforward control signal, and the larger the duty cycle allocation coefficient, the larger the duty cycle allocated to the feedforward control signal. The duty cycle allocation coefficient can be a fixed value or can vary according to the value of the target duty cycle.

[0013] In combination with the second possible implementation of the first aspect, in the third possible implementation of the first aspect, before determining the first duty cycle of the feedforward control signal based on the product of the target duty cycle and the set duty cycle distribution coefficient, the method also includes: determining the duty cycle range to which the target duty cycle belongs; and determining the duty cycle distribution coefficient corresponding to the duty cycle range to which the target duty cycle belongs based on the correspondence between the set duty cycle range and the duty cycle distribution coefficient.

[0014] When the duty cycle distribution coefficient is a variable value, multiple duty cycle ranges can be set, and different duty cycle ranges correspond to different duty cycle distribution coefficients. For example, the duty cycle range can be set to include a first duty cycle range and a second duty cycle range, and the duty cycle in the first duty cycle range is smaller than the duty cycle in the second duty cycle range. When the target duty cycle belongs to the first duty cycle range, the first duty cycle distribution coefficient corresponding to the first duty cycle range is used, and when the target duty cycle belongs to the second duty cycle range, the second duty cycle distribution coefficient corresponding to the second duty cycle range is used. Among them, the first duty cycle distribution coefficient is smaller than the second duty cycle distribution coefficient. In other words, as the target duty cycle increases, the proportion of the duty cycle allocated to the feedforward control signal becomes larger, so that smaller PI parameters can be used and the feedback control signal can be obtained faster. It is not limited to two duty cycle ranges, and can also include more than three duty cycle ranges.

[0015] In combination with the first possible implementation of the first aspect, in the fourth possible implementation of the first aspect, before allocating the target duty cycle according to the set duty cycle allocation strategy and determining the first duty cycle of the feedforward control signal, the method also includes: detecting whether the target duty cycle satisfies a duty cycle threshold that is greater than a set duty cycle threshold.

[0016] When the target duty cycle is small, a smaller PI control parameter can be used to control the DC-DC converter to output a more stable power. In this case, a duty cycle threshold can be set. When the target duty cycle is greater than the duty cycle threshold, the target duty cycle is allocated according to the duty cycle allocation strategy. When the duty cycle is less than or equal to the duty cycle threshold, control can be performed directly based on the feedback control signal, which can simplify the control of the DC-DC converter.

[0017] In combination with the fourth possible implementation method of the first aspect, in the fifth possible implementation method of the first aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy, and the first duty cycle of the feedforward control signal is determined, including: when the target duty cycle is greater than a predetermined duty cycle threshold, using a duty cycle value greater than the duty cycle threshold as the first duty cycle of the feedforward control signal.

[0018] When the target duty cycle is greater than the duty cycle threshold, the duty cycle of the target duty cycle that exceeds the duty cycle threshold can be allocated to the feedforward control signal, thereby controlling the duty cycle of the feedback control signal within a smaller range, thereby improving the system's response speed and stability. For example, if the duty cycle threshold is a and the target duty cycle is b, and b>a, then a duty cycle of ba can be allocated to the feedforward control signal, i.e., the first duty cycle is determined to be ba.

[0019] In combination with the fourth possible implementation method of the first aspect, in the sixth possible implementation method of the first aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy, and the first duty cycle of the feedforward control signal is determined, including: when the target duty cycle is greater than a predetermined duty cycle threshold, the first duty cycle of the feedforward control signal is determined according to the product of the target duty cycle and the set duty cycle allocation coefficient.

[0020] When the target duty cycle is greater than the duty cycle threshold, the target duty cycle may be used to determine the first duty cycle of the feedforward control signal according to a set duty cycle allocation coefficient. The duty cycle allocation coefficient may be a fixed value or a variable value. When the duty cycle allocation coefficient is a variable value, different duty cycle allocation coefficients may be determined based on different duty cycle ranges when the target duty cycle is greater than the duty cycle threshold.

[0021] In combination with any one of the first aspect to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner of the first aspect, the first-side parameter includes the battery voltage and the battery current, and the second-side parameter includes the bus voltage.

[0022] The first side of the DC-DC converter is connected to the battery, and the second side is connected to the DC side, which is used to output the bus voltage. Because different bus voltages, battery voltages, and battery currents affect the target duty cycle of the DC-DC converter, a three-dimensional table can be calibrated based on the corresponding relationship between battery voltage, battery current, bus voltage, and target duty cycle. Based on this calibrated three-dimensional table, the target duty cycle corresponding to any battery voltage, battery current, and bus voltage can be found.

