A high-efficiency dc-dc converter system for supercapacitor linear charge and discharge

Abstract

This invention discloses a high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors. The system divides the rated operating voltage range of the supercapacitor into multiple continuous sub-ranges using a voltage range division module. A control parameter preset module pre-designs and stores the optimal control parameter set based on a small-signal model of typical operating points in each sub-range. During operation, a real-time terminal voltage acquisition module obtains the current terminal voltage of the supercapacitor, and a control parameter adaptive loading module automatically loads the corresponding optimal control parameters according to the sub-range to which the terminal voltage belongs. A voltage outer loop module generates current commands based on the bus voltage deviation, and a current inner loop module, together with a PWM module, achieves precise charging and discharging control. This invention solves the problems of inconsistent dynamic performance and low energy efficiency of traditional fixed-parameter controllers when the supercapacitor voltage changes linearly over a wide range. It achieves adaptive matching of controller parameters with operating conditions, significantly improving the system's dynamic stability, energy conversion efficiency, and operational reliability.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion and control technology, and in particular to a high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors. Background Technology

[0002] Supercapacitors, as a new type of electrochemical energy storage element, have outstanding advantages such as high power density, long cycle life, fast charging and discharging speed, and wide operating temperature range. They have been widely used in fields such as energy recovery during rail transit braking, energy recovery during starting and braking of electric vehicles, voltage fluctuation suppression in DC microgrids, and energy recovery in port cranes.

[0003] However, the inherent characteristics of supercapacitors dictate that their terminal voltage exhibits a strictly linear change during charging and discharging—from a fully charged state to a discharged state, the terminal voltage can drop by about 50% (for example, a supercapacitor module with a rated voltage of 48V typically has a discharge cutoff voltage of 24V). This characteristic means that supercapacitors cannot be directly connected to a DC bus with a constant voltage; a bidirectional DC-DC converter is necessary to achieve voltage conversion and bidirectional energy flow.

[0004] Existing bidirectional DC-DC converters typically employ fixed-parameter PID controllers or 2p2z digital compensators for voltage closed-loop control. The controller parameters are designed and determined only based on a specific typical operating point (usually the rated voltage of the supercapacitor). Because the supercapacitor terminal voltage changes linearly during charging and discharging, the small-signal transfer function of the DC-DC converter changes significantly with the operating point: when the supercapacitor terminal voltage decreases, the DC gain of the converter increases sharply, and the system's phase margin and bandwidth shift significantly.

[0005] Voltage controllers with fixed parameters can only maintain optimal control performance near the design operating point. When the supercapacitor terminal voltage deviates from the design point, the controller's dynamic response performance will significantly decrease, manifesting as increased voltage overshoot, prolonged settling time, and even reduced stability margin, potentially leading to system oscillation in severe cases. This problem directly restricts the energy conversion efficiency and operational reliability of supercapacitor energy storage systems, becoming one of the technical bottlenecks limiting their large-scale application in more fields. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing fixed-parameter DC-DC converters, such as inconsistent dynamic response performance of the controller, reduced energy utilization efficiency, and insufficient operational reliability when the voltage at the supercapacitor terminal varies linearly over a wide range. This invention provides a high-efficiency DC-DC converter system that is adapted to the linear charging and discharging of supercapacitors.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors includes the following modules: The voltage range division module is used to obtain the rated operating voltage range of the supercapacitor module to be controlled, and divide the rated operating voltage range into multiple continuous sub-ranges. The control parameter preset module is used to pre-design a set of optimal control parameters that match the sub-interval based on the small signal model of the typical operating point of the DC-DC converter in the sub-interval for each sub-interval, and store the set of optimal control parameters corresponding to all sub-intervals into the controller. The terminal voltage real-time acquisition module is used to acquire the current terminal voltage of the supercapacitor module in real time during the operation of the converter; The adaptive control parameter calling module is used to call the optimal control parameter set corresponding to the current terminal voltage and its sub-interval from the controller and load it into the voltage controller. The voltage outer loop control module is used to calculate and output the reference command for the current inner loop based on the deviation between the reference value and the actual value of the DC bus voltage, using the voltage controller based on the optimal control parameter set after loading. The current inner loop control and PWM drive module is used to control the PWM drive signal according to the reference instruction through the current inner loop controller, drive the power switching tube of the DC-DC converter, and realize the charging and discharging management of the supercapacitor module.

[0008] Furthermore, the voltage range division module is specifically configured as follows: Obtain the highest charging cutoff voltage of the supercapacitor module and minimum discharge cutoff voltage To determine the rated operating voltage range as follows: ; Based on the control accuracy requirements of the DC-DC converter and the controller storage resources, the number of interval divisions N is preset, wherein the number of interval divisions N is an integer greater than one; Based on the rated operating voltage range and the number of intervals N, the voltage span of each sub-interval is calculated according to the principle of uniform division. The calculation formula is:

[0009] According to the voltage span Calculate the voltage boundary values ​​for each sub-interval to generate N consecutive and non-overlapping sub-intervals; where the lower limit of the first sub-interval is the minimum discharge cutoff voltage. The upper limit of the last sub-interval is the highest charging cutoff voltage. And the upper limit of the k-th subinterval is equal to the upper limit of the k-th subinterval. The lower limit of each sub-interval.

[0010] Furthermore, the control parameter preset module is specifically configured as follows: Within each sub-interval, a typical operating point is selected. This typical operating point corresponds to a specific supercapacitor terminal voltage value and the corresponding DC-DC converter operating state within that sub-interval. The typical operating point voltage of the k-th sub-interval is... The midpoint voltage of this sub-interval is calculated using the following formula:

[0011] In the formula, Let be the lower limit voltage of the k-th sub-interval. This represents the upper limit voltage of the k-th sub-interval; At each of the typical operating points, a small-signal mathematical model of the DC-DC converter is established to obtain the transfer function characteristics of the controlled object at that operating point. Based on the characteristics of the transfer function and combined with the preset dynamic response index, the optimal control parameter set corresponding to each sub-interval is designed so that the DC-DC converter has the desired control performance in the sub-interval. All optimal control parameter sets corresponding to all sub-intervals are stored in the non-volatile storage area of ​​the controller in the form of a lookup table, and a one-to-one correspondence index relationship is established between each set of optimal control parameters and its corresponding sub-interval.

[0012] Furthermore, the step of designing the optimal control parameter set corresponding to each of the sub-intervals specifically includes: For the voltage outer loop controller, a preset closed-loop bandwidth target is set. And the phase margin target PM, as the dynamic response index; wherein, the closed-loop bandwidth target With DC-DC converter switching frequency The relationship is:

[0013] Based on the transfer function characteristics obtained from the small-signal mathematical model, the frequency response curve of the DC-DC converter at the current typical operating point is plotted to determine its original amplitude-frequency characteristics and phase-frequency characteristics. Based on the original amplitude-frequency characteristics and phase-frequency characteristics, combined with the closed-loop bandwidth target... Given the phase margin target PM, the compensator parameters of the voltage outer loop controller are calculated using a frequency domain correction method; wherein, the phase lead that the compensator needs to provide at the desired crossover frequency is... The calculation formula is:

[0014] In the formula, The phase of the controlled object at the desired crossing frequency; The calculated compensator parameters are substituted into the small-signal mathematical model for closed-loop simulation or stability verification to confirm that the system can operate stably and meet the dynamic response index within the sub-interval. If the index is met, the set of compensator parameters is determined as the optimal control parameter set corresponding to the sub-interval.

[0015] Furthermore, the real-time terminal voltage acquisition module is specifically configured as follows: A voltage sampling circuit is configured at the input terminal of the DC-DC converter, and the voltage sampling circuit is electrically connected to the positive and negative terminals of the supercapacitor module. The analog voltage signal acquired by the voltage sampling circuit is filtered and its level adjusted so that its amplitude matches the input range of the analog-to-digital conversion module of the controller. According to the preset sampling period The controller's analog-to-digital converter module is triggered to perform digital conversion on the conditioned analog voltage signal, generating a digital value of the current terminal voltage. ; After each analog-to-digital conversion, according to the preset scaling factor... Calculate the terminal voltage of an actual supercapacitor The calculation formula is:

[0016] The calculated current terminal voltage is stored in a designated storage area of ​​the controller's memory for subsequent use by the control module.

[0017] Furthermore, the control parameter adaptive calling module is specifically configured as follows: The current terminal voltage acquired by the real-time terminal voltage acquisition module is compared with the boundary values ​​of each sub-interval generated by the voltage interval division module to determine the current sub-interval to which the current terminal voltage belongs. Based on the number or identifier of the current sub-interval, generate the storage address or index value of the optimal control parameter set corresponding to the sub-interval in the controller storage area; Based on the storage address or index value, the optimal control parameter set corresponding to the sub-interval is read from the controller's storage area; The read optimal control parameter set is written into the control parameter register of the voltage controller, replacing the control parameters used in the previous control cycle, thus completing the online update of the voltage controller parameters; When the current terminal voltage is located in sub-interval i and sub-interval i When the control cycle switches between adjacent sub-intervals near the boundary and multiple consecutive control cycles, linear interpolation is performed on the two adjacent sets of optimal control parameters to generate a transition parameter set and load it onto the voltage controller until the terminal voltage stabilizes within a single sub-interval. Among them, the weight coefficients of the interpolation operation Based on the current terminal voltage With boundary voltage Calculation of relative position:

[0018] In the formula, The voltage span of the sub-interval; sub-interval The weighting coefficients of the parameter set, the weighting coefficients of the parameter set in subinterval i are... ; The formula for calculating the transition parameter set is:

[0019]

[0020]

[0021]

[0022]

[0023] In the formula, Let be the optimal control parameters for interval i; For interval The optimal control parameters; This is the set of transition parameters after interpolation.

[0024] Furthermore, the voltage outer loop control module is specifically configured as follows: A voltage sampling circuit is configured at the output terminal of the DC-DC converter to acquire the actual value of the DC bus voltage in real time. ; Obtain the reference value of DC bus voltage And calculate the deviation signal between the reference value and the actual value. :

[0025] The deviation signal is amplitude-limited to prevent excessive deviation from causing controller saturation. The amplitude-limited deviation signal... satisfy:

[0026] In the formula, This is the upper limit of the deviation. This is the lower limit of the deviation, and ; The limited deviation signal is used as the input of the voltage controller. Based on the control parameters, the optimal control parameter set currently loaded by the module is adaptively called to perform digital compensator calculation and generate a preliminary current inner loop reference command. The initial current inner loop reference command is subjected to amplitude and rate of change limiting to generate the final current inner loop reference command, which is then output to the current inner loop controller.

[0027] Furthermore, the current inner loop control and PWM drive module is specifically configured as follows: A current sampling circuit is configured in the inductor branch of the DC-DC converter to collect the actual current value flowing through the inductor in real time. ; Obtain the current inner loop reference command output by the voltage outer loop control module. And calculate the current deviation signal between the reference command and the actual current value. :

[0028] The current deviation signal is used as the input to the current inner loop controller. Based on preset fixed high-speed control parameters, incremental PI digital compensator calculations are performed to generate duty cycle control quantity. The calculation formula is:

[0029] In the formula, This is the proportionality coefficient. The integral coefficient is... This is the inner loop control cycle for the current. This represents the current deviation from the previous cycle; Based on the duty cycle control value and the current operating mode of the DC-DC converter, a corresponding PWM drive pulse signal is generated. The PWM drive pulse signal is output to the drive circuit of the power switch to control the power switch to turn on and off. Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, determine whether the current mode is charging or discharging, and adjust the generation logic of the PWM drive pulse signal or the operating state of the power switch accordingly.

[0030] Furthermore, the step of adjusting the generation logic of the PWM drive pulse signal or the operating state of the power switch specifically includes: Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, a current mode status flag is generated, which includes a charging mode flag and a discharging mode flag. Based on the current mode status flag, the corresponding PWM generation logic is selected, wherein: When configured with buck PWM logic in charging mode, the relationship between duty cycle D and voltage conversion ratio is as follows: ; When configured as a boost PWM logic in discharge mode, the relationship between the duty cycle D and the voltage conversion ratio is as follows: ; According to the selected PWM generation logic, the duty cycle control quantity is allocated to the corresponding power switch transistor. In charging mode, the conduction time of the buck switch transistor is controlled, and in discharging mode, the conduction time of the boost switch transistor is controlled. A preset dead time is inserted during the state switching process of the power switch. To prevent the upper and lower switches of the same bridge arm from conducting simultaneously, the dead time must satisfy the following:

[0031] In the formula, This is the maximum turn-off delay time of the switching transistor. This is the minimum turn-on delay time for the switching transistor. For safety margin; Based on the selected PWM generation logic, a PWM signal complementary to the main control switch is generated to control the on and off of the opposite switch in the same bridge arm, thereby establishing a synchronous rectification or freewheeling path.

[0032] Beneficial Effects: Consistent Dynamic Performance Across the Entire Voltage Range: This invention divides the rated operating voltage range of the supercapacitor into multiple continuous sub-ranges and pre-sets optimal control parameters matching the operating conditions of each sub-range, achieving adaptive matching between the voltage controller parameters and the real-time terminal voltage of the supercapacitor. Compared to existing fixed-parameter control methods, this scheme ensures that the supercapacitor maintains a consistent fast dynamic response characteristic across the entire voltage range from fully charged to discharged, effectively avoiding increased overshoot and prolonged settling time caused by operating point offset, and significantly improving the dynamic performance stability of the system.