[0023] In combination with the seventh possible implementation manner of the first aspect, in an eighth possible implementation manner of the first aspect, before searching for the target duty cycle of the DC-DC converter based on the correspondence between the first-side parameter, the second-side parameter, and the duty cycle, the method further includes: setting the battery voltage and the bus voltage according to the calibration step and the calibration range, and generating a battery power instruction; and when detecting that the battery current matches the current corresponding to the battery power instruction and that the battery current meets the set stability requirement, determining that the duty cycle of the control signal of the DC-DC converter is the duty cycle calibrated by the battery current, the battery voltage, and the bus voltage.

[0024] Based on the set calibration step size, the battery voltage, battery current, and bus voltage to be calibrated can be selected within the calibration range. The battery voltage and bus voltage can be fixed first, and then the battery power command can be input. The battery operating current is adjusted based on the battery power command. When the battery operating current matches the battery power command and the operating current stability meets the predetermined requirements, the duty cycle of the DC-DC converter control signal is obtained. This is the duty cycle corresponding to the current battery voltage, bus voltage, and battery current. By repeating the calibration multiple times, the duty cycle corresponding to each calibrated three-dimensional point can be obtained.

[0025] A second aspect of an embodiment of the present application provides a control device for a DC-DC converter, the device comprising: a parameter acquisition unit, configured to acquire first-side parameters and second-side parameters of the DC-DC converter; a target duty cycle determination unit, configured to search for a target duty cycle of the DC-DC converter based on a correspondence between the first-side parameters, the second-side parameters, and the duty cycle, wherein the correspondence between the first-side parameters, the second-side parameters, and the duty cycle is a calibrated correspondence when the DC-DC converter is in a predetermined stable operating state; and a feedforward determination unit, configured to determine a feedforward control signal for the DC-DC converter based on the target duty cycle, and control the DC-DC converter based on the feedforward control signal and a feedback control signal.

[0026] In combination with the second aspect, in a first possible implementation of the second aspect, determining the feedforward control signal of the DC-DC converter according to the target duty cycle includes: allocating the target duty cycle according to a set duty cycle allocation strategy, and determining a first duty cycle of the feedforward control signal.

[0027] When determining the feedforward control signal based on the target duty cycle, the target duty cycle can be allocated based on various duty cycle allocation strategies, such that a portion of the target duty cycle is allocated to the feedforward control signal. Because the feedforward control signal is allocated a portion of the duty cycle, the increase in the feedback control signal can be reduced, thereby improving system response speed. The feedback control signal does not require large PI control parameters, which helps reduce system oscillations and improves system stability.

[0028] In combination with the first possible implementation method of the second aspect, in the second possible implementation method of the second aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy, and the first duty cycle of the feedforward control signal is determined, including: determining the first duty cycle of the feedforward control signal according to the product of the target duty cycle and the set duty cycle allocation coefficient.

[0029] When allocating the target duty cycle, the allocation can be performed according to a set duty cycle allocation coefficient. That is, the value of the first duty cycle of the feedforward control signal is determined based on the product of the target duty cycle and the duty cycle allocation coefficient. The duty cycle allocation coefficient has a value range of [0, 1]. The smaller the duty cycle allocation coefficient, the smaller the duty cycle allocated to the feedforward control signal, and the larger the duty cycle allocation coefficient, the larger the duty cycle allocated to the feedforward control signal. The duty cycle allocation coefficient can be a fixed value or can vary according to the value of the target duty cycle.

[0030] In combination with the second possible implementation of the second aspect, in the third possible implementation of the second aspect, before determining the first duty cycle of the feedforward control signal based on the product of the target duty cycle and the set duty cycle distribution coefficient, the method also includes: determining the duty cycle range to which the target duty cycle belongs; and determining the duty cycle distribution coefficient corresponding to the duty cycle range to which the target duty cycle belongs based on the correspondence between the set duty cycle range and the duty cycle distribution coefficient.

[0031] When the duty cycle distribution coefficient is a variable value, multiple duty cycle ranges can be set, and different duty cycle ranges correspond to different duty cycle distribution coefficients. For example, the duty cycle range can be set to include a first duty cycle range and a second duty cycle range, and the duty cycle in the first duty cycle range is smaller than the duty cycle in the second duty cycle range. When the target duty cycle belongs to the first duty cycle range, the first duty cycle distribution coefficient corresponding to the first duty cycle range is used, and when the target duty cycle belongs to the second duty cycle range, the second duty cycle distribution coefficient corresponding to the second duty cycle range is used. Among them, the first duty cycle distribution coefficient is smaller than the second duty cycle distribution coefficient. In other words, as the target duty cycle increases, the proportion of the duty cycle allocated to the feedforward control signal becomes larger, so that smaller PID parameters can be used and the feedback control signal can be obtained faster. It is not limited to two duty cycle ranges, and can also include more than three duty cycle ranges.