[0033] Significantly improved energy conversion efficiency: This invention maintains excellent dynamic response performance across the entire voltage range. During load changes or operating condition switching, the DC-DC converter can stabilize the DC bus voltage more quickly, reducing voltage fluctuation losses during energy recovery and release. Simultaneously, by employing synchronous rectification technology and an optimized PWM control strategy, switching losses and freewheeling losses are further reduced, thereby improving the overall energy conversion efficiency of the energy storage system.

[0034] The system's operational reliability is significantly enhanced: This invention introduces a frequency domain correction method based on a small-signal model and closed-loop simulation verification in the controller parameter design stage, ensuring that each set of preset control parameters meets the preset closed-loop bandwidth and phase margin requirements, guaranteeing stable operation of the system in each sub-interval. Simultaneously, the scheme incorporates deviation signal limiting and command limiting protection in the voltage outer loop control, and dead-time management and complementary drive control in the current inner loop control. These multiple protection mechanisms work together to effectively prevent abnormal situations such as controller saturation and power transistor shoot-through, enhancing the system's operational reliability.

[0035] Simple to implement and low cost: This invention adopts a control architecture of offline parameter preset + online table lookup call, which does not require complex online parameter identification algorithms, has low computational load, low performance requirements for controller, can be implemented on ordinary DSP or MCU, without additional hardware costs, and has good engineering practicality and promotion value. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the architecture of the high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors, as described in an embodiment of the present invention. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] Example 1 See Figure 1 A high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors includes the following modules: The voltage range division module is used to obtain the rated operating voltage range of the supercapacitor module to be controlled, and divide the rated operating voltage range into multiple continuous sub-ranges. The control parameter preset module is used to pre-design a set of optimal control parameters that match the sub-interval based on the small signal model of the typical operating point of the DC-DC converter in the sub-interval for each sub-interval, and store the set of optimal control parameters corresponding to all sub-intervals into the controller. The terminal voltage real-time acquisition module is used to acquire the current terminal voltage of the supercapacitor module in real time during the operation of the converter; The adaptive control parameter calling module is used to call the optimal control parameter set corresponding to the current terminal voltage and its sub-interval from the controller and load it into the voltage controller. The voltage outer loop control module is used to calculate and output the reference command for the current inner loop based on the deviation between the reference value and the actual value of the DC bus voltage, using the voltage controller based on the optimal control parameter set after loading. The current inner loop control and PWM drive module is used to control the PWM drive signal according to the reference instruction through the current inner loop controller, drive the power switching tube of the DC-DC converter, and realize the charging and discharging management of the supercapacitor module.

[0040] This embodiment constructs a core control architecture of "offline parameter preset + online adaptive calling," fundamentally solving the performance degradation problem of traditional fixed parameter controllers when the supercapacitor voltage changes linearly over a wide range. Compared with existing technologies, the system's voltage overshoot is reduced from 15% to less than 3% across the entire 24V-48V voltage range, the settling time is shortened from 200ms to less than 50ms, and the energy conversion efficiency is improved by 2%-3%.

[0041] In a specific example, the voltage range division module is specifically configured as follows: Obtain the highest charging cutoff voltage of the supercapacitor module and minimum discharge cutoff voltage To determine the rated operating voltage range as follows: ; Based on the control accuracy requirements of the DC-DC converter and the controller storage resources, the number of interval divisions N is preset, wherein the number of interval divisions N is an integer greater than one; Based on the rated operating voltage range and the number of intervals N, the voltage span of each sub-interval is calculated according to the principle of uniform division. The calculation formula is:

[0042] According to the voltage span Calculate the voltage boundary values ​​for each sub-interval to generate N consecutive and non-overlapping sub-intervals; where the lower limit of the first sub-interval is the minimum discharge cutoff voltage. The upper limit of the last sub-interval is the highest charging cutoff voltage. And the upper limit of the k-th subinterval is equal to the upper limit of the k-th subinterval. The lower limit of each sub-interval.

[0043] This embodiment uses the uniform division principle to divide the voltage interval, which has the following advantages: simple calculation, only one division operation is needed to determine the boundaries of all sub-intervals, and no complex nonlinear division algorithm is required; The voltage span of each sub-interval is the same, which facilitates the design and management of subsequent control parameters; The number of intervals N can be flexibly adjusted to achieve an optimal balance between control accuracy and storage overhead. When N=8, each sub-interval is only 3V, the matching accuracy between controller parameters and operating conditions is sufficiently high, and only 8 sets of parameters need to be stored, resulting in minimal storage overhead.

[0044] In a specific example, the control parameter preset module is specifically configured as follows: Within each sub-interval, a typical operating point is selected. This typical operating point corresponds to a specific supercapacitor terminal voltage value and the corresponding DC-DC converter operating state within that sub-interval. The typical operating point voltage of the k-th sub-interval is... The midpoint voltage of this sub-interval is calculated using the following formula:

[0045] In the formula, Let be the lower limit voltage of the k-th sub-interval. This represents the upper limit voltage of the k-th sub-interval; At each of the typical operating points, a small-signal mathematical model of the DC-DC converter is established to obtain the transfer function characteristics of the controlled object at that operating point. Based on the characteristics of the transfer function and combined with the preset dynamic response index, the optimal control parameter set corresponding to each sub-interval is designed so that the DC-DC converter has the desired control performance in the sub-interval. All optimal control parameter sets corresponding to all sub-intervals are stored in the non-volatile storage area of ​​the controller in the form of a lookup table, and a one-to-one correspondence index relationship is established between each set of optimal control parameters and its corresponding sub-interval.

[0046] This embodiment selects the midpoint of the sub-interval as the typical operating point, which can most accurately represent the average operating condition of the sub-interval and ensure that the designed control parameters have good control performance throughout the entire sub-interval. The parameter design method based on the small signal model can obtain the optimal control parameters more accurately and quickly than the traditional trial and error method. The parameters are stored in the form of a lookup table, and only one array index operation is required when calling them online, with a time consumption of less than 1μs, which fully meets the requirements of real-time control.

[0047] In a specific example, the step of designing the optimal control parameter set corresponding to each of the sub-intervals specifically includes: For the voltage outer loop controller, a preset closed-loop bandwidth target is set. And the phase margin target PM, as the dynamic response index; wherein, the closed-loop bandwidth target With DC-DC converter switching frequency The relationship is:

[0048] Based on the transfer function characteristics obtained from the small-signal mathematical model, the frequency response curve of the DC-DC converter at the current typical operating point is plotted to determine its original amplitude-frequency characteristics and phase-frequency characteristics. Based on the original amplitude-frequency characteristics and phase-frequency characteristics, combined with the closed-loop bandwidth target... Given the phase margin target PM, the compensator parameters of the voltage outer loop controller are calculated using a frequency domain correction method; wherein, the phase lead that the compensator needs to provide at the desired crossover frequency is... The calculation formula is:

[0049] In the formula, The phase of the controlled object at the desired crossing frequency; The calculated compensator parameters are substituted into the small-signal mathematical model for closed-loop simulation or stability verification to confirm that the system can operate stably and meet the dynamic response index within the sub-interval. If the index is met, the set of compensator parameters is determined as the optimal control parameter set corresponding to the sub-interval.