[0032] In combination with the first possible implementation of the second aspect, in the fourth possible implementation of the second aspect, before allocating the target duty cycle according to the set duty cycle allocation strategy and determining the first duty cycle of the feedforward control signal, the method also includes: detecting whether the target duty cycle satisfies a duty cycle threshold that is greater than a set duty cycle threshold.

[0033] When the target duty cycle is small, a smaller PI control parameter can be used to control the DC-DC converter to output a more stable power. In this case, a duty cycle threshold can be set. When the target duty cycle is greater than the duty cycle threshold, the target duty cycle is allocated according to the duty cycle allocation strategy. When the duty cycle is less than or equal to the duty cycle threshold, control can be performed directly based on the feedback control signal, which can simplify the control of the DC-DC converter.

[0034] In combination with the fourth possible implementation method of the second aspect, in the fifth possible implementation method of the second aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy, and the first duty cycle of the feedforward control signal is determined, including: when the target duty cycle is greater than a predetermined duty cycle threshold, using a duty cycle value greater than the duty cycle threshold as the first duty cycle of the feedforward control signal.

[0035] When the target duty cycle is greater than the duty cycle threshold, the duty cycle of the target duty cycle that exceeds the duty cycle threshold can be allocated to the feedforward control signal, thereby controlling the duty cycle of the feedback control signal within a smaller range, thereby improving the system's response speed and stability. For example, if the duty cycle threshold is a and the target duty cycle is b, and b>a, then a duty cycle of ba can be allocated to the feedforward control signal, i.e., the first duty cycle is determined to be ba.

[0036] In combination with the fourth possible implementation method of the second aspect, in the sixth possible implementation method of the second aspect, the target duty cycle is allocated according to the set duty cycle allocation strategy, and the first duty cycle of the feedforward control signal is determined, including: when the target duty cycle is greater than a predetermined duty cycle threshold, the first duty cycle of the feedforward control signal is determined according to the product of the target duty cycle and the set duty cycle allocation coefficient.

[0037] When the target duty cycle is greater than the duty cycle threshold, the target duty cycle may be used to determine the first duty cycle of the feedforward control signal according to a set duty cycle allocation coefficient. The duty cycle allocation coefficient may be a fixed value or a variable value. When the duty cycle allocation coefficient is a variable value, different duty cycle allocation coefficients may be determined based on different duty cycle ranges when the target duty cycle is greater than the duty cycle threshold.

[0038] In combination with any one of the second aspect to the sixth possible implementation manner of the second aspect, in a seventh possible implementation manner of the second aspect, the first-side parameter includes the battery voltage and the battery current, and the second-side parameter includes the bus voltage.

[0039] The first side of the DC-DC converter is connected to the battery, and the second side is connected to the DC side, which is used to output the bus voltage. Because different bus voltages, battery voltages, and battery currents affect the target duty cycle of the DC-DC converter, a three-dimensional table can be calibrated based on the corresponding relationship between battery voltage, battery current, bus voltage, and target duty cycle. Based on this calibrated three-dimensional table, the target duty cycle corresponding to any battery voltage, battery current, and bus voltage can be found.

[0040] In combination with the seventh possible implementation manner of the second aspect, in the eighth possible implementation manner of the second aspect, before searching for the target duty cycle of the DC-DC converter based on the correspondence between the first-side parameter, the second-side parameter, and the duty cycle, the method further includes: setting the battery voltage and the bus voltage according to the calibration step and the calibration range, and generating a battery power instruction; and when detecting that the battery current matches the current corresponding to the battery power instruction and that the battery current meets the set stability requirement, determining that the duty cycle of the control signal of the DC-DC converter is the duty cycle calibrated by the battery current, the battery voltage, and the bus voltage.

[0041] Based on the set calibration step size, the battery voltage, battery current, and bus voltage to be calibrated can be selected within the calibration range. The battery voltage and bus voltage can be fixed first, and then the battery power command can be input. The battery operating current is adjusted based on the battery power command. When the battery operating current matches the battery power command and the operating current stability meets the predetermined requirements, the duty cycle of the DC-DC converter control signal is obtained. This is the duty cycle corresponding to the current battery voltage, bus voltage, and battery current. By repeating the calibration multiple times, the duty cycle corresponding to each calibrated three-dimensional point can be obtained.