[0050] This embodiment clarifies the design criteria for closed-loop bandwidth and phase margin, ensuring that the designed controller has both a sufficiently fast dynamic response speed and good stability; This embodiment calculates the compensator parameters using a frequency domain correction method, which can accurately control the crossover frequency and phase margin of the open-loop transfer function, ensuring consistent control performance. This embodiment adds a closed-loop simulation verification step, which can identify problems in parameter design in advance and avoid system instability during actual debugging.

[0051] In a specific example, the real-time terminal voltage acquisition module is specifically configured as follows: A voltage sampling circuit is configured at the input terminal of the DC-DC converter, and the voltage sampling circuit is electrically connected to the positive and negative terminals of the supercapacitor module. The analog voltage signal acquired by the voltage sampling circuit is filtered and its level adjusted so that its amplitude matches the input range of the analog-to-digital conversion module of the controller. According to the preset sampling period The controller's analog-to-digital converter module is triggered to perform digital conversion on the conditioned analog voltage signal, generating a digital value of the current terminal voltage. ; After each analog-to-digital conversion, according to the preset scaling factor... Calculate the terminal voltage of an actual supercapacitor The calculation formula is:

[0052] The calculated current terminal voltage is stored in a designated storage area of ​​the controller's memory for subsequent use by the control module.

[0053] This embodiment pre-calculates the scaling factor. Online calculations require only one multiplication operation, which greatly reduces the computational burden on the DSP and improves the real-time performance of the system.

[0054] In a specific example, the adaptive control parameter calling module is specifically configured as follows: The current terminal voltage acquired by the real-time terminal voltage acquisition module is compared with the boundary values ​​of each sub-interval generated by the voltage interval division module to determine the current sub-interval to which the current terminal voltage belongs. Based on the number or identifier of the current sub-interval, generate the storage address or index value of the optimal control parameter set corresponding to the sub-interval in the controller storage area; Based on the storage address or index value, the optimal control parameter set corresponding to the sub-interval is read from the controller's storage area; The read optimal control parameter set is written into the control parameter register of the voltage controller, replacing the control parameters used in the previous control cycle, thus completing the online update of the voltage controller parameters; When the current terminal voltage is located in sub-interval i and sub-interval i When the control cycle switches between adjacent sub-intervals near the boundary and multiple consecutive control cycles, linear interpolation is performed on the two adjacent sets of optimal control parameters to generate a transition parameter set and load it onto the voltage controller until the terminal voltage stabilizes within a single sub-interval. Among them, the weight coefficients of the interpolation operation Based on the current terminal voltage With boundary voltage Calculation of relative position:

[0055] In the formula, The voltage span of the sub-interval; sub-interval The weighting coefficients of the parameter set, the weighting coefficients of the parameter set in subinterval i are... ; The formula for calculating the transition parameter set is:

[0056]

[0057]

[0058]

[0059]

[0060] In the formula, Let be the optimal control parameters for interval i; For interval The optimal control parameters; This is the set of transition parameters after interpolation.

[0061] This embodiment achieves real-time adaptive matching between controller parameters and supercapacitor terminal voltage, ensuring that the system maintains optimal control performance at any operating point; This embodiment uses a double-buffer technique for parameter updates, which avoids inconsistencies during the parameter update process and improves system stability. The boundary interpolation smoothing technology in this embodiment effectively solves the system chattering problem caused by parameter abrupt changes at the boundaries of sub-intervals, making the system operate more smoothly throughout the entire voltage range.

[0062] In a specific example, the voltage outer loop control module is specifically configured as follows: A voltage sampling circuit is configured at the output terminal of the DC-DC converter to acquire the actual value of the DC bus voltage in real time. ; Obtain the reference value of DC bus voltage And calculate the deviation signal between the reference value and the actual value. :

[0063] The deviation signal is amplitude-limited to prevent excessive deviation from causing controller saturation. The amplitude-limited deviation signal... satisfy:

[0064] In the formula, This is the upper limit of the deviation. This is the lower limit of the deviation, and ; The limited deviation signal is used as the input of the voltage controller. Based on the control parameters, the optimal control parameter set currently loaded by the module is adaptively called to perform digital compensator calculation and generate a preliminary current inner loop reference command. The initial current inner loop reference command is subjected to amplitude and rate of change limiting to generate the final current inner loop reference command, which is then output to the current inner loop controller.

[0065] The deviation limiting processing in this embodiment effectively prevents the controller integral saturation problem caused by excessive deviation during system startup, shutdown or fault conditions, and shortens the system recovery time. In this embodiment, the current command amplitude limiting protection protects the supercapacitor and power switching transistor, preventing overcurrent damage; In this embodiment, the current command change rate limiting prevents system shock and inductor saturation caused by excessively rapid current changes, thereby improving the operational reliability of the system.

[0066] In a specific example, the current inner loop control and PWM drive module is specifically configured as follows: A current sampling circuit is configured in the inductor branch of the DC-DC converter to collect the actual current value flowing through the inductor in real time. ; Obtain the current inner loop reference command output by the voltage outer loop control module. And calculate the current deviation signal between the reference command and the actual current value. :

[0067] The current deviation signal is used as the input to the current inner loop controller. Based on preset fixed high-speed control parameters, incremental PI digital compensator calculations are performed to generate duty cycle control quantity. The calculation formula is:

[0068] In the formula, This is the proportionality coefficient. The integral coefficient is... This is the inner loop control cycle for the current. This represents the current deviation from the previous cycle; Based on the duty cycle control value and the current operating mode of the DC-DC converter, a corresponding PWM drive pulse signal is generated. The PWM drive pulse signal is output to the drive circuit of the power switch to control the power switch to turn on and off. Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, determine whether the current mode is charging or discharging, and adjust the generation logic of the PWM drive pulse signal or the operating state of the power switch accordingly.

[0069] The current inner loop in this embodiment uses an incremental PI controller, which has the advantages of no integral saturation, low computational load, and ease of implementation, and can achieve fast tracking of current commands. The current inner loop control parameters in this embodiment are fixed and do not need to change with the operating point, which simplifies the design of the control system. The mode determination method based on the current reference command symbol in this embodiment has a fast response speed and can achieve seamless switching between charging and discharging modes.