[0042] A third aspect of an embodiment of the present application provides a DC-DC converter, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the method described in any one of the first aspects are implemented.

[0043] A fourth aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in any one of the first aspects are implemented.

[0044] It can be understood that the beneficial effects of the third and fourth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0046] FIG1 is a schematic diagram of an implementation flow of a control method for a DC-DC converter provided in an embodiment of the present application;

[0047] FIG2 is a schematic structural diagram of a DC-DC converter provided in an embodiment of the present application;

[0048] FIG3 is a schematic diagram of a three-dimensional representation determined based on a correspondence relationship provided in an embodiment of the present application;

[0049] FIG4 is a control logic diagram of a DC-DC converter provided in an embodiment of the present application;

[0050] FIG5 is a schematic diagram of a fixed duty cycle distribution coefficient change according to an embodiment of the present application;

[0051] FIG6 is a schematic diagram of a variable duty cycle distribution coefficient provided in an embodiment of the present application;

[0052] FIG7 is a schematic diagram of a duty cycle allocation coefficient determined according to a duty cycle threshold value provided in an embodiment of the present application;

[0053] FIG8 is a schematic diagram of a duty cycle system based on a duty cycle threshold and a variable duty cycle provided in an embodiment of the present application;

[0054] FIG9 is a schematic diagram of a control system of a DC-DC converter provided in an embodiment of the present application;

[0055] FIG10 is a schematic diagram showing a comparison of power response speeds provided in an embodiment of the present application;

[0056] FIG11 is a schematic diagram of a control device for a DC-DC converter provided in an embodiment of the present application;

[0057] FIG12 is a schematic diagram of a DC-DC converter provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0059] In order to illustrate the technical solution described in this application, specific embodiments are provided below.

[0060] When using a DC-DC converter for voltage conversion, a first voltage can be converted to a second voltage, or vice versa. In certain application scenarios, the first or second voltage may experience sudden changes. For example, in an energy storage system, the first side is connected to a battery and the second side is connected to the grid. Due to the time-varying and nonlinear nature of renewable energy generation, the charging voltage or charging current of the energy storage battery may experience sudden changes during charging. The switching of the DC load can also cause sudden changes in discharge power.

[0061] By increasing the PI parameter of the feedback control signal, the power fluctuation on both sides of the DC-DC converter can be suppressed to a certain extent. However, when increasing the PI parameter method, the system response speed is slow and it is easy to oscillate, affecting the stability of the system.

[0062] To address the above-mentioned issues, an embodiment of the present application proposes a control method for a DC-DC converter. The method determines a target duty cycle corresponding to the currently acquired first-side parameter and the second-side parameter based on a predetermined correspondence between the first-side parameter and the second-side parameter of the DC-DC converter and the duty cycle, and determines a feedforward control signal based on the target duty cycle. By controlling the DC-DC converter through the feedback control signal and the determined feedforward control signal, an effective feedback control signal can be obtained without increasing the PI control parameter. The target control signal of the DC-DC converter is determined together with the determined feedforward control signal, which can effectively improve the response speed of the system, reduce system oscillations, and contribute to system stability.

[0063] FIG1 is a schematic diagram of an implementation flow of a control method for a DC-DC converter provided in an embodiment of the present application, which is described in detail as follows:

[0064] In S101 , first-side parameters and second-side parameters of the DC-DC converter are acquired.

[0065] In the embodiments of the present application, the first-side parameter and the second-side parameter are parameters related to the control signal of the DC-DC converter. Regarding the control signal of the DC-DC converter, it can be understood that when any of the first-side parameter or the second-side parameter changes, the control signal of the DC-DC converter will also change.

[0066] For example, a first side of a DC-DC converter is connected to a battery, and a second side is connected to a DC side. First-side parameters may include battery voltage and battery current, and second-side parameters may include bus voltage. Without limitation, since the product of battery voltage and battery current equals battery power, a third parameter can be determined based on any two of the battery voltage, battery current, and battery power. Therefore, first-side parameters may include any two of the battery voltage, battery current, and battery power. For example, first-side parameters may include battery power and battery voltage, or battery current and battery voltage, or battery current and battery power.

[0067] The battery voltage can be measured by a voltage divider resistor or a voltage sensor, and the battery current can be measured by a current sensor.