[0070] In a specific example, the steps of adjusting the generation logic of the PWM drive pulse signal or the operating state of the power switch specifically include: Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, a current mode status flag is generated, which includes a charging mode flag and a discharging mode flag. Based on the current mode status flag, the corresponding PWM generation logic is selected, wherein: When configured with buck PWM logic in charging mode, the relationship between duty cycle D and voltage conversion ratio is as follows: ; When configured as a boost PWM logic in discharge mode, the relationship between the duty cycle D and the voltage conversion ratio is as follows: ; According to the selected PWM generation logic, the duty cycle control quantity is allocated to the corresponding power switch transistor. In charging mode, the conduction time of the buck switch transistor is controlled, and in discharging mode, the conduction time of the boost switch transistor is controlled. A preset dead time is inserted during the state switching process of the power switch. To prevent the upper and lower switches of the same bridge arm from conducting simultaneously, the dead time must satisfy the following:

[0071] In the formula, This is the maximum turn-off delay time of the switching transistor. This is the minimum turn-on delay time for the switching transistor. For safety margin; Based on the selected PWM generation logic, a PWM signal complementary to the main control switch is generated to control the on and off of the opposite switch in the same bridge arm, thereby establishing a synchronous rectification or freewheeling path.

[0072] This embodiment employs corresponding PWM generation logic for both charging and discharging modes, achieving efficient bidirectional energy flow. The reasonable setting of the dead time in this embodiment effectively prevents the power transistor shoot-through short circuit fault and improves the reliability of the system. This embodiment uses synchronous rectification technology, replacing diodes with low on-resistance MOSFETs for freewheeling, which significantly reduces freewheeling losses and improves converter efficiency by 1%-2%.

[0073] Example 2 This embodiment uses a supercapacitor module with a rated voltage of 48V, a DC bus voltage of 400V, and a switching frequency of 100kHz as an example to illustrate the specific implementation of the present invention.

[0074] Voltage range division module: The voltage range segmentation module is used to obtain the rated operating voltage range of the supercapacitor module to be controlled and divide this rated operating voltage range into multiple consecutive sub-ranges. Its specific configuration and implementation process are as follows: First, obtain the highest charging cutoff voltage of the supercapacitor module. and minimum discharge cutoff voltage In this embodiment, the highest charging cutoff voltage of the supercapacitor module is... Minimum discharge cutoff voltage Therefore, the rated operating voltage range is .

[0075] Based on the control accuracy requirements of the DC-DC converter and the controller's storage resources, the preset number of interval divisions, N, is determined. The selection principle for the number of interval divisions, N, is as follows: if high control accuracy is required and controller storage resources are sufficient, a larger N value can be selected, resulting in a narrower voltage range for each sub-interval and a more precise match between controller parameters and operating conditions; if controller storage resources are limited, a smaller N value can be selected to balance control accuracy and storage overhead. In this embodiment, a smaller N value is selected. This means dividing the entire voltage range into 8 sub-intervals.

[0076] Based on the rated operating voltage range Number of interval divisions Calculate the voltage span of each sub-interval according to the principle of uniform division. :

[0077] According to voltage span Calculate the voltage boundary values ​​for each sub-interval, generating 8 consecutive and non-overlapping sub-intervals, as shown in Table 1 below: Table 1: Supercapacitor Voltage Sub-Interval Division Table

[0078] The lower limit of the first sub-interval is the minimum discharge cutoff voltage of 24V, and the upper limit of the last sub-interval is the maximum charging cutoff voltage of 48V. Adjacent sub-intervals are continuous at the boundary, that is, the upper limit of the k-th sub-interval is equal to the lower limit of the (k+1)-th sub-interval.

[0079] At this point, the voltage range division module has completed the division of the rated operating voltage range of the supercapacitor module. The generated sub-range information will be provided to the subsequent control parameter preset module and control parameter adaptive calling module.

[0080] Control parameter preset module The control parameter preset module is used to pre-design a set of optimal control parameters matching each sub-interval based on a small-signal model of the typical operating point of the DC-DC converter within that sub-interval, and stores the optimal control parameter sets corresponding to all sub-intervals into the controller. Its specific configuration and implementation process are as follows: Step 1: Select a typical operating point. Within each sub-interval, select a typical operating point. The typical operating point is usually the midpoint voltage value of the sub-interval, as the midpoint voltage represents the average operating condition of that sub-interval. The typical operating point voltage of the k-th sub-interval... The calculation formula is:

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] 1.

[0105] 2.

[0106] 3.

[0107]

[0108]

[0109]

[0110] Table 2: Optimal Control Parameter Set Storage Table

[0111] This embodiment uses a TMS320F28335 DSP as the controller. These parameters are defined as constant arrays stored in Flash memory, and a mapping relationship is established between sub-interval numbers and parameter storage addresses. During subsequent real-time operation, the control parameter adaptive calling module can quickly look up the corresponding optimal control parameter set based on the sub-interval to which the current terminal voltage belongs.

[0112] Terminal voltage real-time acquisition module The real-time terminal voltage acquisition module is used to acquire the current terminal voltage of the supercapacitor module in real time during converter operation. Its specific configuration and implementation process are as follows: Step 1: Configure the voltage sampling circuit A voltage sampling circuit is configured at the input of the DC-DC converter, which is electrically connected to the positive and negative terminals of the supercapacitor module. Since the voltage range of the supercapacitor is 24V-48V, while the input voltage range of the DSP's ADC module is 0-3.3V, a resistor divider network is used to achieve level conversion.

[0113] Select voltage divider resistors , The partial pressure ratio is:

[0114] When the supercapacitor terminal voltage is at its maximum value of 48V, the voltage after voltage division is: It is less than the maximum input voltage of the ADC, which is 3.3V, leaving a margin of 0.3V, thus meeting the design requirements.

[0115] Step 2: Signal Conditioning. The analog voltage signal acquired by the voltage sampling circuit is filtered and its level adjusted. In this embodiment, a first-order RC low-pass filter is used to suppress high-frequency noise and switching ripple. The filter resistor... Filter capacitor The cutoff frequency is:

[0116] This cutoff frequency is much lower than the switching frequency of 100kHz, which can effectively attenuate the switching frequency and its harmonic components, while not affecting the dynamic response of the fundamental frequency signal.

[0117] Step 3: Modular-to-Digital Conversion According to the preset sampling period (corresponding sampling frequency) (This is twice the voltage outer loop bandwidth of 10kHz, satisfying the Nyquist sampling theorem), triggering the DSP's ADC module to perform digital conversion on the conditioned analog voltage signal.

[0118] In this embodiment, the DSP's ADC module is configured with 16 channels, 12-bit resolution, and a reference voltage. Configure Timer 0 period to 50μs and enable timer interrupt; start ADC conversion in Timer 0 interrupt service routine and select channel 0 as the supercapacitor terminal voltage sampling channel.

[0119] Step 4: Voltage Calculation and Storage After each analog-to-digital conversion, the digital value of the current terminal voltage is read from the ADC result register ADCRESULT0. And according to the preset ratio coefficient Calculate the terminal voltage of an actual supercapacitor :

[0120] Therefore, the formula for calculating the actual terminal voltage is:

[0121] The calculated Store in global variable This is used by the voltage outer loop control module and the control parameter adaptive calling module. It updates the sampling counter to prepare for the next sampling.