[0068] FIG2 is a schematic diagram of the circuit structure of a DC-DC converter provided in an embodiment of the present application. As shown in FIG2 , the right side is the first side of the DC-DC converter, which is used to connect to a battery. The first side parameters to be acquired may include the battery voltage and battery current. The left side is the second side of the DC-DC converter, which is used to connect to the power grid. The second side parameters include the bus voltage output by the voltage converter.

[0069] The voltage converter includes a first switch T11, a second switch T12, a third switch T13, a fourth switch T14, a resonant inductor L1, a bus capacitor Cbus, a flying capacitor Cfly, and a battery capacitor Cbat. The switch pins of the first, second, third, and fourth switches T11, T12, T13, and T14 are connected in sequence: the second switch pin of the first switch T11 is connected to the first switch pin of the second switch T12, the second switch pin of the second switch T12 is connected to the first switch pin of the third switch T13, and the second switch pin of the third switch T13 is connected to the first switch pin of the fourth switch T14. The first end of the first switch T11 is connected to the positive pole of the bus, and the second end of the fourth switch T14 is connected to the negative pole of the bus. The first end of the flying capacitor is connected to the second switch pin of the first switch T11, and the second end of the flying capacitor is connected to the second switch pin of the third switch T13. The second end of the second switch pin is connected to the first end of the resonant inductor L1, and the second end of the resonant inductor L1 is connected to the positive pole of the battery.

[0070] In a possible implementation, the first switch T11 and the fourth switch T14 are a set of switches with complementary control timings, and the second switch T12 and the third switch T13 are a set of switches with complementary control timings. The control timings of the first switch T11 and the second switch T12 differ by a predetermined angle, such as 180 degrees. The present application can determine a feedforward control signal based on the target duty cycle to be found, and obtain a control signal for bidirectional conversion of the DC-DC converter by superimposing the feedforward control signal and the feedback control signal, thereby controlling the voltage converter to achieve step-up or step-down conversion.

[0071] It is understandable that the circuit structure of the DC-DC converter is not limited to the circuit structure shown in FIG. 2 .

[0072] In S102 , the target duty cycle of the DC-DC converter is found according to the corresponding relationship between the first-side parameter, the second-side parameter and the duty cycle.

[0073] In the embodiment of the present application, the correspondence between the first side parameter, the second side parameter and the duty cycle can be calibrated. When calibrating the correspondence, it is first determined that the DC-DC converter is in a predetermined stable operating state, and then, in the predetermined stable state, the target duty cycle corresponding to the first side parameter and the second side parameter is determined. Among them, the predetermined stable state can be understood as the oscillation of the output voltage and / or output current being less than a predetermined amplitude threshold. During the calibration process, the value of the duty cycle can be adjusted until the DC-DC converter is in a state that meets the requirements of the predetermined stable operating state, and the duty cycle used to calibrate the current first side parameter and the second side parameter is determined.

[0074] When the first-side parameters include battery voltage and battery current, and the second-side parameters include bus voltage, the parameter points that need to be calibrated can be determined based on the set calibration range (parameter variation range) and calibration step size. Based on the calibrated parameter points, the corresponding duty cycle of each parameter point can be determined. After calibrating the duty cycle corresponding to each parameter point, a three-dimensional calibration diagram can be obtained, that is, the duty cycle is determined based on the three parameter dimensions of battery voltage, battery current, and bus voltage.

[0075] For example, for a DC-DC converter to be calibrated, the bus voltage calibration range (i.e., the bus voltage operating range) is 1000V to 1500V, the battery voltage calibration range (operating voltage range) is 300V to 1200V, and the battery current calibration range (operating current range) is -50A to 50A. The voltage calibration step size can be set to 100V, and the current calibration step size can be set to 10A.

[0076] During calibration, the bus voltage and battery voltage can be fixed first. For example, the bus voltage can be fixed at 1000V and the battery voltage at 300V. Then, through current commands, the battery calibration current can be switched from -50A to 50A in steps of 10A. The steady-state battery calibration current output by the DC-DC converter is recorded. For example, the duty cycle of the DC-DC converter is determined when the battery current fluctuation amplitude is less than a predetermined amplitude threshold.

[0077] After calibrating all battery currents at a bus voltage of 1000 V and a battery voltage of 300 V, you can switch battery voltages within the battery voltage range according to the preset voltage step size until all battery voltages are calibrated at a bus voltage of 1000 V. For example, calibrate all battery currents at a bus voltage of 1000 V and a battery voltage of 400 V, then increase the battery voltage to 500 V and continue calibrating until the voltage reaches 1200 V.

[0078] For example, when the bus voltage is 1000V, the battery voltage in the range of 300V to 1200V can be calibrated in 100V steps, and the battery current in the range of -50A to 50A can be calibrated in 10A steps. The following calibration table is obtained:

[0079] Wherein, Di (i is a natural number) represents the target duty cycle corresponding to the first side parameters and the second side parameters, namely, the bus voltage, the battery voltage and the battery current.

[0080] After all the required calibration points for the battery voltage and battery current at a bus voltage of 1000V have been calibrated, the voltage can be increased to 1100V in steps. Then, all the required calibration points for the battery voltage and battery current at this voltage are calibrated again until all bus voltage calibration points within the bus battery range are calibrated. The corresponding relationship between the calibrated parameter points for battery voltage, battery current, and bus voltage and the duty cycle is obtained.

[0081] As shown in Figure 3, if the battery voltage, battery current, and bus voltage are used as the X-axis, Y-axis, and Z-axis of the coordinate system, respectively, a three-dimensional coordinate system can be obtained. In this three-dimensional coordinate system, the corresponding duty cycle can be directly found for each calibrated parameter point within the calibration range. The target duty cycle can be found based on the current battery voltage, battery current, and bus voltage.

[0082] It can be understood that the above-mentioned battery voltage and battery current can use any two of battery voltage, battery current and battery power.

[0083] In S103 , a feedforward control signal of the DC-DC converter is determined according to the target duty cycle, and the DC-DC converter is controlled according to the feedforward control signal and a feedback control signal.

[0084] In the embodiment of the present application, when determining the feedforward control signal of the DC-DC converter according to the target duty cycle, part of the target duty cycle can be allocated to the feedforward control signal based on the set allocation strategy.

[0085] The set allocation strategy may determine the first duty cycle of the feedforward control signal according to a fixed duty cycle allocation coefficient.

[0086] The control logic diagram of the DC-DC converter can be shown in Figure 4. The control signal D of the DC-DC converter is generated by superimposing the feedback control signal and the feedforward control signal. A battery command can be obtained based on the battery power command Pset and the battery voltage to determine the reference current Iref. The feedback control signal can compare the reference current Iref in the current command with the feedback current Ifbk. The comparison result is PI-regulated by a PI regulator to obtain the second duty cycle D2 of the feedback control signal. The feedforward control signal is based on the battery voltage Vbat, the bus voltage Vbus, and the reference current Iref. A duty cycle feedforward table lookup is performed based on the obtained battery voltage Vbat and bus voltage Vbus, combined with the reference current Iref in the received current command, to obtain the target duty cycle D0. The target duty cycle is determined based on the set duty cycle allocation coefficient k. The first duty cycle allocated to the feedforward control signal is determined to be D1 = D0*k. By superimposing the first duty cycle D1 and the second duty cycle D2 , a target duty cycle D for controlling the DC-DC converter can be generated, which is used to control the state of the conversion switch of the DC-DC converter.

[0087] Since the feedforward control signal, i.e., the first duty cycle, can be quickly determined by looking up a table, the PI regulator can quickly obtain the corresponding feedforward control signal without using a large PI parameter, thereby reducing the probability of overshoot in the PI regulator and improving system stability.

[0088] When using a fixed duty cycle allocation coefficient, the relationship between the first duty cycle of the feedforward control signal and the target duty cycle is shown in Figure 5. The duty cycle allocation coefficient is a fixed value. In this case, as the target duty cycle increases, the first duty cycle of the feedforward control signal increases by the same proportion. Because the increase in the first duty cycle reduces the variation in the second duty cycle when it is superimposed with the second duty cycle in the feedback control signal to generate the target duty cycle, the requirements for the PI parameters can be reduced, resulting in a more stable system and a faster response.

[0089] In a possible implementation, the duty cycle allocation coefficient can be a variable value. As shown in Figure 6, the target duty cycle can be divided into multiple duty cycle ranges. Each duty cycle range corresponds to a different duty cycle allocation coefficient. For example, as shown in Figure 6, the duty cycle in the first duty cycle range is smaller than the duty cycle in the second duty cycle range. The first duty cycle allocation coefficient k1 corresponding to the first duty cycle range is smaller than the second duty cycle allocation coefficient k2 corresponding to the second duty cycle range. In other words, as the target duty cycle increases, the proportion of the duty cycle allocated to the feedforward control signal increases.

[0090] In a possible implementation, the activation conditions for the duty cycle allocation coefficient can also be set. As shown in Figure 7, a duty cycle threshold can be set. When the target duty cycle is greater than the duty cycle threshold, a portion of the target duty cycle can be allocated to the feedforward control signal according to a fixed duty cycle allocation coefficient. When the target duty cycle is less than or equal to the duty cycle threshold, the feedforward control signal does not participate in the allocation of the target duty cycle.