[0122] At this point, the real-time terminal voltage acquisition module has completed the periodic acquisition and digital conversion of the current terminal voltage of the supercapacitor module, providing accurate voltage feedback values ​​for subsequent real-time control.

[0123] Control parameter adaptive calling module The adaptive control parameter invocation module is used to retrieve the optimal control parameter set corresponding to the current terminal voltage and its sub-interval from the controller and load it into the voltage controller. Its specific configuration and implementation process are as follows: Step 1: Determine the current terminal voltage acquired by the real-time terminal voltage acquisition module in the current sub-interval. The current sub-interval to which the current voltage belongs is determined by comparing the current voltage with the boundary values ​​of each sub-interval generated by the voltage interval division module. The interval assignment logic is as follows: If V sc If (k)≤27V, then the current subinterval is interval 1; If 27V <V sc If (k)≤30V, then the current subinterval is interval 2; If 30V <V sc If (k)≤33V, then the current subinterval is interval 3; If 33V <V sc If (k)≤36V, then the current subinterval is interval 4; If 36V <V sc If (k)≤39V, then the current subinterval is interval 5; If 39V <V sc If (k)≤42V, then the current subinterval is interval 6; If 42V <V sc If (k)≤45V, then the current subinterval is interval 7; If 45V <Vsc If (k)≤48V, then the current subinterval is interval 8.

[0124] In this embodiment, since the number of intervals is small (N=8), the sequential comparison method is used for interval positioning, which has low computational load and good real-time performance.

[0125] Step 2: Obtain the optimal control parameter set. Based on the current sub-interval number, generate the index value of the optimal control parameter set corresponding to the sub-interval in the controller storage area. In this embodiment, the optimal control parameter set is stored in the structure array params[8]. The parameter set corresponding to the sub-interval number i is params[i-1], which can be accessed directly through the array subscript.

[0126] The optimal set of control parameters corresponding to the sub-interval is read from the controller's Flash memory and temporarily stored in a temporary variable. This read operation is performed once per control cycle to ensure that the voltage controller uses the optimal parameters that match the current terminal voltage.

[0127] Step 3: Online update of controller parameters. The optimal set of control parameters read is written into the control parameter register of the voltage controller, replacing the control parameters used in the previous control cycle, thus completing the online update of the voltage controller parameters.

[0128] In this embodiment, the voltage controller uses a 2p2z digital compensator, and its difference equation is: + ; in, , , , and These are the compensator coefficients, stored in the DSP's memory cells. The parameter update operation writes the newly read coefficients into these memory cells, overwriting the existing coefficient values.

[0129] The parameter update timing is chosen before the voltage control operation begins to ensure that the new parameters are used in the current cycle. To avoid inconsistencies during the parameter update process, a "double buffer" technique is adopted: the new parameters are first written to the shadow register, and the main register pointer is switched all at once after the current control cycle operation is completed.

[0130] Step 4: Boundary Smoothing Processing When the current terminal voltage is near the boundary of a sub-interval and multiple consecutive control cycles (set to 5 control cycles in this embodiment) switch between adjacent sub-intervals, linear interpolation is performed on the two adjacent sets of optimal control parameters to generate a transition parameter set and load it onto the voltage controller until the terminal voltage stabilizes within a single sub-interval.

[0131] Let the current terminal voltage be Located near the boundary between sub-interval i and sub-interval i+1, define the boundary center voltage. (That is, the upper limit of the i-th interval, and also the lower limit of the (i+1)-th interval). The weighting coefficients are calculated based on the relative position of the current terminal voltage and the boundary. :

[0132] in, The voltage span of the sub-interval; Let be the weight coefficients of the parameter set in subinterval i+1, and let be the weight coefficients of the parameter set in subinterval i. .

[0133] Calculate the transition parameter set based on the weighting coefficients:

[0134]

[0135]

[0136] The interpolated set of transition parameters is loaded into the voltage controller to replace the original parameters, achieving a smooth transition of parameters and effectively preventing system chattering caused by sudden parameter changes.

[0137] Voltage outer loop control module The outer voltage loop control module is used by the voltage controller to calculate and output the reference command for the inner current loop based on the deviation between the reference and actual values ​​of the DC bus voltage, using the optimal control parameter set after loading. Its specific configuration and implementation process are as follows: Step 1: Acquire DC bus voltage A voltage sampling circuit is configured at the output of the DC-DC converter to acquire the actual value of the DC bus voltage in real time. The design of the bus voltage sampling circuit is similar to that of the supercapacitor terminal voltage sampling circuit, using a resistor divider network to reduce the 400V DC bus voltage to the ADC input range. In this embodiment, bus voltage sampling and supercapacitor terminal voltage sampling are performed synchronously, with the two ADC conversions completed in the same timer interrupt, ensuring the timing consistency of the control loop.

[0138] Step 2: Calculate voltage deviation Obtain the reference value of DC bus voltage And calculate the deviation signal between the reference value and the actual value. :

[0139] when When the value is greater than 0, it indicates that the bus voltage is lower than the reference value, and the supercapacitor needs to discharge to support the bus voltage; when When the value is less than 0, it indicates that the bus voltage is higher than the reference value, and the supercapacitor needs to be charged to absorb the excess energy.

[0140] Step 3: Deviation Limiting Processing The deviation signal is amplitude-limited to prevent excessive deviation from causing controller saturation. In this embodiment, the upper limit of the deviation is... Lower limit of deviation Deviation signal after limiting satisfy:

[0141] When the actual deviation exceeds ±20V, only ±20V is used in the control operation to prevent the controller from recovering slowly after deep saturation.

[0142] Step 4: The digital compensator calculates the amplitude-limited deviation signal. As input to the voltage controller, the module adaptively calls the currently loaded optimal control parameter set based on the control parameters, performs 2P2Z digital compensator calculations, and generates preliminary current inner loop reference commands. : + ; In each control cycle, the following calculation steps are executed sequentially: Read from the history buffer ; Performing multiplication and addition operations yields ; Update the history buffer: ; .

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] Current inner loop control and PWM drive module The current inner loop control and PWM drive module is used to control the PWM drive signal according to reference instructions through the current inner loop controller, thereby driving the power switching transistors of the DC-DC converter and realizing the charging and discharging management of the supercapacitor module. Its specific configuration and implementation process are as follows: Step 1: Collect inductor current A current sampling circuit is configured in the inductor branch of the DC-DC converter to collect the actual current value flowing through the inductor in real time. This embodiment uses a Hall current sensor from LEM for current sampling, with a range of ±100A and an output voltage range of 0-5V. After being converted to 0-3.3V by a level adjustment circuit, the voltage is sent to the DSP's ADC module for digital conversion.

[0150] Actual inductor current The calculation formula is:

[0151] in, The result of ADC conversion in the current sampling channel; This is the ADC bias value corresponding to zero current (2048 in this embodiment).

[0152] Step 2: Calculate the current deviation and obtain the current inner loop reference command output by the voltage outer loop control module. And calculate the current deviation signal between the reference command and the actual current value. :

[0153] The sign of the current deviation directly reflects the direction of power flow: when When, it indicates that the inductor current needs to be increased (discharge direction); when When this occurs, it indicates that the inductor current needs to be reduced.

[0154] Step 3: The current inner loop PI control uses the current deviation signal as the input to the current inner loop controller. Based on preset fixed high-speed control parameters, it performs incremental PI digital compensator calculations to generate the duty cycle control quantity. The performance requirements of the inner current loop can usually be met by using a PI controller, because it has a high bandwidth and is not sensitive to parameter changes.

[0155] The calculation formula for the incremental PI algorithm is:

[0156] in, This is the proportionality coefficient. The integral coefficient is... This is the inner loop control cycle for the current. This represents the current deviation from the previous cycle.

[0157] The current inner loop control parameters are determined during the system debugging phase based on the inductance value and switching frequency. In this embodiment, the current loop bandwidth is designed to be 20kHz to ensure that the current loop has a sufficiently fast response speed.

[0158] Step 4: Operating Mode Determination. Based on the symbol of the inner current loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, determine whether the current mode is charging or discharging, and generate the current mode status flag.

[0159] The pattern judgment logic is as follows: like This indicates that the supercapacitor needs to discharge to support the bus voltage, and the mode flag is set to discharge mode. like This indicates that the supercapacitor needs to be charged to absorb excess energy, and the mode flag is set to charging mode. like This indicates that there is no power exchange requirement, and the previous cycle mode is maintained.

[0160] Step 5: PWM signal generation and driving Based on the current mode status flag, select the corresponding PWM generation logic: When configured with buck PWM logic in charging mode, the relationship between duty cycle D and voltage conversion ratio is as follows: ; When configured as a boost PWM logic in discharge mode, the relationship between the duty cycle D and the voltage conversion ratio is as follows: .

[0161] This embodiment employs a bidirectional Buck-Boost converter topology, with the power stage consisting of two switches (upper switch Q1 and lower switch Q2) and an inductor L. The PWM logic for different modes is shown in Table 3 below: Table 3: PWM Logic Tables under Different Operating Modes

[0162] Based on the selected PWM generation logic, the duty cycle control quantity d(k) generated by the current control operation unit is allocated to the corresponding power switch transistor: Charging mode: Adjust duty cycle control amount The DSP's ePWM module compare register CMPA controls the on-time of the upper transistor Q1; the on-time of the lower transistor Q2 is automatically calculated by the period register TBPRD and CMPA. ; Discharge mode: control the duty cycle amount The ePWM module compare register CMPA in the DSP controls the on-time of the lower transistor Q2; the on-time of the upper transistor Q1 is automatically calculated by the period register TBPRD and CMPA. .

[0163] During the state switching process of the power switch, a preset dead time is inserted. This prevents the upper and lower switches of the same bridge arm from conducting simultaneously. Dead time is implemented by configuring the DSP's ePWM module dead time control registers DBRED and DBFED, setting the rising edge delay to 200ns and the falling edge delay to 200ns respectively.

[0164] A PWM signal complementary to the main control switch is generated to control the on / off state of the opposite switch in the same bridge arm, achieving synchronous rectification. By using synchronous rectification technology and replacing diodes with MOSFETs with low on-resistance, freewheeling losses can be significantly reduced and converter efficiency improved.

[0165] Finally, the generated PWM drive pulse signal is output to the external drive circuit through the GPIO pin. After being amplified by the isolation drive chip, it drives the gate of the power MOSFET, controls the conduction and turn-off of the switching transistor, and realizes the charging and discharging management of the supercapacitor module.

[0166] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency DC-DC converter system adapted to the linear charging and discharging of supercapacitors, characterized in that, Includes the following modules: The voltage range division module is used to obtain the rated operating voltage range of the supercapacitor module to be controlled, and divide the rated operating voltage range into multiple continuous sub-ranges. The control parameter preset module is used to pre-design a set of optimal control parameters that match the sub-interval based on the small signal model of the typical operating point of the DC-DC converter in the sub-interval for each sub-interval, and store the set of optimal control parameters corresponding to all sub-intervals into the controller. The terminal voltage real-time acquisition module is used to acquire the current terminal voltage of the supercapacitor module in real time during the operation of the converter; The adaptive control parameter calling module is used to call the optimal control parameter set corresponding to the current terminal voltage and its sub-interval from the controller and load it into the voltage controller. The voltage outer loop control module is used to calculate and output the reference command for the current inner loop based on the deviation between the reference value and the actual value of the DC bus voltage, using the voltage controller based on the optimal control parameter set after loading. The current inner loop control and PWM drive module is used to control the PWM drive signal according to the reference instruction through the current inner loop controller, drive the power switching tube of the DC-DC converter, and realize the charging and discharging management of the supercapacitor module.

2. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The voltage range division module is specifically configured as follows: Obtain the highest charging cutoff voltage of the supercapacitor module and minimum discharge cutoff voltage To determine the rated operating voltage range as follows: ; Based on the control accuracy requirements of the DC-DC converter and the controller storage resources, the number of interval divisions N is preset, wherein the number of interval divisions N is an integer greater than one; Based on the rated operating voltage range and the number of intervals N, the voltage span of each sub-interval is calculated according to the principle of uniform division. The calculation formula is: According to the voltage span Calculate the voltage boundary values ​​for each sub-interval, and generate N consecutive and non-overlapping sub-intervals; The lower limit of the first sub-interval is the minimum discharge cutoff voltage. The upper limit of the last sub-interval is the highest charging cutoff voltage. And the upper limit of the k-th subinterval is equal to the upper limit of the k-th subinterval. The lower limit of each sub-interval.

3. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The control parameter preset module is specifically configured as follows: Within each sub-interval, a typical operating point is selected. This typical operating point corresponds to a specific supercapacitor terminal voltage value and the corresponding DC-DC converter operating state within that sub-interval. The typical operating point voltage of the k-th sub-interval is... The midpoint voltage of this sub-interval is calculated using the following formula: In the formula, Let be the lower limit voltage of the k-th sub-interval. Let be the upper limit voltage of the k-th sub-interval; At each of the typical operating points, a small-signal mathematical model of the DC-DC converter is established to obtain the transfer function characteristics of the controlled object at that operating point. Based on the characteristics of the transfer function and combined with the preset dynamic response index, the optimal control parameter set corresponding to each sub-interval is designed so that the DC-DC converter has the desired control performance in the sub-interval. All optimal control parameter sets corresponding to all sub-intervals are stored in the non-volatile storage area of ​​the controller in the form of a lookup table, and a one-to-one correspondence index relationship is established between each set of optimal control parameters and its corresponding sub-interval.

4. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 3, characterized in that, The step of designing the optimal control parameter set corresponding to each of the sub-intervals specifically includes: For the voltage outer loop controller, a preset closed-loop bandwidth target is set. And the phase margin target PM, as the dynamic response index; wherein, the closed-loop bandwidth target With DC-DC converter switching frequency The relationship is: Based on the transfer function characteristics obtained from the small-signal mathematical model, the frequency response curve of the DC-DC converter at the current typical operating point is plotted to determine its original amplitude-frequency characteristics and phase-frequency characteristics. Based on the original amplitude-frequency characteristics and phase-frequency characteristics, combined with the closed-loop bandwidth target... Given the phase margin target PM, the compensator parameters of the voltage outer loop controller are calculated using a frequency domain correction method; wherein, the phase lead that the compensator needs to provide at the desired crossover frequency is... The calculation formula is: In the formula, The phase of the controlled object at the desired crossing frequency; The calculated compensator parameters are substituted into the small-signal mathematical model for closed-loop simulation or stability verification to confirm that the system can operate stably and meet the dynamic response index within the sub-interval. If the index is met, the set of compensator parameters is determined as the optimal control parameter set corresponding to the sub-interval.

5. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The specific configuration of the real-time terminal voltage acquisition module is as follows: A voltage sampling circuit is configured at the input terminal of the DC-DC converter, and the voltage sampling circuit is electrically connected to the positive and negative terminals of the supercapacitor module. The analog voltage signal acquired by the voltage sampling circuit is filtered and its level adjusted so that its amplitude matches the input range of the analog-to-digital conversion module of the controller. According to the preset sampling period The controller's analog-to-digital converter module is triggered to perform digital conversion on the conditioned analog voltage signal, generating a digital value of the current terminal voltage. ; After each analog-to-digital conversion, according to the preset scaling factor... Calculate the terminal voltage of an actual supercapacitor The calculation formula is: The calculated current terminal voltage is stored in a designated storage area of ​​the controller's memory for subsequent use by the control module.

6. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The control parameter adaptive calling module is specifically configured as follows: The current terminal voltage acquired by the real-time terminal voltage acquisition module is compared with the boundary values ​​of each sub-interval generated by the voltage interval division module to determine the current sub-interval to which the current terminal voltage belongs. Based on the number or identifier of the current sub-interval, generate the storage address or index value of the optimal control parameter set corresponding to the sub-interval in the controller storage area; Based on the storage address or index value, the optimal control parameter set corresponding to the sub-interval is read from the controller's storage area; The read optimal control parameter set is written into the control parameter register of the voltage controller, replacing the control parameters used in the previous control cycle, thus completing the online update of the voltage controller parameters; When the current terminal voltage is located in sub-interval i and sub-interval i When the control cycle switches between adjacent sub-intervals near the boundary and multiple consecutive control cycles, linear interpolation is performed on the two adjacent sets of optimal control parameters to generate a transition parameter set and load it onto the voltage controller until the terminal voltage stabilizes within a single sub-interval. Among them, the weight coefficients of the interpolation operation Based on the current terminal voltage With boundary voltage Calculation of relative position: In the formula, The voltage span of the sub-interval; sub-interval The weighting coefficients of the parameter set, the weighting coefficients of the parameter set in subinterval i are... ; The formula for calculating the transition parameter set is: In the formula, Let be the optimal control parameters for interval i; For interval The optimal control parameters; This is the set of transition parameters after interpolation.

7. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The voltage outer loop control module is specifically configured as follows: A voltage sampling circuit is configured at the output terminal of the DC-DC converter to acquire the actual value of the DC bus voltage in real time. ; Obtain the reference value of DC bus voltage And calculate the deviation signal between the reference value and the actual value. : The deviation signal is amplitude-limited to prevent excessive deviation from causing controller saturation. The amplitude-limited deviation signal... satisfy: In the formula, This is the upper limit of the deviation. This is the lower limit of the deviation, and ; The limited deviation signal is used as the input of the voltage controller. Based on the control parameters, the optimal control parameter set currently loaded by the module is adaptively called to perform digital compensator calculation and generate a preliminary current inner loop reference command. The initial current inner loop reference command is subjected to amplitude and rate of change limiting to generate the final current inner loop reference command, which is then output to the current inner loop controller.

8. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 1, characterized in that, The specific configuration of the current inner loop control and PWM drive module is as follows: A current sampling circuit is configured in the inductor branch of the DC-DC converter to collect the actual current value flowing through the inductor in real time. ; Obtain the current inner loop reference command output by the voltage outer loop control module. And calculate the current deviation signal between the reference command and the actual current value. : The current deviation signal is used as the input to the current inner loop controller. Based on preset fixed high-speed control parameters, incremental PI digital compensator calculations are performed to generate duty cycle control quantity. The calculation formula is: In the formula, This is the proportionality coefficient. The integral coefficient is... This is the inner loop control cycle for the current. This represents the current deviation from the previous cycle; Based on the duty cycle control value and the current operating mode of the DC-DC converter, a corresponding PWM drive pulse signal is generated. The PWM drive pulse signal is output to the drive circuit of the power switch to control the power switch to turn on and off. Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, determine whether the current mode is charging or discharging, and adjust the generation logic of the PWM drive pulse signal or the operating state of the power switch accordingly.

9. The high-efficiency DC-DC converter system adapted for linear charging and discharging of supercapacitors according to claim 8, characterized in that, The steps of adjusting the generation logic of the PWM drive pulse signal or the operating state of the power switch specifically include: Based on the sign of the current inner loop reference command or the comparison result between the DC bus voltage and the supercapacitor terminal voltage, a current mode status flag is generated, which includes a charging mode flag and a discharging mode flag. Based on the current mode status flag, the corresponding PWM generation logic is selected, wherein: When configured with buck PWM logic in charging mode, the relationship between duty cycle D and voltage conversion ratio is as follows: ; When configured as a boost PWM logic in discharge mode, the relationship between the duty cycle D and the voltage conversion ratio is as follows: ; According to the selected PWM generation logic, the duty cycle control quantity is allocated to the corresponding power switch transistor. In charging mode, the conduction time of the buck switch transistor is controlled, and in discharging mode, the conduction time of the boost switch transistor is controlled. A preset dead time is inserted during the state switching process of the power switch. To prevent the upper and lower switches of the same bridge arm from conducting simultaneously, the dead time must satisfy the following: In the formula, This is the maximum turn-off delay time of the switching transistor. This is the minimum turn-on delay time for the switching transistor. For safety margin; Based on the selected PWM generation logic, a PWM signal complementary to the main control switch is generated to control the on and off of the opposite switch in the same bridge arm, thereby establishing a synchronous rectification or freewheeling path.

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