[0091] Alternatively, as shown in FIG8 , when the target duty cycle is less than or equal to the duty cycle threshold, the feedforward control signal does not participate in the distribution of the target duty cycle. When the target duty cycle is greater than the duty cycle threshold, a portion of the target duty cycle is distributed to the feedforward control signal by varying the duty cycle distribution coefficient to obtain a first duty cycle. By superimposing the first duty cycle of the feedforward control signal and the second duty cycle of the feedback control signal, the target duty cycle is quickly obtained to control the DC-DC converter.

[0092] Figure 9 is a control block diagram of a DC-DC converter provided in an embodiment of the present application. As shown in Figure 9, the control block diagram includes a power command module, a battery voltage feedback module, a bus voltage feedback module, a current feedback module, a current command calculation module, a duty cycle feedforward lookup module, a current loop control module, a duty cycle feedforward gain module, and a PWM modulation module.

[0093] The power command module receives power Pset. The battery voltage feedback module detects the battery voltage Vbat. The bus voltage feedback module detects the bus voltage Vbus. The current feedback module detects the battery operating current Ifbk. The current command calculation module calculates the battery reference current Iref based on the power Pset received from the power command module and the battery voltage Vbat detected by the battery voltage feedback module. The current loop control module compares the reference current with the battery operating current Ifbk and performs PI adjustment on the comparison result to obtain the second duty cycle D2 of the feedback control signal. The duty cycle feedforward lookup module obtains the target duty cycle D0 from a table lookup based on the battery voltage Vbat, the reference current Iref, and the bus voltage Vbus. The first duty cycle D1 is determined based on the duty cycle allocation coefficient k in the duty cycle feedforward gain module. The first duty cycle D1 and the second duty cycle D2 are superimposed to obtain the target duty cycle, which is then used by the PWM modulation module to control the DC-DC converter.

[0094] Figure 10 is a schematic diagram showing a comparison of the output response speed of a DC-DC converter control method provided by an embodiment of the present application. The left figure of Figure 10 is a schematic diagram showing a power change curve for improving power response by increasing the PI parameter, and the right figure is a schematic diagram showing a power change curve determined by determining the target duty cycle based on a lookup table, determining the feedforward control signal based on the target duty cycle, and determining the power response according to a set fixed duty cycle allocation coefficient of 0.8. By comparing the left and right figures, it can be clearly seen that the method of determining the feedforward control signal by looking up the table in the present application effectively improves the power response speed.

[0095] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0096] FIG11 is a schematic diagram of a control device for a DC-DC converter provided in an embodiment of the present application. As shown in FIG11 , the device includes:

[0097] The parameter acquisition unit 1101 is configured to acquire first-side parameters and second-side parameters of the DC-DC converter.

[0098] The target duty cycle determining unit 1102 is configured to search for a target duty cycle of the DC-DC converter based on a correspondence between the first-side parameter, the second-side parameter, and the duty cycle, wherein the correspondence between the first-side parameter, the second-side parameter, and the duty cycle is a correspondence calibrated when the DC-DC converter is in a predetermined stable operating state.

[0099] The feedforward determination unit 1103 is configured to determine a feedforward control signal of the DC-DC converter according to the target duty cycle, and control the DC-DC converter according to the feedforward control signal and a feedback control signal.

[0100] The control device of the DC-DC converter shown in FIG11 corresponds to the control method of the DC-DC converter shown in FIG1 .

[0101] FIG12 is a schematic diagram of a DC-DC converter provided in an embodiment of the present application. As shown in FIG12 , the DC-DC converter 12 of this embodiment includes: a processor 120, a memory 121, and a computer program 122 stored in the memory 121 and executable on the processor 120, such as a control program for the DC-DC converter. When the processor 120 executes the computer program 122, the steps in the above-mentioned embodiments of the control method for the DC-DC converter are implemented. Alternatively, when the processor 120 executes the computer program 122, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0102] Exemplarily, the computer program 122 may be divided into one or more modules / units, which are stored in the memory 121 and executed by the processor 120 to implement the present application. The one or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 122 in the DC-DC converter 12.

[0103] The DC-DC converter may include, but is not limited to, a processor 120 and a memory 121. Those skilled in the art will appreciate that FIG12 is merely an example of the DC-DC converter 12 and does not limit the DC-DC converter 12. The DC-DC converter 12 may include more or fewer components than shown, or may combine certain components or different components. For example, the DC-DC converter may further include input and output devices, network access devices, buses, and the like.

[0104] The processor 120 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0105] The memory 121 can be an internal storage unit of the DC-DC converter 12, such as a hard disk or memory of the DC-DC converter 12. The memory 121 can also be an external storage device of the DC-DC converter 12, such as a plug-in hard disk equipped on the DC-DC converter 12, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. Further, the memory 121 can also include both an internal storage unit of the DC-DC converter 12 and an external storage device. The memory 121 is used to store the computer program and other programs and data required by the DC-DC converter. The memory 121 can also be used to temporarily store data that has been output or is to be output.

[0106] An embodiment of the present application further provides an energy storage system, which includes the above-mentioned DC-DC converter.

[0107] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0108] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0109] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0110] In the embodiments provided in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units 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 units, which can be electrical, mechanical or other forms.

[0111] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0112] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0113] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the process in the above-mentioned embodiment method, which can also be completed by hardware related to computer program instructions. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by the processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0114] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A control method for a DC-DC converter, characterized in that, The method includes: Obtaining the first-side parameters and second-side parameters of the DC-DC converter; Finding the target duty cycle of the DC-DC converter according to the corresponding relationship between the first-side parameters, second-side parameters and the duty cycle, where the corresponding relationship between the first-side parameters, second-side parameters and the duty cycle is the calibrated corresponding relationship when the DC-DC converter is in a predetermined stable operating state; Determining the feedforward control signal of the DC-DC converter according to the target duty cycle, and controlling the DC-DC converter according to the feedforward control signal and the feedback control signal.

2. The method according to claim 1, characterized in that, Determining the feedforward control signal of the DC-DC converter according to the target duty cycle includes: Allocating the target duty cycle according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal.

3. The method according to claim 2, wherein Allocating the target duty cycle according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal includes: Determining the first duty cycle of the feedforward control signal according to the product of the target duty cycle and the set duty cycle allocation coefficient.

4. The method according to claim 3, characterized in that Before determining the first duty cycle of the feedforward control signal according to the product of the target duty cycle and the set duty cycle allocation coefficient, the method further includes: Determining the duty cycle range to which the target duty cycle belongs; Determining the duty cycle allocation coefficient corresponding to the duty cycle range to which the target duty cycle belongs according to the corresponding relationship between the set duty cycle range and the duty cycle allocation coefficient.

5. The method according to claim 2, characterized in that, Before allocating the target duty cycle according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal, the method further includes: Detecting whether the target duty cycle satisfies being greater than the set duty cycle threshold.

6. The method according to claim 5, characterized in that, Allocating the target duty cycle according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal includes: When the target duty cycle is greater than the predetermined duty cycle threshold, using the duty cycle value greater than the duty cycle threshold as the first duty cycle of the feedforward control signal.

7. The method according to claim 5, wherein Allocating the target duty cycle according to the set duty cycle allocation strategy to determine the first duty cycle of the feedforward control signal includes: When the target duty cycle is greater than the predetermined duty cycle threshold, determining the first duty cycle of the feedforward control signal according to the product of the target duty cycle and the set duty cycle allocation coefficient.

8. The method according to any one of claims 1 to 7, characterized in that The first-side parameters include the battery voltage and the battery current, and the second-side parameters include the bus voltage.

9. The method according to claim 8, wherein Before finding the target duty cycle of the DC-DC converter according to the corresponding relationship between the first-side parameters, second-side parameters and the duty cycle, the method further includes: Setting the battery voltage and the bus voltage according to the calibrated step and the calibrated range, and generating a battery power command; When it is detected that the battery current matches the current corresponding to the battery power command and the battery current meets the set stability requirement, determining that the duty cycle of the control signal of the DC-DC converter is the duty cycle calibrated by the battery current, the battery voltage and the bus voltage.

10. A control device for a DC-DC converter, characterized in that, The device includes: A parameter acquisition unit for acquiring first-side parameters and second-side parameters of the DC-DC converter; A target duty cycle determination unit for finding the target duty cycle of the DC-DC converter according to the corresponding relationship between the first-side parameters, the second-side parameters and the duty cycle, wherein the corresponding relationship between the first-side parameters, the second-side parameters and the duty cycle is the corresponding relationship calibrated when the DC-DC converter is in a predetermined stable operating state; A feedforward determination unit for determining a feedforward control signal of the DC-DC converter according to the target duty cycle, and controlling the DC-DC converter according to the feedforward control signal and a feedback control signal.

11. A DC-DC converter, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the method according to any one of claims 1 to 9 are implemented.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.

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